Science Q: Aerodynamic noise and the A10c

[mooshim]

This is cribbed from wikipedia (as most of my science knowledge is):

Different aircraft types have different noise levels and frequencies. The noise originates from three main sources:

1. Aerodynamic noise
   
2. Engine and other mechanical noise
   
3. Noise from aircraft systems
   

 

Aerodynamic noise

 

Aerodynamic noise arises from the airflow around the aircraft fuselage and control surfaces. This type of noise increases with aircraft speed and also at low altitudes due to the density of the air. Jet-powered aircraft create intense noise from aerodynamics. Low-flying, high-speed military aircraft produce especially loud aerodynamic noise.

 

The shape of the nose, windshield or canopy of an aircraft affects the sound produced.

 

Typically noise is generated when flow passes an object on the aircraft, for example the wings or landing gear.

 

 

There are broadly two main types of airframe noise:

 

Bluff Body Noise - the alternating vortex shedding from either side of a bluff body, creates low pressure regions (at the core of the shed vortices) which manifest themselves as pressure waves (or sound). The separated flow around the bluff body is quite unstable, and the flow "rolls up" into ring vortices - which later break down into turbulence.[1]

Edge Noise - when turbulent flow passes the end of an object, or gaps in a structure (high lift device clearance gaps) the associated fluctuations in pressure are heard as the sound propagates from the edge of the object (radially downwards).[1]

 

ORIG. ARTICLE

http://en.wikipedia.org/wiki/Aircraft_noise

 

 

 

Such meticulous attention is paid to DCS sims. I wonder whether this is, in fact, implemented in the a10's flyby sound or is being considered.

 

I'm sorry for the minutiae--have no idea whether this is a completely ridiculous request or whether it's just a matter of a simple mod (replacing one sound file for another).

 

"Inquiring minds...", and all that.

 

Here's one example

 

Would someone in the know about these things be able to weigh in?

 

Many thanks.

 

Cheers,

 

Moosh

[gmohr]

Two points. I'm pretty certain I noticed increased aero noise with the speedbrakes open (i'll have to check this again). And two, noise cancelling headsets remove must such noise from a pilots perception. Not sure if A-10 pilots use such gear, but lots of civ and commercial pilots do.

[mooshim]

Two points. I'm pretty certain I noticed increased aero noise with the speedbrakes open (i'll have to check this again). And two, noise cancelling headsets remove must such noise from a pilots perception. Not sure if A-10 pilots use such gear, but lots of civ and commercial pilots do.

 

Copy that. I was actually referring to the compression of air--the sort of low, "scraping" or "carving" sound--perceived by the stationary ear--as in a flyby view--as opposed to what is heard by the pilot in-cockpit.

 

THX

 

edit:

This A10 clip illustrates the texture of sound I'm referring to.

http://www.youtube.com/watch?v=CwuzIQGRef0&feature=related

 

Perhaps it's enhanced due to the echo against the canyons (?)

Edited June 20, 2011 by mooshim
clip

[mvsgas]

Anyaseo (안녕하세요)

Just my opinion;

But sound it's very dependent on opinion. To many factor affect our perception (ambient factors, equipment use to record sound, etc) I have no idea of any sound changes, but no matter what ED does in DCS A-10 sound, someone will feel it's not accurate because of their personal experience.

Just my two cents

Edited June 20, 2011 by mvsgas

[mooshim]

Yeah, Slacker, I agree. There is something there...on top of the engine noise.

 

 

Anyaseo (안녕하세요)

Just my opinion;

But sound it's very dependent on opinion. To many factor affect our perception (ambient factors, equipment use to record sound, etc) I have no idea of any sound changes, but no matter what ED does in DCS A-10 sound, someone will feel it's not accurate because of their personal experience.

Just my two cents

 

안녕하세요 mvsgas.

 

Yeah, I guess that's a very basic problem with most non-standard, empirically measured aspects of a product like this(as opposed to measuring verifiable things ie avionics, wep system behavior, etc.) .

 

Cheers,

Moosh

 

PS

 

R U at Gunsan? just curious.

Edited June 20, 2011 by mooshim

[mvsgas]

Yes

[mooshim]

Yes

:)

 

--

 

Give us a pm if you are ever up in Seoul and want to get a beer--on me.

 

Cheers~

[Bucic]

I believe there's not much science to talk about. To make that topic any interesting c0ff* would have to pop up with some details on what is actually modeled (or mimicked), what is going to be in the near future and what is not. To give you an example why it's doesn't make much sense to discuss "particles" here - DCS sound engine currently can't even manage multiple overlapping sounds properly (multiple rockets salvo, heli rotors rattling etc.), AFAIK does not do sound occlusion nor is in any way "terrain aware". The sound engine evolves nicely but we'd need some starting point for the discussion.

 

 

* he's the ED team member who usually posts about the new DCS sound engine.