External Audio - P-38/P-39

[jester]

And I believe the H81. These planes from 3rd person have always been significantly quieter than other planes - even ones using the same sound file (Spitfire, Hurricane, etc). Now it is worse than ever. They are near silent. This bug's been around since the new sounds were implemented in 2007, couldn't find an old thread to bump.

 

Edit: how to replicate: simply observe these planes flying from 3rd person, ideally alongside a Spitfire, Hurricane, etc. to compare to.

Edited June 15, 2021 by jester

[undercova]

agreed. i experience the same

[KEMPI]

The 38 should be a bit quieter, actually a completely different, less distinct individual cylinder firing sound, than the short stack v-12s as the exhaust is piped through the turbocharging systems and exits out of the turbines on the top of the booms . Same difference between P&W R2800 powered F4U/F6F and P47's where the P47' are piped through supercharger and out the tail. IRL, even though the same engines, a bit different in both sound and volume.

[madrebel]

48 minutes ago, KEMPI said:

Same difference between P&W R2800 powered F4U/F6F

nope ... yes for the P47 but not for these or the F8. The Navy used a two staged super charger for their R2800s in all the fighter platforms it was in with the really late examples having either fluid coupling on the second stage or in the case of the F8, a variable single or two speed super charger.

 

 

[HATCH]

You lost me. Why are we talking about F8F's and gear driven superchargers in the context of exhaust note (although the F8F is comparable with the F4U and F6F in the context of exhaust collector rings dumping out the sides or bottom of the engine cowling), none of the above piping exhaust back behind the engine through a turbocharger like the P38 and P47?

The point is that short stacks sticking out the side (like P40's/Spits, or collector rings dumping at the back of the cowl like most non-turbocharged radials, F4U/F6F/F8F) are a bit louder and sound different than turbocharged AC like the P38, P47. None of which has anything to do with whether or not the V12 or radial in question is supercharged or normally aspirated.

[madrebel]

The former. Just saying, if we’re talking what should and shouldn’t sound similar then we need to note the differences in this case for the R2800 radial in different planes would lead to much different sounds. 
 

i think you could reasonably fake a future difference between the sound of the P47 and the F6F etc just by turning down the engine sound volume leaving the volume of the prop sound alone. Not that this matters today. would also be nice to hear the turbos on the planes that had them. 
 

fwiw, I’ve heard a 109E3 and a 190A5 fly next to each other. The 109 sounded very tight. Crotch rocket/F1 car kind of tight. The 190 on the other hand was much throatier/beefier. Sounded more like a harley or muscle car.
 

 

[jester]

Not sure why this is marked as solved as it is still going on.

[undercova]

for me Hawks always fly with no running propellers. always fix

[jester]

That's a separate bug which has been around a while too, unrelated to this one. That one isn't as gamebreaking. This one certainly is.

[Mosizlak]

On 7/24/2021 at 4:31 PM, jester said:

Not sure why this is marked as solved as it is still going on.

Been around forever, reported it multiple times. 

When you're on the ground and if there's any background noise, the first time you hear a bell or a p38 or h81 is when it starts firing at you. 

I mean you can barely hear them as they pass 50m over your head. 

[jester]

Correct. This is an easily replicated,  game-breaking bug for which there is no explanation or reason. EDIT: Saw tag was updated to review

Edited August 2, 2021 by jester

[saffroli]

I think the problem is there is no prop wash sound for any plane.

Even an electric plane you would hear the blades distinctly, take a turbo prop commercial plane for example, you hear more of the propeller than you do the actual engine, from inside the plane and out.



So with turbocharging in mind, it definitely will muffle exhaust note speaking from an absolutist perspective, but it's 30's/40's technology, not a modern Turbocharged engine like you see in F1 or a road car that are very efficient at repurposing exhaust gas. These WW2 engines are very noisy just like all the other contemporary aircraft are.

https://youtu.be/aoT2QnKtbdU?t=137

I mean, just listen to it, it's not quiet by any stretch of the imagination is it? You're not listening to that and thinking, hmm it really is distinctively quieter than a Spitfire or 109.. Even at idle it's louder than the Bell in WW2OL in a full power diving flyby...

In the game it's relatively silent. Like, almost ACTUALLY silent.

So whatever the actual dB decrease of the exhaust output aided by turbocharging, it's clearly not nearly enough to be modelled as anything more than 5-10% decrease on relative volume for any of the other planes we have in the game, meanwhile it probably only has 5 or 10% of the volume of any other engine.

Even an Opel is louder than a p39. If I had the know how, I'd use a dB meter overlay standing next to an Opel vs a Bell flyby

 

Edited August 10, 2021 by saffroli

[saffroli]

 Electric aircraft for reference. Ignore the video and just focus on the take off audio. 

[jester]

There is no need in churching this up - it is a simple audio bug and it is not some intended technical difference tied to the specific aircraft due to their engines, etc in any way. It's also been around for a long, long time. 

[JAMES10]

Hello all.

Something worth considering in the discussion on turbochargers.

Most aircraft in WWII actually used supercharges. The P47 and P38 were unusual in that they had actual turbochargers.

Both the supercharger and turbochargers provided a boost in air pressure for induction into the cylinder. More air more power per unit of fuel. They achieved this by differing methods.

The principal differences between a supercharger and a turbocharger are:

A supercharger:
* used direct engine power for its operation. It took engine power away from the engine output.
* a distinctive "wine/whistle" is added to the aircraft sounds.
* responds quicker to the throttle/boost settings as applied by the pilot.

A turbocharger:
* used the waste energy contained within the engine exhaust gas to power the device. It took no power from the engine to operate it.
* effected the exhaust sound of the engine as it was a part of the exhaust system.
* was slower to respond to the differing inputs from the pilot as it had to wind up or spin down in response to the exhaust gas flow.

A lot of modern vehicles use turbochargers from cars, trucks, trains ets. The only modern vehicle I can think of that uses a supercharger are "top fulled racing cars" (Drag Racers).

Cheers.

[jester]

10 minutes ago, JAMES10 said:

The only modern vehicle I can think of that uses a supercharger are "top fulled racing cars" (Drag Racers).

Mustang GT500? Any of the sand-on-a-beach Dodge Hellcat cars? Just to name a couple common examples...

Again there is no need to church this up in technical details when it is just a simple audio volume bug. Easily replicated.

[JAMES10]

Hello jester, how are you doing?

I wouldn't say either are of those vehicles are "common". Mind you Drag Racing cars are also not that common either.

Cheers.

[jester]

Production numbers say otherwise. Dodge alone have made something like 60,000 Hellcat powered cars to date - as I said they are sand on a beach here in the states. Your observation is totally subjective as you may not live where they are sold. (PS if it's Europe, perhaps Jaguar or Volvo ring bells - they both have multiple supercharged models on the market currently)

Either way off topic, and hopefully this annoying bug can be addressed.

[madrebel]

41 minutes ago, JAMES10 said:

Most aircraft in WWII actually used supercharges.

All

41 minutes ago, JAMES10 said:

The P47 and P38 were unusual in that they had actual turbochargers.

Turbo-superchargers. The turbos fed into single-stage single-speed super chargers and over pressure was managed via the waste gate.

[JAMES10]

Hello madrebel, how are you?

The core difference between superchargers and turbochargers is how they are powered. Either directly by the being geared/clutch coupled to the engine crank shaft (supercharger) or being powered by a turbine driven by engine exhaust gasses (turbocharger). Both produce over pressure at the cylinder.

Cheers.

Edited August 11, 2021 by JAMES10

[madrebel]

I understand that, however, the P47 and P38 had both a gear driven super charger (in both cases a single-speed single-stage) and an exhaust driven turbo that fed into the super charger's air intake.

note, supercharger is the wrong language in the above and images like it fuel this confusion. the super charger can be seen below, the red/blue area to the right of this image.

ALL R-2800s had super chargers which as you can see is integral to the design of the engine. You can't just omit the compressor in the above example. The P47 had a single-stage single-speed supercharger fed by a GE turbo. The F6F, F4u, F8F, and other planes used a two-stage two-speed super charger only.

The P38 is similar only it used the inline Alison and the same single-stage single-speed supercharger that the P39, A36, P40 etc used only it fed this super charger via turbo chargers.

[saffroli]

As a mechanical design philosophy a turbocharged supercharger seems [censored] backwards lol.

Seems to me you would basically combine only the negatives of both with probably a very minimal air density increase..

Anyone who's seen a 2Jz knows all you need to increase your power 20fold is just stick a giant as turbo on it the size of the elephant mans head!



I guess it's just a simple case of knowing a lot more now than we did then, superchargers were the only known way at the time of increasing air density, so it makes sense that they stick to running a supercharger system since it's a known quantity.

But in regards to the subject matter I don't know any of the specifics of which engine in what plane or anything like that but based on the image posted it would be more correct to just refer to it as a supercharger rather than turbocharger at all, but I don't know any of the specifics of which engine in what plane or anything like that.

Edited August 16, 2021 by saffroli

[madrebel]

superchargers are hard. no, not a single stage single speed super charger, those are relatively easy. however creating a supercharger with multiple stages and multiple speeds that works well from sea-level to 12KM is very very difficult. in fact, only the Japanese built a two stage three speed ... and they couldn't get it into production. Jumo developed a two stage three speed that was used on late Jumo 213E and F engines as well as mated to the DB605 to produce the DB605L.

see those notches where the power drops off then picks back up, thats the dead spot from one super charger gear to the next.

and for the 109, notice the lack of steps? the 109 had a single stage single speed super charger with a fluid clutch system this was the german answer to the problem of power across altitude bands.

the P47 and P38 on the other hand look like the above. a relatively flat line that goes up from sea level to max altitude.

believe it or not this is a very simple and somewhat elegant solution to the problem. build the motor to always produce X power based off the supercharger's design then make sure that super charger can always provide full boost by way of the turbo feeding it. to avoid over pressure the waste gate for the turbo opens venting any excess pressure.

no drop in manifold pressure and no complicated multi-gear supercharger to worry about either. if all that turbo plumbing gets holes in it though ... well if you're above 4KM altitude you're most certainly going to notice a significant drop in power. The US had the resources to brute force problems like this. other nations just couldn't afford to build designs like either the P47 or the P38. I've looked for years and have never found documentation for how the Germans managed to turbo charge the BMW801. a few hundred of these engines did in fact see operational use with the Ju388s that saw some action in late 44. if anyone knows of anything do let me know.

[saffroli]

5 hours ago, madrebel said:

 

believe it or not this is a very simple and somewhat elegant solution to the problem. build the motor to always produce X power based off the supercharger's design then make sure that super charger can always provide full boost by way of the turbo feeding it. to avoid over pressure the waste gate for the turbo opens venting any excess pressure.

 

True, but just seems mad to me that they wouldn't conclude the crank drag from the supercharger diminishes the turbos ultimate potential.

[vanapo]

To get this back on topic after I did some AA gunnery for my last stream:

It's definitely the case that most US planes in game are almost completely silent (especially compared to other planes) until they are less than 800meters away. I noticed that for the late Hawk and I think for the P-39 as well. As all axis pilots know, the P-38 is very hard to hear as well. All of which is most likely bogus. I don't think a prop flying by at 50 meters altitude, cranked by a turbocharged Allison V-1710 V12, emits less sound than a truck engine on the ground. Of course a ww2 plane can be considerably noisier than another one. Yet it is to doubt any of those reaches modern noice controll standards in a way, it's less noisy than a toy quadcopter.