Author Topic: Vortex Shedding  (Read 1162 times)

Offline Chalenge

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Vortex Shedding
« on: May 21, 2018, 11:46:16 AM »
I have been working on modifying the propeller sounds so that the sound of a prop, as the airplane approaches stall speed, acts as a stall warning buzzer in much the same way that a helicopter blade produces a "slap" as vortex shedding occurs (one blade passing through the air of the preceding blade). My experience has been with sailplanes, though, so I am not sure if this is an accurate way to approach it. It seems logical, but I could easily be over thinking it . . .

If anyone has experience with nose-high stalls in a propeller aircraft I would be interested in hearing your opinion.
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Offline Vraciu

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Re: Vortex Shedding
« Reply #1 on: May 21, 2018, 06:05:43 PM »
I don’t notice anything like that.   Spent hours upon hours teaching stalls.  *Maybe* a minimal buzz if pulling Gs but no slap.

That said, maybe those wth experience in higher performance pistons may have some input that differs.   

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Offline bustr

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Re: Vortex Shedding
« Reply #2 on: May 25, 2018, 02:27:53 PM »
In krupinki's post the stall air turbulence sound he used worked better in the game to help me gauge staying in the bleeding edge than the current buzzer. And it reminded me of all the stall and spin recovery practice I sat through over the years as a kid with my father and all his friends who took me for rides. Wonder where he got it from or maybe he ported it from one of the IL2 games. And it has some nice intro replacement music. He didn't update it for the recent FMOD update so I deleted it.
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Offline Chalenge

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Re: Vortex Shedding
« Reply #3 on: May 25, 2018, 04:11:01 PM »
What I ended up doing is mixing (actual FMOD handles this) my old buffet sound, with the prop slap sounds. I have prop slaps recorded for the P-47, P-51, C-47 . . . basically the American planes I see most often. In the case of the American fighters the gun whistle sound is a pretty good warning that you are at a high AOA, and the same goes for most warplanes to some degree. So in some airplanes you will hear the whistle grow louder, and steadier, while others will mostly be buffet and prop slap.
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Offline Chalenge

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Re: Vortex Shedding
« Reply #4 on: June 03, 2018, 06:16:49 PM »
See if you can detect the vortex shedding in this video.

https://www.youtube.com/watch?v=u2A5ywM8TNk

EDIT: Precious Metal does not have gun ports, so at the higher angles of attack (slower speeds) you do not hear the gun port whistle. Still, the airplane does whistle at high speeds, and that's because of the airflow through the radiator. The Mustangs in AH should have both whistles.
« Last Edit: June 03, 2018, 06:21:31 PM by Chalenge »
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Offline Vraciu

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Re: Vortex Shedding
« Reply #5 on: June 21, 2018, 06:59:40 AM »
See if you can detect the vortex shedding in this video.

https://www.youtube.com/watch?v=u2A5ywM8TNk

EDIT: Precious Metal does not have gun ports, so at the higher angles of attack (slower speeds) you do not hear the gun port whistle. Still, the airplane does whistle at high speeds, and that's because of the airflow through the radiator. The Mustangs in AH should have both whistles.

That's a Griffon engine with counter rotating propellers.   Probably not the best baseline. 


The Mustang whistle is a strange thing in part because it is so rarely heard.   If it is radiator-driven then it has to be the right speed and door position combo.    In four decades of watching these planes fly the only thing rarer than that regarding a P-51 flyby is a proper recording of the Merlin hum.

I'll post a link to that. 
« Last Edit: June 21, 2018, 07:13:50 AM by Vraciu »
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Offline Vraciu

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Re: Vortex Shedding
« Reply #6 on: June 21, 2018, 07:04:22 AM »
Merlin Hum 1:30:12ish.  https://www.youtube.com/watch?v=LbqcDy2R67c

Once you've heard it you never forget, but dang if people can record it.  Must be a Doppler Effect or something.  This is the best I've heard. 

Crazy Horse 2 was recorded once as well that I found but the music and Chatty Cathy messed it up. 

Right after the whistle at around 0:39.

https://www.youtube.com/watch?v=aXqnCI1B_9g
« Last Edit: June 21, 2018, 07:11:59 AM by Vraciu »
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Offline Chalenge

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Re: Vortex Shedding
« Reply #7 on: June 23, 2018, 04:33:42 PM »
Gun whistle @ 8:04 listen as Kermit pulls the throttle back.

https://www.youtube.com/watch?v=eOXxUApaaWo

versus every pass in this video (radiator duct).

https://www.youtube.com/watch?v=BsAmhPEGoAI
« Last Edit: June 23, 2018, 04:35:46 PM by Chalenge »
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Offline Vraciu

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Re: Vortex Shedding
« Reply #8 on: June 26, 2018, 07:01:24 AM »
The radiator certainly has more warble to it.  Almost like an uneven shriek at times.

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Offline Puma44

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Re: Vortex Shedding
« Reply #9 on: July 08, 2018, 05:41:05 PM »
I have been working on modifying the propeller sounds so that the sound of a prop, as the airplane approaches stall speed, acts as a stall warning buzzer in much the same way that a helicopter blade produces a "slap" as vortex shedding occurs (one blade passing through the air of the preceding blade). My experience has been with sailplanes, though, so I am not sure if this is an accurate way to approach it. It seems logical, but I could easily be over thinking it . . .

If anyone has experience with nose-high stalls in a propeller aircraft I would be interested in hearing your opinion.

Just flew a 1.8 in Crazy Horse 2 last week.  Among the fun was a series of stalls.  No “prop slap” noticed, just the normal pebbles, rocks, and boulders vibration.  Although fun to fly and a reasonablely accurate flight model, I find the AH Mustang sounds a bit unrealistic.

Up initial for a full stop.  https://youtu.be/WNr8iCbajGw



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Offline Puma44

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Re: Vortex Shedding
« Reply #10 on: July 11, 2018, 05:02:24 PM »
As a side note, the Mustang flaps are hydraulically operated via the cockpit flap handle and therefore, make no discernible noise when being extended or retracted, unlike the AH electric motor sound.  I realize there has to be some sort of in game feedback for the flap operation since we have no realistic tactile feel.  Just something of interest from the real Mustang operation.



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Offline GrandpaChaps

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Re: Vortex Shedding
« Reply #11 on: November 15, 2018, 05:20:20 PM »
Gun whistle @ 8:04 listen as Kermit pulls the throttle back.

https://www.youtube.com/watch?v=eOXxUApaaWo

versus every pass in this video (radiator duct).

https://www.youtube.com/watch?v=BsAmhPEGoAI

And, for laymen out there, here's a video on "shedding"  https://www.youtube.com/watch?v=ZauGjgZ0rBQ

And, for those (I'm about one of them) who need lesser than laymen terms sometimes....

shedding is... well, watch the movie Top Gun.  It is "... Tom Cruise was cool in Top Gun when he was the Maverick, that's before he went crazy and needed to go do the loops."
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Offline Chalenge

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Re: Vortex Shedding
« Reply #12 on: November 23, 2018, 03:25:12 PM »
As a side note, the Mustang flaps are hydraulically operated via the cockpit flap handle and therefore, make no discernible noise when being extended or retracted, unlike the AH electric motor sound.  I realize there has to be some sort of in game feedback for the flap operation since we have no realistic tactile feel.  Just something of interest from the real Mustang operation.

This could be addressed in a number of ways. You actually can hear a difference in ambient cockpit sound levels, although at full throttle you would certainly never notice. While landing it is only one audible change.
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Offline DaddyAce

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Re: Vortex Shedding
« Reply #13 on: January 21, 2019, 09:41:10 PM »
Just flew a 1.8 in Crazy Horse 2 last week.  Among the fun was a series of stalls.  No “prop slap” noticed, just the normal pebbles, rocks, and boulders vibration.  Although fun to fly and a reasonablely accurate flight model, I find the AH Mustang sounds a bit unrealistic.

Up initial for a full stop.  https://youtu.be/WNr8iCbajGw

Agreed, based on the hour +, (including a stall) I enjoyed  in "Toulouse Nuts" last year.

Offline TwinBoom

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Re: Vortex Shedding
« Reply #14 on: January 22, 2019, 12:54:10 PM »
Just flew a 1.8 in Crazy Horse 2 last week.  Among the fun was a series of stalls.  No “prop slap” noticed, just the normal pebbles, rocks, and boulders vibration.  Although fun to fly and a reasonablely accurate flight model, I find the AH Mustang sounds a bit unrealistic.

Up initial for a full stop.  https://youtu.be/WNr8iCbajGw

I spend everyday there watching during my Lunch.
The museum is doing P40 rides now to. It's awesome to see the TF51s t6 Texan,  t28, and p40 flying everyday
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