Particular sound P51D?

[Tjen il-vec]

Hi all,

Since I'm visiting airdisplays on a regular bases I always wondered where that howling or loud whistling sound comes from when a P51D is flying to-wards the spectators as it banks away right in front of the public. It almost sounds like a loud scream if you like.

I don't think it's the supercharger because that sound is always present and much higher in pitch and lower in volume and typical for a Packard Merlin.

I found out that it only emerges as the P51D is flying to-wards the crowd at high speed or in a turn away from or right above the crowd as it flies away.

It it something typical for the "D" version? This, because I've never heard it from a 'razorback' mustang like the P51B based on Duxford ..

Cheers!

Tjen

[Tjen il-vec]

Does no one know?

[R988]

I think I know the sound you speak of, though I think I may have heard it in Spitfires as well. I think I have some sound bites of a mustang as an example I can post up later when I get home.

[LineguyOKC]

I think the whistle is coming from the oil cooler and radiator in the scoop.
Many fighters had been nick-named for that whistle, like the Corsair and Hellcat.

[MikeGazdik]

I had always thought it was the supercharger too. But I was told or read it was the radiator cooler. I started watching airshow videos on-line. I dont seem to notice the noise you speak of with the Spitfires. I have not seen a Spitfire fly in person, so all I have is videos to make this guess opinion.

[mad_max]

One Mustang pilot and some other folks thinks it's air whistling through the 2 inboard air-cooled gun barrels and others say through the gun ports. Is this the reason? Who knows, but I heard most ponies making this noise at the Mustangs and Legends Show when at higher speed.

Mustang P 51 Circles Dives | Soundsnap

Best,

[Airframes]

The Spitfire does has a distinctive 'whistle' on approach, particularly the later Marks, (pre Griffon engine) such as the MkIX, but the Mustang certainly has 'that noise'. I also think it might be the air passing through the underbelly scoop, exiting through the aft doors. It could also possibly be the gun ports or barrels, but the latter would be 'plugged' anyway, preventing any significant airflow that could cause the 'whistle'.
Even though the supercharger would be inactive at air show altitudes, I have also heard that the 'whistle' was from the turbine blades; it will be interesting to confirm where it actually does originate.

[billswagger]

Originally Posted by mad_max

One Mustang pilot and some other folks thinks it's air whistling through the 2 inboard air-cooled gun barrels and others say through the gun ports. Is this the reason? Who knows, but I heard most ponies making this noise at the Mustangs and Legends Show when at higher speed.

Mustang P 51 Circles Dives | Soundsnap

Best,

Id be guessing, ...... not so much the scoop, but the gap between the scoop and the plane looks like it might make a whistle at high speed, considering the way the air is moving down the fuselage and then gets split, where the air goes into the scoop and where the air goes into that small gap. It then has to work its way out of there with air also moving around the outside of the scoop and the gap....so the air ramming into itself is heard as a whistle...

like i said though, a total guess.