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what is the Merlin Whistle?

Posted: 09 May 2018, 15:58
by cessna lover
this is for the real P-51 aficionados out there. when diving the P-51 what causes here to Whistle at a certain speed? is it the propeller or is it something else? cause I was doing a virtual airshow at my home field and I like scaring the show goers with the whistle :lol:

Re: what is the Merlin Whistle?

Posted: 09 May 2018, 18:30
by AviationAtWar
It's air over the gun barrel tips, just like blowing over the end of a beer bottle...but at 400 MPH.

Re: what is the Merlin Whistle?

Posted: 09 May 2018, 19:01
by DHenriques_
cessna lover wrote:this is for the real P-51 aficionados out there. when diving the P-51 what causes here to Whistle at a certain speed? is it the propeller or is it something else? cause I was doing a virtual airshow at my home field and I like scaring the show goers with the whistle :lol:
Back when I was flying the 51 for display I must have had hundreds of fans ask me about the whistle. We guessed back then it was a combination of several sounds all related to the angle of attack of the relative wind passing over openings.
We almost had it right LOL
I have a friend who flies his 51 on the airshow circuit today (Scott Yoak). He actually ran some flight tests on the Merlin whistle and has proved beyond any doubt that the sound comes from the open INNER gun ports on each side of the leading edge on each wing. This backed up the experiments done by several other expert sources.
The Mustang isn't the only aircraft to make this sound. It can be heard coming from several other types as well. The ME109 for example has this sound.
The sound will especially occur with the aircraft in curved flight under g as the relative wind forms an angle much like your breath does when playing an Irish Flute as it passes over the inside gun barrel opening. The reason it's the inner gun opening is that this opening is a bit different from the rest and its mouth forms an almost perfect "flute effect" as angle of attack increases over the opening.
Dudley Henriques

Re: what is the Merlin Whistle?

Posted: 10 May 2018, 06:49
by cessna lover
:D how cool is that. thank you for the information. I thought it was a turbo or something.