No axis for RPM?

[moggel]

Been holidays’ sales shopping and got the P-51D. But as I was setting everything up I couldn’t find an axis for RPM. Right now I’m stuck with using the in-cockpit control which is very awkward and unnatural. Did I miss something or is it really not possible to bind RPM to an axis?

[Mud]

never mind me :)

 

 

Mud

Edited January 4, 2018 by Mud
Wrong answer given

[saburo_cz]

That axis what you look for is called "Engine RMP Setting"

[moggel]

That axis what you look for is called "Engine RMP Setting"

 

Haha. Ok, now I feel like an ass! :doh:

Thanks! :)

[=475FG= Dawger]

Haha. Ok, now I feel like an ass! :doh:

Thanks! :)

 

You should not feel this way.

 

The labeling is incorrect.

 

The engine RPM is not the same as propellor RPM on the vast majority of WWII aircraft. The prop is required to turn much slower to avoid exceeding the speed of sound at the tips.

 

This is done through a gear reduction system. The reduction ratio on the Pony is approximately 0.47 for all models.

[Art-J]

Still, the RPM gauge in cockpit is engine one, not the prop, and all settings and ratings the pilot uses in flight are engine MAP and RPM related, so the labeling is very much correct.

[=475FG= Dawger]

Still, the RPM gauge in cockpit is engine one, not the prop, and all settings and ratings the pilot uses in flight are engine MAP and RPM related, so the labeling is very much correct.

 

That is a silly way of looking at it.

 

The propeller control is the name of the control. It has a giant P on it.

 

The axis should be labeled for the control not the indication.

 

It is actually a propeller blade angle control that limits the RPM only when engine power output is sufficiently high.

 

Engine RPM is achieved by a combination of propeller blade angle and manifold pressure controlled by the throttle.

 

The Throttle axis is not labeled the Manifold Pressure axis. The throttle is the control used to adjust the MP.

 

It follows that the axis for RPM should be named after the control used to adjust it.

 

AND no where in the P-51 cockpit is anything labeled Engine RPM

[kolga]

That is a silly way of looking at it.

 

The propeller control is the name of the control. It has a giant P on it.

 

The axis should be labeled for the control not the indication.

 

It is actually a propeller blade angle control that limits the RPM only when engine power output is sufficiently high.

 

Engine RPM is achieved by a combination of propeller blade angle and manifold pressure controlled by the throttle.

 

The Throttle axis is not labeled the Manifold Pressure axis. The throttle is the control used to adjust the MP.

 

It follows that the axis for RPM should be named after the control used to adjust it.

 

AND no where in the P-51 cockpit is anything labeled Engine RPM

 

Except the propeller control actually controls the engine RPM at witch the propeller governor adjusts blade pitch to maintain.

[=475FG= Dawger]

Except the propeller control actually controls the engine RPM at witch the propeller governor adjusts blade pitch to maintain.

 

I have over 6000 hours in piston engine types (about 50 different types) and I have never encountered an engine RPM lever. That may be what it indirectly does but that is not what ANYONE actually calls the thing.

 

Including the people who built the Mustang

 

Edited February 12, 2018 by pmiceli

[JG3Siggi]

Otherwise known as a manual pitch control?

[Buzzles]

Otherwise known as a manual pitch control?

 

Not in the P-51D.

[sobek]

Still, the RPM gauge in cockpit is engine one, not the prop

 

I really don't think so. I have yet to come across one plane that indicates engine and not propeller RPM.

[streakeagle]

I can read the P-51 manual online, and it seems to indicate that the Tachometer is engine RPM, not prop RPM. The generator that drives the tach is geared to the engine and it talks about adjusting indicated engine RPM via the prop control, see page 54 of this link: https://books.google.com/books?id=SfwqCTY9I6MC&pg=PA30&lpg=PA30&dq=p-51+mustang+tachometer&source=bl&ots=hQFJYAUUL-&sig=rU8e5a-wYJGZ8fM4OBcGix3ZYvY&hl=en&sa=X&ved=0ahUKEwi2y-DrzaTZAhVItlMKHRWsAfEQ6AEIPDAG#v=onepage&q=p-51%20mustang%20tachometer&f=false

[some1]

I really don't think so. I have yet to come across one plane that indicates engine and not propeller RPM.

 

That's easy to settle.

 

A Mustang propeller has 1.7 m radius. It's circumference is (2*π*r) 10.676 meters. Which means that if 3000 was the prop RPM, then its wingtips would travel at 32028 meters per minute, which gives 1921 km/h. Nearly twice the speed of sound.

 

There were some supersonic propellers in the history of human flight, but not on WWII airplanes.

 

P-51 has a reduction gear with a ratio of 0.479 to 1, which slows the prop wingtips to a more manageable 920 km/h at takeoff.

[muehlema]

I have over 6000 hours in piston engine types (about 50 different types) and I have never encountered an engine RPM lever. That may be what it indirectly does but that is not what ANYONE actually calls the thing.

 

Including the people who built the Mustang

 

 

This is showing a P51 B/C cockpit rather than the D

[Art-J]

I really don't think so. I have yet to come across one plane that indicates engine and not propeller RPM.

 

And I have yet to come across one that indicates prop RPM :D. I'm interested in piston-engined planes, though, don't remember how things are in turboprops - can bbrz comment?

[some1]

And usually only a secondary indicator to the pilot, as rpm remains constant though the flight, or has fixed values for ground, Takeoff, climb and cruise.

[sobek]

And I have yet to come across one that indicates prop RPM :D.

 

Interesting, i would not have thought that the Merlin is such a slow running engine, but given the displacement, it does make sense.

[Art-J]

Slow? Ha! It's one of the highest-RPM aircraft piston engines of the 1940s and '50s, mostly because of being one of the smallest (yes, 27 liters is small in this context :D). Think of it like equivalent of these compact but extremely stressed Japanese car and bike engines of today.

 

Napier Sabre was the only one in the world revving faster at just mindblowing 3800, while most other aircraft engines of the era being in 2400-2800 range (Edit: I forgot about the Jumo we've got in DCS, at 3200 it's not a slouch either :) )

 

But it's all indeed relatively low when compared to smaller, automotive engines.

Edited February 15, 2018 by Art-J

[sobek]

Do you an example for a piston engined aircraft that has a gauge which indicates propeller RPM?

 

In light of this discussion, no i don't. ;)