P-51D vs P-51H: The Definitive Mustang and the Ultimate Mustang

"ttyymmnn" (ttyymmnn) 10/14/2020 at 12:35 • Filed to: wingspan, Planelopnik

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P-51D top, P-51H bottom. The D model was the definitive variant, while the H model was perhaps the best.

When the British approached North American Aviation and asked them to build the Curtiss P-40 Warhawk for them, NAA President James “Dutch” Kindelberger said they could design and build a better fighter in the same amount of time it would take to tool up for the Warhak. Led by chief designer Edgar Schmued, North American did just that in only 102 days. The result was the North American P-51 Mustang. Powered by the remarkable Packard Merlin V-12 engine, the Mustang was arguably one of the greatest piston-powered fighters to come out of WWII, and maybe even the best ever.

The tenth production P-51B was modified and served as the prototype for the P-51D. Note the teardrop canopy with armored windscreen, and angled wing root. The production D model would receive the extended vertical stabilizer, or fin fillet.

The Mustang underwent many changes as it matured throughout the war. But the most notable structural changes came with the P-51D variant, which eliminated the dangerous blind spot behind the pilot by replacing the original canopy with a plexiglass teardrop canopy. With the loss of the dorsal area behind the cockpit, the Mustang experienced yaw instability in a dive, so the vertical stabilizer was extended, though this change was not included in the initial D models. Other outward changes that came with the Mustang D included wing root fillets to accommodate redesigned landing gear which gave the Mustang its characteristic angled leading edge. The P-51D would become the definitive version and serve in the highest numbers.

A California Air National Guard P-51H in flight

Though the Mustang D proved to be an exceptional fighter with remarkable range and maneuverability, there was still room for improvement. Beginning with the XP-51F and G, North American made the aircraft several hundred pounds lighter while extending the fuselage. The vertical stabilizer was made taller to improve yaw performance, while the ventral air intake was reshaped and lengthened. The result was a slightly taller, more slab-sided fuselage. A new Packard V-1650-9 Merlin with water injection and new automatic supercharger boost control provided up to 2,270 hp at full tilt, and a new, uncuffed propeller with rounded tips got the most power from the engine (this prop also appeared on later D production models). With less weight and more power, the H was now capable of speeds up to 472 mph, about 30 mph faster than the D.

P-51D, top, compared to P-51H

The P-51H, along with the improved Republic P-47N Thunderbolt, were planned as the main fighter force for the anticipated invasion of Japan. And while some H model Mustangs did make it to fighting units, none saw action in WWII. With the end of the war, most of the 555 that were built served stateside in Air National Guard units, while the abundant and battle-tested D model fought in Korea. North American also used the H model, or two of them, to create the F-82 Twin Mustang.

The F-82 Twin Mustang was created by joining two P-51H Mustangs.

P-51D Mustangs of the California Air National Guard

P-51H Mustangs of the Maryland Air National Guard

Author’s musings: Though performance was improved in the H model, I can’t help but think that the Mustang lost something in the looks department. Of course, looks don’t win dogfights, but there was a balance to the lines and shape of the classic Mustang D. Somehow, at least to me, the H seems a bit more ungainly, though its performance says otherwise. Maybe it’s also the taller tail, or the extended ventral intake. But somehow, the proportions just seem...off. However, if you like the taller tail with the classic fuselage profile, there’s always the !!!error: Indecipherable SUB-paragraph formatting!!! .

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rctothefuture > ttyymmnn 10/14/2020 at 13:21

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The D is what most people think when they hear “P-51 Mustang”. It’s really a great looking plane, probably why folks prefer them over other models in antique plane culture.

ttyymmnn > rctothefuture 10/14/2020 at 13:48

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I agree. Though as capable, the P-47 doesn’t garner quite the same interest. It doesn’t look fast sitting still like the Mustang does. I was always partial to the Mustang III that got the Spitfire canopy, or Malcolm Hood.

RacinBob > ttyymmnn 10/14/2020 at 13:57

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Nice writing.

ttyymmnn > RacinBob 10/14/2020 at 13:58

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Thank you! After all this time I dare to dream that I’m getting better at it. 

ttyymmnn > RacinBob 10/14/2020 at 14:10

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Your comment made me go back and read it again. And make more changes!

ClassicDatsunDebate > ttyymmnn 10/14/2020 at 14:27

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YEs! I believe this specific aircraft, PK-G flown by S/L Horbaczewski is the most handsome of WWII:

ClassicDatsunDebate > ttyymmnn 10/14/2020 at 14:29

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Very versitile airframe. Here’s a Piper Enforcer from the Pave Coin secret project:

user314 > ttyymmnn 10/14/2020 at 14:30

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Yeah, the Jug is not quite as elegant as the Mustang or Spit, but damn if she wasn’t beast.

ttyymmnn > ClassicDatsunDebate 10/14/2020 at 14:33

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Thing is, I always felt that the extended vertical stabilizer, or fin fillet, helped the aesthetics of the aircraft as it paralleled the bottom line and made the tail less pinchy. I first learned of that sort of thing when reading about the Boeing 307 . Those things were horrible with rudder lock until they extended the tail fin. Prototype is on top. 

ttyymmnn > ClassicDatsunDebate 10/14/2020 at 14:38

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Theres’s also a lot of P-51 in the FJ-1 Fury and the Sabreliner.

ttyymmnn > user314 10/14/2020 at 14:40

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The Jug was a very big fighter. 

ClassicDatsunDebate > ttyymmnn 10/14/2020 at 14:41

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The early D’s didn’t have the extended fin fillet. As I recall, they suffered the same instabillity at high dive speeds as the P-47 when they both went to the bubble canopy and shed their “ridgebacks”. The early D’s look good without it too, IMO.  Here’s a shot of the 8thAF 361 FG in early ‘44 showing a B and early and late D’s

ttyymmnn > ClassicDatsunDebate 10/14/2020 at 14:48

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That’s an interesting mix of versions. 

ClassicDatsunDebate > ttyymmnn 10/14/2020 at 14:54

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yeah, thats why I love that pic so much.

ClassicDatsunDebate > ttyymmnn 10/14/2020 at 14:58

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I have a color version in one of my reference books but it on two pages with a seam in the middle....Found one of the original shots on-line......

ttyymmnn > ClassicDatsunDebate 10/14/2020 at 15:04

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I wonder if that was colorized. There’s an interesting quote in the Wiki article about the Mustang v the Spitfire:

Chief Naval Test Pilot and C.O. Captured Enemy Aircraft Flight Capt. Eric Brown , CBE , DSC , AFC , RN , tested the Mustang at RAE Farnborough in March 1944 and noted, “The Mustang was a good fighter and the best escort due to its incredible range, make no mistake about it. It was also the best American dogfighter. But the laminar-flow wing fitted to the Mustang could be a little tricky. It could not by any means out-turn a Spitfire. No way. It had a good rate-of-roll, better than the Spitfire, so I would say the plusses to the Spitfire and the Mustang just about equate. If I were in a dogfight, I’d prefer to be flying the Spitfire. The problem was I wouldn’t like to be in a dogfight near Berlin, because I could never get home to Britain in a Spitfire!”

ClassicDatsunDebate > ttyymmnn 10/14/2020 at 15:10

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That’s a good quote.

I would say they aren’t colorized, as there are a few from that shoot and theyre all color.

ttyymmnn > ClassicDatsunDebate 10/14/2020 at 15:16

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Eric “Winkle” Brown was the shit. He flew 487 different aircraft, more than anybody else ever and lived to age 97.