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Take that, you radial engine perverts !!!!!

J. Armstrong

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What causes that whistling sound?
It is the airflow over the two innermost gunports - think blowing over the top of a soda bottle. The six gunned P51Ds and Ks have the innermost gun in each wing set back to allow the ammo feeds to pass behind the other guns, which requires a blast tube between the gun muzzle and the gun port. Certain types of high speed airflow over these ports cause the whistle - usually as the plane increases its angle of attack. Four gun 51Bs and Cs don't do it, nor do Ds and Ks if the gun ports are covered or blocked or if the inner blast tubes and guns aren't installed.
Lots of folks believe it is the supercharger, but if that were the case, Spitfires with the same engine would do it, but they don't. There is some supercharger whine, but it is pretty faint and nothing like the gunport shriek.
Interestingly, some models of the Corsair have whistling sound, but in their case it is caused by vanes in the wingroot air intakes which redirect some of the air into the oil cooler ducts.
 
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hkshooter

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You can't hear the super charger whistle on a Merlin because the super charger isn't an exhaust driven turbo charger. Just like you can't hear the blower on a drag car, it isn't exhaust driven so you can't hear the charger through the exhaust, that's a turbo thing. Observe the P-38 Lightening. No exhausts on the side of the cowlings because the exhaust is routed through the exhaust driven super charger at the rear of the nacelles. Most all of the P-38's I've seen fly no longer have the super chargers installed but if one has, I've never noticed a turbo whine.
 

harleyrider

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You can't hear the super charger whistle on a Merlin because the super charger isn't an exhaust driven turbo charger. Just like you can't hear the blower on a drag car, it isn't exhaust driven so you can't hear the charger through the exhaust, that's a turbo thing. Observe the P-38 Lightening. No exhausts on the side of the cowlings because the exhaust is routed through the exhaust driven super charger at the rear of the nacelles. Most all of the P-38's I've seen fly no longer have the super chargers installed but if one has, I've never noticed a turbo whine.
The whine of a supercharger on a car is not due to moving air through the supercharger, but the sound air escaping from being compressed between the blower belt and pulley. You can certainly hear a blown engine whine as they cruise along. Don’t know about V12 Merlins.

IMO, V12 aircraft sound like misfiring VW’s when on the ground. Only when they get airborne does the sound become acceptable.

Corsairs sound beautiful at all speeds, especially at 400 knots. Like butter. 😍

HR
 

J. Armstrong

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The whine of a supercharger on a car is not due to moving air through the supercharger, but the sound air escaping from being compressed between the blower belt and pulley. You can certainly hear a blown engine whine as they cruise along. Don’t know about V12 Merlins.

IMO, V12 aircraft sound like misfiring VW’s when on the ground. Only when they get airborne does the sound become acceptable.

Corsairs sound beautiful at all speeds, especially at 400 knots. Like butter. 😍

HR
Geez, I don't know what kind of VW engines you've been listening to............o_O:);)
 

hkshooter

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The whine of a supercharger on a car is not due to moving air through the supercharger, but the sound air escaping from being compressed between the blower belt and pulley. You can certainly hear a blown engine whine as they cruise along. Don’t know about V12 Merlins.

IMO, V12 aircraft sound like misfiring VW’s when on the ground. Only when they get airborne does the sound become acceptable.

Corsairs sound beautiful at all speeds, especially at 400 knots. Like butter. 😍

HR
From what I've seen a lot of blown cars have gear timing that does the whining. When it comes to modern production cars, I've never heard the supercharger on those types and can only hear the turbo on my own car at fast idle with the hood open. Close the hood and it's gone.
 

harleyrider

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From what I've seen a lot of blown cars have gear timing that does the whining. When it comes to modern production cars, I've never heard the supercharger on those types and can only hear the turbo on my own car at fast idle with the hood open. Close the hood and it's gone.
When I’m thinking of a blower, it’s a 6-71 or 8-71 roots blowers w/ a 3” wide belt drive. I dont have a clue what modern production car blowers look like. 🤔

HR
 

J. Armstrong

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Geez, I don't know what kind of VW engines you've been listening to............o_O:);)
Of course, at least some radials sound like a washing machine full of rocks

!

Actually, I'm just funnin' with you. In this case, it does sound pretty crappy, but I think it's just a fluke of the recording. I do love an R2800, they usually sound great whether idling or in flight, but an Allison or Merlin at full throttle really is my favorite.
 

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I always got a kick out of listening to G Gordon Liddy’s intro music to his radio program which included the Battle of Britain music with all of the screaming, racing and roaring Merlin spitfires.
I forgot about that! Was very cool, I miss that guy some days.
 

Jeff in Pa

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Whatever the whine it gives the P-51 a unique approach announcement. If you are about to be on the receiving end of those 6 .50 cal machine guns you need to take cover!!

Beautiful aircraft.
Late 80s I was racing go karts at Oreville Kart Club. One of my fellow racers was a pilot in the Air National Guard and they had a P-51 in their squadron During the Reading (PA) Air Show, he did a flyover at Oreville.

He was at about 500' flying south. Nice throaty roar. He went into a climb, nosed over and starting down. My former FIL said " Oh shit" and started running. The poor ladies in the scoring building had no idea what was happening as he buzzed the track at literally 75' and roared off back to Reading.

You could feel the thunder in your chest. Cool and scary all at once.
 

Pluribus

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Late 80s I was racing go karts at Oreville Kart Club. One of my fellow racers was a pilot in the Air National Guard and they had a P-51 in their squadron During the Reading (PA) Air Show, he did a flyover at Oreville.

He was at about 500' flying south. Nice throaty roar. He went into a climb, nosed over and starting down. My former FIL said " Oh shit" and started running. The poor ladies in the scoring building had no idea what was happening as he buzzed the track at literally 75' and roared off back to Reading.

You could feel the thunder in your chest. Cool and scary all at once.
I imagine! Just think of one of those screaming down on you in a strafing run. THAT, would indeed be scary.
 

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Love the Allisons and Merlins, also love the radials but for different reasons. I hear the V12's and I get excited in a performance, kind of way. Like watching a close horse race, I get worked up and the hairs on my arms raise. Like hearing a Formula 1 car at 12k, just exciting!

When a radial roars by or, and I can't express my love for this enough, when you are on and I mean ON the taxi way, leaning on the ropes and a big 2800 idles by, oooOOOOO! I get shivers just thinking about it. And if a multi engine rolls by? OMG. The smell of the fuel, the blowing dust, the deep in your gut beating you feel, like standing next to the pit when the crew fires up a top fuel car and turns on the nitro. The instinctual fear combined with excitement, the senses over loaded, it all serves to give me a perma-grin that has to wear off over hours. So freaking awesome.
The 2800s roar and rumble, the Wright 2600's have a nice snap to them that's unique to the engine, I think.
Great, now I want to go to an air show.
 

harleyrider

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Of course, at least some radials sound like a washing machine full of rocks

!

Actually, I'm just funnin' with you. In this case, it does sound pretty crappy, but I think it's just a fluke of the recording. I do love an R2800, they usually sound great whether idling or in flight, but an Allison or Merlin at full throttle really is my favorite.
I’m just kidding around too. I like those Allison’s especially when they’re X 2


HR
 

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Interestingly, the P-51 A,B, & early C's had the Allison engine. Good but only at low & medium altitude. The Brits having some from our "Lend Lease" program didn't like how the Allison operated at high altitude & tried installing the Merlin in it's place.
It transformed the P-51 from a decent fighter to a world class ass kickin' machine! We were so impressed that the Brits allowed us to build Merlin's in America & since the improvement to the make the P-51 D's included that Merlin engine, it became the premier fighter in Europe and excelled in the Pacific theatre as well.
Suprisingly, the P-47 D's also used the PW R-2800 Double Wasp that the Corsair used but for some reason, as fantastic as the "Jug" was it didn't seem to have the sound or the panache of the Corsair.
It can be argued which was the better fighter, the Corsair or the Mustang. The Corsair had good handling (carrier landings could be difficult or a new Ensign) speed, firepower & made a great ground attack plane as well & could absorb a lot of punishment. the "Stang had most of those same qualities but further range. It's a toss up. Kind of a Ford vs Chevy thing. IIRC they were the only prop fighters to also see service in Korea when the jet age was beginning. I think that is a testament to how good both planes were. Perhaps along with the Skyraider, the pinnacle of piston driven aircraft.
 

hkshooter

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the "Stang had most of those same qualities but further range.
Mustang was a shitty ground attack AC if it was being shot at as it didn't have the same ability to absorb punishment. The radiator and associated plumbing for the liquid cooled engine made it vulnerable to even a single hit from small caliber fire. Meanwhile the radials had been known to keep flying with entire jugs shot off the engine. Not very long mind you, it would eventually run out of oil but they took a lot more beating than the liquid cooled planes by far.
 

J. Armstrong

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Interestingly, the P-51 A,B, & early C's had the Allison engine. Good but only at low & medium altitude. The Brits having some from our "Lend Lease" program didn't like how the Allison operated at high altitude & tried installing the Merlin in it's place.
It transformed the P-51 from a decent fighter to a world class ass kickin' machine! We were so impressed that the Brits allowed us to build Merlin's in America & since the improvement to the make the P-51 D's included that Merlin engine, it became the premier fighter in Europe and excelled in the Pacific theatre as well.
Suprisingly, the P-47 D's also used the PW R-2800 Double Wasp that the Corsair used but for some reason, as fantastic as the "Jug" was it didn't seem to have the sound or the panache of the Corsair.
It can be argued which was the better fighter, the Corsair or the Mustang. The Corsair had good handling (carrier landings could be difficult or a new Ensign) speed, firepower & made a great ground attack plane as well & could absorb a lot of punishment. the "Stang had most of those same qualities but further range. It's a toss up. Kind of a Ford vs Chevy thing. IIRC they were the only prop fighters to also see service in Korea when the jet age was beginning. I think that is a testament to how good both planes were. Perhaps along with the Skyraider, the pinnacle of piston driven aircraft.
I suspect the 47s difference in sound comes from being somewhat muffled by the turbocharger. I think all flying 47s have the turbos locked out, but there is still a lot of ducting to change the sound ?
Corsair vs Mustang ? Apples and oranges. The are designed for very different missions. The 51 had a much higher kill record, partly because the Corsair took so long to get into service due to some evil handling problems. Personally I don't think much of the F4U although I can't deny it's admirable service record. One of the more expensive and difficult fighters to build and maintain, exceptionally poor visibility. Give me the mostly forgotten, plain Jane F6F Hellcat. When it comes to kill record, the 'cat was unsurpassed.
ETA: I guess I should qualify that last part - the P51 had marginally more overall kills, but the Hellcats kill/loss ratio was tops by far.
 
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