P-51 Mustang

[Aussie Dave]

History in WWII:

June '40 - British Request
In the Spring of 1940, the British Purchasing Commission, headed by Sir Henry Self, visiting the U.S. asked Dutch Kindelberger, head of North American Aviation, to build Curtiss-designed P-40's for them. While his company had never built a fighter, Kindelberger's designers, led by Edgar Schmued had started design work on a modern fighter.
Already, in 1940, the Curtiss P-40 and the Bell P-39 were inferior to aircraft being flown by Germany and Britain.
Kindelberger offered to design and build the first prototype of the new fighter in 120 days. They signed the contract for 300 of the aircraft in late May.
The new fighter incorporated many of the latest developments in aeronautics, notably the laminar flow wing, a wing that was relatively symmetrical and offered less drag at high speed. The wings were designed to be easy to manufacture, with only two spars. As specified by the British requirement, the new airplane, designated the NA-73X, employed an in-line engine; the Allison V-1710 fit the bill, although it lacked a turbosupercharger for high-altitude performance. The main wheels were set twelve feet apart, for good stability on landing.

In the original design, the British required eight machine guns: four .30 caliber and four .50 caliber. Ultimately, most Mustangs would carry the usual American weaponry of six .50 caliber Brownings. It carried twice as much internal fuel as a Spitfire, 180 gallons in self-sealing wing tanks.

102 days after contract signing, in Sept. 1940, the protoype NA-73X rolled out. Apparently no one quibbled over the fact that it didn't have an engine, nor brakes, nor paint, nor actual gun mounts.

Prototype NA-73X first flight was in Oct. 1940.

While North American (NAA) had developed the prototype quickly, the first stage of production moved along more slowly. The first NA-73 production aircraft did not fly until April 23, 1941, six months after NA-73X. It carried no weapons and was kept by NAA for testing and development. The second production airplane (armed with four .30's and four .50's) arrived in Liverpool in October, 1941 - a year after the prototype's first flight.

Nonetheless, the Mustang was so promising that in late 1941 the RAF ordered another 300 and the USAAF 150. As the exigencies of war demanded, 93 of these 150 (factory designated NA-91) ended up in British service, as Mustang IA's, equipped with four 20mm cannon. The remaining 57, equipped with four .50 caliber machine guns, and known as P-51's, ended up in US service.

As early as May, 1942, Ronald Harker, a Rolls Royce test pilot, first recommended mating the Mustang airframe to the Merlin engine, an idea which would transform the P-51 into a decisive weapon, capable of escorting American bombers all the way to Berlin. Harker test-flew an RAF Mustang on April 30, 1942, and noted that it was 30 MPH faster than the Spitfire Mk V and had almost double the range. Harker's memo recommending the Merlin-Mustang combination (in which he erroneously identified Edgar Schmued as a former Masserschmitt employee) got the attention of Rolls Royce management, who borrowed five RAF Mustangs to test the idea. The British flight-tested the Mustang X in October, and found that the experimental craft significantly out-performed the Allison at high altitudes, generating 200 more horsepower at 20,000 feet and almost 500 more HP at 30,000 feet. While the British research was valuable, the American Merlin Mustang program proceeded almost independently.

In the summer of 1942, Packard Motors was negotiating with Rolls Royce to license-build the Merlin engine at its Detroit plant. Learning of Rolls Royce' Merlin-Mustang plans, Major Thomas Hitchcock, the American military attache in London, and others, pushed for the development of a Mustang powered by the Packard-built Merlin. Authorized in July, 1942, North American began its Merlin Mustang development in August.

The XP-51B included these changes:
a Packard Merlin engine, instead of the Allison V-1710
a four-bladed propeller
stronger underwing racks
a strengthened airframe
a relocated carburetor air intake, from above to below the nose
an intercooler radiator
larger ducts and doors for the radiator system
a deeper scoop under the rear fuselage
removal of the nose-mounted guns

First flown on November 30, 1942, the XP-51B's performance exceeded the engineers' expectations. At 29,800 feet, it made 440 MPH in level flight, 100 MPH better than the Allison models.

The USAAF, desperately needing a long-range bomber escort, contracted for 2200 P-51B's. North American geared up for Mustang production, moving the B-25 program to Kansas City, dedicating the Inglewood plant to the Mustang, and expanding the Dallas plant for the Mustang (Dallas-built versions of the -B model were designated P-51C). P-51B's began rolling out of Inglewood in May, 1943; eventually 1,990 of the -B models would be made. The first of 1,750 P-51C's produced at Dallas flew in August.

After production of the B/C model began, three more changes appeared:
an up-rated Packard Merlin engine, the 1650-7 replacing the 1650-3, for a small increase in HP
an 85 gallon fuel tank installed behind the pilot, giving critically longer reach, but moving the center of gravity aft, thus reducing directional stability until most of the fuel was consumed
the bulbous Malcolm hood, giving much better all-around visibility (a field modification)

By far the most numerous P-51 (over 8,000 produced) and also the best known, the -D model development began in 1943.

It improved two drawbacks of the B/C model:
Poor rearward visibility and inadequate firepower of four machine guns (which were mounted at an angle and were subject to frequent jams).

Even the Malcolm hood hadn't fixed the P-51's rearward visibility problem. Learning from the British installation of a "bubble" or "tear-drop" canopy in the Spitfire, both Republic (for its P-47) and North American Aviation (for the P-51) started work on a Plexiglass bubble canopy in mid-1943.
For stability, and to prevent distortion, the canopy was mounted in a very deep, rubber-lined metal sill; it slid back on rails. To accommodate the canopy, the rear fuselage was cut down.
The new version included six .50 caliber machine guns, mounted upright, minimizing jams.

The 85 gallon fuselage tank was included on the P51-D from the start.
The directional stability problems that it caused for the B/C models worsened in the first D models.
To correct this, a dorsal fin was added.

June 1944 saw the arrival of -D Models in the ETO.

Mid '45 - The Fastest Mustang - P-51H
Based on the improved Packard Merlin V-1659-9 engine, the fastest Mustang, the P51-H was introduced into production in June, 1944. The fuselage was lengthened by two feet, (to 33 feet, 4 inches) and the rudder and fin were increased in height. Other changes were made to the air intake, the canopy, the fuselage fuel tank (reduced to 50 gallons) and the radiator ducts. Bob Chilton took up the first P51-H in February, 1945. Along with the long-range P-47N, the P51-H was intended for the invasion of Japan. Some were issued to operational units in the Pacific before V-J Day, but none entered combat. 555 of the -H model were built before the program was cancelled in 1946.

[cyberia]

Fantastic pics, AD!

[Jim O]

Very informative and very cool!

Thanks.

[temujin77]

As usual, I have a few photos to offer from my website:

WW2DB: Photographs - P-51 Mustang

The P-51 sure is the "Cadillac of the sky", per a young Christian Bale -- random trivia quiz: anyone know where I'm quoting this from?

[Jim O]

Empire of the Sun

[cyberia]

Originally Posted by Aussie Dave

AD, I noticed the red tail on this one. Was this plane from the Tuskegee Squadron, or did other P-51s have red tails as well?

[Jim O]

Originally Posted by cyberia

AD, I noticed the red tail on this one. Was this plane from the Tuskegee Squadron, or did other P-51s have red tails as well?

That's "Ina the Macon Belle" which was a P-51C flown by Lee Archer of the the Fifteenth Air Force, 332nd Fighter Group aka the Tuskegee Airmen.

[cyberia]

Originally Posted by Jim O

That's "Ina the Macon Belle" which was a P-51C flown by Lee Archer of the the Fifteenth Air Force, 332nd Fighter Group aka the Tuskegee Airmen.

Thanks, Jim. Fantastic story behind that group. Brave men who had to fight more than the war itself.

To them-Prosit!

[temujin77]

Originally Posted by Jim O

Empire of the Sun

Ding ding ding, we have the right answer! You win... um... my continued support for this forum! ^_^

[cyberia]