Merlin engine in Ace's

[Masherbrum]

um no - the cockpit gauge shows the engine speed in rpm, the AH "rpm control" controls the prop speed (via its pitch.)

Correct. 

[BulletVI]

Correct. 

Quote from: BulletVI on June 20, 2010, 01:39:02 PM
But HiTech i think there may be 1 factor that has been left out in the game. and that's drag.

You know i was right in a way about this quote Masherbrum

The game  certainty aint a DRAG  ( by that i mean boering   )

[Masherbrum]

Quote from: BulletVI on June 20, 2010, 01:39:02 PM
But HiTech i think there may be 1 factor that has been left out in the game. and that's drag.

You know i was right in a way about this quote Masherbrum

The game  certainty aint a DRAG  ( by that i mean boering   )

Shades accounts are fun to poke with a stick from time to time.   

[Chalenge]

I just tested it offline. The RPM gauge will still hold a reading with the engine off. Changing the RPM via prop control will drop the RPM reading on the gauge. That seems to indicate the RPM gauge is reading prop RPM and not engine RPM.

[BulletVI]

I just tested it offline. The RPM gauge will still hold a reading with the engine off. Changing the RPM via prop control will drop the RPM reading on the gauge. That seems to indicate the RPM gauge is reading prop RPM and not engine RPM.

I have noticed that if your throttle slider is set to change RPM 1 that happens its like you cant stop the prop from spinning at say 2000 rpm but if tou set it to change THROTTLE 1 then when you idle the engine both the engine and prop idle.

[jamdive]

Check again.

Its an engine speed indicator...Whats so hard to understand about this concept? Change the pitch of the prop you change the load on the engine.

[dtango]

I just tested it offline. The RPM gauge will still hold a reading with the engine off. Changing the RPM via prop control will drop the RPM reading on the gauge. That seems to indicate the RPM gauge is reading prop RPM and not engine RPM.

No, no it's indeed reading engine RPM.  How this is related to the propeller is that blade pitch changes the amount of power required to turn the propeller which affects how fast the crankshaft of the engine actually spins.  In a windmilling case the crankshaft continues to spin thanks to oncoming air creating a load on the propeller which spins it.  The engine RPM will vary with variation of the amount of blade pitch because different relative angles of attack on the prop means different thrust and drag produced by the prop and thus the amount of load it actually takes to spin the prop.

In other words RPM setting on a constant speed prop is defining how fast the engine crankshaft can spin by varying the amount of power required to spin the propeller connected to it through adjustment of propeller blade pitch.

[BulletVI]

Its an engine speed indicator...Whats so hard to understand about this concept? Change the pitch of the prop you change the load on the engine.

yes you do at that.

All though an earlier flight sim i used to play years back on the rpm gauge you had 2 needles one was white with red stripes and that was prop rpm the other a white needle and that was engine rpm. i dont know if the real Spits had that set up but hey i dont think the game was true facual based

[Chalenge]

Get into a Spit XVI and look closely at the RPM gauge and you will see that it goes to 12000 RPM. The reason it doesnt go that high in AH is because Hitech decided it would not be fun to have to work the engine controls and that is proven every time anyone has a question like this (or mistaken idea). If you were at 15k IRL and dived upon a con at 6k without pulling your prop RPM back the propeller would overrun and be useless. So in the game it is limited to 3000 RPM (slightly less in the Spit XVI for some reason) depending on manufacturer I guess.

Someone said something about the speed of sound and the size of the Mustang prop but thats inaccurate also. The F4U and P47 props are of much larger diameter and dont have that problem either. None of these airplanes and none of their props ever got near the speed of sound. If they had gotten near the speed of sound then the props would have been destroyed long before the airframes (tip speed on the P-51 is something like 380 mph at 3000 RPM).

jamdive: why does it read RPM with the engine off? Its not reading engine RPMs.

[jamdive]

yes you do at that.

All though an earlier flight sim i used to play years back on the rpm gauge you had 2 needles one was white with red stripes and that was prop rpm the other a white needle and that was engine rpm. i dont know if the real Spits had that set up but hey i dont think the game was true facual based

Its an engine speed indicator.

[BulletVI]

And yet another fact that stoped the prop tips going near the speed of sound was the reduction gear box between the prop and the engine and another control system that was controlled by the engine oil that adjusted the props angle if you over speed the prop in a dive  but that system i believe was only invented in mid 1944

[BulletVI]

Its an engine speed indicator.

I know but that is what an earlier game i used to play had so it was easy to tell and such

[jamdive]

And yet another fact that stoped the prop tips going near the speed of sound was the reduction gear box between the prop and the engine and another control system that was controlled by the engine oil that adjusted the props angle if you over speed the prop in a dive  but that system i believe was only invented in mid 1944

Its a friggin governor.....You being some airframes/powerplant engineer should understand this basic concept.

P/S. stop arguing and go learn something.

[Chalenge]

jamdive... while I agree it should be a tachometer it does not act like a tachometer when it still reads RPMS with the engine off. In the P-51 it was a tachometer but in AH it acts as though it is reading prop RPM. Thats just what the evidence shows.

Now if you can show me that an engine like a Merlin will still rotate once it is turned off and therefore give an indication on an RPM gauge then I might side with you but until then I must conclude the RPM gauge is measuring prop RPM.

[dtango]

Chalenge, you skipped my post above.  The RPM gauge is reading engine RPM.  A windmilling propeller continues to spin the crankshaft of the engine.