Turbine prop sounds

How do you edit the sound.cfg of a turbine powered aircraft so that the sound decreases with the prop rpm decrease rather then the power lever decrease which is incorrect?

The sound.cfg files make NO sense to me at all.

Any help appreciated.

I know its a tricky one. Because I'm thinking there are only 2 people in the entire world who know how to write up a sound file for a turboprop engine done correctly.

I'm just hoping those two guys happen to swing past.

"help me Obi Wan Kanobi, you're my only hope"

:D

Hello JSMR. Well I do wish we had that kind of control over the sound engine, but we do not. The sounds are controlled by the throttle levers. Its always been very tactile to say the least. The accuracy is also lacking. I wish I could be of more help, but alas I cannot. I shared some new ideas with the Microsoft team while beta testing the FSX sound engine. They did not implement any of my suggestions or ideas. One of which was to change how the engine RPM's are addressed in the sound cfg. Bummer! It could have been much better than it is.

Cheers,

Aaron

Skysong Soundworks

The reason why I asked is because there IS a freeware turboprop package available for the King Air and which I've been using with the Aeroworx King Air. It correctly has the sound of the props being controlled by Propellor RPM rather the by the power levers.

A lot of work I guess messing with the sound.cfg.

But the problem is that the turboprop sound aren't convincing for the King Air. I was trying to understand the sound.cfg better so I could do the same with the original Aeroworx sound.cfg.

But it makes no sense at all and microsoft never made it easy to change.

Interesting for those er...interested. The freeware package is well known by Leon Medado. I found a post of his back in 2004 which explains how to correctly modifly the sound.cfg of a turbo prop aircraft so that the sound is changes with RPM and not the power levers.

Guests

Joined 45 Years, 2 Months and 13 Days Ago.

Posted 23 February 2004 - 04:54 AM

In most turboprop sounds, the waves used to represent the sound of the props are controlled by N2 or "COMBUSTION" as MS would call it. Basically, we will remove this unrealistic reliance on N2 and link the prop sounds to the existing yet underutilized Prop RPM system. They will then respond to changes in Prop RPM instead of turbine speed.Check out this thread for some more info on the benefits of such a system:http://forums.avsim....76848&mode=fullSome familiarity with the SOUND.CFG would help in understanding the following instructions. I suggest you read and understand the sound section of the Aircraft Container SDK if you haven't yet.I have used the default King Air SOUND.CFG as an example:(FLTSIM)product_code=FSIM(SOUND_ENGINE)number_of_engines=2eng1_combustion=COMBUSTION.1.00 –

Remove these two COMBUSTION lines since we won't be using them.eng2_combustion=COMBUSTION.2.00 - >eng1_prop=PROP.1.00eng1_starter=starterAeng2_starter=starterBeng1_shutdown=shutdownAeng2_shutdown=shutdownBeng1_combustion_start=combstartAeng2_combustion_start=combstartBeng2_prop=PROP.2.00eng2_jet_whine=JET_WHINE.2.00eng1_jet_whine=JET_WHINE.1.00...

Now comes the tedious part. If we merely linked the N2 or "COMBUSTION" sounds to the prop sounds, at lower power settings the props would sound much higher pitched and louder than they should because the original parameters were not designed for the relatively limited operating range of the props. We need to adjust these parameters to use values that are more appropriate for propellers rather than turbines.But first, an explanation of the vparams line is necessary. Imagine a graph with X (Horizontal) and Y (Vertical) coordinates, both values starting from 0 and rising to the right and up, respectively. There are 8 points on the graph, and each one from left to right is represented as an X and Y coordinate by vparams as shown:vparams=X,Y,X,Y,X,Y,X,Y,...vparams=X,Y(1st Point),X,Y(2nd Point),X,Y(3rd Point),...Given X which is the % of maximum speed (N1, N2, or Prop RPM), the sound will play at Y loudness. FS uses only values equal to or between 0 and 1 for X, while there doesn't appear to be any relevant numerical limitations for Y. While we will not concern ourselves with Y, you may find tinkering with it useful in fine tuning the sound later. When you connect the dots, or rather points in this case (FS will do the interpolation), they form the "Amplitude Envelope" of the sound. We'll need to move all the points to the right so that they match the range of the Props, while maintaining the relative proportions between each of them. The formula for this is:New X = Original X ( 1 - ( Minimum Prop RPM / Maximum Prop RPM )) + ( Minimum Prop RPM / Maximum Prop RPM )Back to the CFG, the first COMBUSTION line reads like this: (COMBUSTION.1.00)filename=kan21flags=0viewpoint=1rparams=0.000000,0.989000,0.998000,1.761000vparams=0.000000,49.000000,0.002000,49.600000,0.169000,55.200000,0.241000,16.000000,0.380000,0.000000,1.000000,0.000000,1.000000,0.000000,1.000000,0.000000link=COMBUSTION.1.01

For example, the King Air's minimum prop RPM is 1050 (Power at Idle, Condition at Low Idle) while it's maximum is 1700. The second point's (Since this is the first sound it's ok for the first point to start at 0), equation would then be :0.618411 = 0.002(1 - 0.617647) + 0.617647We should also set "flags=4" to tell FS that it's a prop sound. Flags=2 doesn't seem to work as well for some reason.After applying the modifications to the relevant remaining points (The points being repeated at the end, 1s and 0s in this case, in the default CFGs aren't crucial) it should look like this:...

(COMBUSTION.1.00)filename=kan21flags=4viewpoint=1rparams=0.000000,0.989000,0.998000,1.761000vparams=0.000000,49.000000,0.618411,49.600000,0.682264,55.200000,0.709794,16.000000,0.762941,0.000000,1.000000,0.000000,1.000000,0.000000,1.000000,0.000000link=COMBUSTION.1.01...

For this example I used all available digits, though in practice this level of precision won't be worth the effort. I used values rounded down to the second decimal place in my sound packages to simplify calculations. From what I've read, users of FSSoundStudio will find entering the values much easier.You should apply these modifcations to each relevant X value in all the COMBUSTION lines. For the default King Air CFG, there are 16 sections in total. 4 internal and 4 external sounds for the left engine under the COMBUSTION.1.0x header, while the COMBUSTION.2.0x header signifies the right engine's set of sounds. The default sounds always have the same parameters for both left and right engines, no doubt to make things easier. You may want to simply cut and paste the vparams for the left engine to the right engine.After all that, scroll all the way to these two sections at the end:...(PROP.1.13)filename=KAP1Dflags=4viewpoint=1rparams=0.060000,0.500000,0.354000,1.431000vparams=0.000000,0.000000,0.058000,0.000000,0.157000,39.200000,0.255000,41.600000,0.377000,11.200000,0.475000,0.000000,0.475000,0.000000,0.475000,0.000000...(PROP.2.13)filename=KBP1Dflags=4viewpoint=1rparams=0.060000,0.500000,0.354000,1.431000vparams=0.000000,0.000000,0.058000,0.000000,0.157000,39.200000,0.255000,41.600000,0.377000,11.200000,0.475000,0.000000,0.475000,0.000000,0.475000,0.000000This is where we link the COMBUSTION sounds to the existing Prop system, as shown (Remember vparams is only one line) :(PROP.1.13)filename=KAP1Dflags=4viewpoint=1rparams=0.060000,0.500000,0.354000,1.431000vparams=0.000000,0.000000,0.058000,0.000000,0.157000,39.200000,0.255000,41.600000,0.377000,11.200000,0.475000,0.000000,0.475000,0.000000,0.475000,0.000000link=COMBUSTION.1.00...(PROP.2.13)filename=KBP1Dflags=4viewpoint=1rparams=0.060000,0.500000,0.354000,1.431000vparams=0.000000,0.000000,0.058000,0.000000,0.157000,39.200000,0.255000,41.600000,0.377000,11.200000,0.475000,0.000000,0.475000,0.000000,0.475000,0.000000link=COMBUSTION.2.00That's pretty much it, although while the result may be technically sound (At max power, try moving the Prop levers up and down) it may not be aesthetically so. After these initial steps, I did a lot of additional tweaking to get the sound just right from startup to shutdown. I may add more tips depending on the response to this thread.BTW, for those looking to apply this to Flight1's Piper Meridian like I have, you'll need to add an entire Prop section manually, since the SOUND.CFG looks like it was taken from the 737.

I was in 'Advanced Maths' in school. But that makes no sense to me. Haha. For instance he said :

New X = Original X ( 1 - ( Minimum Prop RPM / Maximum Prop RPM )) + ( Minimum Prop RPM / Maximum Prop RPM )

then he does it and gets this :

be :0.618411 = 0.002(1 - 0.617647) + 0.617647

I understand the .002. (the old). 0.617647 is max prop/min prop equation.

But my mathematics is failing because I cant for the life of me get 0.618411.

My head hurts.

EDIT: ok I figured it out. But doesn't help in anyway really.