Prop Pitch question...

[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

[comswim]

I can sorta see what your getting at there Rama, but I too would have to agree with Vidar and Sniper on this too. My question is will it be different when BoB comes out.

S!

Comswim

[BSS_Sniper]

Originally Posted by comswim

I can sorta see what your getting at there Rama, but I too would have to agree with Vidar and Sniper on this too. My question is will it be different when BoB comes out.

S!

Comswim

We can only hope and pray.

[Rama]

Actually... nothing Vidar said actually contradict what I said, except the last sentence.

He even sais in another form what I said:

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.

CSP do control pitch and do it constantly to adjust for RPM... I said nothing different.
So for a fixed position of the RPM Lever, then, inside the CS Propellor limits:
- if you increase boost (admission pressure): CSP will adjust pitch and blade angle will increase to keep RPM constant.
- if you decrease boost (admission pressure): CSP will adjust pitch and blade angle will decrease to keep RPM constant.
- If you pull the stick, speed will go down: CSP will adjust pitch and blade angle will increase to keep RPM constant (up you reach the limit of the CSP, then RPM will decrease, and you will risk overtorque if you did set RPM too low)
- If you push the stick, speed will increase: CSP will adjust pitch and blade angle will decrease to keep RPM constant (until you reach the limit of the CSP, then RPM will increase and you'll risk overreving if you did set the RPM lever too high)

I did try to stay as simple as possible to be sure to be understood (since I begin to think my English is so bad that Sniper and Vidar don't understand it.... then I should go to take some English lessons...)

[BSS_Sniper]

Correct me if I'm wrong, but I believe you are saying that if you increase boost (manifold pressure) the prop governor will adjust the prop pitch to keep a particular RPM. Is that correct?
If so, I have to disagree still. lol

[Flyby]

This is an interesting topic, and I'm trying to learn something about about real life prop pitch control. But I see that since IL2's complex engine management is not the most accurate representation for a few planes (P51 as an example?) this topic has turned a bit arcane for me. In other words I've missed how I can use this discussion to improve my engine managment in the game itself. I'll go back and re-read this thread, and maybe I'll get the gist of it. Getting a bit dim in my old age, I guess.
Flyby out

[Rama]

Originally Posted by BSS_Sniper

Correct me if I'm wrong, but I believe you are saying that if you increase boost (manifold pressure) the prop governor will adjust the prop pitch to keep a particular RPM. Is that correct?

Absolutly correct, and that's what CSP is designed for.
In order to absorb the increased torque (power is equal to torque times RPM) the CSP will adjust the propellor pitch.

If so, I have to disagree still. lol

As you want.... but better then get some documentation about CSP... (The link I provided could be a first step...)
Just a simple question: How do you think the CSP maintains constant RPM?
Once you will have answered this one, there will be no more missunderstanding between you and me.

[BSS_Sniper]

Rama, I apologize. I just tend to get excited when I know I'm right about something, especially if someone blatantly says I'm wrong about something that is my profession. I doubt you tell your professional pilot friends "You are wrong" when they correct you on something. No harm intended though. Vidar stated things more clear than I was able to.

I did talk to our company A&P. (airframe and powerplant mechanic) The one time the pitch changes without input of the prop levers is if you go into a dive. The change is, however, so brief that it is not something noticed and only a technical note. It would have to be something extreme so that the relative wind is driving the prop and not the engine. The RPM's will speed up a bit and only VERY briefly. That will change the prop pitch, but the governor will bring them back to what the pilot set them at. It's just a brief second or two of change, nothing that would be noticed normally by the pilot.

So in the end, the throttle (Manifold Pressure) will not change Prop Pitch.