Author Topic: Manifold Vs RPM Engine Sound levels  (Read 2367 times)

Offline Zimme83

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Re: Manifold Vs RPM Engine Sound levels
« Reply #30 on: September 18, 2016, 01:10:59 PM »
If prop rpm is at max and engine at idle the prop will windmill and keep the engine rpm over idle so the prop is driving the engine instead of the opposite.
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Offline FLS

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Re: Manifold Vs RPM Engine Sound levels
« Reply #31 on: September 18, 2016, 01:16:47 PM »
If prop rpm is at max and engine at idle the prop will windmill and keep the engine rpm over idle so the prop is driving the engine instead of the opposite.

The question seems to be how much RPM at what airspeed.

Offline Traveler

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Re: Manifold Vs RPM Engine Sound levels
« Reply #32 on: September 18, 2016, 01:25:13 PM »
The question seems to be how much RPM at what airspeed.

That was not my original point, the relationship between Manifold Pressure and RPM appears to be the same as it was in AHII , except in AHII the engine noise was associated with Throttle (MAP) and a second sound, Prop Sound  was associated with RPM.  In AHIII the engine noise sound associated with Throttle is also associated with RPM. Thus when in a power off approach and I advance my RPM to High or Max RPM the sound is that of an engine increasing in power or at least that is how it sounds to me.
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Offline FLS

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Re: Manifold Vs RPM Engine Sound levels
« Reply #33 on: September 18, 2016, 01:40:29 PM »
That was not my original point, the relationship between Manifold Pressure and RPM appears to be the same as it was in AHII , except in AHII the engine noise was associated with Throttle (MAP) and a second sound, Prop Sound  was associated with RPM.  In AHIII the engine noise sound associated with Throttle is also associated with RPM. Thus when in a power off approach and I advance my RPM to High or Max RPM the sound is that of an engine increasing in power or at least that is how it sounds to me.

Sorry I wasn't clear. The question of how much RPM v air pressure is from the discussion with Colmbo.

RPM changes with no throttle change in a way it didn't in AH2 so there is a difference in the model with sound, RPM, thrust and the associated effects like gyroscopic precession.

Offline Pudgie

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Re: Manifold Vs RPM Engine Sound levels
« Reply #34 on: September 18, 2016, 01:47:15 PM »
Depends on the airplane.  Generally the Prop control is put in the high RPM position to facilitate a power increase if needed.

Modern day flying the B-17 and B-24 the RPM is left at 2000RPM (vs 2500 or 2700) during approach to help prevent having the prop drive the engine which leads to premature engine failure.  As the aircraft touch down the non flying pilot brings the prop control up to High RPM.

Just to put it out there, I've found in game that my Spitty matches up best on final when I set the RPM's to 2,000 as well w\ throttle holding boost around 2-4 lbs at the proper glide path.........

The landings are just beautiful at these power settings..........

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Offline Traveler

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Re: Manifold Vs RPM Engine Sound levels
« Reply #35 on: September 18, 2016, 01:48:42 PM »

RPM changes with no throttle change in a way it didn't in AH2 so there is a difference in the model with sound, RPM, thrust and the associated effects like gyroscopic precession.
Throttle and RPM work exactly the same for me.  I could make independent throttle and RPM changes in AH2 and AH3.
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Offline FLS

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Re: Manifold Vs RPM Engine Sound levels
« Reply #36 on: September 18, 2016, 01:55:04 PM »
Throttle and RPM work exactly the same for me.  I could make independent throttle and RPM changes in AH2 and AH3.

If you dive to high speed you will see RPM increase with no change in settings. If you zoom climb to a stall you will also see an RPM change. Those are new as well as the prop pitch governor lag when you change RPM.

Offline ONTOS

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Re: Manifold Vs RPM Engine Sound levels
« Reply #37 on: September 18, 2016, 02:08:56 PM »
OK, the engine sounds are basically  the same in AH III as in AH II, but that is the default sound. The customs sounds on AH II are very different. When I cut the throttle, the engine stays just as loud, but the pitch changes. If you are looking at the default sounds they are really different from the custom sounds and worse.

Offline FLS

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Re: Manifold Vs RPM Engine Sound levels
« Reply #38 on: September 18, 2016, 02:14:24 PM »
...When I cut the throttle, the engine stays just as loud, but the pitch changes. ...

That's how it was in AH2, and since that's not accurate it was changed for AH3. I understand that you prefer the old model.

Offline hitech

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Re: Manifold Vs RPM Engine Sound levels
« Reply #39 on: September 18, 2016, 02:31:59 PM »
That was not my original point, the relationship between Manifold Pressure and RPM appears to be the same as it was in AHII , except in AHII the engine noise was associated with Throttle (MAP) and a second sound, Prop Sound  was associated with RPM.  In AHIII the engine noise sound associated with Throttle is also associated with RPM. Thus when in a power off approach and I advance my RPM to High or Max RPM the sound is that of an engine increasing in power or at least that is how it sounds to me.

Your post is incoherent because of your terms. ( engine noise was associated with Throttle) I have no idea what this means.
And also I have no idea what this means. ( Prop Sound  was associated with RPM.  ).

Please use the terms Frequency and volume.

In ah3 Manifold pressure is primarily controlling volume (also other sound changes but not frequency), RPM control is changing the frequency of the sound.

The question seems to be how much RPM at what airspeed.

This is a valid question that is not an easy answer and varies with planes and props.

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Offline colmbo

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Re: Manifold Vs RPM Engine Sound levels
« Reply #40 on: September 18, 2016, 11:13:22 PM »
So you're saying the RPM drops but not as much as it should?

Yes, it seems that way to me.  The sound matches the RPM so not so much a sound problem as an engine modeling glitch.
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Offline Chalenge

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Re: Manifold Vs RPM Engine Sound levels
« Reply #41 on: September 18, 2016, 11:29:38 PM »
Why not make some sounds for us all then? I'm sure with your experience they will be perfect!

Anyone working on that?
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Offline FLS

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Re: Manifold Vs RPM Engine Sound levels
« Reply #42 on: September 18, 2016, 11:55:58 PM »
Yes, it seems that way to me.  The sound matches the RPM so not so much a sound problem as an engine modeling glitch.

Do you recall what the B-17 and B-24 RPM rise to from 2000 when the co-pilot sets max RPM on touch down?

Offline colmbo

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Re: Manifold Vs RPM Engine Sound levels
« Reply #43 on: September 19, 2016, 07:31:57 AM »
Do you recall what the B-17 and B-24 RPM rise to from 2000 when the co-pilot sets max RPM on touch down?

The RPM doesn't increase at all, the engines are pulled to idle during the flare for landing.  To increase RPM would require an increase in throttle.
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Offline earl1937

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Re: Manifold Vs RPM Engine Sound levels
« Reply #44 on: September 19, 2016, 10:35:51 AM »
Real life you hear a change in engine sound with RPM changes.  Sometimes only a little, sometimes a lot (like if you roll the RPM way back at high manifold settings)
:airplane: Correct and what I think must of these guys don't undstand is with constant speed props, prop sound is only going to change down around 12 inches of manifolf pressure. Same way with decreasing RPM, say from 2500RPM to 2,000 RPM, sound will change as the manifold pressure will increase, giving the engine or engines a different sound.
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