Author Topic: Ummm about his new engine sound thingy (Read 5127 times)

frank3 · « **Reply #15 on:** February 14, 2004, 08:39:11 AM »

What if, Im flying a B-17 at high altitude and want to slow down abit (IAS) Do I use the rpm or manifold setting?

When I want to save fuel. Do I leave the manifold at the normal cruise speed? (in a B-17 about 35) and reduce the rpm's?

ergRTC · « **Reply #16 on:** February 15, 2004, 09:37:00 AM »

throttle is not tied to rpm

throttle is not tied to rpm

throttle is not tied to rpm

throttle is not tied to rpm

throttle is not tied to rpm

throttle is not tied to rpm

throttle is not tied to rpm

throttle is not tied to rpm

throttle is not tied to rpm

throttle is not tied to rpm

Kweassa you are right.

You guys have to remember the variable pitch props, otherwise you sound like ......

FT_Animal · « **Reply #17 on:** February 15, 2004, 01:22:26 PM »

Quote

Originally posted by Waffle BAS
ok - one more example....

Take remote control planes or gas powered R/C cars.....

When you're piloting them - you can hear your engine just fine at a slow speed...the engine emits a lower frequency audio pitch at a slower cycle. When throttle is applied the audio pitch increases as the engine cycles increase. But, there is very little audio difference in Sound pressure levels, or decibles. Some, but not as much as one would think.

pls note pitch here is related to acoustics, not aerodynamics.

I'm trying to clarify the engine volume thing - not worried about props cutting through air and other noise created by prop driven aircraft.

I understand what you're saying, and for the most part, I totally agree with your theory. But, there are some considerations that you may be over looking which could slitely alter your view.

Adding to your theory, you almost have to consider more then one engine type and model. And for game files your gonna have to find a real tight compromise if you are truly going for accuracy. Theatrics would be a flipside.

All engine types run different, while still functioning around the same fuel engine thoery.

Let me try to use a car engine here for an example. Most American made cars would fall directly under your theory. However, there are other models which perform differently. An engine will have different audio effects if you instantly crush the throttle to nothing, verses a gradual deceleration. If you instantly reduce fuel input the engine is still at a high rpm and will suck air back and cause, in some cases, a popping, much the same way a Harley would. In a gradual deceleration the RPMS are slowing matching the fuel intake, therefore you do not get such a radical effect. My BMW is louder at a low RPMs, with lower tones (sometimes as low as say,..40hz), it resonates my house when I can barely even hear it run. The engine groans on acceleration, pitch climbs rapidly. Then suddenly, as the engine RPMs go over a certain point past 3000 (or as I hit 70 mph) the engine goes completely quiet, even while still accelerating. When I decelerate quickly the audio of the engine comes to life again. Most American cars, on acceleration, will turn into a higher (almost jet like) pitched whine and continue to climb. So we have different effects depending on the engine model or type. This is where you need to really dig into individual engine characteristics to be accurate.

This would most likely lead to HTC having to set each planes’ response to individual settings, and maybe sound files. I would think it would be extremely tiring research alone to do this. It’s almost a science in itself to get total correctness for the game. Higher quality files allowing a wider sound spectrum would include higher and/or lower tones\frequencies to help achieve this goal. So the sound file has to be correct for the combination of file and coding to be accurate. This is why I would think that instead of a global setting for audio it would fall into an individual engine model concept. I highly doubt HTC, much less any other sim, is going to tackle this, but I may be wrong about that.

Now throw into the equation that each plane was insulated, or not.

You HAVE to include prop noise because it does add to volume\pitch as well. Depending on the plane engine and prop design, I some times hear the prop more.]

So while I agree with where you are going with this, I also add my own personal views into the same theory.

Waffle · « **Reply #18 on:** February 15, 2004, 01:55:17 PM »

Ok - lets do this....take your engine out of the plane...Take of the
prop.. mount it to whatever the hell you would mount it to to test it....

Fire it up - How loud is it? Full throttle? Idle?

Lets start here and get this sound in the ball park first.

then we can worry about prop noise. Those should be on a seperate file shouldn't they since they are not tied with engine noise

BTW - what are the commands to increase / decrease prop pitch...did I miss something on day 4 of ah training?

Zanth · « **Reply #19 on:** February 15, 2004, 02:35:48 PM »

I am not smart enough for the physics debate club, but for whatever reason, in real life I do not get a similar audible experience riding in real life aircraft as is currently implemented in Beta 13 and I think that should be the real point.

FT_Animal · « **Reply #20 on:** February 15, 2004, 03:32:16 PM »

> Lets start here and get this sound in the ball park first. Then
> we can worry about prop noise.

Sound good to me.

> Those should be on a seperate file shouldn't they since they are
> not tied with engine noise

Absolutely

GScholz · « **Reply #21 on:** February 15, 2004, 04:28:24 PM »

I have a nice cockpit recording of a 109G-2 with DB605 from start up, take-off, flight and landing. (test flight of a restored warbird). I wish AH (or any flightsim) could reproduce engine sound like this, it's awesome.

It's a 12 meg mp3 file. If anyone can host the file for me, I'll be happy to share it.

Adjuster · « **Reply #22 on:** February 15, 2004, 04:39:05 PM »

We are all in danger of getting too technical here.

I think most of us when we open up the throttle want to hear a sound to remove our fillings and one that sounds like a warbird at an airshow doing a highspeed pass.
When the throttle is at idle it should sound like same warbird on a slow approach put-putting and coughing to touchdown.

Now all of this is seperate and distinct from the engine management fuel economy etc (which btw i think is a good idea).

Basically when fly a virtual Spitfire I want it to sound like virtually every Spitfire I have ever seen and heard ie when you push the loud lever (throttle) it sounds "Big and brash" and when you pull it back to idle its not quiet but "small and polite".

I know there are many reading this that will say ahh but in real life thats not how it should be . That may be so but also in real life we ordinary mortals have a perception of how things should be (all engines should sound like a V8 , all women should have a perfect figure, all men should be hung like a horse et al) so I imagine most of us here will agree that a warbird should sound like a warbird whether its right or wrong.

I think I can see what Pyro was trying to do but it just doesnt work for me.

Adjuster

GScholz · « **Reply #23 on:** February 15, 2004, 04:43:19 PM »

Well, the mp3 I've got sounds exactly right ... because it is exactly right.

And by listening to it you will understand how the engine sounds when applying power, changing revs, increasing speed (wind noise) etc.

ergRTC · « **Reply #24 on:** February 15, 2004, 06:43:07 PM »

give it to me sholz I will host it. Do you know how to sftp?

erg

GScholz · « **Reply #25 on:** February 15, 2004, 07:53:21 PM »

I know what FTP is but SFTP?

Widewing · « **Reply #26 on:** February 16, 2004, 12:31:46 AM »

Quote

Originally posted by Ghosth
Cars are insulated, tuned piped, mufflered, & catilytic convertered, & exit 12 feet behind the driver.

Airplanes are big growly radial engines with NO pipes, NO mufflers ohh & they exit within a few feet in front of the cockpit.

Ya think maybe they'd sound a bit diff?

Start up your lawnblower or snow mower.
Play with the throttle up & down. Hear the difference?

Another oddity is that there is no increase in engine song when engaging WEP. If manifold pressure increases, HP increases, if HP increases there is a corresponding increase in exhaust volume. When I would switch on ADI and push up the boost to my R-2800s (C-118 has four of them, C-131 has two), there was a marked increase in engine volume.

And, what's the story with this unstable taxi nonsense? Don't these guys realize that most aircraft had lockable tail wheels and tricycle types had nosewheel centering devices? I've taxied quite a few aircraft, including several tail draggers and I've never seen anything like the constant swinging in AH2.

My regards,

Widewing

Octavius · « **Reply #27 on:** February 16, 2004, 12:37:59 AM »

I'd like to hear that sound file too GScholz. Get it hosted asap

Widewing · « **Reply #28 on:** February 16, 2004, 01:26:34 AM »

Quote

Originally posted by ergRTC
throttle is not tied to rpm

throttle is not tied to rpm

throttle is not tied to rpm

throttle is not tied to rpm

throttle is not tied to rpm

throttle is not tied to rpm

throttle is not tied to rpm

throttle is not tied to rpm

throttle is not tied to rpm

throttle is not tied to rpm

Kweassa you are right.

You guys have to remember the variable pitch props, otherwise you sound like ......

Sure it is...we don't have turboprops.

With engine running on the runway, set pitch to fine, pull the throttle to idle, What happens to RPM?

It drops.....

It should drop when windmilling too, but it really doesn't. It stays at max rpm with the engine off, until about 100 mph and below, where it then drops just 500 rpm... needs some work.

In any US fighter, to decrease speed, you first pull back the throttle, then adjust rpm. This prevents overboosting. To increase speed, you adjust the rpm up and then add throttle. Again, this prevents overboosting. When at military power, you decrease rpm via pitch, you will get an increase in boost. It doesn't work like that in AH2. If you pull off rpm in AH2, you get a decrease in boost... that is backwards. In the real world, pulling off rpm at max power via pitch would so severely overboost the motor as to do damage within seconds.

I also was unable to get the P-51's RPM below 2,000 rpm. We should be able to get all power settings as they appear on the P-51. Likewise, same problem for the P-38L. The Flight Operation Instruction Chart for the P-38L shows 1,600 rpm at 28 in/Hg (MAP) for most economical cruise... I can't get close to that.

If modeled correctly, engine blowups would be common until people learn that throttle IS tied to rpm ......

Picture some guy cruising along at 2,100 rpm, 34 in/Hg MAP... He spots the enemy boring in and rams the throttle up to max power.... Blam goes the motor!

What he should have done is first push up the rpm, then advance the throttle. Later aircraft like the P-51, P-38 and Fw 190s had a automatic throttle/prop control, which increased rpm according to throttle position.. Older aircraft did not have this feature and many late war aircraft didn't have it either.

This is how it should work in AH2 if realism is important.

Having a couple of thousand hours behind R-2800s and R-1830s, I've seen more than my share of overboosted (and sometimes damaged) engines from careless engine management.

Adding engine management is a good thing... getting it right is even better. I suggest that the guys at HTC get their hands on a few pilot's and NATOPS manuals and review the basic relationship between rpm and throttle in these aircraft.

My regards,

Widewing

Dessy · « **Reply #29 on:** February 16, 2004, 01:55:09 AM »

Quote

I also was unable to get the P-51's RPM below 2,000 rpm. We should be able to get all power settings as they appear on the P-51. Likewise, same problem for the P-38L. The Flight Operation Instruction Chart for the P-38L shows 1,600 rpm at 28 in/Hg (MAP) for most economical cruise... I can't get close to that.

There's a P-38L in AH2?