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fighter1976
04-08-2010, 06:07 AM
Hy!question;how do i adjust the pitch on "complex engine management" setting?what percentage is needed at take off and landing, in combat situation, for speed and so on?
I noticed that if i let the autopilot do the settings just before take off, I can't take off because the engine lost all the pushing force...guess is the propeller pitch...or in flight,if i change the pitch i damage the engine in short time.
Thanks

julian265
04-08-2010, 07:02 AM
A search will yield many threads on this topic. But in general, 100% pitch is good for best acceleration, best climb, and maximum level speed.

AndyJWest
04-08-2010, 08:31 AM
in general, 100% pitch is good for best acceleration, best climb, and maximum level speed.
Yup. And if anyone claims otherwise, ask for evidence. I've seen some weird statements made about prop pitch settings on this forum, but no actual proof that anything other than the obvious setting gives better sustained speed in level flight.

Many, possibly the majority, of the aircraft modelled in IL-2 have constant-speed props, and the 100% setting corresponds with the best engine RPM power band. The only reasons for reducing engine RPM below this are (a) fuel economy or (b) to cure an engine overheat problem, though if you get the latter in level high-speed flight there is probably something wrong with the aircraft cooling system design.

Ba5tard5word
04-08-2010, 10:02 AM
You can leave it at 100% most of the time with planes and not have any problems. You need to reduce it if you are in a really steep and fast dive because if you don't you will overrev the engine and break it. I have "0% prop pitch" set on my keyboard so I press that if I need to make a steep dive, also I use it if I want to land and need to lose a lot of speed--then I also have "100% prop pitch" set so I can bump it back up to 100 when I want it with one press of a key.

A lot of planes, especially German fighters and some Allied planes like some Spitfires, have automatic prop pitch so you won't have to worry about them over-revving in a dive, they'll automatically lower and raise the prop pitch.

WTE_Galway
04-08-2010, 06:16 PM
Originally posted by Ba5tard5word:
You can leave it at 100% most of the time with planes and not have any problems. You need to reduce it if you are in a really steep and fast dive because if you don't you will overrev the engine and break it.

If you switch to manual pitch, you may also need to reduce prop pitch on some aircraft during takeoff (Emil for example) .

One simple technique for using manual pitch on planes that are not a CSP is to set throttle to give revs that match current situation (cruise power or combat power) and then leave throttle alone and control speed with pitch.

jengizbengiz
04-08-2010, 06:36 PM
Originally posted by WTE_Galway:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Ba5tard5word:
You can leave it at 100% most of the time with planes and not have any problems. You need to reduce it if you are in a really steep and fast dive because if you don't you will overrev the engine and break it.

If you switch to manual pitch, you may also need to reduce prop pitch on some aircraft during takeoff (Emil for example) .

One simple technique for using manual pitch on planes that are not a CSP is to set throttle to give revs that match current situation (cruise power or combat power) and then leave throttle alone and control speed with pitch. </div></BLOCKQUOTE>

Hi WTE_Galway,
could you please give a more precise describtion of the whole procedure you are referring to? As far as I read in the forum and M4T, prop-pitch works comparabel to gears in a car. Is this actually true (or more or less a myth?!) and how is this feature implemented (more or less) realisticly in the FM of IL-2?

Regards!

WTE_Galway
04-08-2010, 07:30 PM
Originally posted by jengizbengiz:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by WTE_Galway:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Ba5tard5word:
You can leave it at 100% most of the time with planes and not have any problems. You need to reduce it if you are in a really steep and fast dive because if you don't you will overrev the engine and break it.

If you switch to manual pitch, you may also need to reduce prop pitch on some aircraft during takeoff (Emil for example) .

One simple technique for using manual pitch on planes that are not a CSP is to set throttle to give revs that match current situation (cruise power or combat power) and then leave throttle alone and control speed with pitch. </div></BLOCKQUOTE>

Hi WTE_Galway,
could you please give a more precise describtion of the whole procedure you are referring to? As far as I read in the forum and M4T, prop-pitch works comparabel to gears in a car. Is this actually true (or more or less a myth?!) and how is this feature implemented (more or less) realisticly in the FM of IL-2?

Regards! </div></BLOCKQUOTE>


Well I am not over sure how well the distinction is implemented in the game but I was trying to distinguish between two different types of prop pitch control.

Late war aircraft often had what are termed Constant Speed Units (CSU) where the pitch lever controls the SPEED of the prop (and hence engine). The actually pitch of the prop automatically adjusts in an attempt to keep the prop/engine speed as close as possible to that selected by the lever position. Generally in this type of aircraft you select the prop setting that gives you optimal RPM.

On the other hand aircraft like the Emil tended to just have a variable pitch prop where the lever in the cockpit directly controlled the pitch of the propeller. In this type of aircraft you set throttle and then adjust pitch lever continually to keep engine RPM in optimal powerband.

M_Gunz
04-09-2010, 12:46 AM
The P-40s had the Curtiss Electric CSP from the start. Also Spitfires had CSP IIRC by the Spit II model.
Bf-109s had electric prop with some engine control built in but I don't know which model that began,
maybe from the start like the P-40s.

M_Gunz
04-09-2010, 12:59 AM
Originally posted by fighter1976:
Hy!question;how do i adjust the pitch on "complex engine management" setting?what percentage is needed at take off and landing, in combat situation, for speed and so on?
I noticed that if i let the autopilot do the settings just before take off, I can't take off because the engine lost all the pushing force...guess is the propeller pitch...or in flight,if i change the pitch i damage the engine in short time.
Thanks

Fly along at 100% power and 100% prop pitch in a P-51 and see at some alt what speed you make.
Then cut power to 80% and prop pitch to 80% as well. Note your speed again.
Then raise prop pitch to 100% and see what happens to your speed.

If you don't have the power to keep the prop turning at desired rpm for the speed you are going then the prop blades will
flatten out enough that the power you do have will keep them turning while producing less thrust. That is how they work.
If you are slow then 100% pitch can get you more 'traction' but when you are going too fast the traction works in reverse.
That's actually a very good thing when you're coming in to land. At low power and 100% prop pitch you have very good low
speed control that will go a long way towards eating speed gain from losing height. Open the rads fully, the cockpit if
you can, all the things that hang out and drag and you might find yourself adding power to not drop too fast.

If my top speed is 440mph but I am diving at 550mph then what role is my prop playing just then? It's a freaking brake is
what role it plays. My concern is to have it be less of a brake rather than more, IRL just to keep the prop gearing from
tearing to bits while trying to drive the engine, which it can and IRL had done.

fighter1976
04-09-2010, 01:27 AM
Thanks a lot guys!

Art-J
04-10-2010, 06:02 AM
Originally posted by jengizbengiz:

Hi WTE_Galway,
could you please give a more precise describtion of the whole procedure you are referring to? As far as I read in the forum and M4T, prop-pitch works comparabel to gears in a car. Is this actually true (or more or less a myth?!) and how is this feature implemented (more or less) realisticly in the FM of IL-2?

Regards!

WTE explained it well. You just remeber to be carefull about using "car gearbox" analogy - it's good and makes understanding variable pitch props easier, but it applies only for planes in which you really change the pitch manually. In Il-2 there are only a handful of them - most of the planes with German inline engines or their licence built versions, and even these have automated systems turned on by default, you have to bind a separate key to switch to manual operation!

All the other planes are equipped with constant speed props (CSPs) which are totally different system and work just like WTE said. You can't compare it to any type of a car gearbox - if you tried to do so, you would get a car in which wheels rotate at the same predefined speed no matter how fast the car is driving http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif.

I think the confusion is caused partially by an unfortunate message which appears when you make any operations with prop lever. The message always uses the word "pitch" no matter what plane you fly, while it also should sometimes look like "prop RPM" ot sth like that. It's not a big deal for the game, just a simplification, but it makes things a bit more difficult to understand for the guys who are not yet familiar with all tech details of piston powered planes.

Cheers - Art

julian265
04-10-2010, 06:54 AM
Originally posted by Art-J:
You can't compare it to any type of a car gearbox

Except a CVT - continuously variable transmission, to which it is a good match. The governor chooses an engine RPM, and adjusts gearing accordingly (hourglass friction drive, or variable gap V-pulleys usually). I don't know of any that let the driver choose that RPM though, it's done by computer, but it is certainly adapting gearing to keep the engine at an RPM suitable for the desired speed or acceleration, as we do in IL2 with CSPs.

M_Gunz
04-10-2010, 12:20 PM
If the car was equipped with off-road treads and run on wet ice or fine wet sand then the gear box analogy
might translate better. Wheels spinning not having an immediate effect on actual car movement kind of thing.

Hi Julian, think torque-converter maybe? I've seen them work in cars since the late 60's (what I have seen,
not the complete history of them) and never the other ones you mentioned. From what I understood in 1968 they
work by changing the pitch of blades in a working fluid....

Art-J
04-10-2010, 03:18 PM
Originally posted by julian265:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Art-J:
You can't compare it to any type of a car gearbox

Except a CVT - continuously variable transmission, to which it is a good match. The governor chooses an engine RPM, and adjusts gearing accordingly (hourglass friction drive, or variable gap V-pulleys usually). I don't know of any that let the driver choose that RPM though, it's done by computer, but it is certainly adapting gearing to keep the engine at an RPM suitable for the desired speed or acceleration, as we do in IL2 with CSPs. </div></BLOCKQUOTE>

Point taken! Completely forgot about that one. I remember reading about DAF cars using it years ago... However, I don't think it became very popular, are there any cars with this type of transmition produced today?

Cheers - Art

K_Freddie
04-10-2010, 03:51 PM
100% radiator induces drag which requires more prop or throttle to compensate.

50% radiator induces less drag, which can be compensated by less throttle and/or prop for the same speed. Play around a bit on various a/c

you choose http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

M_Gunz
04-11-2010, 12:40 AM
And at the final bit as you're coming in to land do you want the extra speed you get from losing the last
bit of altitude to be more under your control or less?

At low speed with the most drag you can get and prop pitch at 100%, your speed is more strongly limited by
your throttle than at lower prop pitch.
At LOW power the CSP-equipped plane cannot keep producing thrust above LOW speed. It becomes a source of drag.
Making your plane more draggy only helps with speed control during descent.
It is that simple.
Perhaps by using fewer words I can get an "oh yeah" since I won't make a Youtube demonstration.

I don't expect Freddy to accept this. I won't say why.

JtD
04-11-2010, 12:58 AM
Originally posted by Art-J:
However, I don't think it became very popular, are there any cars with this type of transmition produced today?

I remember the Subaru Justy from the old days, but it got phased out. Subaru is introducing a CVT with the Outback and Legacy models 2010 for the US market. Nice Subaru article on their CVT. (http://www.subarudrive.com/Sum09/Sum09_whatmakes.htm)

Guess there might be more around...

julian265
04-11-2010, 04:16 AM
Originally posted by Art-J:
Point taken! Completely forgot about that one. I remember reading about DAF cars using it years ago... However, I don't think it became very popular, are there any cars with this type of transmition produced today?

Cheers - Art

I had a ride in a DAF (after Volvo bought it?) with belt CVT - it had a 1.3L Renault engine IIRC, but that example still used 12L/100km http://forums.ubi.com/images/smilies/shady.gif

There are some popular recent Nissans that have CVT in Aus, and a few others too I think. I wouldn't have brought it up had they been truly rare. Of course, cars have become appliances so most drivers wouldn't know if their transmission was via rubber-band or CVT! I love the concept, and am annoyed that user acceptance (or lack of it, from knuckle-draggers) has prevented the development that it deserves.

"Improved CVTs capable of handling more powerful engines were developed in the late 90s and 2000s, and CVTs can now be found in cars from Nissan, Audi, Honda, Ford, GM, and other automakers." from http://cars.about.com/od/thing...needtoknow/a/CVT.htm (http://cars.about.com/od/thingsyouneedtoknow/a/CVT.htm)

M_Gunz
04-11-2010, 01:19 PM
I got 36 mi/gallon mixed-mileage (mostly highway that trip) in my 67 VW Type 3 Fastback with 4-speed.
That car was 15 years old when I got it and still tuned up ran that well for me.

How much efficiency do I lose to have a car with no gear shift? Will it be able to handle tricky
twisty roller-coaster roads anywhere near as well, the kind where what you see ahead decides how
you work the gas and shift as much for control as speed and efficiency? I don't think so!
Lazy drivers will never do as well except in cars that handicap really good driving practices.

I love the concept of CVT. If Subaru is using it then it should be efficient compared to what the
competition is using.

My test of efficiency is: will it work if applied to a bicycle?

mortoma
04-11-2010, 04:53 PM
Reducing your prop pitch suddenly in this game, whether flying level or in a dive, from shallow to steep will result in much quicker acceleration. It's kind of an exploit or cheat, really. The best time to do it is when you have accidentally gotten a little slower than you'd like. Reduce your PP to maybe 70% to 80% for a few seconds and it will make you accelerate, ( more like leap ) to a faster speed. Then, once you pick up 50KPH, do it again but don't go down as low, maybe to 85%, you'll get yet another burst. I do it as many as three times until I get up to full speed or nearly so. Makes a huge difference from just jamming the throttle to 100 or 110% and leaving the plane to accel on it's own.

TinyTim
04-11-2010, 05:16 PM
There is a plane in the sim where you have to fiddle with prop pitch if you want to avoid engine damage.

That's a Savoia Marchetti SM.79, which in reality only had two pitch settings - "low" for climbing and takeoff, and "hi" for cruise flight. Kinda like a car with only two gears. It's simulated in a game, all the values above 50% prop pitch correspond to "low" gear, 49% and below is hi one. That's why don't forget to lower your pitch below 50% when above 270 or so kph or you'll ruin your engines (kinda like running a car as fast as it can go in the lowest gear).

AndyJWest
04-11-2010, 05:31 PM
Ah yes, forgotten about that one. I think you should select low pitch for landing too, just in case you need to make a go-around. There are some fairly awkward trim changes due to the automatic flaps, so it takes a bit of getting used to.

julian265
04-11-2010, 05:56 PM
Originally posted by M_Gunz:
I got 36 mi/gallon mixed-mileage (mostly highway that trip) in my 67 VW Type 3 Fastback with 4-speed.
That car was 15 years old when I got it and still tuned up ran that well for me.

How much efficiency do I lose to have a car with no gear shift? Will it be able to handle tricky
twisty roller-coaster roads anywhere near as well, the kind where what you see ahead decides how
you work the gas and shift as much for control as speed and efficiency? I don't think so!
Lazy drivers will never do as well except in cars that handicap really good driving practices.

I love the concept of CVT. If Subaru is using it then it should be efficient compared to what the
competition is using.

My test of efficiency is: will it work if applied to a bicycle?

I would have thought that good CVT controllers will do a better job than conventional stick shift - because they can keep the engine at an RPM suited either to fuel economy or power (mode chosen manually ('sport' button) or by foot position), can smoothly change gear without disengaging, and can easily prevent engine braking when you're off the gas, and of course the gaps in gearing are very small, meaning that you've got the right gear for any speed. It simply adapts to how much power you want at any one time (read through the accelerator pedal). Also, the CVT would prevent all of the drive-train shock which many drivers apply when shifting, which will help the life of joint bearings and axles.

Whether the engineers who design the controllers actually know what they're doing is a possible problem, as I've noticed a few basic mistakes around the place with modern electronically controlled autos, regarding gear selection. Also the driver needs to know what to expect with a CVT, just like with ABS. Some people still think "pressing the brakes caused a nasty noise and vibration, I'd better release them", which is not what you should do with ABS.

There wouldn't be much use for CVTs in cars if they didn't provide performance and efficiency advantages - as they're more complicated than standard transmissions, and more expensive. I think their main challenges are getting good efficiency from belts, or getting grip between friction wheels. What would decide the issue for me is the expected lifetime of the transmission. If they won't last like a normal gear box, or at least be easy and cheap to replace the consumables (eg belts or friction wheels), then I wouldn't be interested.

Also, I wouldn't be using even a scaled down conventional gear box on a bike!

M_Gunz
04-12-2010, 01:15 AM
I mention bicycle because the cogs, roller chain and gearing they use is so highly efficient.
In terms of calories per kilometer even soaring birds are less efficient than a well ridden,
well maintained bicycle as they were around 1970 and they are slightly moreso now.

All transmissions have inherent friction. One that has roller chain pushing on the sides only
is going to be less so than a fixed ratio pulley. The fixed ratio pulley still has friction
and forces other inefficiencies onto the engine. So overall the CVT may be more efficient.

So I bottom line it and ask does this get better mileage than my 1967 VW with the many draggy
bits on an overall clean shape that it had? Even the metal on that was thick compared to the
econo-boxes of the late 70's and onward but then a 5-speed Civic did get better mileage.

Stiletto-
04-12-2010, 01:55 AM
Gunz, you can't really compare your VW's fuel milage to todays cars based on transmission or even engine size to some extent because todays cars due to stringent safety standards and luxury items that are mostly considered standard have raised the weight of a car dramatically. Most cars today weigh half a ton more than your VW did which will obviously have a big influence on fuel mileage, more so than what kind of transmission you have in it as long as they both have an over-drive.

Still it would be interesting to take a single car and change the transmission from a manual to a CVT and compare fuel mileage on similar test runs. I am thinking though, that it is used more for performance than fuel economy. Also, the belt can only stretch so far so it's not really used in the full rev range to keep it at it's engines peak.

My mother has a 2 year old Nissan Altima with the CVT transmission and its pretty awesome, when you put your foot down on a highway on ramp and the speed goes up but the revs just stay the same in peak operating range. It reminds me of the Williams F1 cars that won the champsionship in 1993.

http://www.youtube.com/watch?v=x3UpBKXMRto

M_Gunz
04-12-2010, 03:37 AM
The lightest Type-3 was 880kg, over 1900 lbs. I see Subaru Legacy at 1400kg.
So yes, heavier. Highway mileage is not about weight unless too much hills or
total positive height change though, at least over much distance so perhaps
that could indicate where changes take us.

Just the fact that they have this running in cars known for good mileage and
reliability tells it is good enough. Subaru makes good cars AFAIK.