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View Full Version : Prop Pitch model in IL2 per Oleg Maddox



Aardvark184
06-08-2006, 08:14 PM
I have been confused lately about how exactly prop pitch is modeled in IL2, so I decided to go to the source for the answer. I emailed the bug-report email, and asked:

(paraphrased) Is prop pitch at 100%:
1) when the blades are closest to perpendicular to the fuselage (lay flattest), causing the least thrust, and least drag, or
2) when the blades are angled farthest away from the engine cowling, closest to being feathered.

I know OM is busy, so I asked for a simple 1 or 2. He replied, in a very verbose email:



1.



Just kidding. That's all he wrote, really. So that means that when your prop pitch is at 100%, your engine will spin fastest for the least amount of thrust, and as you decrease the pitch, the blades start to increase their angle away from the cowling. This increases thrust, and effectively slows your engine down.

I know this was REALLY wordy, but I wanted to make myself very clear because I'd been so confused about it for so long that maybe there's at least one more person out there that just doesn't get it either. One person helped makes all this worthwhile.

Now you can go ahead and start flaming me for being airplane-illiterate... pretty bad since I am (or at least was) an Air Force Crew Chief... in all fairness, I've never worked on prop planes.

Cheers!

Tim

Aardvark184
06-08-2006, 08:14 PM
I have been confused lately about how exactly prop pitch is modeled in IL2, so I decided to go to the source for the answer. I emailed the bug-report email, and asked:

(paraphrased) Is prop pitch at 100%:
1) when the blades are closest to perpendicular to the fuselage (lay flattest), causing the least thrust, and least drag, or
2) when the blades are angled farthest away from the engine cowling, closest to being feathered.

I know OM is busy, so I asked for a simple 1 or 2. He replied, in a very verbose email:



1.



Just kidding. That's all he wrote, really. So that means that when your prop pitch is at 100%, your engine will spin fastest for the least amount of thrust, and as you decrease the pitch, the blades start to increase their angle away from the cowling. This increases thrust, and effectively slows your engine down.

I know this was REALLY wordy, but I wanted to make myself very clear because I'd been so confused about it for so long that maybe there's at least one more person out there that just doesn't get it either. One person helped makes all this worthwhile.

Now you can go ahead and start flaming me for being airplane-illiterate... pretty bad since I am (or at least was) an Air Force Crew Chief... in all fairness, I've never worked on prop planes.

Cheers!

Tim

XyZspineZyX
06-08-2006, 08:20 PM
When considering the sense of 100% prop pitch in game, just read it as 100% RPM since this what prop pitch is used for anyway.

JG53Frankyboy
06-08-2006, 08:32 PM
so much topics about pitch the last days http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif
so i had just to copy and paste http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif


the most planes in game have a ConstantSpeedPropeller system.
so you dont control direct the angle of the propeller blades - you set revolutions for the engine that the propeller tries to mantain automaticly by setting the needed Bladeangle with the given power ( throttle setting).
100% is here the max available revolutions.

in a Bf109/Do335 (all german planes with Daimler Benz piston engines) in manual modus its a different story, there you are controling the propeller angle directly ! there you have realy to watch the rev gauge, other wise your engine is going to nirwana very fast !
100% is here the lowest angle , the blades are giving the lowest drag for the propeller revolution !

there are few planes that can overrev in a highspeed dive (even with CSP), G.50 and Mc.200 are comming in my mind . not sure what the Buffaloes are doing in the actual patch version- in the past they did too - and the La7 can also.


the auto mode in the Fw190s and SpitfireIX/VIII is more working like a "link" between the throttle and the pitch lever to reduce work for the pilot when he dont need full power - in real engine endurance was more important as in game

unfortunatly the Fw190 are faster on manual mode ( http://forums.ubi.com/groupee_common/emoticons/icon_frown.gif ) , so their Kommandoger√¬§t (BMW801) and Motorbediengetriebe (Jumo213) is actually a bad joke (in game).

btw, in a Fw190 on manual you can see nicely how the CSP is changing the Bladeangle - it has a gauge for that.
and in a Bf109/Do335 you can see that the angle is constant in manual mode if you dont change it
well, where is this gauge....... -> http://free-st.htnet.hr/dvd/

WWMaxGunz
06-08-2006, 11:13 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Aardvark184:
Just kidding. That's all he wrote, really. So that means that when your prop pitch is at 100%, your engine will spin fastest for the least amount of thrust, and as you decrease the pitch, the blades start to increase their angle away from the cowling. This increases thrust, and effectively slows your engine down.
</div></BLOCKQUOTE>

Mostly that, Chief. Esp with CSP.

The blades actual pitch, rpm and forward movement of the plane combine to give them an AOA
that may be positive (even to stall) or zero or negative (prop drives motor). CSP does the
adjustment but there are IRL limits to the blade angle possible.

There is also torque at rpm of the engines, I am sure you and others know more detail of that
than I do.

I just try things out with the sim and see what differences I get.