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JG14_Josf
01-21-2007, 12:14 PM
I've had a resent correction offered to me concerning the effect of Prop Pitch on deceleration.

Here is the question:

Two identical planes are side by side in level unaccelerated flight at high cruise speed.

One plane pulls the throttle and leaves the CSP Prop Control at max R.P.M. (High Cruise).

The other plane pulls the throttle and resets the CSP Prop Control to minimum R.P.M.

Which plane decelerates faster?

I have an interest in this answer just because I am curious.

My interest includes the application of the accurate answer to the subject of WWII Fighter Combat Tactics and Maneuvering.

The Fw190 and Bf109 airplanes were set-up differently concerning their CPS Prop Control.

When both the Fw190s and the Messerschmitts were operating on automatic CPS Prop Control their engine R.P.M settings were controlled by the throttle lever and various other sensing devices and controls. My curiosity concerns the relative capability of the automatic system to provide the pilot with the ability to decelerate as rapidly as possible.

If, for example, the plane slows down faster with a high R.P.M. setting, then, the German automatic system would not allow that additional decelerating advantage when using the automatic setting.

In the case of the 109 the pilot had the option of switching to manual which de-linked the throttle and the CPS control. That option also de-linked the CSP governor. The manual control fixed the prop pitch angle position until the pilot changed the prop position i.e. removed the constant speed operation from the prop control so the pitch position stopped moving as soon as the pilot switched from automatic to manual. The pilot then had to drive the pitch of the prop with electric switches i.e. a variable speed prop control.

If two identical 109s were flying side by side at high cruise and the two pilots wanted to see which plane over-shot the other plane in a race to slow down, then, one pilot could pull back on the throttle without switching to manual while the other pilot pulls back on the throttle and switches to manual.

The 109 pilot that pulls back on the throttle without switching to manual will reduce fuel/air and reduce the CPS R.P.M setting at the same time with the same lever.

The 109 pilot that pulls back on the throttle without switching to manual will reduce fuel/air and remove the CSP control which would leave the prop at the last pitch setting before the pilot switched to manual control.

That is not the same thing as what happens with a P-47. A P-47, and most of the allied planes, has a throttle lever and a CSP R.P.M control lever.

The same deceleration test between two identical P-47s could have one pilot pulling back the throttle and leaving the R.P.M setting at max R.P.M while the other pilot pulls back on the throttle and the prop lever to reset the R.P.M. from maximum to minimum.

The Fw190 is not the same as either the P-47 or the 109 as far as the documentation I have suggests.

Here:

Characteristics of the BMW 801D2 (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930093290_1993093290.pdf)


The load indication of the constant speed governor of the propeller-pitch control was obtained for each position of the main-servocontrol lever by means of a calibrated position indicator.


Engine speed is maintained constant by means of a fly-ball governor and an incorporated servopiston valve. The loading of the governor is determined by the position of the main-servocontrol lever. For each governor loading, propeller pitch will vary through a range of values; the exact propeller pitch depends on airspeed and air density. The correlation of the propeller-pitch setting with the load indication of the constant-speed governor was not obtained because no actual engine and propeller tests were conducted.


Figure 15 also shows the range through which the constant-speed governor may be loaded by a manually operated lever that overrides the automatic control. (See reference 1, p. 18 for an explanation of the mechanism that over-rides the automatic control.)

The main servocontrol lever, if I am not mistaken, is the lever the pilot moves i.e. Throttle or Throttle/Prop lever.

Here is a possible source of my confusion:


Emergency Control
If failure of the servo-oil system occurs, the automatic engine control can provide limited manual control over the throttle position for emergency operation of the engine at cruising powers. Emergency control over propeller pitch is also provided by an electrical propeller-pitch control, which is manually operated. The electrical propeller-pitch control, however, does not provide automatic regulation of the propeller pitch for constant speed operation of the engine.


Note the difference between this:


Figure 15 also shows the range through which the constant-speed governor may be loaded by a manually operated lever that overrides the automatic control. (See reference 1, p. 18 for an explanation of the mechanism that over-rides the automatic control.)

That is a CSP manual lever that overrides the automatic control.

And this:


Emergency Control
. The electrical propeller-pitch control, however, does not provide automatic regulation of the propeller pitch for constant speed operation of the engine.


That is an emergency adjustable prop pitch control – not constant speed or governed control.

Possible question to ask:

Did the Fw190 have a hydraulic CSP prop pitch drive and an electric drive or only an electrically driven prop pitch changing mechanism? As far as I know the 109s and the P-40s had electric prop pitch changing drives and the P-47 had hydraulic prop pitch drives.

A hydraulic pitch changing drive uses a hydraulic piston and linkage to change prop pitch.
An electric pitch changing drive uses an electric motor instead of a hydraulic piston.

If the Fw190 did have a hydraulic drive to change prop pitch, then, it stands to reason that the loss of hydraulic pressure would be an emergency.

Did the Fw190 have a manual CSP prop control to override the automatic control and an emergency electric adjustable (not CSP) prop control?


In case of failure of the servo-oil system, engine speed can be regulated by an electric propeller-pitch control.


Figure 15 also shows the range through which the constant-speed governor may be loaded by a manually operated lever that overrides the automatic control. (See reference 1, p. 18 for an explanation of the mechanism that over-rides the automatic control.)

Figure 15 shows only "X Minimum reading obtainable by depressing manually operated override lever". The document doesn't include the reference for an explanation of the mechanism that over-rides the automatic control.

Back to the over-shoot race between two identical planes side by side in level flight to see which plane slows down faster as both planes fiddle with the prop pitch control:

My brother has been helping me with this question and he just sent me some news on his experiments with his Beech Bonanza. I've also been invited to go for another experimental flight to confirm the results.

It seems very clear now, according to my brother, that the most efficient method of slowing down quickly involves closing the throttle plate and leaving the R.P.M setting at high R.P.M.

How that works in the game is one thing.

How that works in WWII reality is another thing.

How that works in a Beech Bonanza is something I can see for myself.

The Beech doesn't have a huge prop or 12 or so huge cylinders with large pistons. The forces involved are scaled up. The Beech is a light plane too. At least the Beech has retractable landing gear and it is a low wing – no struts.

If my brother and I were flying side by side in our two identical Beech Bonanza's (I can dream) and one of us cuts the power while the other of us cuts the power and adjusts the prop to a low R.P.M, then, according to the latest test – the one who resets the prop R.P.M. will over-shoot and the one who only pulls the power will be able to slip behind and get a gun solution.

How about WWII planes?

The P-47 pilot, it seems, should simply pull the throttle back and leave the prop lever forward if he wanted to maximize deceleration when forcing an overshoot.

The Fw190 pilot, on the other hand, has no choice when the plane is flown on automatic control. On automatic control the throttle and the Prop control are one and the same lever. Pulling back on the throttle, to maximize deceleration and force an over-shoot, also pulls back the R.P.M. prop control. Unless the pilot has an option to manually override the prop control, then, maximum deceleration is less than maximum compared to a plane having manual control of the CSP governor.

The 109 does not offer manual control of the CSP governor; however – the 109 does offer electric direct control of the prop pitch. The 109 pilot could maximize deceleration by pulling the throttle, switching to manual prop control, and screwing the prop to full flat pitch i.e. further from feather. That is probably too much work and not enough time when trying to force and overshoot.

stathem
01-21-2007, 12:22 PM
What's your point?

JG53_Wotan
01-21-2007, 12:35 PM
What's your point?

Try reading the post. Lines 2 - 6:


Here is the question:

Two identical planes are side by side in level unaccelerated flight at high cruise speed.

One plane pulls the throttle and leaves the CSP Prop Control at max R.P.M. (High Cruise).

The other plane pulls the throttle and resets the CSP Prop Control to minimum R.P.M.

Which plane decelerates faster?

Now what's your point of replying to a thread you can't be bothered to read it.

Hiya Josf...

Wotan

slipBall
01-21-2007, 12:48 PM
Which plane decelerates faster?

This one


One plane pulls the throttle and leaves the CSP Prop Control at max R.P.M. (High Cruise). http://forums.ubi.com/images/smilies/blink.gif

....sorry josf http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif


What have I won http://forums.ubi.com/images/smilies/partyhat.gif

JG14_Josf
01-21-2007, 12:49 PM
Hey back at ya' my most precious wingman buddy.

I'm really getting anxious to get back into simulated combat.

http://mysite.verizon.net/res0l0yx/Art/Pictures/deflection.jpg

I flew your wing on the P-38 kill. You overshot it giving me the angles.

Note the on-topic reference concerning the overshoot.

Herrt and I sandwiched the Mustang flown by Nasty. That one was precious. A half split. No need to cut the throttle. It was sweet.

JG14_Josf
01-21-2007, 12:55 PM
The other plane pulls the throttle and resets the CSP Prop Control to minimum R.P.M.

SlipBall,

Are you sure that you won?

I'm skeptical.

My bother explains it this way:

Leaving the C.S.P. control at higher R.P.M. causes the governor to drive the prop pitch to a higher pitch thereby lessening the lift production of the prop.

Or something like that, so, you can go on knowing your answer to be true while I get a ride in the Bonanza and see this for myself.

The prize is yours to get; I'm not giving out prizes.

I'm the troll remember?

Thanks for the response.

JG14_Josf
01-21-2007, 01:07 PM
SlipBall,

Damn this can be confusing.

Let me try that again:

This was backwards:


Leaving the C.S.P. control at higher R.P.M. causes the governor to drive the prop pitch to a higher pitch thereby lessening the lift production of the prop.

Leaving the C.S.P. control at higher R.P.M. causes the governor to drive the prop pitch to a lower pitch thereby increasing the lift production of the prop.

The governor seeks more R.P.M. and moves the prop to fine pitch.

Fine pitch is a higher angle of attack relative to the Wind which is wind milling the prop and the engine.

What can make it even more confusing on the Beech is the manifold pressure reading.

stathem
01-21-2007, 01:20 PM
Originally posted by JG53_Wotan:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">What's your point?

Try reading the post. Lines 2 - 6:


Here is the question:

Two identical planes are side by side in level unaccelerated flight at high cruise speed.

One plane pulls the throttle and leaves the CSP Prop Control at max R.P.M. (High Cruise).

The other plane pulls the throttle and resets the CSP Prop Control to minimum R.P.M.

Which plane decelerates faster?

Now what's your point of replying to a thread you can't be bothered to read it.

Hiya Josf...

Wotan </div></BLOCKQUOTE>

Pulls the throttle where and how?

Why indicate CSP then go on to talk about Bf-109? What model 109? Why mention 109, 190 and P-47 all together in a post about prop pitch without clarifying the methods of prop pitch control they all use?

Look up 'synopsis'.

Why can't a fish drive a tractor?

msalama
01-21-2007, 01:36 PM
Hmmm...

Put the prop at max. RPM and then find a throttle setting still capable of maintaining that RPM - or maybe a little less - and what you've got then is maximum prop braking per se. But if you cut the throttle any further you're actually reducing the prop RPM too, because the governor can't keep up so you'll end up with _less_ prop braking! But w/ less engine power as well...

So what you should do is probably refer to the manufacturer's notes for the AC in question. And remember to avoid backloading, too, if it's radial engines we're talking about http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

slipBall
01-21-2007, 01:45 PM
I'm the troll remember?


No...you only seek understanding...flight theory will always be discussed, and debated

JG53_Wotan
01-21-2007, 01:49 PM
Pulls the throttle where and how?

Blah, blah, blah...

Josf's question is as clear as an unmuddied lake sir.

As clear as an azure sky of deepest summer.

Try reading it a few more times. http://forums.ubi.com/groupee_common/emoticons/icon_rolleyes.gif

msalama
01-21-2007, 01:57 PM
Well the answer is it depends. http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif But shouldn't we talk about _net_ instead of _prop_ deceleration here?

BM357_Sniper
01-21-2007, 02:34 PM
The short answer is "yes, with props full forward and MP pulled back, it will act as a brake of sorts." I've done it, do it often when decending if I am a little too high and close the the airport. You can feel it as compared to the props still set at cuise rpm's.

You can get more technical though. Depending on the plane type and if they have turbos, you can shock cool them and cause damage by pulling the MP back too far.

WWMaxGunz
01-21-2007, 03:27 PM
You command the prop to keep maximum RPM and don't give it power to do so,
it is going to flatten pitch until forward speed through the air drives the
prop against the engine to be as close to maximum RPM as possible.
The less engine power you have going, the harder the prop must work to make
maximum RPM, the more braking force applied.

109 and 190 automatics ... Kommandogerat controlled more than prop pitch but
what all 109 system controlled and what differences were for -which- 109's
as years went by --- this is a job for Herr Crumpp!

-------------------------------------------------------------------------------

Is there concern that some minute details will not match exactly history?

Be more concerned that in real you cannot just jam a complete backlash against
gearing of high forces without shearing teeth right off the reduction gearing.

I highly suggest that anyone with a dying need to know get into a very expensive
sportscar and try dropping into 1st or 2nd gear then dumping the clutch at say
120+ mph.

JG14_Josf
01-21-2007, 05:32 PM
The short answer is "yes, with props full forward and MP pulled back, it will act as a brake of sorts." I've done it, do it often when decending if I am a little too high and close the the airport. You can feel it as compared to the props still set at cuise rpm's.

BM357_Sniper,

Do you mind offering more information concerning the plane that you can notice the increased deceleration caused by flatter prop pitch angle?

I'm trying to imagine the deceleration that a 109, 190, or P-47 might experience, since, as the information I have so far gathered suggests that the 109 and 190 ˜automated' control will close the throttle and pull the prop setting when moving the throttle lever to a lower setting. The P-47 pilot has two levers so he can pull both back or pull just one back.

I have yet to feel the effect in the Bonanza. My brother's words indicate that the effect is small – hard to notice.

I can get the weight and engine power on the Bonanza. The two blade prop is small but the plane does accelerate swiftly. I can time the take-off run too.

As to radials and shock cooling the Deacon article might be a good read:

Props driving engines (http://www.avweb.com/news/pelican/186778-1.html)

Apparently the oil hole in the main crank journal is set up to oil properly when the engine is turning the prop and not the other way around.

Still...if a P-47 is saddling up and you have one desperate option left such as a forced overshoot, then, which is worse: stressing the crank by restricting the flow of oil or taking many .50 rounds?

I don't think that the P-47 had much to worry about concerning how well it could decelerate compared to the opposition i.e. I don't think it could decelerate well at all.

My opinion is that the best decelerating planes were probably light, big winged, and draggy. The Yak for example was small winged, light, and slippery. It would tend to keep going even though it was light.

I'd like to get a better feel for how much difference the prop pitch control effected deceleration. It seems to be confirmed by more than one source that pulling the prop lever will NOT help make the plane decelerate.

Thanks all for the on-topic responses.

I am definitely learning.
Here is a treat:

http://mysite.verizon.net/res0l0yx/IL2Flugbuch/a8.jpg

Kettenhunde
01-21-2007, 05:35 PM
Kommandogerat controlled more than prop pitch

Yes it did. Here are the areas it controlled:

http://www.onpoi.net/ah/pics/users/503_1169422241_functionsofthekommandog.jpg

Here the RAE copied the chart from the Flugzeug-Handbuch showing the boost and rev check as part of the take off run up:

http://www.onpoi.net/ah/pics/users/503_1169422254_boostandrevcheck.jpg

Let's get a good grasp of how CSP props work. With the exception of some minor details and features, both the allied and axis CSP props worked exactly the same in principle.

In aircraft equipped with CSP's, rpm refers to the propeller and throttle setting is referred to by manifold pressure.

Basic principles of propeller operation:

http://www.onpoi.net/ah/pics/users/503_1169422163_propcharacteristics.jpg

There are different methodologies for exact governor set up but all function on the same principle. As power is applied the governor reduces blade angle if needed to the desired propeller rpm and as velocity increase blade angle increases.

While the both the propeller and engine are independent units the operating limits of both are very closely associated with one another. Overspeed conditions produce large twisting moments on the blades and centrifugal forces which can damage both propeller and engine. More importantly overspeed conditions alter the vibrational characteristics and can cause exciting resonant conditions. Exciting resonant conditions are the most common cause of blade/hub failure especially if they are harmonic. The most common result of shedding a blade in flight is torsional forces rip the engine from the motor mounts. This causes the pilot to have very big weight and balance problem on his hands.

I will use my personal aircraft to explain manual CSP operation:

http://www.onpoi.net/ah/pics/users/503_1169422132_propcontrols.jpg

The yellow is the propeller controls and rpm gauge. The propeller control pulls out to reduce rpm or can be twisted for fine rpm control. The gauge is marked with three tick marks corresponding to Take Off/Maximum climb, Normal Operations/75% cruise, and 65% cruise rpm.

The manifold pressure controls are marked in red. The throttle is pushed in to increase manifold pressure. The manifold pressure gauge is marked with a green arc. This is the operating limit range except for Take Off which can go to 28 in/Hg for take off only.

In a manual CSP/manifold set up you have to keep the manifold pressure in the green arc during normal operations. First you ensure the manifold pressure is in the green arc, then you set the propeller rpm, and finally adjust the manifold pressure to the desired pressure.

If you maneuver then these settings will change. The propeller will try to keep at the desired rpm settings within its limits throughout the maneuver. When it cannot then rpm will change and manifold pressure will too. The idea is to set the propeller and always keep the manifold pressure in the green arc to the rpm stays constant.

I hope that helps.

All the best,

Crumpp

Kettenhunde
01-21-2007, 06:03 PM
The two blade prop is small but the plane does accelerate swiftly.


Aircraft do not like to operate on the backside of the lift curve. They will accelerate very quickly out of the region and begin to slow after exceeding L/Dmax.

All the best,

Crumpp

JG14_Josf
01-21-2007, 06:08 PM
Crumpp,

Nice plane; it has a stick.

On your charts there is a dotted line labeled THRUST AVAILABLE. It has a formula too.

If I read that correctly then thrust is greatest at zero velocity and least at top speed.

Propulsive Power is prop efficiency? What is the significance of 325?

The solid line Windmilling Propeller is not windmilling at the feathered or high pitch setting and therefore not adding to Parasite drag. That would be something possible on a plane with a feathered setting on the prop – no?

If the FW190 and Me109 pulled the power, then, they would also pull the CSP prop to a low R.P.M. which would tend to cause less windmilling since the governor would seek a lower R.P.M and therefore move the Propeller Blade Angle from the flat pitch stop to a higher pitch - no?

Compared to a CSP setting that stays at high R.P.M when the blade angle goes to the flat pitch stop the effect of deceleration is less for the automated control no?

I'm just trying to figure this out since the concept is easily confusing.

I think that the Me-109 didn't have a feathered position for the prop but it did have a manual setting that allowed the pilot to drive an electric motor that moved the Prop angle to the minimum flat blade angle. The pilot could, I suppose, pull back on the throttle and switch to manual if the deceleration effect caused by prop windmilling was a significant enough advantage in deceleration performance. If not, then, the CSP governor would seek the lower R.P.M by changing the prop to a higher pitch and the effect of windmilling deceleration would be less no?

I'm still wondering about the Fw190 manual control. The evidence suggests that the Fw190 had a manual lever to override the CSP control and an Emergency control that completely bypasses any hydraulic and any CSP control.

I'm still wondering about the Fw190 CSP system. Was the prop pitch drive a hydraulic one for the Fw190 or electric or both? I mean; did the Fw190 have a hydraulic piston used to move the blade angle like the P-47 or an electric motor like the 109?

I guess I could be boarding on being obnoxious. I'm just curious.

Kettenhunde
01-21-2007, 06:25 PM
Propulsive Power is prop efficiency?


Yes cross referenced with advanced ratio.

Notice the shape of the advance ration curve.


That would be something possible on a plane with a feathered setting on the prop – no?

Correct. You must be able to feather the propeller.


If the FW190 and Me109 pulled the power, then, they would also pull the CSP prop to a low R.P.M. which would tend to cause less windmilling since the governor would seek a lower R.P.M and therefore move the Propeller Blade Angle from the flat pitch stop to a higher pitch - no?

Both German fighters had automatic features which kept the propeller and engine in the correct operating limits while maneuvering.


I think that the Me-109 didn't have a feathered position for the prop but it did have a manual setting that allowed the pilot to drive an electric motor that moved the Prop angle to the minimum flat blade angle.


Both German fighters could feather the VDM propeller in manual settings.

The VDM propeller on the BMW801 used an electric motor to drive the hydraulic pump which operated the propeller.


I'm still wondering about the Fw190 manual control.

Manual control was for emergency operation and starting when using certain propellers.

All the best,

Crumpp

Kettenhunde
01-21-2007, 06:26 PM
Nice plane; it has a stick.


Thanks. It is blast to fly. I hate yokes, ruins the feel of the aircraft for me.

JG14_Josf
01-21-2007, 06:51 PM
Thanks. It is blast to fly. I hate yokes, ruins the feel of the aircraft for me.

Yea, like driving a damn car.

My time flying was weight shift - no stick, no wheel, proned out like Superman.

I'm still confused about the Fw190 manual control.

One quote on the report linked refers to a lever that over-rode the CSP and the other quote refers to a non CSP manual control that, I guess, drove the electric motor to move the hydraulic fluid used to move the piston moving the prop blades angle.

To us wanna be fighter pilots the controls are important. One must know how best to make his plane decelerate. I'm also curious about accuracy.

If the Fw190 did have a manual CSP control lever, then, the game is accurate and the player could flip to manual control and leave the CSP at high R.P.M. setting when the idea is to slow down really quick, and, be accurate to history – I suppose. The Fw190 over-ride lever remains a mystery as to how it actually controlled the prop.

The game has a simulated manual CSP control like the one in your plane.

I have yet to see the actual results of the CSP declaration test for a Bonanza with the little bitty prop.

I'm being a bother perhaps.

I read one of your posts on CWOS and you wrote that the Fw190D-9 had a more powerful engine and a newer prop to explain why it had better climb performance in reality over the Fw190A-9 (both planes having the same wing design).

I think the person asking the question also said that the Fw190D-9 was heavier.

Anyway; the Prop design is a compromise right; like the prop can be designed for acceleration at the expense of high speed no?

Or

Was the later prop design by FW improved all-round?

I guess the game doesn't have the power right on the 190A-9/D-9 as, I think, the poster said that the game data has the 190A-9 with more power than the 190D-9.

Thrust available, as your chart shows, is another matter. 325 is significant.

Perhaps the recorded climb data does not record WEP climbs when the A-9 would climb steeper and at a higher rate? In the game the WEP climb performance is testable.

Kettenhunde
01-21-2007, 06:59 PM
If the Fw190 did have a manual CSP control lever, then, the game is accurate

The game is not accurate. Manual propeller control was used only if the Kommandogerät failed. This was an inflight emergency.

The settings are called automatic and emergency.

To start the engine with the wide chord wooden propeller you place the setting in emergency and dial the pitch to 12 o'clock on the VDM clock. When the engine starts you place it back in the automatic setting.

All the best,

Crumpp

Kettenhunde
01-21-2007, 07:02 PM
I think, the poster said that the game data has the 190A-9 with more power than the 190D-9.


It depends on the altitude which engine had more power. However thrust is not Pa, thrust is thrust. The FW-190D9 had more thrust in general.

Yes props are tuned for a specific portion of the flight envelope.

All the best,

Crumpp

Kettenhunde
01-21-2007, 07:09 PM
In the game the WEP climb performance is testable.


Most real aircraft cannot climb at WEP or Take Off power unless you want to start watching your compression drop. It damages the motor. Some airplanes are limited in their Vx climb at climb settings due to cooling.

That is something I am pretty sure most games do not simulate. Airplane engines are judged by their compression checks. You can have a high time motor but if it has been taken care of and has good compression then it is considered a good motor.

You can have the reverse as well. A low time motor that has been abused will have lower compressions. Low compression means the motor is not developing the power it should.

BfHeFwMe
01-21-2007, 09:41 PM
There really is no point in a highly detailed discussion over propeller operations. Your missing two most important details, over speeds and negative torque. Until they are modeled it's all mute.

Just because a prop is electric, doesn't mean it isn't hydro also.

Several fighters had latches to pin pitch and throttle together for combat ops.

CSP principles work basically pretty good in game. Pilot only gets a vote, the airspeed, throttle setting, RPM's, and altitude determine if the desired results are achievable. It's the manual that's broken, there are no consequences for abuse, you can slam any setting in at any time, not the case especially for 109's where you take direct control over blade angles.

Again, a useless discussion with those two aspects missing.

Knowing that, and abusing the game, you don't simply pull back prop to decelerate. You pull back both, wait till you drop to minimal engine RPM, than slam pitch lever full up. Now your decelerating 46 UFO style Baby!

Not even worth a discussion, wait for BoB.

FritzGryphon
01-21-2007, 11:04 PM
To the original question, I did a test to see what the relative deceleration was between 100% desired RPM and 0% desired RPM.

-----

P-47D, level deceleration from 700km/h TAS to 300km/h TAS. Sea level, 100% fuel, engine idle.

100% pitch: 43 seconds
0% pitch: 78 seconds

Overall, high desired RPM caused almost double the rate of deceleration. 0% desired RPM is similar to feathering.

------

I tested the glide ratios for both settings.

Same conditions, glide from 1000m. 250km/h IAS glide speed used.

100% pitch: 7:1
0% pitch: 12:1

Again, 0% pitch resulted in much less drag, and significantly improved glide. Very useful information!

msalama
01-21-2007, 11:08 PM
there are no consequences for abuse, you can slam any setting in at any time

Yup, has irked me too. No penalties for mismanaging your RPM vs. MP, no real overheating issues i.e. you can buzz around w/ your throttle @ 100% all day, etc. But then again it's a game isn't it?

But at least the prop braking effect in itself is modelled http://forums.ubi.com/images/smilies/metal.gif

WWMaxGunz
01-21-2007, 11:18 PM
Originally posted by BfHeFwMe:
Not even worth a discussion, wait for BoB.

Even when someone has lost a fight online where the other might have done something he shouldn't
be able to or the loser couldn't do what he thinks he should?

Surely you jest! Not only discussion but an open door to any amount of hyperbole.

msalama
01-21-2007, 11:21 PM
Overall, high desired RPM caused almost double the rate of deceleration. 0% desired RPM is similar to feathering.

Broadly speaking works as expected, then. Would have probably done a world of horrors to that R-2800 IRL however, had you cut the throttle @ 700KMPHTAS w/ max. RPM http://forums.ubi.com/images/smilies/88.gif Which, mind you, doesn't have anything to do w/ the engine being _not_ sturdy - it was - it's just that you starve the bugger of mainshaft bearing lubrication if you let the prop drive the engine at that speed...

But then again war's war, not vintage prop plane enthusiasm http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif

NonWonderDog
01-21-2007, 11:22 PM
It's easiest to understand prop braking from a work and power perspective, rather than force and accelerations (both are always equivalent if you do the math right).

If you set a high RPM with the prop control, the governor will attempt to keep that RPM. Whatever RPM you select has a specific amount of power needed to maintain it, as friction and drag apply work trying to slow the prop down. The higher the RPM, the more power is needed to maintain that RPM. At high throttle setting, this power comes from the engine. If you chop the throttle, however, the power required to maintain RPM counts as drag power, varying with velocity cubed. High RPM settings can slow the
plane drastically more than low RPM settings.

Of course, it's rather complicated if you wanted to actually do the sums. It's completely non-linear, as propeller drag is both a cause of and the result of the prop speed, and I really wouldn't know where to start. The basic premise holds, however, that high RPM settings slow you down more than low RPM settings will at low throttle.


The Kommandogerät's pitch control is a oil CSP governor at heart, too; the automatic bit just sets the oil pressure of the governor. The FW-190's system evidently provided a lever to override the governor setting, as represented in game. There was a (probably very slow) electric motor that could change pitch directly if the governor failed, but that's not in game. It seems that a majority of warbirds had such a control, and none of them have it represented in game.

I read something, somewhere, long ago, mentioning an automatic "landing mode" of the Kommandogerät that sets highish RPM at low throttle, but I have no idea if that existed. I've also read that some Me-109 pilots preferred to land in emergency pitch mode (I certainly do in the game, but I'm an anal retentive bastidge as I'm sure I've said before), but I don't know if that's true either.

msalama
01-21-2007, 11:29 PM
But FWIW prop braking actually works pretty well as it is modelled in the game. I always use it when landing because it indeed _does_ slow you down pretty effectively...

BfHeFwMe
01-21-2007, 11:49 PM
Originally posted by WWMaxGunz:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by BfHeFwMe:
Not even worth a discussion, wait for BoB.

Even when someone has lost a fight online where the other might have done something he shouldn't
be able to or the loser couldn't do what he thinks he should?

Surely you jest! Not only discussion but an open door to any amount of hyperbole. </div></BLOCKQUOTE>

Same old troll bait, you really ought to try a proactive argument, instead of the lamer one, at least once, if you got what it takes. http://forums.ubi.com/images/smilies/88.gif

Surely you jest, the games been this way from day one, you just noticed now. LOL http://forums.ubi.com/images/smilies/34.gif

You've run out of time to fix it sport, where ya been? http://forums.ubi.com/images/smilies/clap.gif

Ratsack
01-22-2007, 12:31 AM
The question has a false premise. Neither the Bf109 nor the Fw190 had constant speed props (CSPs). Both were variable pitch. There is a significant difference.

With a CSP, if you set the RPM, the governor will attempt to maintain that RPM regardless of whatever else you do. The direct control is over prop revs, not the pitch of the prop blades.

With the variable pitch prop, the pilot is controlling the angle of the blades directly. This means that, for a given set of engine settings, given speed, and a given altitude, a particular setting for prop pitch will produce a particular power output and revs. However, if you change one of those flight parameters (e.g., you accelerate), then the same propeller pitch setting will produce different revs and power.

This effect is modelled on the Bf109s in game. If you go to manual pitch and set it so everything is working fine, and then go into a dive, you will discover a whole world of hurt.

In the game, the Fw190A appears to have a strange CSP when in manual. In reality, the Fw190 did not have a CSP but, as Crump has already said, the Kommandosgerat controlled a whole lot of engine parameters automatically, including prop pitch.

cheers,
Ratsack

PS - the way to answer the question, if you actuall want an answer, is to do the tests. Empirical evidence.

Kettenhunde
01-22-2007, 01:31 AM
The question has a false premise.


All CSP's are variable pitch. As we just spent over 50,000 USD a propeller to rebuild our VDM I certainly hope I know if it is a CSP or not!

You are confusing manual operation with automatic. In automatic the VDM is a CSP propeller which adjust's blade angle to maintain rpm like any other CSP.

In manual mode it is a broken CSP in which the pilot has to adjust pitch to maintain rpm. In manual mode the pitch is adjusted by the pilot to reach or maintain the dialed rpm. Manual mode is used in an emergency.

All the best,

Crumpp

major_setback
01-22-2007, 05:00 AM
Why can't a fish drive a tractor?

I give up. Why can't a fish drive a tractor?

msalama
01-22-2007, 05:58 AM
All CSP's are variable pitch.

Yep, because the RPM constant is adjusted by - you guessed it, folks - varying the blade pitch! Why that works is however left as an excercise to the reader http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

WWMaxGunz
01-22-2007, 07:41 AM
Originally posted by BfHeFwMe:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by WWMaxGunz:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by BfHeFwMe:
Not even worth a discussion, wait for BoB.

Even when someone has lost a fight online where the other might have done something he shouldn't
be able to or the loser couldn't do what he thinks he should?

Surely you jest! Not only discussion but an open door to any amount of hyperbole. </div></BLOCKQUOTE>

Same old troll bait, you really ought to try a proactive argument, instead of the lamer one, at least once, if you got what it takes. http://forums.ubi.com/images/smilies/88.gif

Surely you jest, the games been this way from day one, you just noticed now. LOL http://forums.ubi.com/images/smilies/34.gif

You've run out of time to fix it sport, where ya been? http://forums.ubi.com/images/smilies/clap.gif </div></BLOCKQUOTE>

I'm just stating from what I've seen since before day 1 of this sim or the last 3 before it.
Same thing that others before me saw enough of to coin terms like 'dweeb' for the ones that
grab any excuses possible and load up the chat with them rather than change what they do.

Proactive? Yeah, it's called giving good advice. Easy to tell the ones that try things out
from the ones that trot out the same excuses while the far edge that invent new ones.
Just wait.

Why in H did you have to post the subject isn't worth discussing?
I was agreeing with you and made a joke, and look what you come back with!
I don't even know your real take on this so I won't say I know what you mean,
I just thought that I did but not anymore!

This isn't something yet within scope of the software we have and should not be turned into
what it most probably will be. Cutting power and either dropping a bit of flap or using
the airbrakes (sometimes the same thing) was used to effect sometimes IRL, we all know.
But NOW we stand to see 20+ pages over does plane X get the proper benefit, is plane Y
undermodelled in this respect, oh my plane is porked and the rest of it on no real basis
beyond non-quantified supposition.

stathem
01-22-2007, 08:17 AM
Originally posted by major_setback:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> Why can't a fish drive a tractor?

I give up. Why can't a fish drive a tractor? </div></BLOCKQUOTE>

One of its legs is both the same.

naturally. http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif

msalama
01-22-2007, 08:33 AM
I give up. Why can't a fish drive a tractor?

Easy. Tractors don't work underwater.

JG14_Josf
01-22-2007, 09:33 AM
Thanks for the help in discussing this topic.

Interested individuals,

A contention remains:

NonWonderDog states:


The Kommandogerät's pitch control is a oil CSP governor at heart, too; the automatic bit just sets the oil pressure of the governor. The FW-190's system evidently provided a lever to override the governor setting, as represented in game. There was a (probably very slow) electric motor that could change pitch directly if the governor failed, but that's not in game. It seems that a majority of warbirds had such a control, and none of them have it represented in game.

I read something, somewhere, long ago, mentioning an automatic "landing mode" of the Kommandogerät that sets highish RPM at low throttle, but I have no idea if that existed. I've also read that some Me-109 pilots preferred to land in emergency pitch mode (I certainly do in the game, but I'm an anal retentive bastidge as I'm sure I've said before), but I don't know if that's true either.

Kettenhunde states:


The game is not accurate. Manual propeller control was used only if the Kommandogerät failed. This was an inflight emergency.

The settings are called automatic and emergency.

To start the engine with the wide chord wooden propeller you place the setting in emergency and dial the pitch to 12 o'clock on the VDM clock. When the engine starts you place it back in the automatic setting.

And this from Kettenhunde:


Both German fighters could feather the VDM propeller in manual settings.

A. The game is not accurate
B. The game is accurate

The contention remains.

Why is this important to me?

A. I am curious enough about history to want to know the truth
B. I am curious enough about the game to want to know the truth

Discussions help discover the truth about history and the game:

Example:

FritzGryphon reports:


P-47D, level deceleration from 700km/h TAS to 300km/h TAS. Sea level, 100% fuel, engine idle.

100% pitch: 43 seconds
0% pitch: 78 seconds

Overall, high desired RPM caused almost double the rate of deceleration. 0% desired RPM is similar to feathering.

------

I tested the glide ratios for both settings.

Same conditions, glide from 1000m. 250km/h IAS glide speed used.

100% pitch: 7:1
0% pitch: 12:1

Again, 0% pitch resulted in much less drag, and significantly improved glide. Very useful information!

I agree; VERY USEFUL INFORMATION!

Back to the Fw190 contention:

A. The actual, real, Fw190 did not have a separate control for R.P.M. like the game allows with MANUAL PROP PITCH.
B. The actual, real, Fw190 did have MANUAL PROP PITCH control.

I think that Kettenhunde aught to know the true answer since he has access to a real Fw190.

Look at the game feature:

100% pitch: 43 seconds
0% pitch: 78 seconds

That can be the difference between shooting someone down and getting shot down in a desperate scissors fight in the game. That knowledge offered by FritzGryphon confirms the need to leave the Prop Lever at high R.P.M. when rapid deceleration is desired.

The game offers that option to the Fw190 players. Is that accurate?

The game does allow the Fw190 players to switch to manual prop pitch and then keep the high R.P.M setting while chopping the throttle to force an overshoot.

Without that option to switch to manual the Fw190 automatic control lowers R.P.M. CSP settings as the throttle lever is chopped back.

This:

100% pitch: 43 seconds

Cannot happen on Automatic mode in the real Fw190.

On automatic there is only this:

0% pitch: 78 seconds

That would have to be confirmed with game testing. The physical fact, in reality, as far as the evidence shows so far, is that the Fw190 automatic control does lower R.P.M. settings as the throttle lever is lowered. The unknown fact is if the game models the corresponding increase in time elapsed during deceleration (decreased drag).

The 109 should be able to chop the throttle and switch to manual pitch at 0% pitch in the game to maximize deceleration. That too can be tested.

The glide ratio information is also important info for the serious gamer and even, perhaps, for the not so well informed recreational pilots flying real planes.


I tested the glide ratios for both settings.

Same conditions, glide from 1000m. 250km/h IAS glide speed used.

100% pitch: 7:1
0% pitch: 12:1

At times a pilot will be out of engine power and in need of knowing if the altitude and distance to the airport is sufficient to land at the airport. If not, then, the pilot must land somewhere other than the airport.
If the pilot does not know how to maximize L/D, then, the goal of landing at the airport may be impossible because of the pilot's ignorance.

The most obvious means of minimizing the drag that lowers L/D, as far as the prop is concerned, is to set the prop to feather. A feathered prop will stop turning. A feathered prop will not windmill. A feather prop will decrease prop drag to a minimum.

Kettenhunde states:


Both German fighters could feather the VDM propeller in manual settings.

Feathering a prop on a twin engine is a must. On a single engine it must be good for increasing L/D.

Here, if you are interested, is a very good method to use when trying to figure out if you can glide to your airport (with no engine power):

Estimate best glide speed and hold that speed.

Place the gun sight cross hairs on the airport.

If the airport goes up in the gun sight (higher and higher up the wind screen), then, the glide slope is too steep. You won't make it to the airport at that glide angle.

If the airport goes down in the gun sight (disappears under the nose), then, the glide slope is sufficient and you can make it to the airport.

If the airport goes up in the gun sight and you know that you can't make it to the airport at that glide slope, then, you can try picking up the nose (slowing down the glide speed).

If the plane stalls, then, you can't make it to the airport.

When flying at best glide speed and best glide angle it is possible to slow down the plane and still fly (not stall) but the target in the gun sight will move up the gun sight. You are then flying closer to best sink rate.

Best sink rate is the speed just before stalling. The slowest speed possible with wings level and this speed will maximize time of flight but this speed will not maximize distance to goal (it won't get you very far along the ground).

Best glide is the speed that allows the pilot to fix the farthest ground object in the gun sight and keep that object in the gun sight.

Pick an object. Fly to the object. If the plane accelerated, then, pick another object further away. Fly to the new object on the ground fixed in the gun sight. If the plane accelerates, then, pick another object further away. If the plane stops accelerating and the ground object remains in the gun-sight, then, you are at best glide speed. Now feather the prop.

I'd really be surprised if any twin engine plane did not have a prop feather setting in reality.

Check the P-38, for example. If both engines are at idle and one engine is at 100% prop pitch and the other engine is at 0% prop pitch, then, what happens to that plane's acceleration on the Yaw axis?

100% pitch: 43 seconds
0% pitch: 78 seconds

100% pitch: 7:1
0% pitch: 12:1

The rumor mill suggested that a P-38 could be turned tighter with separate throttle control. Bong and McGuire perhaps?

Anyway the topic remains unresolved as to the actual Fw190 controls and the game's simulation of those controls.

A. The game does not model feather
B. The game models manual CSP operation
C. The game does not model direct prop pitch control

It is good news to hear that the game models Prop Pitch Deceleration effect.

Thanks

BfHeFwMe
01-22-2007, 09:48 AM
Huh?

Max, do you even have 46? Anyone feels a need for slowing down using prop or any means for anything besides landing, be my guest! Gotcha covered. http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

Humor? Remember your little exhibit at the end of the Fw thread? I think I've showed far more restraint and patients with you than you did with the poster there. Funny how you piled on only after 'others' corrected his views.

Get over yourself Max, you ain't that great. What else besides name calling are you capable of on a board? "dweeb" http://forums.ubi.com/groupee_common/emoticons/icon_cool.gif

JG14_Josf
01-22-2007, 10:08 AM
Funny how you piled on only after 'others' corrected his views.

BfHeFwMe,

If you are referring to my views, then, there are corrections that remain uncorrected.

Va, for example, changes with weight. Does the speed at which Va occurs change?

My view: No or not much.

Correct my view please; anyone.

It would be nice to get accurate answers.

Like:

Does the game accurately model the Fw190 prop pitch control?

So far the evidence suggests that it does not and this may be an advantage given to the Fw190 that was not available in reality i.e. the ability to slow down as rapidly as possible by driving the prop blades to a flatter pitch during maximum deceleration maneuvering.

Eventually the simulation of WWII Fighter Combat will become more accurate. This is hardly an argument. The movement toward accuracy is obvious. Chuck Yeager's Air Combat was once a very accurate game – once upon a time.

To those who want a more accurate game are my posts directed. To those who just want to argue - my posts endeavor to avoid.

I'm very eager to have my viewpoints corrected.

Does weight change the velocity for Va?

Does the game accurately model the Fw190 manual prop pitch feature?

Does the game model accurate speeds for Va?

Please do correct my viewpoint. Please. I am asking for it – on purpose.

p-11.cAce
01-22-2007, 10:19 AM
My understanding of the prop pitch model in game is that it behaves like a modern constant speed prop and not as a truly pitch adjustable system. The only rl plane I've flown with a constant speed prop is the rotax powered katana and it is worlds away from anything like a WWII fighter (not to mention it sounds like a cheap lawn mower). Here is the best I have on weight and Va changes:

If you are flying in moderate or severe turbulence, you should keep your airspeed below the maneuvering speed, VA. By the same token, you should avoid large, sudden deflections of the controls unless your airspeed is below VA. The idea behind VA is that you want the wing to stall before anything breaks. You may think that a stall is bad, but remember that you can recover from a stall much more easily than you can recover from a broken airplane.
Maneuvering speed means the wing is supposed to stall
before it produces enough Gs to break any part of the airplane.

We say it is supposed to stall, not guaranteed to stall, because the formal definition of VA takes into account only certain types of rough control usage, and only certain types of turbulence (namely purely vertical updrafts and downdrafts). In real life, other possibilities must be considered. For instance, if you start out at VA and encounter a large horizontal wind shear, arbitrarily large forces can be developed. For this and several other reasons, the exact value of VA should not be taken too literally.

Still, the general idea of VA makes sense: If you observe or anticipate a situation that imposes large G loads on the airplane, you should slow down and/or confine yourself to gentler maneuvers.

Unlike VNO, the maneuvering speed varies in proportion to the square root of the mass of the airplane. The reason for this is a bit tricky. The trick is that VA is not a force limit but rather an acceleration limit. When the manufacturers determine a value for VA, they are not worried about breaking the wing, but are worried about breaking other important parts of the airplane, such as the engine mounts. These items don't directly care how much force the wing is producing; they just care about the acceleration they are undergoing.

By increasing the mass of the airplane, you decrease the overall acceleration that results from any overall force. (Of course, if you increase the mass of cargo, it increases the stress on the cargo-compartment floor --- but it decreases the stress on unrelated components such as engine mounts, because the acceleration is less.)

This means you should put VA along with VS and VY etc. on your list of critical airspeeds that vary in proportion to the square root of the mass of the airplane. However, VA depends on real mass not on weight, so unlike the others it does not increase with load factor.
how it flies (http://www.av8n.com/how/htm/aoa.html#@default116)

JG14_Josf
01-22-2007, 01:07 PM
By increasing the mass of the airplane, you decrease the overall acceleration that results from any overall force.

p-11.cAce,

That is a curious word choice written on the subject of Va.

The angle of view that returns to my current perspective on Va is:

1. The wing design can generate a maximum force measurable as weight at a given airspeed.

Example:

Wing A can generate 60,000 kg of force at 400 km/h.

2. The wing design will permanently deform under a known load measurable as weight.

Example:

Wing A will deform when loaded to 60,001 kg.

Va for Wing A is 400 km/h

3. Va is calculated for a given aircraft weight.

Example:

Wing A has a Va of 400 km/h when the aircraft is loaded up to 10,000 kg aircraft weight.

4. If weight is changed, then, Va does not change.

Example:

The aircraft weight is changed from 10,000 kg to 20,000 kg. The stall speed goes up in proportion to the increase in force, measured in weight, applied to the wing structure at the higher weight.

As a math problem:

Wing A
Aircraft at 10,000 kg weight
The wing produces 60,000 kg lift force at 400 km/h at Max AOA
The g load at 400 km/h is 6 g at that aircraft weight
10,000 kg times 6 equal 60,000 kg
Va is 400 km/h since 60,001 kg will permanently deform wing A

Wing A (deforms at 60,001 kg force)
Aircraft at 20,000 kg weight
The wing produces 60,000 kg lift force at 400 km/h at Max AOA
The g load at 400 km/h is 3 g at that aircraft weight
20,000 kg times 3 equal 60,000 kg
Va is 400 km/h since 60,001 kg will permanently deform wing A


By increasing the mass of the airplane, you decrease the overall acceleration that results from any overall force.

Same force (60,000 kg wing lift force at max AOA) lower acceleration (from 6 g to 3 g) as mass increases (from 10,000 kg to 20,000 kg).

Have I been corrected by others or is there further need for correction by others?

I'd like to know.

I'd also like to know if the Fw190 did, in fact, not have a manual CSP R.P.M control.

I'd also like to know if the Fw190 did, in fact, adjust R.P.M. settings, on automatic, with the throttle lever i.e. full throttle equals full R.P.M. and minimum throttle equals minimum R.P.M. The same applies to the 109 i.e. CSP R.P.M. control linked to the Throttle lever in Automatic mode.

My opinion is that Kettenhunde is correct and the game is incorrect. There was no manual pitch like the game simulates for the Fw190 – therefore all simulated performance capabilities should match up with the automatic pitch settings including top speed, climb, turn, and deceleration performance. Meaning: the Fw190 should be poor in deceleration performance concerning prop pitch deceleration effect on automatic prop pitch control.

I have no delusion concerning IL2 being made more accurate in these matters. I don't even think that BOB will be any different. I just want to know what is accurate and what is not accurate. I want to know if the game I play is accurate. That way I˜ll know what is an accurate game and what is not as accurate a game.

Discussion of these things can help uncover the truth. Arguing can generate arguments.

Finding quotes that seem to make sense helps like this:


By increasing the mass of the airplane, you decrease the overall acceleration that results from any overall force.

That is a curious choice of words.

Like this:


Most real aircraft cannot climb at WEP or Take Off power unless you want to start watching your compression drop. It damages the motor. Some airplanes are limited in their Vx climb at climb settings due to cooling.

Take-off is a climb. The time spent at WEP as well as the time spent with the manifold pressure low and the R.P.M. high determines how much damage is done no?

It would be nice to know why the same wing design for the A model Fws appear to be quite different in performance compared to the D model Focke-Wulfs.

It would also be nice to know why the same wing design for the A model loaded light (190A-4) is quite different in performance compared to the A model loaded heavy (190A-8 or 190A-9); even though power to weight increases with the later model Fws.

It would be nice to know if those differences in performance for the same wing design are accurate differences in performance.

I'm patient as it seems to me that the answers will be discovered eventually.

There are enough interested people who desire accuracy to drive the simulation industry toward ever greater perfection. I see no reason to argue that fact.

p-11.cAce
01-22-2007, 01:35 PM
By increasing the mass of the airplane, you decrease the overall acceleration that results from any overall force.
I'll start here - think about it like this: apply 10 pounds of force to a tricycle and 10 pounds of force to a car - which accelerates faster? More mass = lower acceleration from any overall force.

Wing A
Aircraft at 10,000 kg weight
The wing produces 60,000 kg lift force at 400 km/h at Max AOA
The g load at 400 km/h is 6 g at that aircraft weight
10,000 kg times 6 equal 60,000 kg
Va is 400 km/h since 60,001 kg will permanently deform wing A
If you are at Va and max AoA the wing <span class="ev_code_RED">stalls</span> at 60,001 kg, if you are ABOVE Va it deforms (or as more often happens it breaks).

T_O_A_D
01-22-2007, 02:13 PM
I haven't done it in a long time, but a patch long ago, I was playing with the 47 in a dive.

I coaxed one of my buddies to fly beside me in the same version of 47. From 10,000 we went straight down in a dive.
I never mentioned to him to turn his prop pitch to zero. His plane exploded, and mine kept right on diving and gaining speed, and held together, and I was able to pull out of it and fly on.

He was like WTH why didn't yours explode bla bla bla.

I finally let him in on what was going on.

I interpeted the 0% pitch forced the eng to a loer RPM thus removing the vibration forces of the over reaved eng and prop he had going on due to 100% pitch.

Never agreed with the scale in game though.
In boat props the higher the number of Pitch% the slower the Top RPM limit is, and vice versa. Why would it be differnt on an aircraft, or is it just the games interpetation of reality just backwards.

Sergio_101
01-22-2007, 04:00 PM
Originally posted by T_O_A_D:
I haven't done it in a long time, but a patch long ago, I was playing with the 47 in a dive.

I coaxed one of my buddies to fly beside me in the same version of 47. From 10,000 we went straight down in a dive.
I never mentioned to him to turn his prop pitch to zero. His plane exploded, and mine kept right on diving and gaining speed, and held together, and I was able to pull out of it and fly on.

He was like WTH why didn't yours explode bla bla bla.

I finally let him in on what was going on.

I interpeted the 0% pitch forced the eng to a loer RPM thus removing the vibration forces of the over reaved eng and prop he had going on due to 100% pitch.

Never agreed with the scale in game though.
In boat props the higher the number of Pitch% the slower the Top RPM limit is, and vice versa. Why would it be differnt on an aircraft, or is it just the games interpetation of reality just backwards.


Airscrews/props work in a similar manner.
most boat props are not variable pitch, but not all.

Same rules. Same results.

The game has the lower number for pitch representing lower rpm.
This means more "feathered."

Fine pitch it represented by a higher number.

Seems ok to me. It works.

Sergio

Kettenhunde
01-22-2007, 04:13 PM
Let's be clear.

Both German fighters flew normally with the VDM propeller and Laderuckregular set to automatic. Flying the propeller on manual setting is for emergency use.

What is unrealistic is fact it seems to be a "performance" boost in IL2 operating on manual. Facts are the laderuckregular does a much better job of keeping the propeller operating at optimum efficiency than the pilot could on manual.

A variable pitch propeller was used by the early Bf-109's, Spitfires, and Hurricanes. Quite a few very early war fighters used them. Variable pitch props do act like "changing" gears in a car. Most variable pitch propellers have two settings, a course pitch and a fine pitch setting.

The VDM is a CSP propeller that in an emergency can be manually controlled.

All the best,

Crumpp

JG14_Josf
01-22-2007, 05:04 PM
T_O_A_D,

Thanks. I wonder if that effect is still modeled in the game.

I'm sure that my brother will not try to windmill his prop at high speed. His tests are done in a normal descent and I have yet to ride shotgun to experience it first hand.

If the flyweight governor on the CSP prop is set to an R.P.M. setting (pressure on the flyweight spring), then, that setting causes the governor to change the prop angle (pitch) when the engine is not at that specific R.P.M. If the engine isn't turning at that R.P.M., then, the governor turns the prop angle (pitch) until the engine is turning at that R.P.M. If the R.P.M is lower than the set R.P.M., then, the prop angle (pitch) is turned to a lower pitch (flat). If the R.P.M. is higher, then, the governor turns the prop angle to a higher pitch (course). Under normal operation when the engine is driving the prop (not windmilling) the idea is to load the engine with more work (lift production) when the R.P.M. tries to go past the set R.P.M., and, when the engine R.P.M., slows down (for any reason) the governor tries to unload the engine work load by moving the prop pitch to a flatter or finer pitch.

So...if the pilot dives from a hammerhead at slow speed with the engine at idle (actually at low manifold pressure or at minimal air/fuel) and the governor R.P.M. is set to 2700 R.P.M and the prop is only turning 800 R.P.M., then, the governor will change the prop angle to a lower pitch (trying to unload the engine work load) and the governor will keep changing the prop pitch angle to a lower pitch until the engine turns to 2700 R.P.M. or until the prop blades hit the flat pitch stop, where, the prop blades cannot go any flatter or finer in pitch.

Then the plane accelerates straight down and the prop blades start turning the engine against the resistance of having to turn those pistons like a vacuum pump. If the air speed is sufficient to turn the engine to 2700 R.P.M., then, the governor will keep the prop blade angle at the fine pitch stop; flat against the wind and generating enough prop blade lift to windmill the engine at 2700 R.P.M. If the plane continues to accelerate and if the R.P.M. continues to increase past 2700 R.P.M., then, the governor moves the prop blade angle from the flat pitch stop toward a higher pitch in the effort to load up the engine and slow it down. What actually happens, it seems, is that the higher pitch lowers the AOA for lift production. If windmilling continues in the dive past 2700 R.P.M, then, the plane goes fast enough to move the prop blade angle to the high pitch stop and then the R.P.M can increase past 2700 R.P.M and there is no more governed control of R.P.M. The R.P.M. can increase past 2700 R.P.M as dive speed increases and as windmilling increases.

I think that setting the R.P.M to a lower R.P.M will simply change the speed at which the governor moves the prop from the flat pitch stop to the course pitch stop in a power off dive. Even in a power on dive the governor would move the blade angle quickly toward the full course stop as soon as the windmilling effect caused the engine R.P.M to increase past the lower governed R.P.M. setting. I don't think that 0 pitch setting means Zero R.P.M. Certainly not in the Bonanza.

If the lowest possible R.P.M setting for the governor is 1,000 R.P.M., then, the governor will start moving the prop angle toward the course stop as soon as the windmilling effect has enough force to drive the engine past 1,000 R.P.M. As soon as the windmilling effect does turn the engine past 1,000 R.P.M is as soon as the blade pitch is at the course pitch stop (if it can't go to feather). If it can go to feather, then, it will probably be something the pilot has to do manually. At feather the blade angle is extremely course or at an extremely high pitch and the prop can no longer generates windmill lift. Feather is the least amount of prop drag setting if the plane has a feather setting. That is why multi-engined planes have feather settings. Trying to fly with one engine thrusting is one thing while trying to fly with one engine thrusting and the other engine windmilling is going to cause a lot of yaw action.

As to high g lift force at Va:

I think it is work. The wing can accomplish the same amount of work at 400 km/h. If the work is 60,000 kg of work, then, the wing can accomplish 60,000 kg of work. If the plane weight is 10,000 kg, then, the wing can accomplish the task of lifting 60,000 kg AT 6g and AT 400 km/h. If the plane weight is 20,000 kg, then, the wing can accomplish the task of lifting 60,000 kg AT 3g and AT 400 km/h.

6 g is a rate of accomplishing the lifting of 60,000 kg AT the plane weight of 10,000 kg
3g is a lower rate of accomplishing the lifting of 60,000 kg AT the plane weight of 20,000 kg

400 km/h is the speed at which the wing can lift 60,000 kg.

If that is correct, then, the Fw190A-3 should have the same Va as the Fw190A-8 or close to it.

If that is correct, then, the Fw190A-3 should have the same or nearly the same accelerated stall line steepness (but lower on the EM chart).

As weight increases, perhaps, the rate of increase in lift vector acceleration decreases for any value of forward vector velocity while the amount of work done remains constant.

On an EM chart, it seems, the Va plot would stay at the same velocity (400 km/h for example) and move vertically down to a lower rate of acceleration, while, the 1 g stall plot would move right on the chart to a higher forward vector velocity.

http://mysite.verizon.net/res0l0yx/images/WWIIEMgameerror.jpg

Kettenhunde
01-22-2007, 05:10 PM
engine turns to 2700 R.P.M.


Propeller rpm not engine rpm.

JG14_Josf
01-22-2007, 05:12 PM
Kettenhunde,

Is it 2 to 1 gear reduction?

The engine is turning at 5400 R.P.M.?

Thanks

Bremspropeller
01-22-2007, 05:18 PM
Crumpp, was it possible to feather the 190's prop all the way (meaning ALPHA of the prop-blades was almost zero in relation to the airstream), or was it just like 30? or so?

Some guy said, that was the reason why a 190 would glide like a brick (maybe it was even you http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif ).

Kettenhunde
01-22-2007, 05:21 PM
Is it 2 to 1 gear reduction?


If the gear ratio was that high.

Kettenhunde
01-22-2007, 05:35 PM
Crumpp, was it possible to feather the 190's prop all the way


Yes:

I answered Lumino off the top of my head. If you read my next post to him I read the manual.

The propeller was limited to 50 degrees in automatic. In order to reach segelstellung, the pilot had to put the laderuckregular in manual and then dial in 90 degrees.

All the best,

Crumpp

JG14_Josf
01-22-2007, 05:36 PM
If the gear ratio was that high.

I was thinking Fw BMW VDM.

It didn't occurre to me that R.P.M. was anything other than engine R.P.M. It just didn't register. Thanks.

Any chance that you would hazard an accurate guess for Va for the Fw190A-4, Fw190A-8, and Fw190D-9?

How about the one g stall for those planes?

Bremspropeller
01-22-2007, 05:58 PM
Thanks Crumpp http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

So how was the prop switched from "auto" to "manual" - where is the "switch" ?

I recon there's a "bar" on the throttle-lever (in game). I guess I'd have to push it somewhere..
How do I manage to shift the pitch-settings then? Twisting the "bar"?

JG14_Josf
01-22-2007, 06:13 PM
How much drag did the cooling fan (with gills open some) eliminate when the fan turned (not windmilling, not producing thrust, and not stopped)?

Here is one account of the famous Fw glide slope:


One word of warning was sounded, however. If, for any reason, the Focke-Wulf's engine did stop, the advice was to get out – quickly. Powerless, the Fw190 had ˜the glide characteristics of a brick. As soon as the engine faltered, the nose pointed earthwards, flowed by the rest of the airframe in close formation'. Opinions were to vary as the advisability of trying to land with a dead engine. Some pilots swear they never witnessed a single successful attempt at a deadstick landing. Others claim to have actually done so, with varying degrees of damage to self and aircraft. All are agreed, however, that such action was a course of last resort and not one to be recommended on a regular basis. Belly landings, on the other hand, offered the pilot a reasonable chance of walking away from the resultant mayhem. The forward momentum of the BMW, ensconced behind its armoured ring, tended to brush aside all but the most immovable of obstacles. The trick, on pilot discovered, was in setting the prop blades to as fine a pitch as possible immediately prior to impact. As soon as they hit the ground, they bent backwards and doubled as makeshift skis. Some future ground-attack pilots would even profess to being able to make smother wheels-up landings on their fuselage and wing weapons-racks then they ever did by performing a three-pointer!

That is printed in Focke-Wulf Fw 190 Aces of the Russian Front
John Weal
Osprey Aircraft of the Aces 6

As to the three point landing procedure:


Raise the tail too early and there was every danger that the propeller would dig in and flip the aircraft on to its back.
(Ibid – John Weal)


How much work could those props accomplish measured in tons of air moved?

Not even the weight of the plane and not even at very high speeds (prop R.P.M.).

It takes a wing to move 6 or 10 times the weight of the plane and the wing must be going fast.

WWMaxGunz
01-22-2007, 07:05 PM
Originally posted by BfHeFwMe:
Huh?

Max, do you even have 46? Anyone feels a need for slowing down using prop or any means for anything besides landing, be my guest! Gotcha covered. http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

Humor? Remember your little exhibit at the end of the Fw thread? I think I've showed far more restraint and patients with you than you did with the poster there. Funny how you piled on only after 'others' corrected his views.

Get over yourself Max, you ain't that great. What else besides name calling are you capable of on a board? "dweeb" http://forums.ubi.com/groupee_common/emoticons/icon_cool.gif

I did finally get and install my copy of 1946 and I do use it.

Little exhibit at the END of the FW thread? WTF you talking about? My last post there got
UBI-gobbled as did other posts in days preceding the crash. Had I known it was for points....
I don't come here anywhere near 24/7, just pop in and leave so yeah there have been 20+ hour
stretches I am not around to put in a reply for clowns that seem to be keeping score.

Dweeb is a term well known in the WB community that Bullethead explained in his training pages.
The biggest dweebs on WB were the Spitdweebs that always took 'the best' plane and always had
to whine loud and long when 'their plane' didn't win and was supposed to. Everyone else is a
cheat and the game is wrong --- but I guess we don't get that here?

I never said I was great and hey I can still point out a thing or two without your permission.
If you can't see anything but name calling from me then you have your own problems.

WWMaxGunz
01-22-2007, 07:28 PM
TOAD, where they measure pitch from could be the difference. I am guessing that you buy a
fixed prop for better low or high end efficiency.

----------------------------------------------------------

Prop pitch acceleration/deceleration have been working pretty much the same since FB 1.0.

Is it a critical detail? A big advantage? Then here is a secret but nobody tell, okay.
The secret maneuver most every pilot uses to slow down a plane that doesn't have speedbrakes
and always works no matter what else is called.. a.. sideslip. But don't tell!

JG14_Josf
01-22-2007, 09:57 PM
http://www.white1foundation.org/prop_rebuild/total%20report_02.jpg

http://www.white1foundation.org/parts/prop_assemb2.jpg

http://www.white1foundation.org/parts/801_work3.jpg

The small fan goes 2 times prop R.P.M.?

Bremspropeller
01-23-2007, 07:28 AM
IIRC it was 3.7 times.
Got that from Peter Rodeike's book.

JG14_Josf
01-23-2007, 07:59 AM
http://fw190.hobbyvista.com/wadman3.jpg

Note the distance between prop tip and ground.

The pictures from The White 1 Foundation clearly show that the VDM Prop Pitch Mechanism is not hydraulic like a Hamilton Standard.

Like this:

http://www.twinbeech18.com/images/servicenotes/sn3-5.gif

Hamilton Standard (http://www.twinbeech18.com/servicenotes/sn_hs_prop_care.htm)


Three fundamental forces are utilized to control the blade angle variation required for constant speed propeller operation.

1. A centrifugal twisting moment which tends at all time to move the blade into low pitch.

2. Oil at engine oil pressure on the inboard piston side *the outboard piston side on early model propellers) which is introduced to supplement the blade centrifugal twisting moment toward low pitch.

3. Oil, taken from the engine supply and boosted in pressure by the engine-driven propeller governor, is supplied to the outboard piston side (the inboard piston side on early models) to balance Forces 1 and 2, and used to move the blades toward high pitch.

These hydraulic and centrifugal forces are transformed into mechanical force by the piston and cylinder, and the cams transmit this force to the blades through the bevel gears. The required balance between the three control forces is maintained by the propeller governor which, in addition to boosting the engine oil pressure, meters to or drains from the piston the exact quantity of oil necessary to maintain the proper blade angle setting for constant speed operation. See figure 4

So the answer to one of my questions is definitively:

The Fw190 did not have a Hamilton Standard type Hydraulic pitch angle changing mechanism or drive.

Apparently, and I'm repeating to make sure that I've got this straight, the Fw190 and the Me109 had electric motors that turned those gears on the VDM prop which in turn turned the prop blade angle, and, the manual control on both the Fw 190 and the Me 109 bypassed the governed constant speed prop mechanism and manually drove the blade angle to a fixed blade angle, and, the pilot could drive the prop to feather.

Therefore the game models the Me 109 almost right and the game models the Fw190 wrong.

The Me 109 should have the ability to drive the prop to feather which, and correct this please if it is wrong, should stop the prop blade rotation from windmilling while the engine power is out. The same goes for the Fw 190.

Both the Me 109 and the Fw 190 should be modeled with CSP Constant Speed Prop operation in Automatic mode where the Prop R.P.M control is controlled by the throttle lever, and, both the Me 109 and the Fw 190 should have a manual over-ride that eliminates CSP operation and allows the pilot to manually drive the prop pitch blade angle manually from flat to course or from fine to feather and anywhere in between.

The game that does model the Fw190 accurately will not model a poor performing automatic prop pitch CSP mode that is less prone to overheat and a manual automatic mode that is more prone to overheat.

Here is a test for anyone wanting to see how the game models the Fw190 CSP.

Run the Automatic Prop Pitch mode at full throttle, even on the ground, and note the engine R.P.M.

Switch to Manual Prop Pitch mode at 100% Prop Pitch and note the engine R.P.M. change.

Now lower the Manual Prop Pitch percentage down from 100% until the R.P.M drops to the Automatic Prop Pitch mode R.P.M.

What is simulated is this:

Automatic Prop Pitch mode is a lower than 100% R.P.M. setting for the simulated governor. In one patch the Automatic Prop Pitch R.P.M. setting was 50% prop pitch at 100 percent throttle.
A player could, in an earlier patch, get the same exact performance from Automatic Mode at 100% throttle as Manual Prop Pitch 100% throttle and 50% R.P.M setting.

I remember testing that once in an earlier patch and I noticed how the game simulated the pilot perspective being pushed back in his seat as the plane lurched ahead when switching from Automatic mode to Manual Prop Pitch 100% mode. The pilot perspective lurched ahead when switching back to Automatic mode; like someone put on the air brakes.

That is not an accurate way to model the Fw190, apparently, and any flight performance tests done on Automatic Prop Pitch is, in fact, testing the simulated performance of that plane at a lower R.P.M. setting.

In reality the pilot simply moved the throttle which in turn set the governed R.P.M.

Please correct me if this is wrong:

In reality the full forward position of the throttle on the Fw190 was maximum governed manifold pressure (maximum fuel/air, spark advance, etc.), AND, maximum governed R.P.M.
In the case of the early models that would be 1.42 ata and 2700 R.P.M.
If that particular engine was de-rated, then, a screw was placed in the throttle gate that limited the movement of the throttle. The position of the screw limited both the manifold pressure and the R.P.M. to a desired lower maximum such as 1.32 ata or 1.35 ata and 2,450 R.P.M. like this:


Climb
The rate of climb up to 18,000 ft [5,488m] under maximum continuous climbing conditions at 1.35 atmospheres boost 2,450 r.p.m. 165 m.p.h. is between 3,000 and 3.250 ft/min [15.24 to 16.51 m/sec].


That above are the British test results of a captured Fw190A-3 (de-rated and running rough on the wrong gas with fouled spark plugs) so the performance is bound to be someone less than a RATED motor tuned up on the right gas.

Any game testing done to match the British tests would, theoretically, require 100% throttle (the throttle not pushed past the screw and the throttle not pushed all the way forward in the gate). The game Prop Pitch setting should be set to 2,450 R.P.M. If the game doesn't produce 2,450 R.P.M. on the Automatic Prop Pitch setting, then, the game provides the inaccurate ability to adjust the CSP R.P.M. setting manually. The game test pilot could reset the R.P.M. manually to the 2,450 R.P.M. setting as it should be for the game climb test. The speed for the climb test is given in the British test at 165 m.p.h.

This, of course, assumes that the game accurately displays R.P.M. and Manifold pressure gauge readings which are a stretch since the game requires NO COCKPIT MODE just to get accurate Air Speed information.

Future games made more accurate will not model the Fw190 with a de-linked CSP lever that is not controlled by the throttle lever. The 109s are modeled as they should be for VDM electric prop drives – it seems. So why model the Fw190 wrong?

Will no one offer a reasonable number for Va and the 1 g accelerated stall speed for these:

-------------------------1 g -----------Va
Spitfire VB-----------Blank---------Blank
Spitfire IX-----------Blank---------Blank
Fw190A-4-----------Blank---------Blank
Fw190A-8-----------Blank---------Blank

No interest whatsoever in accurately determining high speed turn performance?

Kettenhunde
01-23-2007, 08:59 AM
the Fw190 and the Me109 had electric motors that turned those gears on the VDM prop


Sort of Josf. The VDM propeller in the Focke Wulf used an electric motor to turn a hydraulic pump which the govenor used to turn the gears to adjust blade angle.

That is why it is a hydra-electric propeller and not just electrical.

As for Va here is a quick SWAG:

269.32 mph at sea level

All the best,

Crumpp

Kettenhunde
01-23-2007, 09:04 AM
Nice pic of our engine. I will let Ramon know he is famous now.

All the best,

Crumpp

JG14_Josf
01-23-2007, 09:13 AM
Here is more information on the throttle gate screw in the Fw 190 (De-rating).

This quote comes from the book Luftwaffe Fighter Ace by Norbert Hanning
Edited and translated by John Weal


By this time all training had been shut down at Liegnitz and the twelve Fw 190A-6s of the Einsatzstaffel prepared for take-off. When I climbed into the cockpit of my machine and checked the controls I discovered that a screw was inhibiting the full travel of the throttle. This had the effect of reducing engine output by ten per cent, which was a justifiable measure on a training aircraft. It helped to protect the engine and increased the number of flying hours. But in combat it could mean the difference between life or death if maximum engine power was not available.

Norbert Hannig, the WWII fighter pilot, went on to describe a fight with Mustangs escorting bombers like this:


"Hang on, Heino," I shouted, "I'm coming down." I dived towards the ground as fast as my doctored throttle would allow. At a range of 3000 meters I loosed off a few bursts at the three P-51s bringing up the rear of the case. When they spotted my cannon shells exploding on the ground around them they broke into 360 turn which put them out of the running for awhile.

Norbert Hannig was ordered to use his training flight into further combat:


I rammed the throttle forward – I'd made sure that all the Einsatzsaffel machines had had those damned inhibitor screws removed – pulled up into a steep climb and easily eluded my would–be assailant.

Norbert Hannig above was describing a fight between Me109s attacking his Fw190 formation. The Luftwaffe, at that time, was being manned by inexperienced pilots – like Spitfire pilots in 1941 – very few hours of flying time and no combat time.

Anyway – the screw was the device used in the throttle gate to De-rate an engine. It simply limited the performance of the engine just like the wire gate in other Fighter Planes. The wire gate could be broken by the pilot if needed. The screw was removed by the mechanic if the pilot demanded it. In either case the engine life shortened. Time at maximum performance was an important factor.

Example:

This from the book Green Hearts Dora 9 by Axel Urbanke


Not until just short of Hanover did Ungar and Zech suddenly find themselves alone. The Spitfires, probably running low on fuel, had turned back. At 10:00 am the two Focke-Wulfs landed at Hanover-Langenhagen. Fritz Ungar wrote of the landing:

The mechanics almost had a heart attack when they saw the manifolds of my D-9, which, glowing red, were hanging down. They had to force the engine cowling open. Reason-I had forgotten to switch off the emergency boost after ten minutes and thus had severely overheated the engine.

JG14_Josf
01-23-2007, 12:20 PM
Sort of Josf. The VDM propeller in the Focke Wulf used an electric motor to turn a hydraulic pump which the govenor used to turn the gears to adjust blade angle.

Kettenhunde,

I've been a mechanic, of sorts, for 25 years. Please tell Ramon that I am jealous. A hydraulic pump, gear pump, vane pump, or even a piston pump, pumps. There must be another device between the pump and the gear such as a hydraulic motor. Hamilton Standard uses a spring, hydraulic piston, and inclined planes. These mechanical advantage devices interest me; not as much as the Va number you offer.

Here is my short list (requested):

------------------------1 g -----------Va
Spitfire VB-----------Blank---------Blank
Spitfire IX-----------Blank---------Blank
Fw190A-4-----------Blank---------Blank
Fw190A-8-----------Blank---------Blank

Here is one offering:

269.32 mph at sea level

I'd rather use metric.

269.32 mile/hour (mph) = 433.428 526 08 kilometer/hour

If my SWAG is right, then, Va (the forward velocity number) is the same for both the Fw190A-4 and the Fw190A-8 like this:

------------------------1 g -----------Va
Spitfire VB-----------Blank---------Blank
Spitfire IX-----------Blank---------Blank
Fw190A-4-----------Blank---------433 km/h
Fw190A-8-----------Blank---------433 km/h

I can't yet plot that number on an EM chart.

I need either turn rate or g load (acceleration rate on the lift vector) for either or both Fw190 airplanes and Spitfires would be nice too.

The lift acceleration for the Fw190A-8 is bound to be lower than the lift acceleration for the Fw190A-4 since the higher weight cannot be accelerated as fast for two reasons:

A: The higher weight stalls the plane at that speed before reaching that acceleration rate on the lift vector (g). But the wing will lift the same weight – not as fast.
B. The higher weight would deform the wing at that speed and at that rate of lift vector acceleration (g) if it could but it can't. The wing lifts the same weight at a lower speed.

Possible examples:

------------------Va forward vector velocity---- Va lift vector acceleration
Fw190A-4--------------433 km/h-------------------------14 g
Fw190A-8--------------433 km/h-------------------------13 g

My arbitrary guess is not good enough to plot. That would be ridiculous.

I can use a kind-of, sort-of, airspeed for the 1 g accelerated stall plot like this:


The stalling speed of the Fw190A-4 in clean configuration was 127 mph [204 km/h] and the stall came suddenly and virtually without warning, the port wing dropping so violently that the aircraft almost inverted itself. If fact, if the German fighter was pulled into a g stall in a tight turn, it would flick out into the opposite bank and an incipient spin was the inevitable outcome if the pilot did not have his wits about him.

------------------------1 g -----------Va @ 13g ------Va @ 14g
Spitfire VB-----------Blank---------Blank-----------Blank
Spitfire IX-----------Blank---------Blank------------Blank
Fw190A-4---------204 km/h-------Blank-------------433 km/h
Fw190A-8-----------Blank---------433 km/h-------stall/deform wing

Here is a note on how a German pilot identified the stall and uses the Fw190 flick stall in combat:

From Norberg Hannig converting from 109G to 190A-4:


Since February the pilots of I and II Gruppen [JG 54 1943] had been rotating back to the homeland in small batches for conversion on to the Fw190A. The ˜Forke', or ˜Pitchfork', as we christened it, was a much more robust bruiser of a fighter than the Me 109G. It was powered by a 1,700 hp BMW radial engine and...
The Fw 190's performance and flying characteristics were equally impressive. In a dive it could exceed 700 km/h. It was highly responsive around all axis, could be reefed into a tight turn, and gave its pilot ample warning of a stall by sharp, jerky aileron movements. If these were ignored, the machine would automatically go into a flick half roll, losing height and turning through 180 degree in less time than it takes to describe here. This manoeuvre was virtually impossible for another pilot to follow. If you were in a dogfight, and had sufficient altitude, it was a sure way of getting an opponent off your tail. This 'built-in' escape tactic was the saving of many Forke pilot who found himself in extremis.
This conversion course took place at Heilingenbeil airfield in East Prussia, where the new fighters were delivered direct from a nearby factory. The Geschwader kept a rear party based at the field, who were responsible for conducting the conversion training.

From Norbert Hannig flying a de-rated Fw190A-6 trainer version in combat against bombers (June 1944):


As we broke through above them we became aware of condensation trails lancing down towards us. In bunches of four, these could only be the bombers' top cover fighter escorts. Within seconds I had four, then eight, and finally twelve Mustangs sitting on my tail. But while I was flying close above the stream they were unable to open fire on me for fear of hitting their own bombers. This dubious sanctuary did not last long. The high combined closing speed which had protected us during our frontal assault on the bombers now worked against me and I soon found myself hurtling past the last squadron in the formation and out into clear sky beyond.
I immediately began to yo-yo; turning steeply, diving and climbing, climbing and diving. My pursuers didn't seem to know what to make of my Russian front aerobatics. They clung on grimly behind me, but couldn't hold me in their sights long enough to get in an effective burst. I spied a welcome bank of cumulus ahead of me and slightly below. After three more complete circles I was directly above one of the larger clouds. I yanked the stick to the left back into my belly and trod hard on the full right rudder. My machine spun down into the cloud.
In my temporary haven I let go of the controls. The trusty Forke at once righted itself and I shot out from the bottom of the cloud into sunlight again. Where were the Mustangs? I looked up and saw them circling the cloud-top above me. I put my nose down and got out of there fast.


That is the same engagement where this happened:


I dived toward the ground as fast as my doctored throttle would allow.

One more note on Norbert Hannig and his experiences with spins:

April 1943 on a Jabo mission with a 109G (no model number mentioned):


We released our bombs and watched their fall...
...we were at an altitude of 7,000 meters. But Walter continued to climb. We were in a gentle left-hand turn, flying in tight formation, with me tucked in on the inside close beside Walter. I was aware of him watching me.
It was at that moment that my wing leading-edge slots popped open, an indication that I was in danger of stalling. If I stayed in the inside position, and if Walter continued to fly this close to stalling speed, I would not be able to hold the Gustav very much longer. I had no other option but to try to change sides; to take up station on Walter's right on the outside of the turning circle. The throttle was already fully forward, I could not get another ounce of power out of it. So I eased off slightly, sacrificed a little height, and began to slide under and behind his aircraft.
Suddenly I found myself caught in his propeller wash. My machine rocked violently and then – with its wings remaining almost perfectly level – began to rotate about its vertical axis. There was no response from either stick or rudder pedals, the controls were completely slack. As the Me 109 started sinking toward the ground, whirling round and round like the blades of a helicopter rotor...
I pushed the stick forward as far as it would go – nothing!!!
...I had one last chance, the large tailplane trim wheel down to the left beside my seat. If I could alter the trim to make the machine sufficiently nose heavy, maybe that would enable me to get it pointing earthwards. I began to crank the wheel with all my might...
This was something I had been shown how to handle during training. I applied full opposite ruder and held the sick pressed forwards with both hands. The spinning motion slowed down and stopped. But I was sill diving vertically towards the ground. The altimeter had unwound to just 1,000 meters and the airspeed indicator was showing 650 km/h as I gently eased the stick back. The Gustav's snout came up with 500 meters to spare I was flying straight and level.


Trimming nose heavy causes the neutral ˜hands-off' flight to be a dive or negative g situation. Trimming nose heavy can also compensate for changes in speed.

Example:

A plane flying neutral at stall speed in a climb may be trimmed tail heavy.
The same plane trimmed tail heavy goes into a dive and accelerates to 650 km/h.
That plane may then be trimmed way too tail heavy.
Trimmed neutral in a stalling climb may be way too tail heavy for a dive at 650 km/h.
The stick may be neutral in the stalling climb at that trim.
The stick may need to be pushed with two hands forward at that tail heavy trim while diving at 650 km/h.
The Fw 190 and the Me 109 were trimmed with tail plane incidence angle adjustment; no in cockpit adjustable trim tabs on the elevator.
The horizontal stabilizer angle of attack was adjusted to adjust pitch trim on the Fw 190 and the Me 109.

Adjusting the AOA on the tail plane to a higher angle of attack will do what?

A. Pitch the nose down.
B. Pitch the nose up.

Note these words:


The altimeter had unwound to just 1,000 meters and the airspeed indicator was showing 650 km/h as I gently eased the stick back. The Gustav's snout came up with 500 meters to spare I was flying straight and level.


Pitch trim does, in fact, change stick force requirements during turning flight.

Trimming fully nose heavy (tail plane at high AOA lifting the tail up) at slow speed may require much back pressure just to stay in level flight.

Trimming fully tail heavy (tail plane at low AOA diving the tail down) at 650 km/h may require forward pressure just to stay in level flight.

Myths concerning heavy stick forces may arise from confusions concerning trim.

I'm not a WWII Fighter Plane with years of combat experience flying 109s and 190s against Russian and American Fighter planes.

Bremspropeller
01-23-2007, 12:29 PM
Josf, where are these 190-quotes from?

The Osprey-book, western front edition?

JG14_Josf
01-23-2007, 12:34 PM
Josf, where are these 190-quotes from?

The Osprey-book, western front edition?

Those quotes come from the book Luftwaffe Fighter Ace by Norbert Hanning
Edited and translated by John Weal

Here (http://www.amazon.com/Luftwaffe-Fighter-Ace-Norbert-Hannig/dp/1904010946/sr=1-1/qid=1169580863/ref=sr_1_1/103-2426623-3413408?ie=UTF8&s=books)

Scen
01-23-2007, 12:34 PM
Originally posted by JG14_Josf:
SlipBall,

Damn this can be confusing.

Let me try that again:

This was backwards:

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Leaving the C.S.P. control at higher R.P.M. causes the governor to drive the prop pitch to a higher pitch thereby lessening the lift production of the prop.

Leaving the C.S.P. control at higher R.P.M. causes the governor to drive the prop pitch to a lower pitch thereby increasing the lift production of the prop.

The governor seeks more R.P.M. and moves the prop to fine pitch.

Fine pitch is a higher angle of attack relative to the Wind which is wind milling the prop and the engine.

What can make it even more confusing on the Beech is the manifold pressure reading. </div></BLOCKQUOTE>

I think you're confused... Almost everything in this last message is backward.

CSP is a device that attempts to keep the prop at a certain set RPM regardless of Engine Power. Thats all it does. It has nothing to do with a throttle setting. BTW what we have in game is nothing like a CSP. It's actually quite odd. It's sort of a variable pitch prop more than a CSP.

So if you want to slow down faster you set the RPM to a Higher RPM meaning a finer AOA on the prop. Higher RPM with a lower bite means higher drag relative to forward flight. Think of it as a downshift in car to a lower gear for a moment.

Low RPM means the prop has a much larger AOA and is biting more air. Hence I higher gear in a car.

Where you want to be careful is when you make changes to power before RPM. In other words high power setting with too low of an RPM puts a much larger workload on the motor.

I hope that helps a bit.

JG14_Josf
01-23-2007, 12:58 PM
I think you're confused... Almost everything in this last message is backward.

Scen,

The facts are facts and those facts can be proven even while I am confused.

You wrote:

CSP is a device that attempts to keep the prop at a certain set RPM regardless of Engine Power.

The fly weight governor decreases prop pitch if R.P.M. is insufficient.

The fly weight governor increases prop pitch if R.P.M. is excessive.

That is how it works and it doesn't matter if I am confused. That is how it works.


Scen fails to unconfused me (I'm not sure about anyone else):

It has nothing to do with a throttle setting.

If the engine is at full throttle turning the fly weight governor, then, that has something to do with what happens.

If the engine is not a full throttle and nothing is turning the fly weight governor, then, that has something to do with what happens.

If the fast movement of air mass turns the engine and the fly weight, then, something happens. It has something to do with it.


BTW what we have in game is nothing like a CSP.

I don't know what game you are playing. The first time I tried IL2 with the 109 I had a blast sitting on the runway with manual prop pitch and the engine off imagining the electric motor turning the VDM CSP prop from high to low pitch and back again while watching the prop pitch indicator clock on the instrument panel. It was a blast - still is.

I noticed right away that the CSP system in the game worked exactly like it was supposed to work in reality. The R.P.M. setting increased and decreased as the throttle was moved forward and back, as if, like reality, the prop lever was linked to the throttle lever. It was really, really neat to see that much detail modeled into a half C note game.

Scen continues:

It's sort of a variable pitch prop more than a CSP.


The 109 has both in reality and both in the game. The allied planes like the P-47 are modeled with CSP props just like the real thing. It's amazing.

The Fw190 is wrong.

Scen straightens out the backwards confusion:


So if you want to slow down faster you set the RPM to a Higher RPM meaning a finer AOA on the prop. Higher RPM with a lower bite means higher drag relative to forward flight. Think of it as a downshift in car to a lower gear for a moment.

This is what I wrote:

Leaving the C.S.P. control at higher R.P.M. causes the governor to drive the prop pitch to a lower pitch thereby increasing the lift production of the prop.

This is what I corrected myself as being wrong:


Leaving the C.S.P. control at higher R.P.M. causes the governor to drive the prop pitch to a higher pitch thereby lessening the lift production of the prop.

What is – is.

When I'm backwards I think I can admit it. I did.

Thanks for this:

Where you want to be careful is when you make changes to power before RPM. In other words high power setting with too low of an RPM puts a much larger workload on the motor.

I hope that helps a bit.

It helps to read carefully before jumping to conclusions. I am guilty of jumping to conclusions too often. When I can find my errors I try to correct them.

It helps.

Thanks.

WWMaxGunz
01-23-2007, 01:45 PM
Originally posted by JG14_Josf:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">BTW what we have in game is nothing like a CSP.

I don't know what game you are playing. The first time I tried IL2 with the 109 I had a blast sitting on the runway with manual prop pitch and the engine off imagining the electric motor turning the VDM CSP prop from high to low pitch and back again while watching the prop pitch indicator clock on the instrument panel. It was a blast - still is.

I noticed right away that the CSP system in the game worked exactly like it was supposed to work in reality. The R.P.M. setting increased and decreased as the throttle was moved forward and back, as if, like reality, the prop lever was linked to the throttle lever. It was really, really neat to see that much detail modeled into a half C note game.
</div></BLOCKQUOTE>

190 and 109 had control systems that did not work as US and British CSP.

With CSP the RPM's do not change with power or speed unless the prop is at a pitch limit.
Prop speed (engine speed for that matter) and control is independant of throttle control.

Prop control flyweights do turn with tha engine that turns with the prop, btw. So just
take it that the flyweights are set up to use prop speed to control prop pitch. Throttle
does affect that but so does airspeed just as much in a power dynamic. Pitch changes to
keep the prop and engine at constant speed in CSP system.

German plane automatics did more than keep prop speed the same though sometimes that is
the goal. Sometimes not. The German automatics are not strictly CSP but something else.
If you don't include the whole control system then you are making your own picture.

WWMaxGunz
01-23-2007, 01:48 PM
Josf ask your brother if he adds an extra 500 lbs to a Cessna, does that change the speed
at which he will dare a full deflection?

JG14_Josf
01-23-2007, 02:06 PM
Maxi,

If my brother were to read your f'ing garbage he would laugh. Buzzz off troll.

BfHeFwMe
01-23-2007, 11:23 PM
There's more to the design and function of automatic variable pitch props, especially one fitted to a high performance fighter. One need understand the compromises a manufacturer must make.

They need to deliver extreme power, also need the lightest weight possible. The propeller reduction gearbox via design can be lightened, "if" you design it to bear steady torque one direction only.

Your ring, planetary, and sun gear components can be milled and lightened if they are to bear a load consistently and continuous in one direction only. This alone allows for light weight gearboxes, and features like being made out of lighter alloys such as magnesium.

It requires a solid and reliable mechanism to govern and balance the forces throughout the power train. The governor must have control over certain features in order to do it's job, mainly blade angles and fuel flow. Yes, you can send in a request via your levers, but it doesn't mean your flight conditions as seen by the governor is going to allow it.

The reduction gearboxes are pretty fragile compared to the load they are bearing, so it's critical to have a quality governing system to keep consistent control over the forces applied.

There's even more, this stuff can get pretty system specific. Take for instance the cases of planes taking a hit in the oil systems, yet pilots riding till the fluid is gone and the motor cooked before bailing. How's that possible, loss of oil should make the prop cease functioning almost immediate, shouldn't it? Well, not if it has mechanical low pitch stops built in. It's a spring loaded angle in the prop piston cam that must have oil pressure to force it beyond that point.

Another safety system uses splines with spring loading to immediately engage and hold the plunger in it's current position upon loss of oil pressure, allowing you a chance to cruise out of there.

Just pointing out a few possible subsystems you'll see within a CSP. Reason, it's not a simple subject, not a simple universal model can fit all, even in similar setups. Think of the programming that is required to get this stuff right, it's not an easy or simple task.

There are few who have complete and thorough understanding of how the entire system works. Pilots tend to know how one operates, but it takes a mechanic to know what its actually doing and how it does it.

WWMaxGunz
01-24-2007, 12:50 AM
I've seen that some period VSP's had a failure mode that went to the low stops allowing
for the pilot to land the plane. I think Curtiss Electric worked that way but not total
sure.

WWMaxGunz
01-24-2007, 12:58 AM
Originally posted by JG14_Josf:
Maxi,

If my brother were to read your f'ing garbage he would laugh. Buzzz off troll.

I didn't ask for him to read my posts, jerkwad.
Just ask him the question as written and see what he says since he MIGHT be someone you
can believe.

I know what professional pilots would say since I have gone through systems training courses
in FlightSafety Centers as part of a software development job I had and yes, the subject does
come up. The more weight in the plane, the lower the speed you dare apply full control.

In fact, if you are going to apply more than one control to a large extent, you can get in
trouble even below Va, at least IRL.

But you wander around in your own special fog where if you don't see it, it doesn't matter.

Kettenhunde
01-24-2007, 04:34 AM
It has nothing to do with a throttle setting.

You should clarify this because harmonically it has everything to do with an engine setting.

Fine pitch is the default setting for the vast majority of single engine propellers. Most twins will default to a feathered position.

JG14_Josf
01-24-2007, 06:57 AM
------------------------1 g -----------Va @ 13g ------Va @ 14g
Spitfire VB-----------Blank---------Blank-----------Blank
Spitfire IX-----------Blank---------Blank------------Blank
Fw190A-4---------204 km/h-------Blank-------------433 km/h
Fw190A-8-----------Blank---------433 km/h-------stall/deform wing

Nothing more on that?

I find it hard to believe that an intelligent person can't see how easy it would be to identify high speed performance in the manner started above. Half answers are curious answers.

As to the jerkwad:

Look idiot just because you think something doesn't mean that it is true. You have no concept of my thinking or my relationship with my brother and our level of understanding.

We have gone over Va intensely, in fact, it was his discovery that Va was generally misunderstood that led him to ask me what I though about it.

Many aviators suggest that a plane should be flown slower that Va when flying under weight. Which is true because passengers and seats can be stressed at higher rates of lift acceleration during maneuvering gusts; however – the publication of those warnings may suggest the opposite i.e. it is OK to fly fast when heavy (higher stall speed).

It is probably well known by most aviators that flying fast when heavy is very very bad even though the stall speed for the Va g (acceleration on the lift vector) increases. What my brother's concern was, as far as I have understood so far, is that the publications, like the Bonanza book he loaned me, (I have to get back my Boyd and Shaw book from him), suggest, even if only slightly, that flying slower when light is more important that flying slower when heavy through gusts.

The warning speaks as if the comfort of the passengers was more important than the wing structure.

Sure, the wing may stall at the published Va speed when loaded heavy, and sure the plane will accelerated faster on the lift vector in a gust when loaded light even at slower than the published Va; but – when loaded heavy at speeds above the published Va, in a gust, the wing will deform much more easily than when the plane is loaded light.

You, Maxi-pad, should get off our rag and start reading the words people write rather than the one's you make up as you construct your imaginary hell hole.

Get off my case. People on this board express their appreciation of my writing. If you want me to limit my posts (because you are protecting the people from me), then, I can limit my posts to one thread at a time JUST FOR YOU.

I will not leave this forum until the moderator asks and they don't have to ask.

p-11.cAce
01-24-2007, 10:09 AM
It is very important that mass is considered in these discussions and not just G loading. G loading by itself is meaningless unless it is coupled to mass - a 2kg mass at 10g produces the same loading as a 10kg mass at 2g. So why is this important in this discussion? Well Va is NOT the airspeed at which the plane breaks, it is the airspeed at which a full control deflection will result in a stall and NOT break the plane. Va airspeed will change greatly with changes to the mass of the aircraft as it is the loading factor on the aircraft parts and not the acceleration alone which causes a failure.

The idea that flying a heavy plane faster than a light one comes at the discussion from another angle. Va is a reference to control inputs and NOT gust loading. In turbulent conditions it is true that a heavily loaded aircraft will experience lower accelerations in relation to similar gust levels than the same aircraft when it is lighter. However, because of the increase in weight the critical mass loading factor will occur at a lower rate of acceleration. The point is that when speaking of acceleration independently half of the discussion is missing.

NonWonderDog
01-24-2007, 11:33 AM
Actually, Va is defined by limit g-load. It's NOT defined by the max wing loading in psi.

This seems completely backwards, but it's for a good reason: it's not necessarily the wings that will break first. As an example, suppose the motor mounts are limited to 10000 psi. The engine always weighs the same amount, no matter how much payload is on the plane. Perhaps 10000 psi in the motor mounts is reached at 5G (no matter the payload weight), and the lowest speed at which the plane can turn at 5G under normal load is 400 km/h. If nothing else limits maneuverability (bear with me), Va would be 400 km/h. If you fly the plane light, you might be able to pull 5G at 350 km/h. That doesn't mean you can safely pull 6G at 400 km/h, because that would overstress the motor mounts in our example (even though the wings might see exactly the same load as in the heavier plane at 5G).

Dynamic loading is also important in determining how likely something is to break. I'm not sure if Va takes it into account, however. That's mostly what Vb is for ("turbulence penetration" or "rough air" speed), which is seemingly never published for light planes, only jumbos.


If you overload the plane, that absolutely doesn't mean you can put more max wing loading on the plane safely. First off, if the plane is overloaded, you shouldn't be flying it. Va no longer really applies, because depending on how overloaded the plane is the wings might actually be the first things to break. Perhaps there could be a second maneuver speed limit for maximum wing loading for an overloaded plane that can't develop limit g-load, but that's just silly.

In addition, control surfaces are only stressed for up to 1/3 maximum deflection above Va. If you deflect the controls by more than that, you have become a test pilot. Don't be surprised if your ailerons fall off.


Just to fend off the more rabid amongst us (although it would be a good question), I am entirely aware that the definition of Va at MTOW is potentially dangerous and not entirely intuitive. Not many pilots can work out the variation of maneuver speed with weight; some might not be aware that maneuver speed decreases with decreasing weight, and that Va will aways be less than what's listed in the POH. That's how it's defined, though, for historical reasons or whatever.

JG14_Josf
01-24-2007, 02:07 PM
Actually, Va is defined by limit g-load. It's NOT defined by the max wing loading in psi.
Nowonder? P.S.I.?




So why is this important in this discussion? Well Va is NOT the airspeed at which the plane breaks, it is the airspeed at which a full control deflection will result in a stall and NOT break the plane.

p-11.cAce,

Please do continue pointing out what is important in this discussion. I think you are right. But: Va is corner speed as far as I am concerned and that speed is a combat air speed. The plane can fly at corner speed; not stall. The idea is to know the speed at which your plane can turn the smallest possible radius and the fastest possible turn rate.

It seems that a few things must be known to find corner.

A. At what speed can the wing produce a given quantity of lift (measurable as weight)?
B. What is the maximum weight a wing can lift before suffering damage?

If B is known then B can be the weight used for A.

When A and B are known, then, corner speed (Va) is known.

The factor of acceleration is not needed.

The aircraft weight is not needed.

If the wing will not deform and suffer permanent damage at 60,000 kg of weight bearing down on the wing but the wing will deform and suffer permanent damage at 60,001 pounds of weight bearing down on the wing, then, B is 60,000 kg.

The Bonanza book describes the process of finding Va as:


Limit and Ultimate Load Factors
The limit load factor is the maximum load factor which a given airplane can withstand without suffering any permanent deformation of the primary structure, e.g. wrinkled skins. The Bonanza is licensed in the utility category, and that means it has a limit load factor of 4.4 (The straight 35 is in the utility category only at reduced weight.) By comparison, most general aviation aircraft are licensed in the normal category with a limit load factor of 3.8, jet fighters may have limit load factors of 7.5, and the 747 (like most transports) has a limit load factor of 2.5.
If the actual load factor exceeds the limit load factor, primary structure may be permanently deformed, but it should not fail completely unless the load factor exceeds 1.5 times the limit load factor. This is the "ultimate load factor". If this value is exceeded, primary structure may fail and separate from the airplane. Ground static tests are required to establish the integrity of the airframe at its ultimate load factor.


This:


Ground static tests are required to establish the integrity of the airframe at its ultimate load factor.


Static Testing (http://classicairshows.com/Education/Stuctures/StrengthTesting.htm)
http://classicairshows.com/Education/Stuctures/StrengthTesting/FebThree5.jpg

This:



The limit load factor is the maximum load factor which a given airplane can withstand without suffering any permanent deformation of the primary structure, e.g. wrinkled skins.


Just before the primary structure suffers permanent deformation is the load limit factor and that can be measured as weight bearing down on the primary structure.

If you read the article on static test you can see how loads are tested. A test can be conducted on the battery box, the tail plane, the pilot's seat or the motor mounts. The wing, if I am not mistaken, is the primary structure that determines Va.

A static press loads up a force. If the force is supplied by hydraulics, then, the force can be measured as deflection in inches. If I am not mistaken, the force determining Va, is calculated as weight. A hydraulic jack, for example, can lift the weight of a car when the hydraulic Jack is pressurized to 2,000 P.S.I. and the car weighs 2,000 pounds and the jack piston is one square inch.

The static test, therefore, finds the weight at which the primary structure deforms permanently. That can be the limit load factor.

Having that weight and knowing the speed at which a wing can generated that same amount of lift force (measurable as weight) can find Va.

If that weight is 60,001 kg, then, corner speed is the lowest speed at which the wing can produce 60,000 kg of lift force.

If the wing is flown slower than the lowest speed at which the wing can produce 60,000 kg of lift force, then, the wing can't produce 60,000 kg of lift force i.e. the wing will stall before lifting 60,000 kg of weight at that lower speed.

If the wing is flown higher than the lowest speed at which the wing can produce 60,000 kg of lift force, then, the wing can produce more than 60,000 kg of lift force at that higher speed above Va i.e. the primary structure will deform when the wing produces 60,001 kg of lift force at that higher speed above Va.

If you have read my writing then you may be familiar with my angle of view whereby a plane is on the runway loaded up to the Va load limit.

Suppose the Va load limit is 60,000 kg (measured as weight).

The plane has a long runway to test Va.

The plane tries to take off at the Va load limit weight of 60,000 kg.

When the plane is flying too slow, accelerating down the runway, the plane stalls when trying to fly.

When the plane is flying at corner speed, accelerating down the runway, the plane can fly. Perhaps the end of the runway is like an aircraft carrier at 10,000 feet. The plane can fly. Just barely and perhaps only at best glide angle – not enough engine power.

When the plane accelerates faster than corner speed, then, the wing can generate 60,001 kg of force (measurable as weight) and the pilot can permanently deform the wing at speeds above corner in that imaginary flight from the carrier deck at 10,000 feet in a controlled crash with a plane loaded up to the limit load factor (measured as weight).

So...I think this is true:


It is very important that mass is considered in these discussions and not just G loading.

I think this, when filled out accurately, will be a method of measuring true high speed turn performance for those planes – accurately.

----------------------1 g -----------Va @ 13g ------Va @ 14g
Spitfire VB-----------Blank---------Blank-----------Blank
Spitfire IX-----------Blank---------Blank------------Blank
Fw190A-4---------204 km/h-------Blank-----------433 km/h
Fw190A-8-----------Blank---------433 km/h-------stall/deform wing

WWMaxGunz
01-24-2007, 03:13 PM
Originally posted by JG14_Josf:
Sure, the wing may stall at the published Va speed when loaded heavy, and sure the plane will accelerated faster on the lift vector in a gust when loaded light even at slower than the published Va; but – when loaded heavy at speeds above the published Va, in a gust, the wing will deform much more easily than when the plane is loaded light.

The wing should stall at Va (I don't need to say speed since V is Velocity) for a given load.
If no load is given then Va is for the plane fully loaded.

You can say that with more loading the wing will deform much more easily and you can say that
the higher the speed the greater the lift and yet...........

Richard Deakin (go look up his resume) in an article about T-34's facing being grounded
has written a sub-chapter "A Short Course in G-Loading".

In that he makes several observations icluding how buffets increase wing stress beyond what
the G-meter shows and how each and every buffet adds to wing stress count, but that is only
extra.

From that article since some people just can't believe -anything- I write:
-----------------------------------------------------------------------------------------
The FARs also address the certification standards for rolling the aircraft, and Va gives
full protection for stresses on the wing at Va with full aileron deflection.

But not a 6g in pitch!

Read that again, please, it's critical to what follows.

In other words, you may pull full back at Va, or you can apply full aileron at Va,
but you can't do both at once!

Any combined pitch and roll loads are called "asymmetric wing loading" and are of major
importance.
--------------------------------------------------------------------------------

He goes from there into example of military AC (F-16) practices and much more.

Full article: Archived Pelican's Perch Article Here (http://www.warmkessel.com/jr/flying/td/jd/20.jsp)

This all over an accident during a Sky Warriors session in I guess 1999 where a long time
airline pilot and a Sky Warrior instructor did break a wing in a T-34 during mock combat.
Richard covered it as thoroughly as he could given being denied the major evidence of the
video and audio tapes made during the flight. In the process he explains MUCH USEFUL INFO
for pilots beyond what is required to get a license.

Va for a T-34 is 148 knots. This is for an Army trainer.

I have to have a huge amount of patience with my little brother as my much older brother
has with me but I can tell that one guy out there is worthy of sainthood!

JG14_Josf
01-24-2007, 04:17 PM
Max!

That was a great link.

Thanks.

Deacon (one of my favorite authors):

(Now folks, I'm T-34 qualified, but not F-15 qualified, and so I may have some of those specific numbers a little bit wrong. Give me a little room for error there, and try to understand the principle, which I do not have wrong.)

Eric Brown (someone who flew the Fw190):


Incredible aileron turns were possible that would have torn the wings from a Bf 109 and badly strained the arm muscles of any Spitfire pilot trying to follow.

John Boyd (The guy who designed the F-16 and F-18):

Barrel Roll Attack (Aileron turn):


1. Stalk your target and attempt to reduce angle-off as much as possible. If this is impossible, employ the procedures outlined below.

2. Dive below and inside your opponent's turn radius, maintaining nose-tail separation throughout the maneuvers.

3. Pull up and zoom inside your opponent's turn radius if you feel he is not strongly oriented toward the scissors maneuver (sometimes this is difficult to determine).

4. Barrel-roll, nose-high, in a direction away from your opponent's turn. If he turns right, barrel-roll left, and vice versa. The roll will reduce vector velocity and the height of the yo-yo apex, yet maintain a higher aircraft velocity.

5. Continue the roll and employ bottom rudder as the aircraft comes through the nose-high inverted position. This will provide a 270deg change of direction and place you with longitudinal separation, at a reduced angle off above your opponent, diving toward a six-o'clock-low position. The longitudinal separation will be less than that acquired from an ordinary yo-yo.

6. Do not employ bottom rudder if your opponent rolls away from the turn and pulls up into the attack. Instead, employ top rudder and continue the roll from the inverted position. This will place you in a nose-high attitude at six-o'clock-low - a perfect set-up for a GAR-8 launch.


Back to Deacon:

What does this do to the airplane? Since the roll is to the left, the right wing is forced to suddenly produce "more lift" by the aileron deflected downwards. That moves the leverage at the wing root well outboard, and well aft, producing a major twisting force on the wing, loading the rear spar far beyond design limits.

I don't think that a Barrel Roll Attack is a roll, then a turn, then a roll, then a turn and if I understand the geometry of a Barrel Roll Attack right, then, the idea is to maximize turn rate and minimize turn radius during the asymmetric turn i.e. corner speed.

What was Va for a combat weight Fw-190 or Spitfire?

Ignorance is bliss? I don't think so. I'm asking.

Did this happen a lot in WWII:

Deacon:


In the F-15, any attempt to pull more than 2.5g in pitch and use full aileron deflection at the same time will probably destroy the airplane, because this is outside the operating envelope. An entire F-16 squadron in Europe was trashed because the pilots were either unaware of this limit, or routinely pushed it just a little too much, and caused too much fatigue over time.

I've read, and I may find the quote again, where Fw190 pilots wrinkled the skin on their fighter planes.

Was Va not known as an important and therefore documented velocity?

If so, then, it stands to reason that asymmetric loads were also ignored.

Eric Brown:


Incredible aileron turns were possible that would have torn the wings from a Bf 109 and badly strained the arm muscles of any Spitfire pilot trying to follow.

Apparently Eric Brown was up to speed.

WWMaxGunz
01-24-2007, 05:17 PM
Originally posted by JG14_Josf:
If so, then, it stands to reason that asymmetric loads were also ignored.

If you want to ignore that barrel rolls are not made with full deflection then go ahead.

JG14_Josf
01-24-2007, 05:35 PM
If you want to ignore that barrel rolls are not made with full deflection then go ahead.

Maxi,

When you can do more than repeat your baseless conjecture, then, you will have something worth reading. Like your link to Deacon.

WWMaxGunz
01-24-2007, 06:15 PM
Who says exactly about asymetric loads and speed, you don't roll while at FULL elevator.
Deakin states the case.

Who barrel rolls at full deflection? Barrel roll is a roll around an axis over the pilots
head and it is a DRAGGY maneuver. Understand that? From the quote you provided: "the roll
will reduce the velocity vector". You know what velocity is? You call it speed.
Boyd also describes using the barrel roll to make a directional change but that is additional.

The "conclusions" you think you draw are the usual BS you post when you try and push your
stick-jerking views. Are you as confused as the blather you post or are you just trying to
confuse everyone else? If you can't dazzle them with brilliance, you baffle them with BS?
Forget it, too many people here know better. The ones that answer, you argue with.

Yeah, and we all don't know diddly about gravity too.

p-11.cAce
01-24-2007, 07:16 PM
c-130 crash video (http://www.youtube.com/watch?v=DS0kr4QWhn8)
I've included this only to demonstrate the multitude of variables we can discuss regarding ultimate loads and accelerations regarding aircraft. This aircraft was lost in the reverse sense of what we have been discussing - it was a sudden loss of mass which resulted in a rapid unloading of a spar weakened by fatigue which caused the catastophic failure. I do not know what the airspeed of the a/c was at the time of the failure but I suspect it was around Va to allow for manuvering to a precise location at low level. Who would have thought the unloading an airframe would lead to this? http://forums.ubi.com/images/smilies/sadeyes.gif

JG14_Josf
01-25-2007, 09:19 AM
Maxi,

I sent the Deacon link to my brother and he responded:


Hi Joe,



This is quite a subject amongst the American Bonanza Society members. There have been two or three similar failures with the T-34's, which has the fleet currently grounded. There is also a cracking issue with the carry-through spar on all Bonanzas, so a 500hour inspection AD is in effect. It's one of the big things I looked at prior to buying mine. Also, another recent change is that there is no tolerance for structural cracks at all, where there once was. Cracks have been found, but so far only in very high time, highly stressed airframes like the T-34's. Mine has no sign of any cracks, I've had it inspected by a good shop in Phoenix, and again by Rex and very carefully by myself.



This asymmetrical wing loading has been postulated in another article I've read somewhere else. Of course, it would be very difficult to know exactly what happened. It's fair to say that pilot error played a role, as is nearly always the case.



Thanks



Bob



You can appreciate it or stuff it; I could care less.

WB_Outlaw
01-25-2007, 01:57 PM
Originally posted by p-11.cAce:
Who would have thought the unloading an airframe would lead to this?

Any mechanical engineer worth an ounce of horse pee should be aware of the effects of fully reversed bending stresses, especially as they relate to the endurance limit. They should also know that aluminum has no endurance limit which is why it's so very important to keep records of crack growth in airframes.


--Outlaw.

BfHeFwMe
01-25-2007, 08:44 PM
Originally posted by p-11.cAce:
c-130 crash video (http://www.youtube.com/watch?v=DS0kr4QWhn8)
I've included this only to demonstrate the multitude of variables we can discuss regarding ultimate loads and accelerations regarding aircraft. This aircraft was lost in the reverse sense of what we have been discussing - it was a sudden loss of mass which resulted in a rapid unloading of a spar weakened by fatigue which caused the catastophic failure. I do not know what the airspeed of the a/c was at the time of the failure but I suspect it was around Va to allow for manuvering to a precise location at low level. Who would have thought the unloading an airframe would lead to this? http://forums.ubi.com/images/smilies/sadeyes.gif

That airplane was never meant to fly again, it was bone yarded along with every other A model left in the USAFR inventory due to corrosion and fatigue cracking throughout the airframes. The A's took their own series of wing distinct from later varients, there are no new replacements in existence.

Funny thing though, structurally the A's wing when new was the strongest. This accident started a huge investigation into how these A models were ever released in the first place. The accident report specifically mentions the thermals off the fire and low altitude as a major factor, along with stress cracks.

Sergio_101
01-27-2007, 11:00 AM
Most if not all large radial engines of WWII
were operated at under 3,000 RPM.
Wright based 14 cylinder radials, like the BMW801
series were restricted to under 2,700 rpm.
If the gear reduction was 2:1. then the max prop
rpm was 1,350 rpm.

Contrart to popular myth, the higher ratio
was better for high speed since the prop tips
were more easily kept sub sonic at high power settings.

Fastest turning large aircraft engines
were the Napier Sabre series at over 4,000 rpm.

Merlins were usually 3,000 rpm or slower.

Late Allisons were cleared to go as high as 3,400 rpm.

I know of NO radials cleared for more than 2,700 rpm.

Sergio

JG14_Josf
01-27-2007, 11:26 AM
Most if not all large radial engines of WWII
were operated at under 3,000 RPM.
Wright based 14 cylinder radials, like the BMW801
series were restricted to under 2,700 rpm.
If the gear reduction was 2:1. then the max prop
rpm was 1,350 rpm.

Sergio_101,

Thanks. That data conflicts with this earlier exchange:


My presumption was stated:


engine turns to 2700 R.P.M.

A correction was made:


Propeller rpm not engine rpm.


I tried again:


Is it 2 to 1 gear reduction?

The engine is turning at 5400 R.P.M.?

Reply:


If the gear ratio was that high.

Please consider providing definitive supporting evidence.

I'll look myself. Misinformation is worse than ignorance.

5400 R.P.M. on a big radial did and does seem high.

2700 R.P.M. on a prop, now that I think about it, also seems high.

Knowing is better than guessing.

Thanks again.

Prop speed calculator (http://www.pponk.com/HTML%20PAGES/propcalc.html)

Kettenhunde
01-27-2007, 04:15 PM
My A & P corrected me on that. It is actually engine rpm on the gauge in the cockpit but is labeled as propeller rpm on the pilot checklist, operating instructions, and sometimes the tachometer itself.

The Focke Wulf propeller turns a .54 times the engine rpm.

2700U/min = 1458 propeller rpm with the 9-130006 reduction gear.

All the best,

Crumpp

T_O_A_D
01-27-2007, 09:09 PM
Originally posted by Sergio_101:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by T_O_A_D:
I haven't done it in a long time, but a patch long ago, I was playing with the 47 in a dive.

I coaxed one of my buddies to fly beside me in the same version of 47. From 10,000 we went straight down in a dive.
I never mentioned to him to turn his prop pitch to zero. His plane exploded, and mine kept right on diving and gaining speed, and held together, and I was able to pull out of it and fly on.

He was like WTH why didn't yours explode bla bla bla.

I finally let him in on what was going on.

I interpeted the 0% pitch forced the eng to a loer RPM thus removing the vibration forces of the over reaved eng and prop he had going on due to 100% pitch.

Never agreed with the scale in game though.
In boat props the higher the number of Pitch% the slower the Top RPM limit is, and vice versa. Why would it be differnt on an aircraft, or is it just the games interpetation of reality just backwards.


Airscrews/props work in a similar manner.
most boat props are not variable pitch, but not all.

Same rules. Same results.

The game has the lower number for pitch representing lower rpm.
This means more "feathered."

Fine pitch it represented by a higher number.

Seems ok to me. It works.

Sergio </div></BLOCKQUOTE>

More Feathered = More agresive pitch(more bite) Engine running?

But if engine is turned off the position has less drag?

If not feathered,(100%) it would be less pitch thus it would turn easier causing more drag?

Also more engine response due to less bite per revolution of prop?

Sorry for delay just got back into the discussion.

I hate text, I could get this wrapped right up with the voice I'm sure.

WWMaxGunz
01-27-2007, 11:55 PM
The blades move in a helix path (unless the plane is stopped, then they just spin) which has
a pitch of its own (yes that is a technical term, what is the pitch of a 1/4-20 bolt?) that
reduces with speed as that 'pitch' is measured as turns per length, 20 turns per inch for the
bolt. That sets a pitch angle that the faster the plane goes, the coarser the pitch of the
helix made by a blade tip, the slower it goes, the finer the helix. The angle is measured
between the helix and the perpendicular of the axis of rotation, ie across the bolt and not
along it. Just being clear.

OTOH faster rpm makes the pitch of the helix finer and lower rpm makes it coarser so the
coarsening effect of higher speed can be offset by the re-fining effect of higher rpms.
Which is good right up until the blade tips go past their critical mach and of coarse there
is a maximum RPM which is why I _specified_ full rpm on all the above. Tip speed is length
of tip path around the helix, per time (m/s) which grows with both speed and rpms. You
can shorten the blades but then you cut how much wing you are applying power to and you can
add blades but the return efficiency lowers with more blades and you can talk about blade
foil design and blade twist which may be optimised for different speeds but let's consider
once you got the prop there's no changing it either.

Go fast enough and no matter your power you gotta lower rpm or have the tips at mach.
Like in a steep dive you might get about any prop turned into a negatively-stalled windmill
even at the high stops unless it is feathered. Then it's much less drag.

Say you run along at 50% power and CSP at 100%. Your blade is at some AOA just enough to make
thrust to balance drag at your stabilized speed. You're not going real fast so the helix path
is fine and you don't have that much drag so your AOA does not add a whole lot of angle.
What happens if you crank it up and you have a monster engine? The CSP moves to add pitch to
keep the prop from overspeeding. With enough excess power the blades will pass critical AOA
and the thrust returned will actually be reduced from too high blade AOA. The plane should
speed up anyway and that coarsens the helix which effectively lowers the AOA of the blade,
at some speed the engine will no longer be making so much power as to pull the blades into
a stall condition and the inefficiency limiting acceleration will end, or the pilot can
control power intellegently by bringing it up till acceleration slows and then waiting until
forward speed is such that he can apply full power without stalling the prop.

There is a saying. With power must come responsibility.

JG14_Josf
01-28-2007, 05:45 AM
More Feathered = More agresive pitch(more bite) Engine running?


Feathered is too aggressive and beyond ˜bite', beyond full course pitch. While feathered with engine running the prop makes no thrust because the blade pitch angle is past the stall at any airplane speed. The prop blades are pointing parallel to the flight path center line. The wind cannot windmill the blades set to feather. That is why the blades have a feathered or full course pitch setting i.e. to minimized prop drag.

If the plane were on the runway at 2700 R.P.M and fine pitch (during engine run up) and the pilot suddenly adjusted the prop pitch angle to feather, then, the engine would shake, rattle, and fall off the motor mounts trying to turn the prop blades sideways through the air. The load on the engine from sideways or full course prop blades would stall the engine or break it. This is much like an automatic car transmission stall test. Put the car transmission in drive and then rev up the engine is like putting the airplane prop angle at feather and then rev up the engine. Put the airplane engine at high R.P.M. and then go to feather is like putting the car engine at high R.P.M. and then putting the automatic engine from neutral to drive. The difference is that the car impeller is moving hydraulic fluid and the airplane propeller is moving air mass.

I have not seen a prop engine prop stall test as described but I've heard someone describe it. The engine shakes, rattles, and appears to come off the engine mounts when running at high R.P.M. and the pilot suddenly moves the prop blade angle from fine (small load on the engine) to course (large load on the engine), and, feather is the most load possible on the engine (and produces no forward thrust and feather produces no rotating lift due to windmilling).


More Feathered = More agresive pitch(more bite) Engine running?

But if engine is turned off the position has less drag?


No ˜bite' at feather; meaning feather cannot produce thrust for the same reason that feather generates the least drag with the engine off. The prop blade lift vector is perpendicular to the velocity vector of the plane.


If not feathered,(100%) it would be less pitch thus it would turn easier causing more drag?


100% is a game term that can mean 100% R.P.M. Constant Speed Prop or maximum R.P.M. setting with the Constant Speed Prop manual control lever.

Less pitch = fine pitch = flat pitch = farthest from feather = least load on the engine = prop blade lift vector is parallel with the plane's velocity vector = the most engine power used to move air from the front of the plane to the back of the plane (thrust) AND the most drag when the engine is not running but the plane is flying as windmilling is greatest at fine, flat, pitch.


If not feathered,(100%) it would be less pitch thus it would turn easier causing more drag?

Also more engine response due to less bite per revolution of prop?


100% is a game term that should be an engine R.P.M. setting for the CSP prop pitch lever.

Like this:

100% = 2700 R.P.M = WEP R.P.M.
80% = 2450 R.P.M = Maximum continuous R.P.M.
60% = 2100 R.P.M. = High Cruise R.P.M.
50% = 1900 R.P.M. = Low Cruise (fuel savings) R.P.M.

The actual blade angle at 2700 R.P.M. and 200 km/h air speed in a climb is (or may be) fine or flat or farther from feather than the actual blade angle at 2700 R.P.M. at 700 km/h air speed in a dive because the engine must have a low enough load on the engine to keep the R.P.M up to 2700 R.P.M (while climbing or accelerating against drag) or a high enough load on the engine to keep the engine down to 2700 R.P.M. (while decelerating against drag or diving). If the Constant Speed Prop R.P.M. lever is set to 2700 R.P.M. (100%), then, the automatic governor maintains 2700 R.P.M. by loading up and unloading the engine with work (moving more air with higher prop blade angles or moving less air with lower prop blade angles). As the plane air speed goes up to 700 km/h the prop blade angle changes according to the load on the engine. As the plane air speed goes down to 200 km/h the automatic governor changes the prop blade angle to compensate for changes of work load on the engine. If the air is trying to move or windmill the prop, then, the work load on the engine decreases and, then, the blade angle moves to a higher or course pitch. If the plane is climbing or accelerating, then, the momentum of the plane can't be windmilling the prop, instead, the prop is moving the plane and the work load on the engine is high so the governor moves the blade angle to a lower or fine pitch allowing the engine to rev higher under the load of moving large quantities of air mass during acceleration or lifting of air plane mass.

Thinking in terms of 100% being direct prop pitch blade angle is a mistake that the game causes, yet, that direct prop pitch blade angle ability is possible in the game with the 109 on manual and should be, according to much of the evidence, the same ability with the 190 on manual prop pitch.

All automatic prop pitch WWII planes use constant speed governed props; as far as I know.

The game models the Fw 190 wrong and the game models the Me 109 almost right. You can see the prop blade angle move while flying the plane on automatic and manual.

The allied planes should have no automatic/manual setting because the allied planes have constant speed prop R.P.M. control levers that change the setting of the constant speed prop governor from high R.P.M. to low R.P.M.

The German planes on Automatic prop pitch SHOULD and apparently does link the throttle lever with the constant speed prop R.P.M. lever as one and the same lever.

As the German planes, on Automatic setting, move the throttle from low to high manifold pressure they also move the prop lever from low to high R.P.M. Constant Speed Governed R.P.M. setting. The Germans planes 190 and 109 both have LINKED throttle and CSP prop control levers as one lever.

The allied planes have two separate levers = no automatic/manual choice.

This may be confusing because the allied planes have more choices. The allied planes can close the throttle and leave the R.P.M. high to maximize deceleration as the high R.P.M. setting causes flatter prop pitch positions (under certain conditions) thus causing higher drag; where the German planes, on automatic, cannot. The German planes on automatic will automatically close the throttle and set a lower R.P.M. setting which causes higher prop angles during decelerations and thereby decreasing windmilling drag.

However; the 109 and 190 can also switch to manual (only the 109 can in the game) and directly move the blade angle during decelerations.

The 190 in the game is modeled with a linked C.S.P. to throttle automatic setting like it did in reality and the 190 in the game is modeled like an allied plane with a Constant Speed Prop R.P.M. adjusting lever like the allied planes (on manual in the game) which is wrong; it didn't have that option. The Fw 190 should be set up like the 109 in the game i.e. Automatic linked throttle and prop lever on the same lever and manual direct prop blade angle control – no allied type Constant Speed Prop R.P.M. control lever without being linked to the throttle – according the current evidence supplied by Kettenhunde – according to my interpretation.

Text is not as good as hands on experience.

Modern planes have the allied type Constant Speed Prop R.P.M. control levers or push/pull/turn cables.

T_O_A_D
01-29-2007, 05:52 PM
Thanks you two
You have made the best post I ever seen on clarifying my questions.

I pretty well understood it before 99% sure, but your post anchored it in solid this time.

http://forums.ubi.com/images/smilies/11.gif

JG14_Josf
01-29-2007, 06:21 PM
T_O_A_D,

When I first saw the prop pitch angle gauge in the 109 I knew this game was going to be fun. It is the one that looks like a clock down low on the right.

<S>