Prop Pitch question...

[BSS_Sniper]

Originally Posted by 41Sqn_Banks

Thats wrong. Your comparison with a manual transmission in a car is only valid when having a manual pitch control, but not for constant speed. A csp is a car with automatic transmission where 100% rpm is for "sporty" driving and everything below 100% rpm is for economical driving.

Top Speed is at maximum rpm and maximum boost, just look at historic performance tests, for top speed they always were at maximum rpm and maximum boost. Why would they do this when there was more speed at lower rpm

CEM is so messed up in this game, I mean, he never really had it modeled.

I believe you got things mixed up a bit. Manual pitch control and constant speed propellers are the same thing. When you set a RPM with your prop lever you are doing two things, changing the angle of the blade AND setting a particular RPM. Neither change with power (manifold pressure) inputs.

If you're confused in game about how to use these things, its understandable since it isn't modeled correctly. Each aircraft has a chart in the pilot operating handbook that shows manifold pressure and prop settings for different phases of flight ie; takeoff, climb, cruise climb, cruise, decent, approach and landing. For full power and speed its always full MP and full Prop. Again, this game doesn't model it correctly and the little tricks learned to do different things in here (concerning CEM) would not work in a real plane, it would destroy the engine.

I fly aircraft with constant speed propellers daily for work, turbines included. My boss would kill me if I pulled my pp back to 50% (as it is in game) and had full power. lol

Here's an example that explains a bit of what you shouldn't do, generally. It puts it into words better than I can.

"For any given RPM, there is a
manifold pressure that should not be exceeded. Manifold
pressure is excessive for a given RPM when the cylinder
design pressure is exceeded, placing undue stress on them.
If repeated or extended, the stress would weaken the
cylinder components and eventually cause engine failure."

http://www.coryat.com/faa-pp-written/index11.html

Read the Q & A there. It should help explain things a bit. The short answer to someone about pulling your PP back for more speed isn't correct. Again, before you even begin to pull your prop back you have to pull your throttle back or you will damage your engine, just not in game because it isn't modeled.

One last thing, that info is for real world aircraft/flying. In game you can do whatever and have different results, none of which are correct in the real world.

[Rama]

Originally Posted by BSS_Sniper

I believe you got things mixed up a bit. Manual pitch control and constant speed propellers are the same thing. When you set a RPM with your prop lever you are doing two things, changing the angle of the blade AND setting a particular RPM. Neither change with power (manifold pressure) inputs.

Sorry, but you're wrong.
With CSP, inside the CS governor limits, the blade angle WILL change with speed and attitude variations.
Since Speed and attitude will change il you change power (manifold pressure), then blade angle WILL change.... and same if you use elevator input to climb or dive.

Manual pitch control is different: The pitch angle is directly controlled by the pitch lever.

With IL2, almost all planes are CSP equiped when they don't have fixed pitch.
Only Bf109 (and maybe Bf110... don't remenber...) use manual prop pitch when automatized control is off.
Even FW190 never use manual controlled pitch, but CSP when Kommandogerät is off.

[BSS_Sniper]

Originally Posted by Rama

Sorry, but you're wrong.
With CSP, inside the CS governor limits, the blade angle WILL change with speed and attitude variations.
Since Speed and attitude will change il you change power (manifold pressure), then blade angle WILL change.... and same if you use elevator input to climb or dive.

Manual pitch control is different: The pitch angle is directly controlled by the pitch lever.

With IL2, almost all planes are CSP equiped when they don't have fixed pitch.
Only Bf109 (and maybe Bf110... don't remenber...) use manual prop pitch when automatized control is off.
Even FW190 never use manual controlled pitch, but CSP when Kommandogerät is off.

I think you misunderstood me or vice versa. The RPM's remain the same after you set them with the prop lever is what I was trying to convey. Either way, this sim does not model anything even close to what should happen other than the RPM you see on the gauge.

I see you were refering to an old system "manual pitch" otherwise known as controllable pitch. Most aircraft are CSP if they have a prop lever today. That threw me off.

In any of the convention constant speed aircraft, for example the P51 or F6F Hellcat. If you have run low rpm settings with a high manifold pressure, you will/can damage the engine. The way you explained it makes it sound as if the blade angle will adjust for the MP change and it will not. In the 190's and 109's, its automatic.

[Rama]

Originally Posted by BSS_Sniper

In any of the convention constant speed aircraft, for example the P51 or F6F Hellcat. If you have run low rpm settings with a high manifold pressure, you will/can damage the engine. The way you explained it makes it sound as if the blade angle will adjust for the MP change and it will not. In the 190's and 109's, its automatic.

The blade angle will adjust for the MP change, until the the CS governor limit is reached, then blade angle will stay fixed and MP will change. (when low stop limit or high stop limit is reached)
This is actually modelled in the game, and with most of the planes, if you set RPM very low and Boost at max, engine will heat, then breake (so you can overtorque)
Overrev is modelled only for some planes, so with most off them you can dive with high RPM without risking overreving (which isn't realistic)

So I agree the game is much more tolerant to overreving and overtorque than reality..

For Bf109, the automatic control can be switched off, and then you get manual prop pitch (not CSP, but pitch direct input). This is correct in real and correctly modelized.
For FW190, when automatic control (Kommandogerät) is switched off, then you get the standard CSP for pitch control.

[BSS_Sniper]

Originally Posted by Rama

The blade angle will adjust for the MP change, until the the CS governor limit is reached, then blade angle will stay fixed and MP will change. (when low stop limit or high stop limit is reached)
This is actually modelled in the game, and with most of the planes, if you set RPM very low and Boost at max, engine will heat, then breake (so you can overtorque)
Overrev is modelled only for some planes, so with most off them you can dive with high RPM without risking overreving (which isn't realistic)

So I agree the game is much more tolerant to overreving and overtorque than reality..

For Bf109, the automatic control can be switched off, and then you get manual prop pitch (not CSP, but pitch direct input). This is correct in real and correctly modelized.
For FW190, when automatic control (Kommandogerät) is switched off, then you get the standard CSP for pitch control.

I believe you're just reading stuff on the internet without practical experience. You had me second guessing myself and doing that because of this sim could get me killed in RL. lol I even called my father who is a 30+ thousand hour professional pilot. He started on DC3's, Elektra's, DC4's and 727's. He basically said the same as I have. Please don't take this as flaming, it is not. Yes on CSP aircraft, the pitch will change if you change the MP, but only a minute amount. It will NOT make up for large changes in MP. A good example is at idle. Although I have my prop lever at full, I will still idle at about 700 rpm. The same goes if I am at a lower RPM and shove my throttle up to max MP, it will damage the engine because the prop governor will try to keep the RPM's constant, but the MP pushing the engine to its limits or past.

I have tested over and over for extended periods in game. I will take, for example, a P51 run it at full throttle and drop my PP to 50% and run all day without damage. That is what I'm talking about.

Again, I am only referring to standard US aircraft. I have very little knowledge of German, Russian and British planes.

[Bearcat]

Most of the American ones do... and as far as a CSP prop goes.... think throttle = Manifold pressure prop pitch = RPM.. If you do not let your RPM redline you will get more out of the engine.

[Rama]

Originally Posted by BSS_Sniper

I believe you're just reading stuff on the internet without practical experience.

Well... you're wrong... don't try to guess... just stick on what you know.
I have my pilot license (I'm only a sunday pilot) and I'm an engineer with quite good knowings in fly mechanics

Yes on CSP aircraft, the pitch will change if you change the MP, but only a minute amount. It will NOT make up for large changes in MP.

You didn't read or understood what I said.... well... it's not a big problem.

A good example is at idle. Although I have my prop lever at full, I will still idle at about 700 rpm. The same goes if I am at a lower RPM and shove my throttle up to max MP, it will damage the engine because the prop governor will try to keep the RPM's constant, but the MP pushing the engine to its limits or past.

I totally agree with that. It doesn't contradict what I said.
Like I said, in this case you will overtorque the engine.

I have tested over and over for extended periods in game. I will take, for example, a P51 run it at full throttle and drop my PP to 50% and run all day without damage. That is what I'm talking about.

Now try at full throttle and 0% PP... you will see (I'm not 100% sure for the P51, but for other planes I experienced in game engine heating and breakdown after a few minutes)

So In game overtorque IS modelled, but not reastically, the game is too tolerant (and even more for overreving)
... as I said in previous post.

[BSS_Sniper]

Originally Posted by Rama

Well... you're wrong... don't try to guess... just stick on what you know.
I have my pilot license (I'm only a sunday pilot) and I'm an engineer with quite good knowings in fly mechanics


You didn't read or understood what I said.... well... it's not a big problem.


I totally agree with that. It doesn't contradict what I said.
Like I said, in this case you will overtorque the engine.


Now try at full throttle and 0% PP... you will see (I'm not 100% sure for the P51, but for other planes I experienced in game engine heating and breakdown after a few minutes)

So In game overtorque IS modelled, but not reastically, the game is too tolerant (and even more for overreving)
... as I said in previous post.

Respectfully, you being an engineer has zero bearing on your weekend knowledge of being an amature pilot. For the sake of simplicity, the pitch angle does not change with throttle changes. I'll see if I can get some other professional pilots in here. My dad just shakes his head at this. He recalls the worst pilots he ever flew with were the ones that were too "book smart". There's more to flying than by the book, you gotta feel it and live it. If you can't get past all the technical/books you'll be confined in a box.

The game is exceptionally tolerant to anything concerning CEM to the point of being arcadish.

[Rama]

Despite you saying "respectfully", you don't show much respect... no problems... if you feel superior, that's your problem.
It's just making a difference with all the pro pilots I know... all very nice guys.
... and you obviously you have a problem with understanding CSP mecahnical fonctionning and CS governor...
CS governor controls pitch angle and adjust it to keep RPM constant. that's why when you adjust throttle pitch do change (adjusted by CSP to keep RPM constant).
not much knowing is needed to understand that... look there for example: http://www.pilotfriend.com/training/...wing/props.htm

[Vidar_710]

Maybe this will clear things up. Let's keep it simple.

Throttle Levers control power and RPM from idol up to Flight power settings.
Prop Levers control and refine RPM and Prop Pitch.
Mixture Leverscontrol fuel flow.

*NOTE: Throttle does NOT have any input to prop pitch settings what-so-ever.

The reason for Constant Speed/Variable Pitch propellors is to Optimize the pitch of the propellor in conjuction with power -i.e.throttle- settings at various stages of flight.

High RPM/Low pitch with Hi power setting for take-offs.
Med-Hi RPM/Low Pitch with Medium Power setting for climb-outs.
Medium RPM/Medium Pitch with Medium Power setting for Cruise flight.
High RPM/Low pitch with Low power setting for final stage -i.e. last few hundred feet- before landing. WHY you ask?

1. The flat-low pitch helps slow the plane down.
2. The Low pitch/Hi RPM is readily available without danger of overspeeding via manifold presure inputs from the throttle for Go-Arounds proceedures.

Keep in mind...
Medium - Hi Power settings may only be a difference of 2" of Manifold Pressure, and Medium to Hi RPM may only range 200-300 RPM from max power back down to Cruise flight.

Depending on the power plant, there are specific limits to manifold pressure to specific RPM settings. You never want to put manifold pressure past the specified RPM setting.

Everything Mr Sniper has said is completley correct.



V