PDA

View Full Version : Combat Flaps



XyZspineZyX
09-25-2003, 04:57 AM
You can climb at 3800fpm in a P-39 simply by lowering combat flaps. Try it. I think it works fairly well in most other planes too. I was able to get 3400fpm in a P-40.

Proof positive that the FB Quality Assurence team (assuming there even is one) is completely asleep at the wheel.

XyZspineZyX
09-25-2003, 04:57 AM
You can climb at 3800fpm in a P-39 simply by lowering combat flaps. Try it. I think it works fairly well in most other planes too. I was able to get 3400fpm in a P-40.

Proof positive that the FB Quality Assurence team (assuming there even is one) is completely asleep at the wheel.

XyZspineZyX
09-25-2003, 06:57 AM
Interesting claim.

Please post the climb times in that condition, if possible, so we may compare.



-----------
Due to pressure from the moderators, the sig returns to..

"It's the machine, not the man." - Materialist, and proud of it!

XyZspineZyX
09-25-2003, 07:44 AM
I tried this with P-39N1.

Climb to 4000m with combat flaps, and without. 100% power, 100% fuel, summer, noon. Climb speed used is 240km/h IAS, as indicated by IL2compare. Flaps climb speed used is 220 IAS, arbitrarily picked to reflect high lift config.

No flaps (240IAS): 4000m in 4:43
Combat flaps (220IAS): 4000m in 4:17

So something appears to be wrong, either simply that the best ROC values in FB are wrong, or that the flaps are actually increasing the climb rate.

XyZspineZyX
09-25-2003, 05:15 PM
Yeah I wasn't that scientific about it, but all I know is that I climbed from takeoff with 25% fuel, 110% power, vents closed, combat flaps, and the fpm guage was indicating about 3800. I was climbing so fast that another pilot in a P-39N on the 401Cdn server last night commented, "Geez, man, how many times did you circle the field to get so high!" I fly P-39 a lot, ever since original game, and I just know from anecdotal experience that this is really not right. But, I'll try some more scientific tests when I get a chance. I used it a few more times in-game, but its such an incredible advantage that now I just feel bad about it because its such a glaring FM bug that it feels like a cheat. My favorite plane is ruined now.

XyZspineZyX
09-25-2003, 05:18 PM
Oh, one more thing, I find that about 290 is best climb speed without flaps, but with the flaps I was climbing at about 200-210. So I think, compared to the previous post, that the desparity will be even greater if your non-flaps climb is done at the faster speeds. But like I said, I'll do some more scientific testing and let you know what I find.

XyZspineZyX
09-25-2003, 05:37 PM
People moan about combat flaps and climb rates. The thing is, too my knowledge, the flaps have the same notch setting regardless of the aircraft. We all know this wasn't the case and that aircraft had different numbers of notches represented in degrees of elevation. I'm not certain about this but I think the flap positions in the game are standard for all aircraft which is going to affect climb rate because the setting are different to their real-life counterparts - the big ooo ahhh at the moment. This could mean that the climb rates are correct for the aircraft providing the flaps are retracted.

XyZspineZyX
09-25-2003, 07:37 PM
OK here's what I found out.

P-39N-1 100% fuel, vents closed, no flaps, 100% power takeoff from a standing start to 3000 meters, climb at 270-280 on the speedbar:

5 trials, averaged 3:43

Same configuration, but with combat flaps, 190kph on the speedbar:

5 trials, averaged 3:36

_________
It seemed no matter what my fuel, the difference between climbing with flaps or without was about 5-15 seconds faster with flaps. Guage was indicating 4000fps climb rate. By the way, over 5 trials, I found it extrememly difficult to get really consistent results. As a side note, I think everyone needs to do 10-20 trials or more to get any valid statistics. The wider the difference, the larger sample size we need.


I could only find P-39 time to altitude documented at 0-5000ft in 2.0 mins for the Q-5. My time to 1700 meters was 2:19 without flaps, 2:05 with. I only did it once, additional trials I think would result in a smaller difference.


So I'm not here to dispute the accuracy of the P-39 FM with regards to time to alt. (it seems pretty close), but I'm just very surprised that we get consistently better climb times with combat flaps. Is this accurate? Are everyone else's time trials skewed by not using flaps? I had no idea that 10 deg or so of flaps yields better times to alt., and I haven't seen anyone else mention it recently. In the end, somebody is wrong -- either accurate time to alt numbers need to be sought with flaps in combat position, or the FM is wrong with respect to lift combined with the drag coefficient of flaps extended. One or the other, I think.

XyZspineZyX
09-25-2003, 09:31 PM
I think that Oleg needs to go back and make a global physics change to FB so that the planes dont hang on their props.Keep thrust the same but add weight to all planes and then do some aerodrag recalculating for max speeds.I say this because it seems that there is too much thrust and we all know these planes didnt climb almost vertical in sustained climbs.By adding more weight to """"all"""" planes we can reduce this rocket ship performance since I dont think aero drag is really in equation at slow speeds and then reduce aero drag for max speeds to readjust.

XyZspineZyX
09-26-2003, 02:39 AM
Couldn't check this out myself, but if whatyou guys tested are true, then it is seriously wrong. Smells like the flaps are not producing enough drag.



-----------
Due to pressure from the moderators, the sig returns to..

"It's the machine, not the man." - Materialist, and proud of it!

XyZspineZyX
09-26-2003, 05:00 AM
OK lets look at this.

In the interest of "accuracy" the trim controls modeled for specific planes reflect what they had in real life.
So the 190's dont get to trim in flight for yaw and roll
and the 109's are the same I believe.

YET, The flap settings and controls for all planes are the same?? Is this allowing some planes that had all or nothing flaps to get better turn performance than they should?

If that is so, it seems to be a huge contradiction to me.

XyZspineZyX
09-26-2003, 05:41 AM
i think oleg maybe get in trouble with the FM which established dy his complex formula.this FM could give this sim veryhigh quality but even can bring lots unexpectable problem.

XyZspineZyX
09-26-2003, 06:00 AM
As a reference point, here is the flight manual climb data for P-39Q-1 (note: 7600 lbs. is full combat load):

http://www.axishq.wwiionline.com/~ring/planes/p39/Bel-P39-Q1-Manual/original/p29.jpg




--AKD

http://www.flyingpug.com/pugline2.jpg

XyZspineZyX
09-27-2003, 12:57 AM
I was under the impression that by lowering flaps to combat position, you are actually creating more wing area and more lift? The drag seems to be there, too, because his speed drops 20km/h.

Landing flaps provide much lift, but the drag is heavier, as I feel is represented in the sim. Landing flaps are perfect for getting over the top of a slow loop, using every last ounce of energy, to get nose-down on a stalling opponent below you./i/smilies/16x16_smiley-wink.gif

I'm going to go out on a limb here and say flaps work the closest now to RL, than they have in any version of IL2.

Isn't the function of flaps to provide additional lift? I think the formula just needs to be employed here for lift and we'll maybe see that the angle of climb is increasing, slightly more than the speed is lowering. The two climbs are not that far off. My .02.

_______________________________________
çk?¯kT 2003**

XyZspineZyX
09-27-2003, 03:07 AM
Doesn't make sense.

A plane reaching a "best rate of climb speed" at certain speeds, literally means that it is the best configuration possible for that plane.

Addition of combat flaps during climb will create lift, and allow higher AoA momentarily, achieving a better climb rate through same speed+sharper climb angle.

However, the lift comes with the price of additional and significant drag, which will bring the speed down eventually, to the point that the higher climb angle will become meaningless, as the climb speed will fall back that in the long run, the climb rate is actually lower than the best ROC config.

Thus, we have two possible guesses assuming the climb tests done by people are correct:

1) If the P-39s are reaching a better climb rate at higher climb angle made possible by use of combat flaps, it means the climb speed is not falling down to the level it should go down to - literally "insufficient E-bleeding".

2) However, if all planes are doing that, it would suggest it's not a problem of "E retention" but a problem of the flaps not creating enough drag per amount lift it generates.


ps) only certain types of flaps get more wing area through engagement. None of the planes we have in FB, are equipped with that type of flap.


-----------
Due to pressure from the moderators, the sig returns to..

"It's the machine, not the man." - Materialist, and proud of it!

Message Edited on 09/27/0311:08AM by kweassa

XyZspineZyX
09-27-2003, 06:31 AM
Then how do they create lift? They obviously are entering the air flow under the wing and creating more surface for the air to travel over, no? Isn't this what creates lift?

It's possible it dosen't bleed enough E, but flaps should certainly help lift. And they do that. It's possible the drag is not high enough, I guess in real life you would not be able to climb faster with combat flaps than you would with no flaps?

I'm asking, because I'm not sure and am trying to learn me something./i/smilies/16x16_smiley-wink.gif

_______________________________________
çk?¯kT 2003**

adlabs6
09-27-2003, 07:31 AM
It's been a while since I thought on this topic, but I'll try to explain anyway.

Most flap usage is intended to reduce stall speed, increase lift, and create drag.

Stall speed is lowered due to geometery changes to the wing chord. Lift increases, but not becaues of the traditional causes of lift, pressure differences, but rather this lift is a deflection type of lift (the correct name escapes me now). And of coures drag is the consequence of enlarging the profile of the aircraft. In most cases this drag is desirable, as intended during landing.

Now let me clarify the "lift" that most flaps generate. Wings of course produce lift by creating pressure differences above and below the wing. This type of lift is very effective at higher speeds. Lift generated by most flaps is not an extension of the pressure differences created by the wing, but rather a vertical deflection of airflow. This type of lift is economical at lower speeds, but requires very high thrust to maintain flight at high speeds (lifting body designs).

Much the same as sticking ones hand out the car window while driving. Obviously there is no aerodynamic lift given the shape of the human hand. But, but using an increased angle of attack (as flaps do) lift can be generated simply by deflection. The high cost of this is felt as the wind pulls back against ones arm.

I believe that most aircraft are designed for maximum lift power in wing geometry, rather than from flap deflection. In fact, excessive deflection below an airfoil can interupt the aerodynamic lift process if I remember correctly, decreasing lift performance.

EDIT: This is also the basis of the flare at landing. By increasing the angle of attack, we are also increasing the amount of deflection lift the wings are producing, as well as increasing drag. At the same time, as the angle of attack increases to a certain point, the effectivness of the wings aerodynamic lift is reduced slightly, and we both bleed energy and lift only inches above the ground.

I hope thats correct....

<html>
<body>
<table cellpadding="2" cellspacing="0" border="0" width="600" align="center">
<tbody>
<tr>
<td valign="top" bgcolor="#ffffff">
<font face="Helvetica, Arial, sans-serif"><font color="000000">adlabs<font color="#ff9900">6</font></font>
</td>
</tr>
<tr>
<td valign="top" bgcolor="#42524e">
<div align="center"><font color="#999999">
http://www.geocities.com/adlabs6/B/bin/sigtemp.JPG (http://mudmovers.com/Sims/FB/fb_skins_historical_adlabs6.htm)
<small><font color="#ff6600">NEW</font> at mudmovers! Click the pic to download my skins from mudmovers.com!</small>
</font>
Skinner's Guide at mudmovers (http://mudmovers.com/Sims/FB/fb_skinnersguide.htm) | Skinner's heaven (http://www.1java.org/sh) | IL2skins (http://www.il2skins.com)
<font color="#999999">
My Forgotten Battles Webpage (http://www.geocities.com/adlabs6/B/index.html) Current Wallpaper: <font color="#999999">Bf-109 Morning Run</font></font>

<A HREF="http://forums.ubi.com/messages/message_view-topic.asp?name=us_il2sturmovik_gd&id=zhiwg" TARGET=_blank>"Whirlwind Whiner"
The first of the few</A>
</div>
</td>
</tr>
</tbody>
</table>
</body>
</html>

Message Edited on 09/27/0306:39AM by adlabs6

adlabs6
09-27-2003, 07:44 AM
j145198 wrote:
- You can climb at 3800fpm in a P-39 simply by
- lowering combat flaps.

Yes, I remember seeing this once. Once I was recording a track online, and when I reviewed it later, I was watching a P-39 pilot takoff. His method was to get to speed down the strip, with NO flaps lowered. Then, he pulled the plane into a steep climb, and at the same time, dropped his combat flaps for a few seconds. He then retracted flaps and climbed at speed.

I tried this and it seems to give a nice kick to getting the plane up quickly from the strip in a hurry. I think it was v1.0, but it still may work now.



<html>
<body>
<table cellpadding="2" cellspacing="0" border="0" width="600" align="center">
<tbody>
<tr>
<td valign="top" bgcolor="#ffffff">
<font face="Helvetica, Arial, sans-serif"><font color="000000">adlabs<font color="#ff9900">6</font></font>
</td>
</tr>
<tr>
<td valign="top" bgcolor="#42524e">
<div align="center"><font color="#999999">
http://www.geocities.com/adlabs6/B/bin/sigtemp.JPG (http://mudmovers.com/Sims/FB/fb_skins_historical_adlabs6.htm)
<small><font color="#ff6600">NEW</font> at mudmovers! Click the pic to download my skins from mudmovers.com!</small>
</font>
Skinner's Guide at mudmovers (http://mudmovers.com/Sims/FB/fb_skinnersguide.htm) | Skinner's heaven (http://www.1java.org/sh) | IL2skins (http://www.il2skins.com)
<font color="#999999">
My Forgotten Battles Webpage (http://www.geocities.com/adlabs6/B/index.html) Current Wallpaper: <font color="#999999">Bf-109 Morning Run</font></font>

<A HREF="http://forums.ubi.com/messages/message_view-topic.asp?name=us_il2sturmovik_gd&id=zhiwg" TARGET=_blank>"Whirlwind Whiner"
The first of the few</A>
</div>
</td>
</tr>
</tbody>
</table>
</body>
</html>

XyZspineZyX
09-27-2003, 08:37 AM
Thanks, adlabs. That explanation looks good enough for me.

(I hope it's right.)/i/smilies/16x16_smiley-wink.gif

So, flaps do provide lift, but in this case, the drag may not be modeled high enough for the P39. Does that sound about right?

_______________________________________
çk?¯kT 2003**

XyZspineZyX
09-27-2003, 01:53 PM
Flaps do provide extra lift and are used if you need to increase your <u>angle</u> of climb, to clear an obstacle at the end of the runway perhaps. But they also increase drag, like many of you have said, which is a 'waste' of energy. <u>Rate</u> of climb should always be better with the flaps retracted. Much as you get a steeper climb by pulling the stick back, but get a faster climb by pushing it back down to obtain the best climb speed.

The next question is what other ac gain RoC by dropping a notch of flap?

Kernow
249 IAP

XyZspineZyX
09-27-2003, 07:05 PM
Slick, resort to this link for detailed info on wing thingamajics. In their engineer's tongue, flaps work this way:

"When deflected, flaps increase the upper camber of the wing, increasing the negative pressure on the top of the wing. At the same time, they allow a build up of pressure below the wing."


http://www.allstar.fiu.edu/aero/Wing33.htm


Note in their flap drawings, that only the "Fowler" type actually increases wing area. These type of flaps were extensively used in the P-38 and the Japanese fighters. I don't think any VVS or LW plane had this design, though.







-----------
Due to pressure from the moderators, the sig returns to..

"It's the machine, not the man." - Materialist, and proud of it!

XyZspineZyX
09-27-2003, 08:13 PM
Yes, but the flaps we have must be providing that same extra pressure under the wing for more lift, no?

Drag seems to be the main issue here or lack of enough thereof. Good info, All.

Wow, learning CAN be fun./i/smilies/16x16_smiley-wink.gif

_______________________________________
çk?¯kT 2003**

XyZspineZyX
09-27-2003, 08:35 PM
SlickStick wrote:
- Yes, but the flaps we have must be providing that
- same extra pressure under the wing for more lift,
- no?

The shape of the airfoil as seen from one end of the wing, the camber, provides that the distance the air must travel over the top of the wing is greater (due to the curvature) than the distance on the undersurface. The velocity of the airflow over the top of the wing therefore "speeds up" and, according to Bernoulli, results in lower pressure than that under the wing. This pressure differntial causes lift. The fact is, the wing is "sucked up" moreso than it is being "pushed up" by the air. Lowering flaps changes the camber and increases the distance over the topside of the wing, thus creating more lift, but with increased drag.

XyZspineZyX
09-27-2003, 08:45 PM
Thanks for that, Spectre. Clearer for me now.

_______________________________________
çk?¯kT 2003**

adlabs6
09-27-2003, 09:49 PM
Thanks for that nice link.

I found there that the type of deflection lift I was referring to but couldn't recall the name of is "dynamic lift". As I said, this "dynamic lift" only plays a mentionable role at lower speeds and with high flap angles combined with high AoA. Read more about it here...

http://www.allstar.fiu.edu/aero/flight41.htm

<html>
<body>
<table cellpadding="2" cellspacing="0" border="0" width="600" align="center">
<tbody>
<tr>
<td valign="top" bgcolor="#ffffff">
<font face="Helvetica, Arial, sans-serif"><font color="000000">adlabs<font color="#ff9900">6</font></font>
</td>
</tr>
<tr>
<td valign="top" bgcolor="#42524e">
<div align="center"><font color="#999999">
http://www.geocities.com/adlabs6/B/bin/sigtemp.JPG (http://mudmovers.com/Sims/FB/fb_skins_historical_adlabs6.htm)
<small><font color="#ff6600">NEW</font> at mudmovers! Click the pic to download my skins from mudmovers.com!</small>
</font>
Skinner's Guide at mudmovers (http://mudmovers.com/Sims/FB/fb_skinnersguide.htm) | Skinner's heaven (http://www.1java.org/sh) | IL2skins (http://www.il2skins.com)
<font color="#999999">
My Forgotten Battles Webpage (http://www.geocities.com/adlabs6/B/index.html) Current Wallpaper: <font color="#999999">Bf-109 Morning Run</font></font>

<A HREF="http://forums.ubi.com/messages/message_view-topic.asp?name=us_il2sturmovik_gd&id=zhiwg" TARGET=_blank>"Whirlwind Whiner"
The first of the few</A>
</div>
</td>
</tr>
</tbody>
</table>
</body>
</html>

XyZspineZyX
09-27-2003, 11:27 PM
Also, note that the lift comes at a price of drag. Those two factors interact, so in the case when combat flaps are engaged during climb, the plane will have a nose-up attitude and retain higher AoA, at a price of loss of speed - which, will in turn, actually lower the climb rate.

The advantage in climb gained by the extra lift, is smaller than the disadvantage of losing climb speed. Hence, the best rate of climb is a balance between angle and speed. Combat flaps, will destroy that balance and have a negative effect.



-----------
Due to pressure from the moderators, the sig returns to..

"It's the machine, not the man." - Materialist, and proud of it!