THE 456th FIGHTER INTERCEPTOR SQUADRON

T PROTECTORS OF  S. A. C.

 

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North American P-51"MUSTANG"

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North American P-51D Mustang

The P-51 was designed as the NA-73 in 1940 at Britain's request. The design showed promise and AAF purchases of Allison-powered Mustangs began in 1941 primarily for photo recon and ground support use due to its limited high-altitude performance. But in 1942, tests of P-51s using the British Rolls-Royce "Merlin" engine revealed much improved speed and service ceiling, and in Dec. 1943, Merlin-powered P-51Bs first entered combat over Europe. Providing high-altitude escort to B17s and B-24s, they scored heavily over German interceptors and by war's end, P-51s had destroyed 4,950 enemy aircraft in the air, more than any other fighter in Europe.

Mustangs served in nearly every combat zone, including the Pacific where they escorted B-29s to Japan from Iwo Jima. Between 1941-5, the AAF ordered 14,855 Mustangs (including A-36A dive bomber and F-6 photo recon versions), of which 7,956 were P-51Ds. During the Korean War, P-51Ds were used primarily for close support of ground forces until withdrawn from combat in 1953.

The P-51D on display was obtained from the West Virginia ANG in 1957 and was the last prop-driven USAF fighter assigned to a tactical unit. It is painted as the -D flown by Col. C.L. Sluder, CO of the 325th Fighter Group, 15th Air Force, in Italy in 1944. The name of this aircraft, Shimmy IV is derived from the names of Col. Sluder's daughter and wife; Sharon and Zimmy.

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SPECIFICATIONS
Span:
37 ft. 0 in.
Length: 32 ft. 3 in.
Height: 13 ft. 8 in.
Weight: 12,100 lbs. max.
Armament: Six .50-cal. machine guns and ten 5 in. rockets or 2,000 lbs. of bombs.
Engine: Packard built Rolls-Royce "Merlin" V-1650 of 1,695 hp.
Cost: $54,000
Serial Number: 44-74936
Displayed as (S/N): 44-15174

PERFORMANCE
Maximum speed:
437 mph.
Cruising speed: 275 mph.
Range: 1,000 miles
Service Ceiling: 41,900 ft.

 

The Allison V-1710

The Rolls Royce Packard Merlin 1650

The Allison Mustangs

The Merlin Mustangs

 

Allison-engine nose, air intake on top

Relocated carburetor air intake, from above to below the nose, as shown

Merlin-engined nose, air intake below

 

UNKNOWN

 

 North American P-51 "MUSTANG" A Brief History

BY Joe Baugher

 

North American NA-73

 

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The P-51 Mustang was perhaps the most famous fighter of World War II, and, many would say, the best all-round piston-engine fighter produced by any of the combatants during that conflict. Total production of all Mustangs amounted to 15,575 in the USA and 100 in Australia, ranking only behind the P-47 Thunderbolt in being the fighter manufactured in greatest numbers for the USAAF. Mustangs accounted for 4950 of the 10,720 air combat victories claimed by the USAAF in Europe, and 4131 of the 8160 ground strafing claims made in the same theatre, accounting for 48.9 percent of total losses inflicted on the enemy. They shot down more than 230 V-1 "buzz bombs", and they even managed to score some kills against Luftwaffe jet fighters.

North American Aviation, Inc had been formed on December 6, 1928 as a holding company with interests in a long list of prominent aircraft companies--Curtiss Aeroplane and Motor Company, Curtiss- Robertson Airplane Manufacturing Company, Curtiss-Caproni Corporation, Wright Aeronautical, Travel Air, North Aircraft Corporation, and Keystone Aircraft Corporation. The prime mover behind this holding company was Clement M. Keys, who had run the *Wall Street Journal* newspaper. In 1929, Keys merged the two old rivals Curtiss and Wright to form the Curtiss-Wright Corporation. All of these various companies managed to retain their own separate identities and continued to function as more-or-less independent entities while Keys continued to expand his empire. Sperry Gyroscope Co., Inc, Pitcairn Aviation Inc (which started Eastern Air Transport in 1930), Berliner-Joyce Aircraft Corporation, Ford Instrument, Transcontinental and Western Air (the TWA of today), Intercontinental Aviation Inc, and a substantial interest in the Douglas Aircraft Corporation were all picked up fairly cheaply during the early years of the Depression.

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In 1933, General Motors bought a sizeable interest in North American Aviation, Inc. In addition, it acquired the General Aviation Corporation (which had taken over the Fokker Aircraft Corporation) and the Dayton- Wright Corporation. Ernest R. Breech of General Motors was appointed as president of North American Aviation, Inc., and the companies were grouped into two large conglomerates: General Aviation Manufacturing Corporation (which comprised Berliner-Joyce, General Aviation, and Curtiss Caproni) and the Sperry Corporation (which comprised Sperry Gyroscope Co., Inc, Ford Instrument, Curtiss-Wright Corporation and Intercontinental Aviation).

However, control of Sperry Corporation was disposed of a few months later. In addition, the Air Mail Act of 1934 made it illegal for aircraft manufacturing industries to have controlling interests in airlines, and North American Aviation, Inc. was forced to divest itself of its shares in Eastern and TWA. At this time Ernest R. Breech handed over the management of the company to James H. "Dutch" Kindelberger, who had an extensive background in aviation both as a pilot and as a degreed aeronautical engineer. Kindelberger accepted the job under the condition that his friend and colleague John Leland "Lee" Atwood could join him as vice-president. Under Kindelberger's leadership, North American Aviation, Inc. became a "real" aircraft manufacturing concern rather than just a holding company, with General Aviation becoming the manufacturing arm with factories at Dundalk, Maryland and another factory being opened up in January 1936 at Inglewood, California near Mines Field (now part of the Los Angeles airport). Not only was Kindelberger an excellent businessman, he was also a capable aeronautical engineer. As early as 1938, Kindelberger had made numerous trips to Europe seeking orders for his company, and he had the opportunity to see up close some of the airplanes that would be in combat in the war that almost everyone believed would shortly be coming. After hostilities broke out, Kindelberger eagerly sought out combat reports from both sides and developed some ideas of his own.

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The F-82 Twin Mustang

Although Kindelberger had no experience with fighters, he collaborated with his friend and colleague J. Leland Atwood to formulate an outline for a fighter project. A project team was formed at North American, made up of such people as Raymond H. Rice, Edgar Schmued, Larry Waite and E. H. Horkey. A sort of urban legend has grown up about Edgar Schmued, which claims that he had once worked for Willy Messerschmitt and that the Mustang was heavily influenced by the Bf 109.

Following the outbreak of war in Europe, the British Purchasing Commission, headed by Sir Henry Self, was posted to New York to determine if American combat aircraft could be of any use to the Royal Air Force. The Bell P-39 Airacobra and the Curtiss P-40 Warhawk were ordered in substantial numbers, even though they were not up to the performance standards of the latest British and German fighters.

One of the corporations that Self had contacted had been the North American Aviation corporation. North American had already been building NA-16 trainers, and the British ordered a number of them for the RAF as the *Harvard*. In April of 1940, Kindelberger was summoned by the British Air Purchasing Commission and asked to manufacture the Curtiss Hawk 87 (P-40D) under license for the RAF. Kindelberger responded that NAA could do that if it were really required, but countered that he and his company could build a better fighter than the P-40 and that they could design a REAL fighter in the same time that it would take to put the P-40 into production. The British commission felt that they could take Kindelberger at his word, and on April 10, 1940 they accepted his proposal on the condition that the first prototype be ready in 120 days. The design was assigned the company project name of Model NA-73.

At that time, the USAAC reserved for itself the right to block any foreign aircraft sales that it regarded as not in the Army's interest, for whatever reason. On May 4, 1940, the US Army reluctantly agreed not to block the British sale, but they added a condition. Two examples of the initial NA-73 lot for Britain were to be transferred to the USAAC for testing free of charge.

The NA-73X prototype contract was signed on May 23, 1940. The British insisted that a heavy eight-gun armament be fitted. NAA had actually been quietly working on such a fighter project since the summer of 1939, and by that date they had actually already completed much of the detail design. On May 29, a provisional RAF procurement was issued for 320 aircraft, contingent on satisfactory testing of the prototype. NAA agreed to start deliveries in January 1941. RAF serial numbers were to be AG345 through AG664, and the aircraft was given the name Mustang I in RAF service.

Another urban legend surrounding the Mustang is that it owed a great deal to the Curtiss XP-46 and, in fact, stole numerous design features from that fighter. It is true that the British had insisted that since NAA had no fighter experience they should secure all current data from Curtiss about both the P-40 and the XP-46. Although NAA did pay $56,000 to Curtiss for technical aerodynamic data on the XP-46, there was only a very broad resemblance between the XP-46 and the NA-73X. The Curtiss aircraft shared only a similar radiator/ oil-cooler configuration with the NA-73X, and did not have laminar flow wings. In point of fact, the development of the XP-46 lagged behind that of the NA-73X, and prototypes were not ready for flight until February of 1941. In addition, preliminary design of the NA-73X was completed before NAA gained access to the Curtiss material. It could even be argued that the XP-46 data was most useful to NAA in guiding them in what NOT to do. The NA-73X appears to owe virtually nothing to any previous fighter design. Nevertheless, despite convincing denials from both Edgar Schmued and aerodynamicist Edward Horkey, the full magnitude of the contribution of Curtiss to the NA-73X design remains controversial to this day.

The NA-73 featured an all-metal stressed-ski structure, with the wing having a sheet-web main spar and an almost equally strong rear spar to carry the ailerons and the flaps. Special attention was paid to features which would make the aircraft simple and inexpensive to manufacture. The two wing spars had to be far enough apart to accommodate the length of a 0.50-in machine gun, with only the barrel protruding ahead of the main spar. Most previous NAA aircraft had left and right wings bolted to a horizontal center section, but the Mustang had the wings meeting on the centerline, with dihedral emanating from that line.

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A special NACA laminar flow wing profile was adopted for the Mustang. This was an aerofoil which had a thickness that kept on increasing far beyond the usual location, i.e., to 50 percent chord rather than the usual 20 percent. These profiles had little camber, the undersurface being almost a mirror image of the upper. This wing was much more "slippery" than the old profiles, and provided lesser aerodynamic drag at high speeds than did more conventional aerofoil. However, it also had less lift at low speeds, so the NA-73X had to have large and powerful flaps to keep landing speeds from being impractically high.

The wing structure was designed to be as simple and as easy to construct as possible. The leading and trailing edges were straight lines to the extent possible, and the underlying structure was simple and easy to manufacture. The wing was made in left and right halves that were joined at the centerline. Each wing had two straight spars that were far enough apart for a 0.5-inch Browning machine gun to fit between them with only the barrel projecting through the front spar.

The main landing gear members had a track of almost 12 feet, which made landing much easier than in such fighters as the Spitfire and Bf 109. The main wheels retracted inward into wheel wells in the wing forward leading edge, the leading edges being kinked forward at the fuselage join to provide sufficient room. The retracted wheels were covered by doors hinged near the aircraft centerline, and were closed again by their own jacks when the landing gear was fully extended. The tail wheel was fully retractable into a compartment with twin doors. The tail-wheel was steerable and was linked to the rudder.

The British also specified that a liquid-cooled inline engine be used, and the Allison V-1710 twelve-cylinder Vee was the only American-built engine which fit the bill. The Allison V-1710 was a little bigger than the Merlin, slightly lighter, and similar in power at low altitudes. However, at higher altitudes the Allison suffered from a rapid drop in power in comparison to the Merlin. NAA briefly considered using a turbo-supercharger to improve high-altitude performance, but ruled against it on the grounds of a tight schedule.

The Allison engine had a downdraft carburetor, so the ram inlet of the NA-73X was located above the cowling. Radiators for cooling the ethylene glycol and lubricating oil were located in a single heat-exchanger installed underneath the rear fuselage in a streamlined duct. The duct actually had the ability to add some propulsive thrust, by adding heat energy to the incoming air and expelling it out the back at a higher velocity. The drawbacks of such a cooling arrangement were the extra weight and the added combat vulnerability of the long pipes that led to and from the engine.

Fuel was housed in two self-sealing tanks housed in the wing spars, one in each inboard wing. Total capacity was 180 US gallons, almost twice the fuel capacity of a Spitfire.

At British insistence, armament was somewhat heavier than American standards of the day. Two 0.5-inch M2 Browning machine guns were installed in the underside of the nose beside the engine crankcase, synchronized to fire through the propeller arc. The left gun was staggered ahead of the right in order that the magazines could lie one behind the other. Two 0.50-inch guns were mounted upright inside the wings, outboard of the landing gears. Four 0.30-inch Browning machine guns were mounted further outboard on the wing, with each inboard 0.30-inch gun being mounted lower so that its muzzle was below the leading edge. Ammunition for all the wing guns was in three long span wise boxes outboard of the guns.

Final assembly and engine installation began on September 9, 1940, 102 days after the initial British order.

In a contract approved on September 20, 1940, it was agreed that the fourth and tenth production NA-73s would be the planes diverted to the Army. The designation XP-51 was to be assigned to these two planes.

On September 24, 1940, the RAF increased their Mustang I order to 620 planes.

The NA-73X prototype emerged from Inglewood plant in only 102 days, thus meeting the 120-day deadline with time to spare, although the airplane rolled out of the factory without an engine, which had been delayed at the Allison factory. In the absence of the new disk brakes, the aircraft was rolled on wheels borrowed from an AT-6 trainer. It was completely unpainted except for six aperture shapes painted on the wing leading edges to show where the guns would be installed. These aperture shapes were retouched out in many reproductions of the most famous photographs of the aircraft. Only later was the civil registration NX19998 applied and the fuselage ahead of the cockpit painted with anti-dazzle black.

The reason for the delay in engine delivery was because it was "government-supplied equipment" that was furnished on an as-available basis. Since the NA-73X was a private venture it was not allocated a very high priority in comparison with P-40s that were then rolling off the production lines. The engine that was eventually installed was an un-turbo-supercharged Allison V-1710-F3R liquid-cooled Vee, rated at 1100 hp.

Veteran test pilot Vance Breese flew the NA-73X for the first time on October 26, 1940. Weights were 6278 lbs empty, 7965 lbs normal loaded. It was a clear 25 mph faster than the P-40, even in spite of being powered by the same engine.

Following tests, there were several changes in the geometry of the ventral ducting and the controllable flaps. By the time that the NA-73 had been cleared for production, the duct had had its inlet moved downward so that its upper lip was lower than the underside of the wing, thus avoiding the ingestion of a turbulent boundary layer of air into the radiator cooler.

On November 20, 1940, while on the fifth test flight of the NA-73X, test pilot Paul Balfour forgot to change fuel tanks, ran out of gas, and suffered a forced landing. The plane ended up on its back in a farmer's field. This mishap put the prototype out of action for several months. However, since this accident was not the fault of the aircraft itself, this did not unduly delay the program. The NA-73X aircraft resumed flying on January 11, 1941 and continued in the initial development program until being retired on July 15, 1941.

In December 1940, the RAF ordered 300 more of the Mustang Is which embodied only minor modifications. These were designated NA-83 by the factory. RAF serials were AL958/AL999, AM100/AM257, and AP164/AP263. They differed from the NA-73s only in having broad fishtail ejector exhausts.

 

The bulbous Malcolm hood, giving much better all-around visibility (a field modification), as shown below

P51-B original 'birdcage' canopy P51-B, with Malcolm hood

 

"Mustang" I/IA for RAF

 

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Mustang I in flight - AL 958; Allison-powered Mustang for RAF

Since the NA-73X had encountered very few problems during tests, production for the RAF began almost immediately. The first production Mustang I for the RAF (AG345) flew for the first time on April 23, 1941, well behind the original schedule. It was retained by NAA as a development machine, and was used in an extensive series of tests to iron out bugs and eliminate problems. Perhaps the most noticeable change was the extension of the carburetor inlet right up to the nose in order to give good ram recovery at extended angles of attack. This machine was initially unpainted, but it later got an RAF paint job with camouflage, but it remained at Inglewood and did not ever get any guns.

Armament was fitted to the second aircraft off the production line (AG346). It was equipped with four 0.50-in machine guns and four 0.30-inch guns. Two of the 0.50-in guns were mounted in the lower fuselage and were synchronized to fire through the propeller arc. The rest of the guns were mounted in the wings and fired clear of the propeller arc. This aircraft was accepted by the RAF in September and started a long journey to Britain, finally arriving in Liverpool on October 24, 1941. It lacked a radio, a gun sight, and certain other equipment which was by contract to be supplied by British manufacturers. Once the British equipment was installed, the complete aircraft was evaluated at the Aeroplane & Armament Experimental Establishment at Boscome Down and by the Air Fighting Development Unit at RAF Duxford.

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Most of the first 20 RAF Mustang Is were retained for special measurements and trial installations. Mustangs delivered under the original contract were similar to the original model but had an F-24 camera mounted in an installation immediately behind the pilot's head armor, looking obliquely out to the left and to the rear. A single gun camera was added near the left wing tip. Later, a second camera was installed vertically ahead of the tail-wheel for photography from higher altitudes.

In December 1940, the RAF ordered 300 more of the Mustang Is which embodied only minor modifications. These were designated NA-83 by the factory. RAF serials were AL958/AL999, AM100/AM257, and AP164/AP263. They differed from the NA-73s only in having broad fishtail ejector exhausts.

Mustang I AM106 was experimentally fitted successively with eight rocket projectiles on zero-length launches, special long-range fuel tanks, and eventually with two 40-mm Vickers cannon in under-wing mountings.

On March 11, 1941, the Lend/Lease Act was passed by Congress, permitting the "lending" of American-built aircraft to nations deemed "vital to the security of the United States". On September 25, 1941, the US Army ordered 150 Mustangs under the provisions of Lend-Lease for delivery to Britain. All previous RAF Mustangs had been direct purchases by Britain.

These Lend-Lease Mustangs were designated Mustang Mark IA by the RAF and NA-91 by the factory. The RAF serial numbers assigned to this lot were FD418/FD567. For contractual purposes, these aircraft were assigned the US designation of P-51, and the Allison V-1710-F3R engine was given the US Army designation V-1710-39. The P-51s were assigned the USAAF serials 41-37320/37469. The Mustang IA differed from earlier versions in having the machine guns replaced by four 20-mm wing-mounted Hispano cannon, with most of the long barrels protruding well ahead of the wing. Throughout 1941, the Army referred to these aircraft under the name *Apache*, but this was changed to *Mustang* at about the time the deliveries began in mid- 1942.

The British did not get all of these NA-91s. Since the RAF deliveries took place after Pearl Harbor, many were repossessed by the Army before they reached England. These included RAF Mustang IA serials FD418/FD437, FD450/FD464, FD466/FD469, and FD510/FD527. The Army planes were armed with four 0.50-inch machine guns rather than the 20-mm cannon and were fitted with two K-24 cameras in the fuselage. Most retained their RAF camouflage and serial numbers, although some were indeed painted with their equivalent USAAF serials. These were designated as tactical reconnaissance aircraft and were designated F-6A, but this designation was soon changed to P-51.

 

Service of "Mustang" I/IA With RAF

The newly-arrived Mustang was quickly recognized as being the best fighter aircraft yet to be delivered from the USA. It was found to be superior to the Kitty-hawk, Airacobra and Spitfire in both speed and maneuverability at low altitudes. Maximum speed was 382 mph at 13,000 feet. At all heights up to 20,000 feet, the Mustang was faster than any other fighter then in service with the RAF. Rate of climb, acceleration, speed in a dive, stability, handling in all configurations, rate of roll and radius of turn were all rated as being satisfactory to outstanding. The armament of four 0.50-inch and four 0.30-inch machine guns was heavy and effective. The range was nearly double that of any RAF single-engine fighter. It was 25 to 45 mph faster than the Spitfire V at altitudes up to 15,000 feet. The problem was the rapid fall-off in performance at altitudes above 15,000 feet, caused by its low-altitude Allison engine which was supercharged for best performance at low levels. The Spitfire could climb to 20,000 feet in seven minutes, while the Mustang required 11. Both the Spitfire and the Messerschmitt Bf 109 were more nimble at higher altitudes. The Mustang weighed about a third again as much as a Spitfire, and was considered as being somewhat underpowered.

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The relatively poor high altitude performance of the Mustang was more than just a minor deficiency, since most aerial combat over Europe at that time was taking place at medium to high altitudes. Consequently, it was decided that the Mustang I could be best used for low-level tactical reconnaissance and ground attack, where full advantage could be taken of its exceptional low-altitude performance.

The first RAF unit to receive the Mustang was No 26 Squadron at Gatwick which began to operate the fighter in February 1942. In April, two more squadrons received Mustangs, and eight more in June. Most of the aircraft went to Army Cooperation Command, usually replacing Curtiss Tomahawks or Westland Lysanders. The first Mustang combat mission was undertaken by Flying Officer G. N. Dawson of No. 26 Squadron on May 10, 1942, strafing hangars in France and shooting up a train.

It was initially feared that the Mustang I might be mistaken for a Bf 109 during the stress of combat, and most of the Mustang Is in front-line RAF service had bright yellow bands painted across their wings.

The first Mustang I operational sortie was on July 27, 1942. Mustang Is participated in the disastrous Dieppe landings by British commandos on August 19, 1942, where it saw the first air-to-air action. During this operation, pilots of No 414 Squadron of the RCAF were attacked by Fw 190s. An American RCAF volunteer, F/O Hollis H. Hills, shot down one of the enemy, which was first blood for the Mustang.

In October of 1942, On a mission to the Dortmund-Elms Canal and other objectives in Holland, the Mustang I became the first single- engine fighter based in the UK to penetrate the German border. By this time, the Mustang I equipped Nos 2, 4, 16, 26, 63, 169,239, 241, 268, and 613 Squadrons of the RAF, plus Nos 400, 414 and 430 Squadrons of the RCAF, and No 309 (Polish) Squadron of the RAF.

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Tactical reports from RAF army cooperation units were laudatory. The Mustang I and IAs were able to take an incredible amount of battle damage. The long range of the Mustang made it an excellent tactical reconnaissance aircraft and its heavy armament made it effective against most ground targets. In 18 months of operation 200 locomotives and 200 barges were destroyed or severely damaged, and an undetermined number of enemy aircraft were destroyed on the ground. This was accomplished at the expense of only one Mustang being shot down by enemy fighters, five lost to flak, and two vanishing with no record of their fate. At low altitudes, the Mustang was faster than either the Bf 109 or the Fw 190. At sea level, the Mustang could run away from any enemy aircraft. The flaps were very useful in combat to reduce the turning radius.

Mustang Is and IAs served with the RAF up until 1944. It knew few equals in the role of low-altitude interdiction and reconnaissance.


 

North American XP-51 "Mustang"

 

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XP-51  S/N 41-039; 2nd a/c built

In 1940, the US Army had given its permission for the initial British Mustang delivery to proceed, with the proviso that two of the NA-73s destined for England be made available to the Army for tests free of charge. In a separate contract dated September 20, 1940, the two aircraft delivered to the Army were to be the fourth and tenth production NA-73s, and the planes were to be designated XP-51.

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XP-51  S/N 41-039

The fourth and tenth NA-73s were duly delivered to the US Army in May of 1941 for testing at Wright Field, Ohio. They bore the designation XP-51 and were assigned the serial numbers 41-038 and 41-039. They were initially unpainted except for national insignia and the black antiglare panel over the forward fuselage ahead of the pilot. The Army painted the serials 1038 and 1039 on the fin and on each side of the nose, together with the WRIGHT arrowhead emblem on the rear fuselage. Much later, they were both painted olive drab overall.

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XP-51  S/N 41-038; 1st a/c built; 16 Oct 41; Wright Field

The testing of the two Wright Field XP-51s was rather slow at first, almost as if the Army didn't really want to bother with these airplanes and that they were some sort of nuisance that the Army wished would just go away. Some authors have suggested that there were dark and evil motives behind the Army's reluctance to test the XP-51s. However, the slow pace of the testing of the XP-51s can probably be blamed more on bureaucratic inertia than on anything all that sinister. At that time, the Army was overloaded with other test programs, the Lockheed P-38 Lightning, Bell P-39 Airacobra, and Republic P-47 Thunderbolt being thought to meet all the Army's requirements for fighter aircraft. Furthermore, the Mustang was a "foreign" type not built to any American specification, and was therefore way down on the Army's list of priorities.

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XP-51  S/N 41-038

XP-51 Cockpit

Nevertheless, the testing of the XP-51s did eventually get underway at Wright Field, and the Army's test pilots reported very favorably on the performance of these planes. Inexplicably, no Army orders were forthcoming. Much later, the Senate Special Committee to Investigate the National Defense Program (better known as the "Truman Committee", after its chairman Sen. Harry S Truman of Missouri) was given the task of investigating the system under which military production contracts were awarded during wartime conditions. They looked specifically into the reason why the Army had sat on its hands for so long before ordering any examples of the Mustang, an airplane which had such demonstrably superior performance. Some insiders claim that NAA President "Dutch" Kindelberger had been asked to pay bribes in exchange for a production contract, but that he had refused all such demands in no uncertain terms. The primary cause of the long delay in Army acquisition of the Mustang may be somewhat less sinister. The Mustang may have been the victim of the "Not Invented Here" (NIH) syndrome, in which the Army looked askance at an upstart aircraft which had not been designed in response to any of its official requirements.


 

North American A-36 "Invader"

 

Only after Pearl Harbor did the US Army finally agree to order the Mustang for its own use. General H. H. "Hap" Arnold, Chief of Staff of the USAAF, was instrumental in breaking up the bureaucratic log-jam and getting the Army to relent and order the Mustang for its own use. On April 16, 1942, the Army finally ordered 500 NA-97s. The NA-97 was a ground attack version and was designated A-36A (in the attack series rather than the fighter series). Serial numbers were 42-83663/84162.

The A-36 seems to have been known by several different names--it was initially called *Apache*, which was the name that the Army initially assigned to the P-51, but there was an effort to change the name to Invader following the invasion of Sicily. However, the name Mustang was generally applied by most people to the A-36.

The A-36A differed from previous Mustang versions in having a set of hydraulically-operated perforated door-type dive brakes mounted at approximately mid-chord on both the upper and lower wing surfaces outboard of the wing guns. The brakes were normally recessed into the wings, but were opened to 90 degrees by a hydraulic jack to hold diving speeds down to 250 mph. A rack was fitted under each wing for a 500-pound bombs, a 75 US gallon drop tank, or smoke-curtain equipment. A built-in armament of six 0.50-inch machine guns (two in lower fuselage nose, four in the wings) was fitted, however the two nose guns were often omitted in service. The wing guns were moved closer to the main landing gear strut in order to minimize stress under taxi and takeoff conditions. The engine was the Allison V-1710-87 (F21R), rated at 1325 hp at 3000 feet. Normal and maximum loaded weights rose to 8370 pounds and 10,700 pounds, and the maximum speed in clean condition fell to 356 mph at 5000 feet and 310 mph with the two 500-lb bombs fitted. With the bombs, range and service ceiling were 550 miles and 25,100 feet respectively.

The first A-36A flew on September 21, 1942. Deliveries of the A-36A were completed by the following March. The A-36A equipped the 27th and 86th Fighter Bomber Groups based in Sicily and in Italy. They initially were painted in olive-drab and light-gray finish and were painted with yellow wing bands and yellow circles around the national insignia. Both of these Groups arrived in North Africa in April of 1943 just after the end of the Tunisian campaign. They saw their first action during aerial attacks on the island of Pantelleria, with the first sortie being flown on June 6, 1943. The A-36A was involved in the taking of Monte Cassino, and participated in the sinking of the Italian liner Conte di Savoia.

The only other A-36 user was the 311th Fighter Bomber Group, based in India. It saw extensive use in the China-Burma-India theatre.

Several sources list the Invader as not being particularly effective during combat. It seems that this is not strictly correct. Although losses during low-level attacks were rather high, the A-36 was actually a good dive bomber and it was a stable and effective ground strafer. The engine was very quiet, and it was often possible for an A-36 to get nearly on top of an enemy before he realized that an attack was imminent. Dive bombing was usually initiated from an altitude of 10,000 feet to 12,000 feet, with bombing speed held to around 300 mph by the dive brakes. The bombs were dropped at an altitude of 3000 feet, and pullout was at approximately 1500 feet. The Invader was fairly rugged and easy to maintain in the field. The A-36 could consistently stay within 20 feet of the deck and could easily maneuver around trees, buildings, and other obstacles while strafing. The A-36A was able to take a considerable amount of battle damage and still return to base. Nevertheless, a total of 177 A-36As were lost in action.

The A-36s did not see very much air-to-air combat, since it was optimized for low-altitude operations and lost its effectiveness above 10,000 feet altitude. It was generally believed that the A-36 Invader was no match for the Messerschmitt Bf 109 at high altitudes, and that it was therefore best for A-36 pilots to avoid such encounters if at all possible. If air-to-air combat was unavoidable, it was thought best to force the battle down to altitudes below 8000 feet, where maximum advantage could be taken of the A-36A's excellent low-altitude performance. Although it was not a fighter, the Invader claimed 101 enemy aircraft destroyed in air-to-air combat. One of the pilots of the 27th Fighter Bomber Group, Lt Michael T. Russo, became the only ace in the Allison-engine Mustang, although several other of his colleagues did score victories as well.

A sort of urban legend has sprung up about the A-36A's dive brakes. According to some stories, the dive brakes of the A-36A were next to useless and were deliberately wired shut at the manufacturers so that they could not be used. This story is totally incorrect. On the contrary, the dive brakes proved to be quite effective in combat, and the aircraft was so stable with the dive brakes extended that bombing while in a dive was particularly accurate. The origin of this legend seems to have been in the United States, at a time before the Invaders first went overseas. It seems that A-36A pilots were told by their officers in the USA that their dive brakes would be all but useless in combat and it would be best if they simply wired them shut. This turned out to be incorrect, and the dive brakes were used to great effect throughout the Sicilian campaign and the Italian invasion.

One A-36A was supplied to the RAF in March of 1943 for experimental purposes. Its RAF serial number was EW998.

There are very few A-36As still surviving today. A-36A Ser No 42-83665 is on display at the WPAFB Museum in Dayton, Ohio. 42-83731 is with the Lone Star Flight Museum in Texas. 43-83738 is currently undergoing restoration as a P-51B at the Warhawk Air Museum in Boise, ID. Another A-36A is with the Collings Foundation, where it is undergoing restoration.

Serial numbers of the A-36 were 42-83663/84162.

 

 

North American P-51/F-6A "Mustang"

 

The British did not get all of these NA-91s. Since the RAF deliveries took place after Pearl Harbor, many were repossessed by the Army before they reached England. These included RAF Mustang IA serials FD418/FD437, FD450/FD464, FD466/FD469, and FD510/FD527. The Army planes were armed with four 0.50-inch machine guns rather than the 20-mm cannon and were fitted with two K-24 cameras in the fuselage. Most retained their RAF camouflage and serial numbers, although some were indeed painted with their equivalent USAAF serials. These were designated as tactical reconnaissance aircraft and were designated F-6A, but this designation was soon changed to P-51.

The P-51s went to Peterson Field in Colorado, where they were assigned to the newly-established aerial reconnaissance school. In March of 1943, a batch of 25 F-6A/P-51s were assigned to the 154th Observation Squadron at Oujda in French Morocco. This was the first US Mustang unit. The first mission was a photographic coverage of Kairouan airfield in Tunisia on April 10, 1943, which was the first USAAF Mustang mission of the war. No. 225 Squadron of the RAF frequently borrowed Mustangs from the 154th to augment its shorter- range Spitfires. The F-6A/P-51 was quite successful in operation, but it did have one important defect--it bore a similar shape to that of the Messerschmitt Bf 109. The 154th's first combat loss was a friendly fire incident in which Allied AAA failed to recognize the differences, with fatal results.

Two P-51 airframes were diverted to the XP-78 project, about which much more will be said later!
 

 

North American P-51A "Mustang"

 

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P-51A-NA S/N 43-6004; 2nd -A model built; "Slick Chick"

The next Army contract for Mustangs consisted of an order on August 24, 1942 for 1200 NA-99 versions with the USAAF designation of P-51A. Unlike the A-36A, these aircraft from the start were meant to be fighters, not bombers. The first P-51A flew on February 3, 1943, and the first deliveries began the next month. In the event, only 310 P-51As were actually built between March and May of 1943 before production was switched over to the Merlin-powered P-51B.

These aircraft had the same external stores capability as the A-36A Invader, but had no dive brakes and no fuselage guns, the armament being limited to four 0.50-inch machine guns mounted in the wings. The inboard pair had 350 rpg and the outboard pair had 280 rpg. An under-wing load consisted of two 250 lb, 325, or 500-pound bombs. Maximum takeoff weight rose to 10,600 pounds, but maximum ferry range was increased to 2350 miles. The P-51A had the Allison V-1710-81 (F20R) engine rated at 1200 hp for takeoff and 1125 hp at 18,000 feet, with significantly better high-altitude performance than the V-1710-39 of the P-51. The engine was fitted with a new supercharger which further enhanced low-altitude performance. In addition, a larger-diameter propeller was fitted. Maximum speed rose to 409 mph at 11,000 feet, faster at medium altitudes than any other fighter then in service.

Because of the thin wing cross section, the wing guns lay almost on their sides and the ammunition belt feeds had to be built with some rather sharp kinks in them in order to direct the bullets into the guns. This awkward arrangement resulted in many gun jams, particularly after maneuvers in which high g-values were pulled.

Three production blocks were built with the following serials:

43-6003/6102 	P-51A-1-NA 
43-6103/6157 	P-51A-5-NA 
43-6158/6312 	P-51A-10-NA 

Of the 310 P-51As built, 35 of them were fitted with twin-K24 camera installations and had their guns removed. These were re-designated F-6B.

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P-51A 2 ship formation - 1st Air Commandos; #1 (background) flown by C.O. Phil Cochran; #13 Miss Virginia flown by Deputy Commander Petty

50 P-51As went to the RAF, becoming Mustang IIs. These planes replaced the NA-91s that had been diverted from RAF Mustang IA orders for conversion as USAAAF F-6As. The RAF serials of the Mustang IIs were FR890/FR939. Deliveries were made late in 1942. Mustang II FR901 was fitted with special deep-section fuel tanks beneath the wings for ultra-long-range flying. FR893 was tested at Boscombe Down, and demonstrated a best rate of climb of 3800 feet per minute at 6000 feet, with n altitude of 20,000 feet being reached in 6.9 minutes and 34,000 feet in 24 minutes. The Mustang I, IA, and II had astonishingly long service with the RAF, with the last front-line RAF Allison-engine Mustangs being phased out in early 1945.

The first P-51A group was the 54th, which remained in Florida for replacement training. Later, P-51As went to Asia with the 23rd, 311th, and 1st Air Commando Groups. Almost all of the P-51As served in the China, Burma, India (CBI) theatre of operations. On November 25, 1943, the 530th Fighter-Bomber Squadron of the 311th Fighter Bomber Group flew the first of the Mustang's long-range escort missions, using drop tanks to escort B-24 Liberators in an attack on Rangoon, Burma, a round trip of nearly 900 miles.

The F-6Bs, on the other hand, served in Europe, mainly with the 107th Tactical Reconnaissance Squadron based in England.

One P-51A was given to the US Navy for evaluation (BuAer #57987).

When production of the Allison-engine Mustang ended, 1580 examples had been built.

 

Specifications of P-51A-10-NA:

 

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P-51A-NA  Ski mod.; S/N 43-6003; 1st -A model built

One 1200 hp Allison V-1710-81 twelve-cylinder Vee liquid cooled engine. Performance Maximum speed was 340 mph at 5000 feet, 360 mph at 10,000 feet, 380 mph at 15,000 feet, and 390 mph at 20,000 feet. Range on internal fuel was 750 miles at 300 mph at 10,000 feet. Range with two 125 Imp. gall. drop tanks was 2000 miles at 266 mph and 2350 miles at 228 mph. An altitude of 5000 feet could be attained in 2.2 minutes, 10,000 feet in 4.4 minutes, and 20,000 feet in 9.1 minutes. Service ceiling was 31,350 feet. Weights: 6433 lbs empty, 8600 lbs normal loaded, and 10,600 lbs maximum loaded. Dimensions: Wingspan was 27 feet 0 1/4 inches, length was 32 feet 2 1/2 inches, height was 8 feet 8 inches, and wing area was 233 square feet. Armament: Four 0.50-inch machine guns mounted in the wings. The inboard pair had 350 rpg and the outboard pair had 280 rpg. An under-wing load consisted of two 250 lb, 325, or 500-pound bombs.

 

 

North American P-51B/C "Mustang"

 

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On April 30, 1942, Ronald W. Harker, a test pilot for the British Rolls-Royce engine manufacturer, took a brief hop in a RAF Mustang at the airbase at Duxford. Like lots of other pilots, he was highly impressed with the Mustang. It was 30 mph faster than the Spitfire VB at similar power settings and had nearly twice the range. Upon landing, he is reported to have said that the airplane would be a natural for the new Merlin 60 series of engines that Rolls Royce was just beginning to produce. The Merlin 60 had originally been intended for the pressurized high-altitude Wellington VI bomber, but had hastily been adapted to the Spitfire VIII.

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P-51B prepare for take-off - 361st FG, 376th FS; includes S/N 42-106707 "Sleepy Time Gal" and S/N 42-106945 marked E9V

Rolls Royce management was intrigued by the idea and immediately jumped into action. They requested that three Mustangs be loaned to them so that they could fit them with Merlin's. Rolls Royce studied various Merlin's, including the single-stage Mk XX and the two-stage Mk 61. The two-stage Merlin was the better choice because of its far superior high-altitude performance. The Merlin Mk 61 engine crankshaft was geared to two supercharger blowers stacked in series. Because of the rapid compression of air, the temperature of the air after it passed through both stages of the supercharger increased by 200 centigrade degrees. In order to lower this temperature and thus increase the mass flow of the air entering the engine, an intercooler was added, requiring an extra radiator. After much thought, it was decided to mount the extra radiator underneath the nose, in the same duct as the ram inlet for the updraft carburetor.

This conversion was authorized on August 12, 1942. Initially, three Mustang Is were allocated to the program, but two more were added later. Their RAF serials were AM121, AM208, AL975, AM203, and AL963. They were assigned the designation Mustang X. No two of these Mustang Xs were exactly alike, but they all featured small chin-type radiators mounted underneath the engine, all had four-bladed propellers to absorb the extra engine power, and they were all powered by the Merlin 65, which in comparison with the Merlin 66 had a lower full-throttle height but gave higher power at lower altitudes. In comparison to the Allison V-1710, it was 205 hp more powerful at 20,000 feet and 490 hp more powerful at 25,000 feet. The first Mustang X (AL975) took to the air on October 12, 1942, piloted by Captain R. T. Shepherd. It initially had a regular Spitfire IX Rotol propeller but was later fitted with a lerger specially-designed propeller. AL963 flew for the first time on November 13, 1942, and AM121 followed on December 13. AM121 went to the AFDU at Duxford for service evaluation. The fourth and fifth were evaluated by the USAAF in full USAAF markings. These Mustang Xs were to be kept busy throughout the rest of the war, testing various later marks of the Merlin engine.

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P-51B  S/N 42-106923; "Daddy's Pet"; 357th FG

The performance of these re-engined aircraft was excellent, with maximum speed obtained at Boscombe Down being 433 mph at 22,000 feet. However, the yaw stability was degraded by the increased side area of the nose. The success of these tests led Rolls Royce to propose the production of 500 Merlin 65 engines to re-engine most of the RAF's Mustang fleet to Mark X standards. However, there was no place where these conversions could be done, and such plans were never carried out.

One of the more bizarre proposals considered by Rolls-Royce was the possible installation of a 2400 hp Rolls-Royce Griffon 63 engine mounted amidships in a Mustang airframe a la P-39 Airacobra, driving a contra-rotating propeller via an extension shaft. The cockpit was to be moved forward to a position well ahead of the wing. It was anticipated that this modification would make it possible to achieve speeds as high as 500 mph. A mockup of this configuration was carefully prepared, but the concept was abandoned before work could proceed any farther.

Meanwhile, in May of 1942, Rolls-Royce had informed Major Thomas Hitchcock, US military attaché in London, that they planned to convert Mustang airframes to the Merlin engine. It just so happened that Major Hitchcock had been thinking of just this idea himself. He passed the word along to Wright Field and to North American Aviation. The idea attracted immediate interest. It just so happened that at this very time negotiations were taking place with the Packard Motor Car Company of Detroit, Michigan for license manufacture in the United States of the new Merlin engine with the two-stage supercharger. On July 25, 1942, North American was authorized to convert two Mustangs to Merlin 65 engines imported from England. These aircraft were considered sufficiently different from the existing Mustang that they were given a new designation--XP-78.

NAA selected two P-51s from the batch of Mustang IAs that had been repossessed from the RAF by the USAAF. Their serial numbers were 41-37350 and 41-37421. NAA gave the project the company designation NA-101. The designation of these two aircraft was changed to XP-51B while the work was progressing. Although the early work by Rolls-Royce in conversion of Mustangs to the Merlin engine provided valuable insight to North American engineers, the British engine manufacturer did not directly participate any further in the project.

P-51B "City of Paris"; S/N 43-6438 at Rivenhall, England in Early 1944; R.C. McWherter (Pilot).

The North American engineers moved the carburetor air intake from above to below the nose in order to accommodate the Merlin's updraft induction system. The intercooler radiator was added to the radiator group already located inside the scoop underneath the rear fuselage, and the ventral radiator group was made noticeably deeper than before and had a sharp-angled inlet standing more than two inches away from the underside of the fuselage. The matrix and door arrangement of the ventral radiator system were modified. Instead of the oil cooler being situated in the center of a circular coolant radiator, it was relocated to the front of the duct and provided with its own ventral exit door. Further downstream, in a greatly enlarged duct, was the huge rectangular coolant matrix, with a much bigger exit door at the rear. The airframes were strengthened in order to make full use of the increased power available. New ailerons were fitted and the under-wing racks were increased in capacity to take two 1000-lb bombs or their equivalent weight in drop tanks. A new four-bladed Hamilton Standard hydro-matic paddle-bladed propeller was fitted. Provisions for fuselage- mounted guns were totally eliminated, plans being made for four 0.50-in machine guns mounted exclusively in the wings.

In August of 1942, 400 P-51Bs were ordered on the basis of NAA's performance estimates, even before the first example had flown.

The first XP-51B was flown by Bob Chilton on November 30, 1942. It was initially flown without armament. The performance improvement was nothing short of astounding. The XP-51B achieved a level speed of 441 mph at 29,800 feet, over 100 mph faster than the Allison-engine P-51 at that altitude. At all heights, the rate of climb was approximately doubled.

The USAAF now finally had an aircraft which could compete on equal terms with the Fw 190 and the later models of the Bf 109. The USAAF was finally fully sold on the Mustang, and a letter contract for 2200 P-51Bs was issued. The engine was to be the Packard V-1650-3, based on the Merlin 68. As 1943 dawned, the Mustang program suddenly expanded. Massive production of Merlin engines was to take place at both Packard at Detroit and at Continental at Muskegon. The huge Inglewood, California factory was greatly expanded and dedicated solely to Mustang production, with the B-25 Mitchell program being transferred to Kansas City. Production of the AT-6 series of trainers had earlier been transferred from Inglewood to a new plant built in great haste at Dallas, Texas. The USAAF instructed NAA to expand the Dallas plant even further as a second source for Mustangs. Inglewood-built Mustangs were designated P-51B, Dallas-built Mustangs were designated P-51C. These aircraft were almost identical, and can generally be distinguished only by serial number.

By the end of January 1943 the production standard for the P-51B/C had been decided. In order to take full advantage of the additional power, the airframe was re-stressed in detail and the aircraft was made capable of operating at considerably greater weights than was previously possible. The wing racks were eventually cleared to carry bombs of 1000 pounds each or a wide range of other stores including drop tanks or triple rocket tubes.

The engine installation was further refined, with a rectangular filtered-air inlet being added in each side of the carburetor duct, and the exhaust expelled through individual ejector stubs projecting through a slim fairing. The ailerons were modified aerodynamically and structural, although the changes were visible externally only by the fact that the tabs were made of plastic. The armament was to be four 0.50-inch Browning MG53-2 guns in the wings, with 350 rounds for each inner gun and 280 rounds for each outer gun. The fuselage nose guns were deleted.

The first P-51B flew on May 5, 1943, and the first P-51C flew on August 5 of that year. Inglewood built 1988 P-51Bs and Dallas built 1750 P-51Cs. The P-51Cs on the 1942 and 1943 budgets were given the company designation NA-103. 1350 NA-103s were built. Texas-built aircraft in the 1944 budget were designated NA-111.

Initially, the P-51B and C had the Packard V-1560-3 engine rated at 1400 hp for takeoff and 1450 hp at 19,800 feet and carried four 0.50-inch machine guns with a total of 1260 rounds. There were four hundred P-51B-1-NAs and 250 P-51C-1-NTs built.

In the pursuit of still more range, a P-51B was experimentally fitted with an extra 85 US gallon self-sealing fuel tank behind the pilot's seat, bringing the total fuel to 419 US gallons (including 2 drop tanks). Although the Mustang already offered outstanding range performance, this additional fuel made it even better. This extra range was being demanded by expanding operations in both the European and Pacific theatres. However, this extra fuel tank moved the center of gravity aft, which made the directional stability of the Mustang quite poor, so that the pilot would have to spend the first hour or so concentrating on keeping his airplane pointed in the right direction until this new tank was finally empty. The last 550 P-51B-5-NAs were fitted with this extra tank, becoming P-51B-7-NAs, and into P-51C-1-NTs, becoming P-51C-3-NT. In addition, some earlier P-51Bs and Cs were modified in the field to accommodate this tank. In service, however, the directional instability caused by the presence of a full fuel tank behind the pilot's seat was a hazard for new or inexperienced pilots, and the tank was usually restricted to 65 US gallons. This extra tank, nevertheless, still made a crucial difference in combat radius, and it was standard equipment in all future production versions. With this extra fuel, Mustangs were able to escort bombers all the way to Berlin from bases in Britain.

During the P-51B-10-NA and P-51C-1-NT production run, it was decided to omit the olive drab camouflage and to deliver the aircraft in their natural metal finish. The objective was now to try and bring the Luftwaffe into battle, not to hide from it. This move saved extra cost, weight, and drag.

P-51B  - "Shoo Shoo Baby"; 357th FG

With the introduction of the P-51C-5-NT onto the Dallas production line and the P-51B-15-NA in the Inglewood production line, the Packard V-1560-7 engine was adopted as standard. It offered 1450 hp for take off and a war emergency rating of 1695 hp at 10,300 feet. Maximum speed at 20,000 feet was reduced from 440 to 435 mph, but increased from 430 to 439 mph at 25,000 feet. 398 P-51B-10-NAs, 390 P-51B-15-NAs, and 1350 P-51C-10-NTs were built, all powered by the V-1650-7 engine.

A total of 91 aircraft from the Block-10 production lot (71 P-51B-10-NAs and 20 P-51C-10-NTs) were fitted with two oblique K24 cameras, or a K17 and a K22, to become F-6C-NA or -NT photo aircraft. Most of these aircraft retained their guns. In each case the cameras were mounted immediately in front of the structural break ahead of the tailwheel, looking out the left side.

One of the problems encountered with the Merlin-powered P-51B/C was the poor view from the cockpit, particular towards the rear. The "Malcolm hood" fitted to the P-51B/C was an early attempt to correct this deficiency. Two P-51B-10-NAs (42-106539/106540 were completed on the production line as XP-51Ds to test out the validity of the concept of replacing the

The first combat unit equipped with Merlin-powered Mustangs was the 354th Fighter Group, which reached England in October of 1943. The 354th FG consisted of the 353rd, 355th and 356th Fighter Squadrons, and was part of the 9th Air Force which had the responsibility of air-to-ground attacks in support of the upcoming invasion of Europe. However, they were immediately ordered to support the bomber operations of the 8th Air Force. The 354th flew their first cross-Channel sweep mission on December 1, 1943, and scored their first victory on a mission to Bremen on December 16. However, inexperienced pilots and ground crews and numerous technical problems limited operations with the P-51B/C until about eight weeks into 1944. From the early spring of 1944, the Merlin-powered Mustang became an important fighter in the ETO.

The first P-51 ace was Major James H. Howard of the 354th Fighter Group. On January 11, 1944, he shot down five German fighters to become an "ace-in-a-day". He was awarded the Medal of Honor for this feat.

The 357th Fighter Group, also initially assigned to the 9th Air Force but was quickly transferred to operational control of the 8th Air Force for bomber escort. It flew its first P-51B escort mission on February 11, 1944.

The 363rd Fighter Group became the third P-51B operator in Europe on February 23, 1944.

The Fifteenth Air Force had been formed in November 1943 with three P-38 Lightning groups to escort Allied bombers. They were based in the Mediterranean theatre of operations. During April of 1944, Merlin-powered Mustangs began replacing Spitfires with the 31st and 52nd Fighter Groups, which transferred from the 12th to the 15th Air Force. The 31st flew its first mission on April 21, 1944, when its Mustangs escorted B-24s in an attack on the oil refineries at Ploesti in Romania.

The third fighter group to join the Fifteenth Air Force was the 332nd Fighter Group. It was a unit manned entirely by black airmen trained at Tuskegee, the Army being a segregated service in those days. They transitioned to the P-51C in June of 1944 while they were based at Foggia in Italy. The airmen of the 332nd FG had to spend nearly as much time battling segregation as they did the forces of the Third Reich. The top scorer was Lea Archer, with five air and six ground victories, although one aerial victory was later reallocated to another pilot to prevent him from becoming an ace. The proudest feat of the 332nd FG was that it never lost a bomber in its charge.

In March of 1944, Merlin-powered Mustangs accompanied B-17 Fortress and B-24 Liberator bombers all the way on a 1100-mile round trip to Berlin. The ability of escort fighters to accompany bomber formations all the way to their targets and still effectively counter intercepting Luftwaffe fighters after jettisoning their nearly empty drop tanks caused the German defenses no end of problems, and added considerable impetus to the American daylight bombing offensive.

Most of the P-51B/Cs were assigned to the 8th and 9th Air Forces in England, with a lesser number with the 12th and 15th USAAF in Italy. The P-51B/C remained the prime Mustang variant in service from December 1943 until March of 1944, when the bubble-topped P-51D began to arrive. However, P-51B/C fighters remained predominant until the middle of 1944, and remained in combat until the end of the war in Europe even after the arrival of large numbers of P-51Ds. Even as late as the last month of the war, 1000 out of the 2500 Mustangs serving in the ETO were of the P-51B/C variety.

P-51Bs and Cs were assigned to the following fighter groups in the European Theatre:

	4th Fighter Group, 8th Air Force 
	20th Fighter Group, 8th Air Force 
	335th Fighter Group, 8th Air Force 
	339th Fighter Group, 8th Air Force 
	352nd Fighter Group, 8th Air Force 
	357th Fighter Group, 8th Air Force 
	359th Fighter Group, 8th Air Force 
	361st Fighter Group, 8th Air Force 
	479th Fighter Group, 8th Air Force 
	354th Fighter Group, 9th Air Force 
	363rd Fighter Group, 9th Air Force 
	52nd Fighter Group, 12th Air Force 
	325th Fighter Group, 15th Air Force 
	31st Fighter Group, 15th Air Force 
	332nd Fighter Group, 15th Air Force 

Perhaps the best known P-51B aircraft is "Shangri La", a P-51B-5-NA (Ser No 44-6913) flown by the Fourth Fighter Group ace Don Gentile. Although the bubble-topped P-51D is far better known, the P-51B/C was actually the aircraft that turned the tide of the bomber war over Germany.

The Merlin-powered Mustang entered service in the China-Burma-India (CBI) theatre in September 1943. These aircraft were assigned to the 23rd and 51st Fighter Groups of the 5th Air Force. Early in 1944, the 311th Fighter Group of the 10th Air Force saw action in Burma with its Mustangs, flying in support of airborne troops attacking Japanese lines of communication. The top Mustang ace of the CBI theatre was Major John C. "Pappy" Herbst, with 18 kills.

P-51B  S/N 43-6999; Note wingtip damage; 357th FG

In June 1944, the 10th Tactical Reconnaissance Group picked up the 12th and 15th Reconnaissance Squadrons, equipped with F-6B and F-6C photographic reconnaissance aircraft. F-6s served with the Eighth, Ninth, Twelfth, and Fifteenth Air Forces, and with the Fifth Air Force in the Far East. The F-6s retained their four 0.50-inch machine guns, and had frequent encounters with Luftwaffe fighters. Captain Clyde East of the 15th Squadron was the war's top-scoring reconnaissance pilot, with 15 aerial victories.

In late 1942, a deal was worked out between Britain and the USA in which Spitfire VBs would be transferred to the 8th Air Force in England, mainly for use as fighter-trainers. This cleared the way for Lend-Lease supplies to continue of the new Mustang model to the RAF. The RAF equivalent to the USAAF P-51B/C was the Mustang III. The RAF ultimately received 274 P-51Bs and 626 P-51Cs. A total of 59 Mustang IIIs were diverted to the Royal Australian Air Force and to other Allied air arms.

About 100 P-51Bs and Cs were supplied to the Chinese Air Force in 1943-44.

During late 1944, French units acquired some F-6Cs and began to operate them over Germany in January of 1945 on photo-mapping missions.

After the Mustang III aircraft had been delivered to England, the RAF decided that the hinged cockpit canopy offered too poor a view for European operations. A fairly major modification was made in which the original framed hinged hood was replaced by a bulged Perspex frameless canopy that slid to the rear on rails. This canopy gave the pilot much more room and the huge goldfish bowl afforded a good view almost straight down or directly to the rear. This hood was manufactured and fitted by the British corporation R. Malcolm & Co., and came to be known as the "Malcolm Hood". This hood was fitted to most RAF Mustang IIIs, and many USAAF Eighth and Ninth Air Force P-51B/C fighters received this modification as well.

In search of a more lasting solution to the problem of poor cockpit visibility from the P-51B/C, a P-51B (43-12101) was modified with a teardrop-shaped all-round cockpit canopy and re-designated XP-51D. Having proved that the concept was valid, two P-51B-10-NAs (42-106539/106540 were completed on the production line with teardrop-shaped bubble canopies and were re-designated P-51Ds. These became the prototypes for the famed P-51D series of Mustangs.

However, many pilots regarded the Malcolm-hooded P-51B/C as the best Mustang of the entire series. It was lighter, faster, and had crisper handling than the later bubble-hooded P-51D and actually had a better all-round view. Its primary weakness, however, was in its armament--only four rather than six guns, which often proved prone to jamming. Some of the modifications applied to the P-51D to improve the ammunition feed were later retrofitted into P-51B/Cs, which made their guns less prone to jamming. With modified guns and a Malcolm hood, the P-51B/C was arguably a better fighter than the P-51D, with better visibility, lower weight, and without the structural problems which afflicted the D. Its departure characteristics were also more benign.

Some 3740 P-51Bs and Cs were built. Some of the served with front-line units until the end of hostilities, but others were converted as two-seat trainers or squadron hacks. The last P-51B passed out of service in 1949, having been re-designated F-51B in 1948.
 

 

"Excalibur III"

 

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Capt. Andrew D. Turner in P-51C - C.O. of the 322 FG; Tuskegee Airmen

P-51C-10-NT 44-10947 spent the entire war stateside serving in training roles. At the end ofthe war, it was turned over to the Reconstruction Finance Corporation (RFC) facility at Searcy Field in Oklahoma. This was a government-run facility which was charged with the disposal of surplus military property. It was purchased by Paul Mantz and raced under the civilian registration NX1202. It won the transcontinental Bendix Air Race of 1946, a 2048 mile trip between Van Nuys, California to Cleveland, Ohio, at an average speed of 435.5 mph. On February 28, 1947, Paul Mantz set new west-east record for a piston- engined aircraft by flying NX1202 from Burbank, California to LaGuardia Field, New York in 6 hours 7 minutes and 5 seconds. Mantz won the Bendix race again in 1947. He returned to California via LaGuardia, setting a new east-west record for this class of aircraft, reaching Burbank in 7 hours and 5 seconds. Paul Mantz won again in 1948, but this time he flew NX1204, another P-51C that he had purchased from the RFC.

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P-51C - apparently after nearby explosion.

In 1950, N1202 was sold to Capt. Charles F. Blair, who had plans for establishing a new round-the-world speed record. He named the plane *Stormy Petrel*, but soon changed it to *Excalibur III* On January 31, 1951, Captain Blair flew from New York International Airport to London in 7 hours and 48 minutes. The average speed was 450 mph, assisted by strong tailwinds. This broke the old New York-London record by 1 hour and 7 minutes. The record still stands for piston-engine aircraft. The next spring, Captain Blair then flew from London to Bremen, Oslo, and Bardufoss in Norway and then over the North Pole to Fairbanks, Alaska, landing there on May 29, 1951. On September 18,1952, President Harry S Truman presented Captain Blair with the Harmon International Trophy for his accomplishments.

Following these flights, Excalibur III was donated to the Smithsonian Institution. Its sister ship, NX1204, was donated to the International Flight and Space Museum in Santa Ana, California.
 

Surviving P-51B/C Aircraft

Although literally hundreds of P-51Ds are still in existence today (many of them still flying), very few P-51B/C fighters have survived to the present, even in museums. Ed Maloney's Air Museum in Ontario, California, the National Air Museum, and the Movieland Museum of the Air are reported to have P-51B/C aircraft on display. No others are known to exist. Anyone have further details?

 

Serial numbers of P-51Bs:

43-12093/12492		North American P-51B-1-NA Mustang 
				(NA-102)  c/n 102024541/24940.  400 aircraft
43-6313/7112 		North American P-51B-5-NA Mustang 
			(NA-104)  c/n 104-22816/23305, 24431/24540, 24941/25140.
				800 aircraft
43-7113/7202 		North American P-51B-10-NA Mustang 
				(NA-104) c/n 104-25141/25230.  90 aircraft
42-106429/106540		North American P-51B-10-NA Mustang 
				(NA-104) c/n 104-25231/25342.  112 aircraft
42-106541/106738		North American P-51B-10-NA Mustang 
				(NA-104) c/n 104-25343/25540.  198 aircraft
42-106739/106978		North American P-51B-15-NA Mustang 
				(NA-104) c/n 104-25541/25780.  240 aircraft
43-24752/24901		North American P-51B-15-NA Mustang 
				(NA-104) c/n 104-25781/25930.  150 aircraft

	total of 1990 P-51Bs
 

Serial numbers of P-51Cs:


42-102979/10332	North American P-51C-1-NT Mustang 
		        (NA-103) c/n 103-22416/22765.  350 aircraft
42-103329/10377	North American P-51C-5-NT Mustang 
		    (NA-103) c/n 103-22766/22815, 103-25933/26332. 450 aircraft
42-103779/10397	North American P-51C-10-NT Mustang 
			(NA-103) c/n 103-26333/26532.  200 aircraft
43-24902/25251	North American P-51C-10-NT Mustang
			(NA-103) c/n 103-26533/26882.  350 aircraft
44-10753/10782	North American P-51C-10-NT Mustang 
			(NA-111) c/n 111-28886/28915.  30 aircraft
44-10783/10817	North American P-51C-11-NT Mustang 
			(NA-111) c/n 111-28916/28950.  35 aircraft
44-10818/10852	North American P-51C-10-NT Mustang 
			(NA-111) c/n 111-28951/28985.  35 aircraft
44-10853/10858	North American P-51C-11-NT Mustang 
			(NA-111) c/n 111-28986/28991.  6 aircraft
44-10859/11036 	North American P-51C-10-NT Mustang 
			(NA-111) c/n 111-28992/29169.  178 aircraft
44-11037/11122 	North American P-51C-11-NT Mustang 
			(NA-111) c/n 111-29170/29255.  86 aircraft
44-11123/11152 	North American P-51C-10-NT Mustang 
			(NA-111) c/n 111-29256/29285.  30 aircraft

	total of 1750 aircraft

Specification of P-51B-1-NA:

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P-51B-NA  - S/N 43-12095

One 1620 hp Packard Merlin V-1650-3 twelve cylinder Vee liquid-cooled engine. Maximum speed was 388 mph at 5000 feet, 406 mph at 10,000 feet, 427 mph at 20,000 feet, 430 mph at 25,000 feet, 440 mph at 30,000 feet. Range on internal fuel was 550 miles at 343 mph at 25,000 feet, 810 miles at 253 mph at 10,000 feet. With maximum external fuel, maximum range was 2200 miles at 244 mph. An altitude of 5000 feet could be attained in 1.8 minutes, 10,000 feet in 3.6 minutes, 20,000 feet in 7 minutes. Service ceiling was 42,000 feet. Weights were 6840 lbs empty, 9200 lbs normal loaded, 11,200 lbs maximum loaded. Wingspan was 37 feet 0 1/4 inches, length was 32 feet 3 inches, height 8 feet 8 inches, and wing area was 233 square feet.

 

Specification of P-51C-10-NT:

One 1695 hp Packard Merlin V-1650-7 twelve cylinder Vee liquid-cooled engine. Maximum speed was 395 mph at 5000 feet, 417 mph at 10,000 feet, 426 mph at 20,000 feet, 439 mph at 25,000 feet, 435 mph at 30,000 feet. Range on internal fuel was 955 miles at 397 mph at 25,000 feet, 1300 miles at 260 mph at 10,000 feet. With maximum external fuel, maximum range was 2440 miles at 249 mph. An altitude of 5000 feet could be attained in 1.6 minutes, 10,000 feet in 3.1 minutes, 20,000 feet in 6.9 minutes. Service ceiling was 41,900 feet. Weights were 6985 lbs empty, 9800 lbs normal loaded, 11,800 lbs maximum loaded. Wingspan was 37 feet 0 1/4 inches, length was 32 feet 3 inches, height 8 feet 8 inches, and wing area was 233 square feet.
 

 

Mustang III For RAF

In late 1942, a deal was worked out between Britain and the USA in which Spitfire VBs would be transferred to the 8th Air Force in England, mainly for use as fighter-trainers. This cleared the way for Lend-Lease supplies to continue of the new Mustang model to the RAF.

The RAF equivalent to the USAAF P-51B/C was known as the Mustang III. The RAF ultimately received 274 P-51Bs and 626 P-51Cs. RAF serials were FB100/FB124, FB135/FB399, FR411, FX848/FX999, FZ100/FZ197, HB821/HB962, HK944/HK947, HK955, HK956, KH421/KH640, SR406/SR438, and SR440. Serial numbers FX848, 849, 907, 909, 910, 911, 913, 914, 915, 916, 918, 927, 928, 932, 948 were handed back to the USAAF upon arrival in Britain. HK944/947, 955, 956 were ex-Twelfth USAAF aircraft. KH490 crashed in the USA before delivery. Serial numbers SR406/438 and SR440 were a mixed bag of P-51Bs and Cs delivered to the RAF from the USAAF--US serial numbers were respectively 43-12162, 43-12407, 43-12412, 43-12473, 43-12484, 43-12427, 43-70114(?), 43-12189, 43-12177, 43-7039, 43-6831, 43-12155, 43-12188, 43-12456, 43-12480, 43-12399, 42-10663(?), 42-106683, 42-106630, 42-106687, 43-7071, 43-7144, 43-5595, 43-7171, 43-6829, 43-12420, 43-7152, 43-7135, 42-103209, 42-106478, 42-106431, 43-7007, 43-12420, 43-7159. (Question marks denote serial numbers which are probably erroneous). The first RAF squadron to receive the Mustang III was No. 65 Squadron based at Gravesend, which received its planes in December 1943.

A total of 59 Mustang IIIs were diverted to the Royal Australian Air Force and to other Allied air arms.

After these Mustang III aircraft had been delivered to England, the RAF decided that the hinged cockpit canopy offered too poor a view for European operations. A fairly major modification was made in which the original framed hinged hood was replaced by a bulged Perspex frameless canopy that slid to the rear on rails. This canopy gave the pilot much more room and the huge goldfish bowl afforded a good view almost straight down or directly to the rear. This hood was manufactured and fitted by the British corporation R. Malcolm & Co., and came to be known as the "Malcolm Hood". This hood was fitted to most RAF Mustang IIIs, and many USAAF Eighth and Ninth Air Force P-51B/C fighters received this modification as well.

Many pilots regarded the Malcolm-hooded P-51B/C as the best Mustang of the entire series. It was lighter, faster, and had crisper handling than the later bubble-hooded P-51D and actually had a better all-round view. Its primary weakness, however, was in its armament--only four rather than six guns, which often proved prone to jamming. Some of the modifications applied to the P-51D to improve the ammunition feed were later retrofitted into P-51B/Cs, which made them less prone to jamming. With modified guns and a Malcolm hood, the P-51B/C was arguably a better fighter than the P-51D, with better visibility, lower weight, and without the structural problems which afflicted the D. Its departure characteristics were also more benign.

The first RAF base to receive Mustang IIIs was at Gravesend in Kent. The Mustang III initially equipped No. 65 Squadron in late December of 1943, followed by No. 19 Squadron in March of 1944. Later the Mk. III also equipped Nos 64, 65, 66, 93, 94, 112, 118, 122, 126, 129, 165, 234, 237, 241 249, 250, 260, 268, 306, 309, 315, 316, 345, 430, 441, 442, and 516 Squadrons and No. 541 Squadron of RAF Coastal Command. These units included four Polish squadrons (306, 309, 315, 316), three RCAF, and one Free French.

The new RAF Mustang IIIs began operations late in February 1944, escorting US heavy bombers as well as both US and RAF medium bombers.

Numerous RAF Mustang IIIs were diverted to the interception of V-1 "buzz-bombs". Some of them were "souped up" by using a special high-octane fuel and internal engine adjustments in order to increase the intake manifold pressure and made it possible to achieve a speed of 420 mph at 2000 feet. Since the typical V-1 flew at 370 mph, this made the "souped-up" Mustang very useful against these weapons.
 

 

North American P-51D/K "Mustang"

 

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The North American P-51D Mustang: Beautiful then, beautiful now.

The P-51D/K with its bubble-top canopy was perhaps the best-known version of the Mustang. It was also the most widely used variant of the Mustang, a grand total of 8102 machines of this type being produced (6502 at Inglewood and 1600 in Dallas).

One of the problems encountered with the Merlin-powered P-51B/C was the poor view from the cockpit, particular towards the rear. The "Malcolm hood" fitted to the P-51B/C was an early attempt to correct this deficiency. However, a more lasting solution was sought. In January of 1943, Col Mark Bradley had been sent to England, and while there he saw how the newly-invented "bubble" or "teardrop" canopy had given Spitfire and Typhoon pilots unobstructed 360-degree vision. He returned to Wright Field in June, and immediately began exploring the possibility of putting bubble canopies on USAAF fighters.

Republic Aviation put a bubble canopy on the P-47D Thunderbolt in record time, and Bradley flew it to Inglewood to show it to Kindelberger. Following discussions with the British and after examination of the clear-blown "teardrop" canopies of later Spitfires and Typhoons, North American Aviation secured an agreement with the Army to test a similar canopy on a Mustang in order to improve the pilot's view from the cockpit.

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P-51D prototype in flight - S/N 43-12102; Modified P-51B;

A P-51B (43-12101) was selected to be modified as the test vehicle for the new all-round bubble canopy. The aircraft was re-designated XP-51D. The new bubble-shaped hood gave almost completely unobstructed vision around 360 degrees with virtually no distortion. The large rear section did not reach its point of maximum height until a point well aft of the pilot's head was reached, since wind tunnel testing showed that this shape was found to offer the best combination of viewing angles and minimum aerodynamic drag. The Plexiglas of the hood was mounted in rubber in a metal frame, the sill around the bottom being very deep. This was needed to provide the strength and rigidity required to avoid distortion and to prevent the binding or jamming of the canopy in the fuselage rails while it was being opened and closed. There were three rails, one along each side of the cockpit and one along the upper centerline of the rear fuselage. The canopy was manually opened and closed by a handle crank operated by the pilot.

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three distinct P-51 profiles

In order to accommodate the new all-round vision hood, the rear fuselage of the Mustang had to be extensively cut down. However, the amount of retooling needed to accomplish this was not extensive, and very little re-stressing of the fuselage structure was necessary.

The newly-modified XP-51D took off on its first flight at Inglewood on November 17, 1943, test pilot Bob Chilton at the controls.

Having proven the concept, NAA diverted two P-51B-10-NAs (serial numbers 42-106539 and 42-106540) from the Inglewood production line and completed them as NA-106s with cut-down rear fuselage and bubble canopy. These two aircraft were re-designated P-51D.

One of the shortcomings of the P-51B was its limited firepower of only four machine guns. In addition, the guns in each wing were tilted over at quite sharp angles, requiring a sharp kink in the ammunition belt feeds and resulting in frequent gun jams. NAA took the opportunity afforded by the introduction of the new Mustang to correct this problem. The gun installation was completely redesigned, and the result was the installation of three MG53-2 0.50-inch machine guns in each wing, all of them mounted upright and all fed by un-kinked ammunition belts. The inboard guns each had 400 rpg, and the others each had 270 rpg. However, Mustang users had the options of removing two of the guns and having just four, with 400 rounds each, and some pilots did actually select this option.

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P-51D with Ramjets - S/N 4463528 with two XRJ-30-MA Ramjets; May 1948 Wright-Patterson AFB

Another visible change introduced by the P-51D was in the increase of the wing root chord. The main landing gear was strengthened in order to accommodate the additional weight, but the wheels maintained the same diameter of 27 inches. However, the wheel bays and doors were modified and the "kink" in the wing leading edge was made much more pronounced. The "kink" in the wing of the P-51B was barely noticeable, but it was much more pronounced in the P-51D.

Four P-51D-1-NA Mustangs had been completed with the original B-type canopy before the first P-51D-5-NA model (company designation NA-109) rolled off the production line.

Readers may recall the problems with the installation of the 85-gallon tank in the rear fuselage of the P-51B and its adverse effects on the directional stability. Things got still worse for the P-51D, in which the cutting down of the top line of the rear fuselage caused a lot of keel area to be lost. In order to provide for better directional stability, a dorsal fin was added ahead of the rudder during the production run of the P-51D Block 10. Some of the earlier P-51Ds (plus a few P-51Bs) were retrofitted with this dorsal fin. The extra weight and drag caused by this fin was quite small, but it helped a lot in improving the directional stability, especially when the rear fuselage fuel tank was full.

The P-51D/K introduced the K-14 computing gyro gun sight, based on a British (Ferranti) design. When it first appeared, it was considered almost miraculous. The pilot needed only to dial in the wingspan of the enemy aircraft he was chasing and then feed in the target range by turning a handgrip on the throttle lever. Everything was then done by an analog computer. All that the pilot had to do then was to get the wingtips of his target lined up on the bright ring projected on the gun sight, and press the trigger. The K-14 was fitted almost from the start of P-51D production, the P-51K receiving this sight from mid-1944. This sight played a major role in the P-51D's impressive score of aerial victories.

Inglewood delivered 6502 P-51Ds, ordered as the NA-109 (D-1 to D-10), NA-111 (D-15 and D-20) and NA-122 (D-15 and D-30). P-51Ds were also constructed in NAA's Dallas plant, the Dallas plant building some 1600 of these planes before production finally ceased. Dallas-built blocks D-5 through D-20 were known as NA-111, with blocks D-25 and D-30 being known as NA-124

Almost all Block-25 and subsequent Ds had under-wing hard-points not only for bombs and fuel tanks but also for various types of rocket launchers. These included zero-length stubs for six 5-inch rockets or as many as ten if no drop tanks were carried. Alternatively, "Bazooka" tubes could be carried in triple clusters. There were a few field conversions to special armament fits, examples including two tanks and six 100-lb bombs, four 100-lb bombs, plus 36 fragmentation bombs, or        four 75-Imp gall drop tanks. CBI aircraft usually had a direction-finding loop antenna ahead of the fin.

The Dallas plant also built 1500 P-51Ks, which differed from the P-51D in having an 11-foot diameter Aeroproducts propeller in place of the 11 feet 2 inch diameter Hamilton Standard unit. These were all known as NA-111 by the company. The P-51K had a slightly inferior performance to that of the P-51D. Rocket stubs were introduced on the -10-NT and subsequent batches of the K production line at Dallas.

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P-51D with Pulsejets

A total of 163 of these P-51Ks were completed as F-6K photo-reconnaissance aircraft. 126 Inglewood-built P-51Ds from blocks 20, 25, and 30 were converted after completion as F-6Ds. A few others were similarly converted near the end of the war. All of these photographic Mustangs carried two cameras in the rear fuselage, usually a K17 and a K22, one looking out almost horizontally off to the left and the other one down below looking out at at an oblique angle. Most F-6Ds and Ks carried a direction- finding receiver, serviced by a rotating loop antenna mounted just ahead of the dorsal fin. Most F-6Ds and Ks retained their armament.

P-51D 44-14017 was temporarily borrowed by the US Navy to determine if it would be suitable for carrier-based operations. Bureau number 57987 was assigned. The P-51D was found to be unacceptable, primarily because of the poor rudder control at low airspeeds, particularly at high angles of attack.

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F-6D  S/N 44-13666; Photo Reconnaissance aircraft

Several Dallas-built P-51Ds were modified as two-seat trainers with an additional seat fitted behind the pilot's seat. Serial numbers were 44-84610, 44-84611, 44-84662, and 45-11443/11450. These were given the designation TP-51D. In order to accommodate the second seat, the radio equipment had to be relocated and an additional seat with full dual controls was installed behind the normal seat. The standard bubble canopy was large enough to accommodate the extra seat. One of the TP-51Ds was modified for use as a special high-speed observation post by Supreme Allied Commander General Dwight D. Eisenhower, which he used to inspect the Normandy beach-heads in June of 1944.

The P-51D began to arrive in Europe in quantity in March of 1944. The 55th Fighter Group was the first to get the P-51D, trading in its P-38s for the new bubble-topped fighters. The change from the torque less twin-engine P-38 to the single-engine P-51 did cause some initial problems, and the lack of directional stability caused by the presence of a full fuselage tank took a lot of getting used to. However, once their pilots became fully adjusted to their new mounts, they found that the P-51D possessed a marked edge in both speed and maneuverability over all Luftwaffe piston-engine fighters at altitudes above 20,000 feet. However, Luftwaffe pilots considered the Mustang to be rather vulnerable to cannon fire, particularly the liquid-cooled Merlin engine which could be put out of action by just one hit.

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P-51D - "My Girl" taking off from Iwo Jima

The Mustang was the only Allied fighter with sufficient range to accompany bombers on their "shuttle" missions in which landings were made in Russia after deep-penetration targets had been attacked from English bases. The Mustangs also participated in low-altitude strikes on Luftwaffe airfields, a rather dangerous undertaking as these fields were very heavily defended by flak.

In 1943, the Allies were aware that the Luftwaffe was planning to introduce jet-powered aircraft over Germany, and that these would provide a serious threat to Allied bombers and to their escorting fighters. Mustangs first encountered Messerschmitt Me 163 Komet rocket-powered fighters on July 18, 1944, when a pair of Me 163s flew unscathed through a flight of P-51s. On August 5, 1944, Me 163s destroyed three bombers and shot down three escorting P-51s. On August 16, a Mustang flown by Lt. Col. John B. Murphy of the 359th Fighter Group finally managed to shoot down a Me 163. Although the Me 163 gained much publicity and threw the Allied high command into a near panic, the rocket-powered fighter had an extremely short endurance in the air and was very dangerous to fly. It is doubtful that these rocket-powered fighters destroyed more than a dozen or so Allied aircraft during the entire course of the war.

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P-51D S/N 44-73157

Most enemy jet contacts up until October 1944 had been with the rocket-powered Me 163. In that month, the Messerschmitt Me 262 began to appear in combat. The first jet kill by a Mustang was on October 7, 1944, when Lt. Urban L. Dreq of the 361st Fighter Group shot down two Me 262s while they were taking off from their base. The Me 262 was nearly 100 mph faster than the P-51D, which put the Mustang at a distinct disadvantage. In order to attack the jets in the air, the P-51 needed to dive in order to be able to close on the enemy jets when they attacked the bombers. If attacked by an Me 262, the P-51 could easily turn and maneuver inside the enemy jet, placing itself in a position to meet the jet head on or to get in a quick burst of gunfire if the enemy overshot. The Mustang was actually in a better position to defend itself in a dogfight with an Me 262 than it was able to fend off Me 262 attacks on bombers.

Eventually it was decided that the best strategy in fighting the jets was to jump them while they were taking off from or landing at their bases. The early jets had very poor acceleration and were thus extremely vulnerable during takeoff and landing. The usual tactic was for scores of Mustangs to circle high over known Me 262 bases, daring the jets to take off. If any rose to the challenge, diving Mustangs would be upon them almost before their wheels could be retracted. If the Messerschmitts refused to take the bait, the bases would be strafed and the jets would be destroyed on the ground.

Units operating the P-51D in the ETO included the following:

4th Fighter Group, 8th Air Force..334th, 335th, 336th Fighter Squadrons.
20th Fighter Group, 8th Air Force.  55th, 77th, 79th Fighter Squadrons
55th Fighter Group, 8th Air Force.  38th, 338th , 343rd Fighter Squadrons
78th Fighter Group, 8th Air Force.  82nd, 83rd, 84th Fighter Squadrons
339th Fighter Group, 8th Air Force.  503rd, 504th, 505th Fighter Squadrons
352nd Fighter Group, 8th Air Force.  328th, 486th, 487th Fighter Squadrons
353nd Fighter Group, 8th Air Force.  350th, 351st, 352nd Fighter Squadrons
355th Fighter Group, 8th Air Force.  354th, 357th, 358th Fighter Squadrons
356th Fighter Group, 8th Air Force.  359th, 360th, 361st Fighter Squadrons
357th Fighter Group, 8th Air Force.  362nd, 363rd, 364th Fighter Squadrons
359th Fighter Group, 8th Air Force.  368th, 369th, 370th Fighter Squadrons
361st Fighter Group, 8th Air Force.  374th, 375th, 376th Fighter Squadrons
364th Fighter Group, 8th Air Force.  383rd, 384th, 385th Fighter Squadrons
479th Fighter Group, 8th Air Force.  434th, 435th, 436th Fighter Squadrons


67th Tactical Reconnaissance Group, 9th Air Force 
68th Tactical Reconnaissance Group, 9th Air Force 
69th Tactical Reconnaissance Group, 9th Air Force. 10th, 22nd Squadrons.
354th Fighter Group, 9th Air Force.  353rd, 355th, 356th Fighter Squadrons
363rd Fighter Group, 9th Air Force.  380th, 381st, 382nd Fighter Squadrons
370th Fighter Group, 9th Air Force.  401st, 402nd, 485th Fighter Squadrons


31th Fighter Group, 15th Air Force.  307th, 308th, 309th Fighter Squadrons
52nd Fighter Group, 15th Air Force.  
325th Fighter Group, 15th Air Force.  
332nd Fighter Group, 15th Air Force.  This was the famous all-black outfit.  

Several Mustang pilots became "ace-in-a-day", scoring five or more victories during one mission: Lt. William R. Beyer of the 361st Fighter Group, Capt. William T. Whisner, Capt. Donald S. Bryan of the 352nd Group, Lt. Claude J. Crenshaw of the 359th Group, Capt L. K. Carson of the 357th Group, Lt. J. S. Daniel of the 339th Group, Capt. William J. Hovde of the 355th Group, and Mister Right Stuff himself, Capt. Charles E. "Chuck" Yeager of the 357th Group. Maj. George Preddy of the 352th Group held the ETO Allied record of six victories on one mission, which he achieved on August 6, 1944. Major Preddy was the top USAAF Mustang ace of the war, scoring 23.83 out of his 26.83 victories while flying a P-51. (Why this odd fraction?)

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P-51D 8 aircraft formation

The top-scoring Mustang-equipped fighter group was the 357th, with 609 air and 106 ground kills from February 11, 1944 to April 25, 1945.

By the time that Germany surrendered, all of the Escort Groups of the 8th Air Force and some of the groups in the 9th Air force had converted to P-51s.

The Royal Air Force received 281 Ds and 594 Ks, designating them Mustang IV and Mustang IVA respectively. The type did not enter RAF service until September 1944, with the earlier Mustang III still remaining in active service.

Because of the higher priority of the war in Europe, the P-51D Mustang did not arrive in the Pacific until late in 1944. P-51Ds were initially based in the Philippines and on Iwo Jima. By that stage of the war, Japanese fighter opposition was rare, and Philippine-based Mustangs mostly performed close-support work. However, while flying over Japanese-occupied regions of Luzon on January 11, 1945, Captain William A. Shomo managed to shoot down six Tonys and one bomber in one day while flying an F-6D photo-recon aircraft. For this action, he was awarded the Medal of Honor, becoming the second Mustang pilot of World War 2 to receive this award.

As Japanese resistance on Luzon came to an end, the Philippine-based Mustangs were used to bomb and strafe Japanese forces based on Formosa. Iwo Jima-based Mustangs flew the first escort missions with B-29 bombers attacking Japan, and they undertook the first land-based fighter strikes against Tokyo on April 7, 1945, when B-29s hit the Nakajima Aircraft Engine Factory. Such missions involved flights lasting up to seven or eight hours, covering distances of over 1500 miles. When General Curtis LeMay decided that most B-29 missions would take place at night from medium altitudes, the Iwo Jima-based Mustangs went over to ground attack missions against Japanese airfields. Extensive use was made of the five-inch rockets which were carried under each wing.

 

USAAF Mustang Groups in Pacific Theatre of Operations:

8th Reconnaissance Group
15th Fighter Group, VII Fighter Command
21st Fighter Group, VII Fighter Command, 46th, 72nd, 531st Fighter Squadrons
506th Fighter Group, VII Fighter Command, 457th, 458th, 462nd Fighter Squadrons
23rd Fighter Group, Fourteenth Air Force

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XP-51F  S/N 43-43332

The P-51D remained in service in considerable numbers with the USAAF for many years after the Second World War ended. In 1948, the newly-formed USAF eliminated the P-for-pursuit category and replaced it with F-for-fighter. The designation of the P-51 was changed to F-51. In addition, the old category of F for photographic reconnaissance was eliminated, and F-6D and F-6K photographic reconnaissance aircraft became RF-51D and RF-51K respectively. Two seat F-6D conversions became TRF-51D.

In May 1946, the Air National Guard (ANG) was reformed and ANG fighter units received most of the P-51D/K Mustangs withdrawn from regular USAAF service. It was agreed that the Mustang would go primarily to ANG groups west of the Mississippi, with the ANG groups east of the Mississippi being equipped with the P-47 Thunderbolt. By December of 1948, over 700 Mustangs were serving with 28 ANG squadrons. RF-51D reconnaissance aircraft also served with the ANG. No fewer than 22 of the 27 ANG wings saw service in the Korean War.

The Mustang was in action once again when the Korean War began on June 25, 1950. The Mustang was better suited to the small airstrips of Korea than were the F-80s and F-82s based in Japan. Japan-based F-51Ds were immediately transferred to Korea and pressed into service in an attempt to halt the rapid North Korean advance. The Mustangs were based at Kimpo, Pusan, and Pohang, flying out of one field then another in close support operations against the advancing North Koreans. They were called on to carry the brunt of air support missions during these difficult early days of the war, since the jet aircraft of the day did not have enough range to permit sufficient loiter time over the target.

In order to build up close support forces, 145 F-51s were brought over from the USA aboard the aircraft carrier USS *Boxer*. These planes were quickly assembled and flown out to combat units. The 18th Fighter-Bomber Wing gave up its F-80 jets for Mustangs, perhaps one of the few occasions in history in which a combat outfit traded in its jets for piston-engined aircraft. The Mustangs were instrumental in halting the North Korean advance, giving United Nations forces enough time to build up sufficient strength to be able to go over onto the offensive. Mustangs flew 62,607 tactical support combat missions. 351 Mustangs were lost in action, most of them the victims of antiaircraft fire. The Mustang was not the best choice for low-level air to ground combat--its belly-mounted radiator and its reliance on liquid coolant made it dangerously vulnerable to ground fire. Although their primary mission was close support, USAF Mustangs did manage to shoot down a few North Korean Yaks when these aircraft made their infrequent appearances. When Mustangs were jumped by Chinese-piloted MiG-15 jet fighters, however, they were faced with an opponent with a far superior performance. When this happened, there was little the Mustangs could do save to try to turn inside the MiGs, hit the deck, and run for home.

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XP-51F  with 5-blade propeller

 Mustang pilot Major Louis J. Sebille, commander of the 67th FBS/18th FBW, in an F-51D 44-74394 flew straight into a concentration of enemy troops

The last American active-duty Mustang was P-51D-30-NA Ser No 44-74936, which was finally withdrawn from service with the West Virginia ANG in 1957. This airplane is now on display at the WPAFB Museum in Dayton, Ohio. It is, however, painted as P-51D-15-NA Ser No. 44-15174.

Specification of the P-51D-25-NA:

One 1695 hp Packard Merlin V-1650-7 twelve-cylinder Vee liquid-cooled engine. Maximum speed: 395 mph at 5000 feet, 416 mph at 10,000 feet, 424 mph at 20,000 feet, 437 mph at 25,000 feet. Range was 950 miles at 395 mph at 25,000 feet (clean), 2300 miles with maximum fuel (including drop tanks) of 489 US gallons under most economical cruise conditions. Initial climb rate was 3475 feet per minute. An altitude of 5000 feet could be reached in 1l7 minutes, 10,000 feet in 3.3 minutes, 20,000 feet in 7.3 minutes. Service ceiling was 41,900 feet. Weights were 7125 pounds empty, 10,100 pounds normal loaded, 12,100 pounds maximum. Wingspan was 37 feet 0 1/4 inches, length was 32 feet 3 inches, height was 8 feet 8 inches, and wing area was 233 square feet.

Serials of the P-51K:

44-11353/11552	North American P-51K-1-NT Mustang 
			c/n 111-29486/29685.  200 aircraft
44-11553/11952	North American P-51K-5-NT Mustang 
			c/n 111-29686/30085.  400 aircraft
44-11953/12552	North American P-51K-10-NT Mustang 
			c/n 111-30086/30685.  600 aircraft
44-12553/12852	North American P-51K-15-NT Mustang
			c/n 111-30686/30885, 111-36036/36135.  300 aircraft

	total of 1500 P-51Ks.


 

XP-51J

 

Click on Picture to enlarge

In early 1943, joint discussions were held between British authorities and North American Aviation dealing with the subject of what the next generation of Mustangs should look like. The original NA-73 had been designed to higher load factors than the British Air Purchasing Commission had required. As a result, the structure of the Mustang was considerably heavier than that of the Spitfire, and it was felt that a considerable improvement in performance might be obtained if structural weight could be reduced. Edgar Schmued that traveled to England and had inspected the Supermarine factory, and he had also studied captured Messerchmitt and Focke-Wulf fighters. In January of 1943, North American Aviation suggested to the USAAF that they build a special lightweight version of the Mustang. It was agreed that a thorough redesign would be carried out, mainly to reduce weight but also to simplify systems, improve maintenance, and enhance performance without changing the engine. The new Mustang was to be designed to a combination of optimal British and American strength requirements, but mainly to those laid down in British Air Publication 970.

The project was given the company designation NA-105. Two prototypes were ordered under the designation XP-51F, the contract being amended in June of 1943 to cover the purchase of five XP-51Fs, all powered by Packard V-1650-3 engines. Serial numbers were 43-43332/43336. The British Air Commission requested that two of these aircraft be given to then for evaluation. A request by the Technical Command for the procurement of twenty-five service test P-51Fs was not authorized, since it was felt that prototype trials should be made before any quantity production was undertaken.

Resemblance to the previous Mustang was only coincidental, since the structure of the aircraft was almost completely redesigned and almost no parts were common. Most of the changes were made in an attempt to save weight. The main landing gear members were redesigned and the wheels and tires were greatly reduced in size. New disc brakes were fitted to the wheels. The wing was slightly larger in area, and had a straight-line leading edge, completely eliminating the familiar "kink" of the earlier Mustang versions. The wing aerofoil was changed to an even newer low-drag "laminar flow" profile. The inboard wing guns were deleted, the remaining four guns having 440 rounds each. The two wing tanks were reduced in capacity to 102 US gallons each, and the fuselage tank was eliminated entirely. The engine mounting was simplified, the "integral" engine cradle for the V-1650-7 saving over 100 pounds of weight and improving the access to the engine. The hydraulic system was simplified and increased in pressure. The engine coolant and intercooler radiators were redesigned and installed in a completely new duct which had a vertical inlet which was placed even farther away from the underside of the wing. The oil cooler was removed from the rear radiator group, enabling the latter to be made smaller and making it possible to eliminate the long and vulnerable oil pipes. The oil was passed through a heat exchanger mounted on the front of the oil tank and next to the engine intercooler. The flow of glycol carried away the heat from the oil. The cockpit layout was improved (with the standard British panel being adopted), and the pilot's back armor was made integral with the seat. The canopy was made much larger in an effort to reduce the drag still further. Aerodynamic control surfaces were improved, and the tail surfaces were made larger. The ailerons were given a larger degree of movement, and the chord of the flaps and the ailerons were made equal. Still more weight was saved by using a three-bladed Aeroproducts hollow-steel propeller. Many minor metal parts were replaced with molded plastic parts.

Click on Picture to enlarge

Before construction began, it was agreed that the last two of the NA-105 airframes would be fitted with Rolls Royce Merlin 145M engines obtained from England under reverse-Lend/Lease. These aircraft were designated XP-51G and bore the serial numbers 43-43335/43336.

Engineering inspections were held in February 1944. The first XP-51F was flown by Bob Chilton on February 14, 1944. The second and third XP-51F flew on May 20 and 22 of that year. Equipped empty weight was about 2000 pounds less than that of the P-51D, and combat weight was 1600 pounds less. The engine was the Packard Merlin V-1650-7 engine of 1695 hp, same as the power-plant of the P-51D. Considering that the equipped empty weight was about a ton less than that of the P-51D, the performance improvement was not as spectacular as might have been anticipated-- maximum speed was 466 mph at 29,000 feet.

Work on the conversion of the fourth and fifth NA-105 airframes as XP-51Gs began in January 1944, with the Merlin 145M engines arriving in February. Five-bladed propellers were fitted, but the XP-51G was otherwise similar to the XP-51F. The date of the first flight of the XP-51G is a matter of some dispute--most sources claim that first XP-51G was flown by Ed Virgin on August 10, 1944, but the manufacturer credits Bob Chilton with the first flight on August 12, while other s claim that Joe Barton may have taken the XP-51G up for the first time on August 9. The second machine followed on November 14. The engine was the Rolls-Royce Merlin 145M engine rated at 1910 hp., driving a Rotol propeller with five wooden blades (almost identical to the propellers of the Spitfire XIV). However, the XP-51G flew only once with the five-bladed propeller during a 20-minute flight, and all other flying was carried out with a more conventional Aeroproducts Unimatic A-542-B! four-bladed propeller. It was readily apparent that this was the hottest Mustang yet-- maximum speed was 472 mph at 20,750 feet.

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The third XP-51F was shipped to the United Kingdom on June 20, 1944 after preliminary flight checks. It was painted in RAF camouflage and was named Mustang V. The RAF serial number was FR409. The A&AEE at Boscombe Down found the Mustang V to weigh only 7855 pounds in interceptor trim. They rated it very highly except for a severe lack of directional stability which required frequent heavy application of rudder in certain flight conditions.

The second XP-51G was shipped to the United Kingdom in February 1945. This plane was also named Mustang V, and bore the RAF serial number FR410. It is widely reported to have achieved a speed of 495 mph during tests at the A&AEE at Boscombe Down in February 1945, although NAA claimed only 472 mph for the other G at the same altitude. However, by this time RAF priorities had changed, and no further flight testing took place. The fate of FR410 after the end of test flying is uncertain.

Neither the XP-51F nor the G ever proceeded any further than the prototype stage. The Merlin 100-series of engines had not quite reached the stage where they were fully ready for production. In the meantime, the Packard Motor Car Company had set up its own development program and had come up with the V-1650-9 version of its license-built Merlin, capable of delivering a war emergency power of 1900 hp at 20,000 feet with water/alcohol injection. Packard said that they could deliver this new engine starting in late 1944. Consequently, this engine was chosen to power the next production Mustang, which was designated P-51H. Neither the P-51F nor the G were developed any further, although the work on these two airplanes was invaluable in the development of the P-51H.

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XP-51J - S/N 44-76027; 1st of two -J models built

The last prototype in the lightweight NA-105 series was the XP-51J, which was similar to the F and G models except that it reintroduced the Allison V-1710 engine to bring the Mustang full circle. The Allison engine was, however, the V-1710-119 version with a two stage, gear-driven supercharger, rated at 1500 hp for takeoff and 1720 hp with water injection at 20,700 feet. Unlike earlier Allisons, this engine had an updraft carburetor. The nose geometry was substantially modified, and all air inlets in the nose were completely eliminated. Instead, the carburetor air was taken in through a ram inlet at the front of the radiator duct and piped to the engine. A dorsal fin was fitted.

Two XP-51J prototypes were ordered, with serial numbers being 44-76027 and 44-76028. 44-76027 made its first flight on April 23, 1945, piloted by Joe Barton. The XP-51J weighed 6030 pounds empty and 7550 pounds normal loaded. It was anticipated that a maximum speed of 491 mph could be achieved at an altitude of 27,400 feet, but this was never achieved during tests because the new Allison had not yet been cleared for full power operations. XP-51J Ser No 44-76027 was, in fact, loaned to Allison so that they could use it to iron out the bugs in their engine. The other XP-51J prototype, Ser No 44-76028, was never actually flown, but was scavenged for spare parts to keep the other example flying. The end of the war in the Pacific brought all further work on the XP-51J to an end.

It is an odd fact that no in-flight photos were ever taken of the XP-51F, G, or J. It seems that pilots and other people were too busy with wartime testing to schedule photo sessions. In later years, historians have looked in vain for a photographic record of these lightweight Mustangs in the air.                                                                                                                                                                 

Click on Picture to enlarge

However, XP-51G 43-43335 has survived all these years. In the 1980s, John Morgan of La Canada, California attempted to restore and fly this aircraft. Unfortunately, the parts of the XP-51G are not interchangeable with those of the far more numerous P-51D, and the aircraft has a different center of gravity.

Specification of XP-51F

466 mph at 29,000 feet, and an altitude of 19,500 feet could be reached in 4.9 minutes. Service ceiling was 42,500 feet. Normal range was 650 miles, and maximum range was 2100 miles. Weights were 5635 lbs. empty, 7610 lbs. normal loaded, and 9060 lbs. maximum. Wingspan was 37 feet 9 1/4 inches, length was 32 feet 2 3/4 inches, height was 8 feet 8 inches, and wing area was 233 square feet.

Specification of XP-51G:

One Rolls-Royce Merlin 145M engine rated at 1910 hp., driving a maximum speed was 472 mph at 20,750 feet, and an altitude of 20,000 feet could be reached in 3.4 minutes. Service ceiling was 45,700 feet. Normal range was 485 miles, and maximum range was 1865 miles. Weights were 5750 lbs. empty, 7265 lbs. normal loaded, and 8885 lbs. maximum. Wingspan was 37 feet 9 1/4 inches, length was 32 feet 2 3/4 inches, height was 8 feet 8 inches, and wing area was 233 square feet.

Specification of XP-51J:

One Allison V-1710-119 liquid-cooled eigine with a two stage, gear-driven supercharger, rated at 1500 hp for takeoff and 1720 hp with water injection at 20,700 feet.
 

 

North American P-51H Mustang

 

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P-51H  S/N 44-64164; 5th production -H model

The ultimate version of the Mustang was the P-51H, which was the fastest Mustang variant to see service and one of the fastest (if not the fastest) piston-engined fighters to enter production during the Second World War. However, it was destined never to see any combat, having entered service too late to participate in the final action against Japan.

The P-51H was an outgrowth of the experimental XP-51F and G lightweight Mustang projects of early 1944. Rather than commit the F or G versions to production, the USAAF decided instead to produce a version powered by the uprated Packard Merlin V-1659-9 engine. This engine had the Simmons automatic boost control for constant manifold pressure maintenance and was equipped with a water injection system which made it possible to overboost the engine to achieve war emergency powers in excess of 2000 hp for brief periods. North American Aviation gave the project the company designation NA 126, and it was ordered into production as the P-51H in June of 1944 even before much of the initial design work was done.

The weight-savings program which produced the XP-51F and XP-51G was put to good use in the design of the P-51H. The fin and rudder were significantly increased in height and the rear fuselage was lengthened to produce an overall length of 33 feet 4 inches (nearly two feet longer than the P-51D). Other features were taken directly from the XP-51F project--it had the same shallower carburetor air intake underneath the nose and modified cowling with integral engine mounting, the same simplified undercarriage with smaller wheels and disc brakes, and it had the same broad-chord wing (without the leading edge "kink"). However, the cockpit canopy was much smaller than that of the XP-51F, being more nearly equal in size to that of the P-51D. The profile of the canopy was somewhat different from that of the P-51D, with the top of the hump being much closer to the front just above the pilot's head. The radiator installation was increased in depth and the matrix was increased in size. The front edge of the inlet duct was vertical as it was in the lightweight versions, and the bottom line downstream was almost straight rather than bulged. The fuselage was modified in order to raise the cockpit to give an 8-degree gun sight deflection angle looking down along the top line from gun sight to spinner. Armament returned to six machine guns with 1880 total rounds, although alternative installations of four guns with 1600 total rounds could be fitted. Provisions were made for normal loads of external stores, similar to that which could be carried by the P-51D/K. Access for gun servicing was improved by redesign of the wing doors and ammunition feed system, and by making the ammunition boxes removable. The fuselage fuel tank was restored, but its capacity was fixed at 50 US gallons, giving a total internal fuel capacity of 255 US gallons.

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The first P-51H-1-NA was flown by Bob Chilton on February 3, 1945. There were 20 P-51H-1-NAs built, all with the XP-51F tail. The distinctive taller tail was installed on the P-51H-5-NA and later production block aircraft and was later retrofitted to earlier P-51H-1-NAs. This new tail once and for all eliminated the yaw instability problem which had been characteristic of all earlier Merlin-powered Mustangs.

Along with the Republic P-47N Thunderbolt, the P-51H was intended to be the leading USAAF fighter used during the upcoming invasion of Japan. 2000 P-51Hs were ordered, made up of 555 NA-126s and 1445 NA-129s with minor differences. All of these planes were to be built at the Inglewood factory. 1629 more examples were ordered from NAAs Dallas plant under the charging number of NA-124, these being designated P-51M by the USAAF. The P-51M differed primarily in having the V-1650-9A engine, which had a lower war emergency rating by virtue of having the water injection deleted.

One P-51H was given to the RAF for evaluation at Boscombe Down. Its serial was KN987.

A P-51H (44-64420) was borrowed by the US Navy In August of 1945 for trials to determine the type's suitability as a carrier-based fighter. The earlier P-51D had been deemed to be unsuitable because of the lack of adequate rudder control at low speeds, especially at high angles of attack. The tests proved that the P-51H did indeed provide adequate rudder control, but since the war was already over, the possibility of a carrier-based P-51H was not considered any further. A second P-51H 44-64192 was acquired by the Navy in 1948 for tests of various aerofoil shapes at transonic speeds at the Grumman Aircraft Corporation. While in Navy service, the plane became BuNo 09064. After the tests were over in 1952, the plane was transferred to the Air National Guard.

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P-51H S/N 44-64164

The P-51H was too late to see action in the war in Europe. By the late summer of 1945, some P-51Hs had been issued to a few operational units. These units were in the process of working up to operational status when the war in the Pacific ended with the Japanese surrender. None had the opportunity to see any combat. At the time of V-J Day, 555 P-51Hs had rolled off the Inglewood production lines. With the coming of peace, orders for 1445 more P-51Hs were cancelled, along with the entirety of the order for the Dallas-built P-51Ms after only one example (45-11743) had been completed.

Also cancelled was an order for 1700 P-51Ls (company designation NA-129). They were to have been similar to the P-51H but were to be equipped with the more powerful V-1650-11 engine with a Stromberg speed/density injection-type carburetor, rated at a peak power of 2270 hp with water injection. None were built.

The last P-51H rolled off the production line in 1946.

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NORTH AMERICAN AVIATION

Pilots generally found the P-51H to be even more delightful to fly than the D model. However, some pilots were distrustful of the H's lighter structure, preferring the greater sturdiness of the D. Consequently, it was not considered as being suitable for combat operations in Korea.

Specs of the P-51H-5-NA:

One Packard Merlin V-1650-9 twelve-cylinder Vee liquid cooled engine rated at 1380 hp for takeoff and a a war emergency power of 2218 hp at 10,200 feet and 1900 hp at 20,000 feet with water injection. Performance: Maximum speed was 444 mph at 5000 feet, 463 mph at 15,000 feet, and 487 mph at 25,000 feet. Range in clean condition was 755 miles at 359 mph at 10,000 feet, 1975 miles at 239 mph at 10,000 feet. Range with two 62.5 Imp. gall. drop tanks was 1150 miles at 339 mph at 10,000 feet and 1530 miles at 243 mph at 10,000 feet. An altitude of 5000 feet could be reached in 1.5 minutes, 15,000 feet in 5 minutes. Service ceiling was 41,600 feet. Weights: 6585 pounds empty, 9500 pounds normal loaded, and 11,500 pounds maximum. Dimensions: Wing span was 37 feet 0 inches, length was 33 feet 4 inches, height was 8 feet 10 inches, and wing area was 235 square feet.

Serials of the P-51H and P-51M:

44-64160/64179	North American P-51H-1-NA Mustang 
44-64180/64459	North American P-51H-5-NA Mustang
44-64460/64714	North American P-51H-10-NA Mustang
45-11743		North American P-51M Mustang 
P-51 Mustang Specifications
Model   XP-51 P-51A P-51B/C-1 P-51B/C P-51D/K P-51H
Production Count   2 310 650 3738 9602 555
Combat Record   4950 Air Kills, 4131 Ground Kills, 230 V-1 Kills
P-51 Survivors   Less than 300 P-51's exist today, about 145 flying.
UNITS   (feet, pounds, miles per hour, minutes, US gallons
DIMENSIONS
Model   XP-51 P-51A P-51B/C-1 P-51B/C P-51D/K P-51H
Length   32.25 32.25 32.25 32.25 32.25 33.33
Height   12.2 12.2 13.67 13.67 13.67 13.67
Wing Span   37.04 37.04 37.04 37.04 37.04 37.04
Wing Area   233.19 233.19 233.19 233.19 233.19 233.19
WEIGHTS
Empty Weight   6280 6433 6840 6985 7635 7040
Normal Takeoff   8400 8600 9200 9800 10100 9500
Max. Gross Weight     10600 11200 11800 12100 11500
POWERPLANT
Manufacturer  
*Rolls-Royce Merlin 68  
Allison
V-1710-39
Allison
V-1710-81
Packard*
V-1650-3
Packard*
V-1650-7
Packard*
V-1650-7
Packard*
V-1650-9
CID   1710 1710 1649 1649 1649 1649
Normal T.O. HP   1150 1200 1380 1490 1490 1380
War Emergency HP   na na 1620 1720 1720 2270
PERFORMANCE
Model   XP-51 P-51A P-51B/C-1 P-51B/C P-51D/K P-51H
Maximum Speed   382 @ 13k 390 @ 20k 430 @ 25k 439 @ 25k 437 @ 25k 487 @ 25k
Cruise Speed   300 305 325 @ 10k 325 @ 10k 325 @ 10k  
Climb to 20,000 feet     9.1 7 6.9 7.3 6.8
Service Ceiling   30800 31350 41500 41900 41900 41600
Fuel Capacity   180 180 180 269 269 255
    - with drop tanks   330 330 330 419 489 475
Combat Range (int. fuel)   750 750 755 1180 1155 755
    - speed/altitude     300 @ 10k 290 @ 20k 294 @ 20k 294 @ 20k 359 @ 10k
Range w/drop tanks     1375 1450 1900 2055 1530
    - speed/altitude     280 @ 290 @ 20k 294 @ 20k 280 @ 20k 243 @ 10k
ARMAMENT
Model   XP-51 P-51A P-51B/C-1 P-51B/C P-51D/K P-51H
Machine Guns     4x .50 cal 4x .50 cal 4x .50 cal 6x .50 cal 6x .50 cal
    - rounds available     1260 1260 1260 1880 1880
Bombs - lbs.     2 x 500 2 x 1000 2 x 1000 2 x 1000 2 x 1000
    - or 5" rockets   na na na na 10 10

 

Piper Enforcer

 

NORTH AMERICAN XP-51F, G, J  "MUSTANG"

 

Click on Picture to enlarge

This saga of the P-51 Mustang ends with the story of the Enforcer--an attempt to bring the Mustang back in to service in the 1980s!

Even the end of the Korean War and the official withdrawal of the last Mustang from ANG service in 1957 was not to be the end of the story for the Mustang. Many Mustangs served with foreign air arms, remaining as first-line equipment well into the 1970s. Hundreds of surplus Mustangs ended up on the civilian market, and many of these were used on the unlimited racing circuit during post-war years. Many are still being raced at present.

The last Mustang officially left ANG service in 1957. It is not generally known, but there have been periodic attempts to reintroduce the Mustang into USAF service in the years after that. In fact, such efforts continued up until the early 1980s.

The final withdrawal of the Mustang from USAF and ANG service dumped hundreds of P-51s out onto the civilian market. The rights to the Mustang design were purchased from North American by the Cavalier Aircraft Corporation, which attempted to market the surplus Mustang aircraft both in the US and overseas. In 1967 and again in 1972, the USAF procured additional batches of Mustangs from Cavalier, most of them destined for air forces in South America and Asia that were participating in the Military Assistance Program (MAP). These aircraft were remanufactured from existing F-51D airframes but were fitted with new V-1650-7 engines, a new radio fit, tall F-51H-type vertical tails, and a stronger wing which could carry six 0.50-inch machine guns and a total of eight under-wing hard-points. Two 1000-pound bombs and six five-inch rockets could be carried. They all had an original F-51D-type canopy, but carried a second seat for an observer behind the pilot. Although these new Mustangs were intended for delivery to South American and Asian nations through the Military Assistance Program (MAP), they were delivered with full USAF markings and were allocated new serial numbers (67-14862/14866, 67-22579/22582 and 72-1526/1541). One additional Mustang was a two-seat dual-control TF-51D (67-14866) with an enlarged canopy and only four wing guns.

In 1968, the US Army employed a vintage F-51D (44-72990) as a chase aircraft for the Lockheed YAH-56 Cheyenne armed helicopter project. This aircraft was so successful that the Army ordered two F-51Ds from Cavalier in 1968 for use at Fort Rucher as chase planes. They were assigned the serials 68-15795 and 65-15796. These planes had wing-tip fuel tanks and were unarmed. Following the end of the Cheyenne program, these two chase planes were used for other projects. One of them (68-15795) was fitted with a 106-mm recoilless rifle for evaluation of the weapon's value in attacking fortified ground targets.

Cavalier believed that the Mustang design still had potential for further development. In the late 1960s, the company began to explore the possibility of replacing the Packard Merlin piston engine of the F-51D with a turboprop engine. The owner of Cavalier, Dave Lindsay, preferred to use the Lycoming T55 turboprop as the power-plant of the re-engined Mustang, but was unable to obtain one. In 1968, the company mounted a 1740 e.s.h.p Rolls-Royce Dart 510 turboprop into a F-51D and flight-tested the aircraft as the Turbo-Mustang III. It bore the civilian registration number of N6167U.

However, the Cavalier company decided to sell the rights for further development to the Piper Aircraft Corporation, and cancelled any further work on the re-engined Mustang project. On November 4, 1970, the Dart-powered Mustang prototype was delivered to the Piper factory at Vero Beach.

At that time, the US was embroiled in the Vietnam War, and combat experience indicated that there was a need for a low-cost, high-performance close-support aircraft for use by foreign air forces obtaining MAP assistance. This project was given the name *Pave Coin*.

In pursuit of production contracts under the *Pave Coin* program, the Piper company undertook a more ambitious Mustang conversion effort. One single-seat F-51D and one two-seat TF-51D airframe were fitted with the 2455 s.h.p. Lycoming T55-L-9 turboprop engine. The project was given the name *Enforcer* by Piper. The first Enforcer conversion was flown on April 19, 1971. Later that year, the USAF evaluated one of these Enforcers and confirmed the original performance claims, but did not show very much enthusiasm for the project.

Even though the USAF never saw any use for the Enforcer, Congressional pressure led eventually to a contract in September 1981 for Piper to construct two new prototypes for evaluation. They were known under the company designation of PA-48. The two PA-48 prototypes were given civilian registrations rather than military serial numbers, and were never given any military designations.

The PA-48 Enforcer bore only the slightest resemblance to the F-51D--only ten percent of the parts were in common. The fuselage was lengthened by 19 inches aft of the wing and larger tail surfaces were fitted. Power was provided by a Lycoming T55-L-9 turboprop. The familiar trademark Mustang ventral scoop was completely removed, and a large turboprop exhaust was fitted on the left-hand side of the fuselage just ahead of the cockpit. A Yankee rocket ejector seat was fitted in the single seat cockpit. Provisions for wingtip tanks were made, and ten under-wing hard-points were fitted. The fixed wing-mounted guns were removed, and all gun armament was carried within under-wing pods. The two PA-48s first flew on April 9 and July 8, 1983 respectively, and the USAF conducted its evaluations at Elgin AFB and Edwards AFB during 1983/84. Gross weight was 14,000 pounds. Maximum speed was 403 mph and cruising speed was 363 mph. Service ceiling was 37,600 feet and combat radius (with two gun pods) was 469 miles.

The PA-48 Enforcer was unsuccessful in obtaining any production orders, and both prototypes were put in storage by the USAF in late 1986. One of them (N481PE) is now on display in the Annex building at the WPAFB Museum in Dayton, Ohio.

 Joe Baugher

Sources:

  • American Combat Planes, Ray Wagner, Third Enlarged Edition, Doubleday, 1982.
     
  • The American Fighter, Enzo Angelucci and Peter Bowers, Orion Books, 1987.
     
  • War Planes of the Second World War, Fighters, Volume Four, William Green, Doubleday 1964.
     
  • United States Military Aircraft since 1909, Gordon Swanborough and Peter M. Bowers, Smithsonian, 1989.
     
  • Fighting Mustang: The Chronicle of the P-51, William N. Hess, Doubleday, 1970.
     
  • Classic Warplanes: North American P-51 Mustang, Bill Gunston, Gallery Books, 1990.
     
  • Famous Fighters of the Second World War, Volume I, William Green, 1967.
     
  • British Military Aircraft Serials, 1912-1969, Bruce Robertson, Ian Allen, 1969.
     
  • North American P-51 Mustang: The Fighter That Won the War, Bill Gunston and Robert F. Dorr, Wings of Fame, Vol 1, 1995.
     
  • E-Mail from Mark Waddell.
     
  • E-mail from Bob Storck on surviving A-36As.
 

 

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