The P51 whine

[Simpo Two]

A freind asks what causes the P51 to whine during certain manouvers. I thought it was the supercharger, but then Spitfires have the same and sound different. Google dosn't help, half the answers being supercharger and half gunports... does anyone have a definitive answer? Maybe both?

[TEKNOPUG]

The Yank pilot.

[2 sMoKiN bArReLs]

I thought it was the wind whistling through the machine gun holes

[2 sMoKiN bArReLs]

https://www.youtube.com/watch?v=h5fjKEXXPQ8

[Simpo Two]

Well I suppose if it goes up and down with rpm it's supercharger, and if it's speed dependent it's gunports. Still not sure though...

[Eric Mc]

I've read it's the gunports. The Hispano Buchon also makes a similar whine.

[Simpo Two]

Clearly we need to borrow one, tape over the gunports and see if that stops it...

[2 sMoKiN bArReLs]

Completely unrelated, but whilst watching Mustangs I stumbled over this:

https://www.youtube.com/watch?v=pmy_8bUMOIU

I like the one on the beach best when all the deck chairs etc are scattered!

[davepoth]

Simpo Two said:

A freind asks what causes the P51 to whine during certain manouvers. I thought it was the supercharger, but then Spitfires have the same and sound different. Google dosn't help, half the answers being supercharger and half gunports... does anyone have a definitive answer? Maybe both?

I've got a feeling it's got something to do with the air scoop underneath - it's designed to create thrust by the Meredith effect.

http://www.historicracer.com/aviation/p51-mustang-...

The Spitfire did use this too but nowhere near as much.

In effect the mustang had a tiny little jet engine hanging on its belly, spewing warm air out through a restricted orifice just like a kettle does when it is on the boil. A likely candidate I reckon.

[Eric Mc]

Do you know that the chap who designed the underside air scoop for the Mustang was also involved in designing the Space Shuttle. The Mustang and the Space Shuttle were built by the same company, and Dale Myers was a key person in both projects.

[Flooble]

Eric Mc said:

Do you know that the chap who designed the underside air scoop for the Mustang was also involved in designing the Space Shuttle. The Mustang and the Space Shuttle were built by the same company, and Dale Myers was a key person in both projects.

Just shows how the pace of technological advancement has slowed. Be lucky to find an aerospace engineer today who gets to work on more than one aircraft from inception to delivery throughout their career.

[Simpo Two]

2 sMoKiN bArReLs said:

Completely unrelated, but whilst watching Mustangs I stumbled over this:

https://www.youtube.com/watch?v=pmy_8bUMOIU

I like the one on the beach best when all the deck chairs etc are scattered!

6'38" is only a few feet away from being the accidental manouver now called 'a Hunter'

[Eric Mc]

Flooble said:

Just shows how the pace of technological advancement has slowed. Be lucky to find an aerospace engineer today who gets to work on more than one aircraft from inception to delivery throughout their career.

He actually worked on all of North American Aviation's major projects from the Harvard through the P-51, B-25, F-86, F-100, X-15, Vigilante, XB-70, Apollo Command- Service Module etc. What a list of great aircraft and spacecraft to be connected to.

Myers only passed away last year at the age of 93.

[aeropilot]

TEKNOPUG said:

The Yank pilot.

Especially if his name is Yeager

[aeropilot]

Simpo Two said:

A freind asks what causes the P51 to whine during certain manouvers.

It's the open gunports on certain aircraft, or rather installed replica gun barrels, that's why they don't all make the noise.

Edited by aeropilot on Sunday 23 October 20:58

[Simpo Two]

[lufbramatt]

When we photographed Big Beautiful Doll (before it crashed at Duxford), then then owner, Rob Davies, said it was air flowing through the gun ports.

[Vitorio]

2 sMoKiN bArReLs said:

Completely unrelated, but whilst watching Mustangs I stumbled over this:

https://www.youtube.com/watch?v=pmy_8bUMOIU

I like the one on the beach best when all the deck chairs etc are scattered!

Holy balls... in that first clip the pilot can probably just extend his gear and hit the brakes to stop...

[Eric Mc]

I'm currently working on the 1/72 Academy plastic kit of the Allison powered P-51 Mustang. I want to finish it as an early RAF Mustang I.
I wonder if these earlier Mustangs also exhibited the whine. There are a couple of Allison Mustangs still flying but I've never heard or seen one for real.

[aeropilot]

Eric Mc said:

I wonder if these earlier Mustangs also exhibited the whine.

Even if they have replica barrels fitted, I suspect they won't make the whine.
The most technical explanation I've seen of the reason (whether its correct or not is another matter!) from a USA P-51 owner/restorer is it's the air flow around the inboard gun barrel, which on a P-51 B/C/D etc is staggered slightly compared to the outer pair....and its this disrupted air flow at this barrel that causes the whine....
So, with the A model only having the 4 x fifties (i.e the same as the outer pairs on the later models) my guess is the A's won't make the noise?