The North American P-51 Mustang

Mustang I and IA for the RAF

In 1934, James H. "Dutch" Kindelberger became president of North American Aviation, Inc. 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. 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.

In April of 1940, Kindelberger was summoned by the British Air Purchasing Commision and asked to manufacture the Curtiss Hawk 87 (P-40D) under license for the RAF. Kindelberger countered that NAA could do better than that airplane 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 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 P-40, and, in fact, stole numerous design features from that fighter. Although NAA did pay $56,000 for technical aerodynamic data on the Curtiss XP-46, the NA-73X owed virtually nothing to any previous design and certainly did not owe anything to the Curtiss P-40.

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.

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 aerofoils. 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 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 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 ethlyene glycol and lubricating oil were located in a single heat-exchanger installed underneath the rear fuselage in a streamlined duct. The drawback of such an arrangement was the extra weight and combat vulnerability of the long pipes that led to and from the engine. Military innovations such as self-sealing fuel tanks, cockpit armor, and a bulletproof windshield were to be provided from the start.

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. The engine that was eventually installed was an unsupercharged Allison V-1710-F3R liquid-cooled Vee, rated at 1100 hp. The NA-73X bore the civil registration NX19998. Veteran test pilot Vance Breese flew it 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.

On November 30, 1940, while on the third test flight of the NA-73X, another test pilot forgot to change fuel tanks, ran out of gas, and suffered a forced landing 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.

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 gunsight, 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.

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 Kittyhawk, Airacobra and Spitfire in both speed and maneuverability at low altitudes. Maximum speed was 382 mph at 13,000 feet. The armament of four 0.50-inch and four 0.30-inch machine guns was heavy and effective. Handling was excellent. The range was nearly double that of any RAF single-engined 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. This 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.

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.

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 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.

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 H. 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- engined 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.

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.

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 underwing mountings.

With the passage of Lend-Lease, 150 more Mustangs were ordered by the US Army, all of which were intended for delivery to Britain. These were designated Mustang Mark IA by the RAF and NA-91 by the factory. 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. For contractual purposes, these aircraft were given the US designation of P-51 and assigned the USAAF serials 41-37320/37469. The RAF serial numbers assigned to this lot were FD418/FD567. The Allison V-1710-F3R engine was given the US Army designation V-1710-39. 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.

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.

In March of 1943, a batch of 35 P-51/F-6As were assigned to the 154th Observation Squadron at Oujda in French Morocco. This was the first US Mustang unit. Its first mission was a photographic coverage of Kairouan airfield, Tunisia on April 10, 1943.

Mustang IA, P-51, Apache

These aircraft 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 long gun 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 first began in mid-1942.

The British did not get all of these NA-91s. Since the RAF deliveries of the Mustang IA began after Pearl Harbor, many of them were repossessed by the Army before they ever got to Britain. FD418/FD437, FD450/FD464, FD466/FD469, and FD510/FD527 were diverted from the RAF order and delivered to the US Army. These were the first Mustangs to serve with the Army. The Army planes were fitted with two K-24 cameras in the fuselage. Some were fitted with four 0.50-inch machine guns, but most retained their quartet of 20-mm cannon. 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. One was coverted as P-51-1 (42-37320), and the rest were converted as P-51-2. The serial numbers of the Mustang IAs that were diverted to the USAAF were 41-37320/47339, 41-37352/37366, 41-37368/37371, and 41-37412/37429.

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.

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

XP-51, A-36A Invader

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.

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.

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.

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). 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. Serial numbers were 42-83663/84162.

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-engined Mustang, although several other of his colleagues did score victores 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.

A-36A Ser No 42-83665 is on display at the WPAFB Museum in Dayton, Ohio. This may be the sole surviving Invader.

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

P-51A, Mustang II

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 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.

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

Another 50 examples went to the RAF, becoming Mustang IIs. These planes replaced the NA-91s 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.

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

Specifications of P-51A-10-NA:

One 1200 hp Allison V-1710-81 twelve-cylinder Vee liquid cooled engine. 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 were 6433 lbs empty, 8600 lbs normal loaded, and 10,600 lbs maximum loaded. 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.

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.

P-51B, P-51C, Mustang III, Packard Merlin engine

Rolls Royce management immediately jumped into action. They requested that three Mustangs be loaned to them so that they could fit them with Merlins. Rolls Royce studied various Merlins, 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 under the nose, in the same duct as the ram inlet for the updraft carburetor.

This conversion was authorized on August 12, 1942. Four Mustang Is were allocated to the program (AM208, AL975, AM203, and AL963). They were assigned the designation Mustang X. The first Mustang X took to the air on October 12, 1942. No two of these Mustang Xs were exactly alike, but they all featured small chin-type radiators underneath the engine and four-bladed propellers to absorb the extra power. These Mustang Xs were to be kept busy throughout the rest of the war, testing various later marks of the Merlin engine.

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 contrarotating 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 attache 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. At this time, negotiations were taking place with the Packard Motor Car Company of Detroit 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.

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 underwing racks were increased in capacity to take two 1000-lb bombs or their equivalent weight in drop tanks. A new four-bladed Hamilton Standard hydromatic 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.

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-engined 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. All airframes were to be manufactured by North American at their factory in Inglewood, California and at a completely new plant built in great haste at Dallas, Texas. 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.

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.

800 P-51B-5-NAs were built, all of them powered by the V-1650-3. 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). This extra fuel 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. 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 the introduction of the P-51C-5-NT onto the Dallas 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 photo aircraft. Most of these aircraft retained their guns.

The first combat unit equipped with Merlin-powered Mustangs was the 354th Fighter Group, which reached England in October of 1943. 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.

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

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.

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. 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).

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 P-51 received this modification as well.

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.

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.

The last P-51B passed out of service in 1949, having been re-designated F-51B in 1948.

Specs of P-51B-1-NA:

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.

Specs 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.

Serial numbers of P-51Bs:

43-12093/12492 North American P-51B- 1-NA Mustang
43-6313/7112 North American P-51B- 5-NA Mustang
43-7113/7202 North American P-51B-10-NA Mustang
42-106429/106540 North American P-51B-10-NA Mustang
42-106541/106738 North American P-51B-10-NA Mustang
42-106739/106978 North American P-51B-15-NA Mustang
43-24752/24901 North American P-51B-15-NA Mustang

42-102979/103328 North American P-51C- 1-NT Mustang
42-102979/103328 North American P-51C- 1-NT Mustang
42-103329/103778 North American P-51C- 5-NT Mustang
42-103779/103978 North American P-51C- 5-NT Mustang
44-10753/10782 North American P-51C-10-NT Mustang
44-10783/10817 North American P-51C-11-NT Mustang
44-10818/10852 North American P-51C-10-NT Mustang
44-10853/10858 North American P-51C-11-NT Mustang
44-10859/11036 North American P-51C-10-NT Mustang
44-11037/11122 North American P-51C-11-NT Mustang
44-11123/11152 North American P-51C-10-NT Mustang
43-24902/25251 North American P-51C-10-NT Mustang

P-51D, P-51K

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, and it was thought that the Mustang might be amenable to being equipped with a bubble-type all-round vision canopy similar to those fitted by the British to later marks of the Supermarine Spitfire and the Hawker Typhoon. 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.

One of the early P-51B-1-NAs was chosen for the initial modifications. 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 behind 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.

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 restressing of the fuselage structure was necessary.

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 redesignated 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 0.50-inch machine guns in each wing, all of them mounted upright and all fed by unkinked ammunition belts. The inboard guns each had 400 rpg, and the others had 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.

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 very early on in the production run of the P-51D. 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 gunsight, based on a British design. The pilot needed only to dial in the wingspan of the enemy aircraft he was chasing, feed in the target range by turning a handgrip on the throttle lever, then get the wingtips of his target lined up on the bright ring projected on the gunsight, and press the trigger.

P-51Ds were also constructed in NAA's Dallas plant, the Dallas plant building some 1454 of these planes before production finally ceased.

Almost all Block-25 and subsequent Ds had underwing hardpoints 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.

The Dallas plant also built 1337 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. 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.

A total of 163 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.

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 torqueless twin-engined P-38 to the single-engined 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-engined 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.

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.

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
 20th Fighter Group, 8th Air Force
 27th Fighter Group, 12th Air Force
 31th Fighter Group, 15th Air Force
 52nd Fighter Group, 15th Air Force
 55th Fighter Group, 8th Air Force
 67th Tactical Reconnaissance Group, 9th Air Force 
 68th Tactical Reconnaissance Group, 9th Air Force
 69th Tactical Reconnaissance Group, 9th Air Force
 78th Fighter Group, 8th Air Force
325th Fighter Group, 15th Air Force
332nd Fighter Group, 15th Air Force - This was the famous all-black outfit
339th Fighter Group, 8th Air Force
352nd Fighter Group, 8th Air Force
353nd Fighter Group, 8th Air Force
354th Fighter Group, 9th Air Force
355th Fighter Group, 8th Air Force
356th Fighter Group, 8th Air Force
357th Fighter Group, 8th Air Force
359th Fighter Group, 8th Air Force
361th Fighter Group, 8th Air Force
363rd Fighter Group, 9th Air Force
364th Fighter Group, 8th Air Force
370th Fighter Group, 9th Air Force
479th Fighter Group, 8th Air Force

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.

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, 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 Congressional Medal of Honor.

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.

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. 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. Although their primary mission was close support, they 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.

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.

Specs 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-51D:

44-11153/11352 	North American P-51D- 5-NT Mustang
44-12853/13252 	North American P-51D-20-NT Mustang
44-13253/14052 	North American P-51D- 5-NA Mustang
44-14053/14852 	North American P-51D-10-NA Mustang
44-14853/15752 	North American P-51D-15-NA Mustang
44-63160/64159 	North American P-51D-20-NA Mustang
44-72027/72626 	North American P-51D-20-NA Mustang
44-72627/74226 	North American P-51D-25-NA Mustang
44-72227/75026 	North American P-51D-30-NA Mustang
44-84390/84989 	North American P-51D-25-NT Mustang 
45-11343/11542 	North American P-51D-25-NT Mustang
45-11543/11742 	North American P-51D-30-NT Mustang

44-11353/11552 North American P-51K- 1-NT Mustang
44-11553/11952 North American P-51K- 5-NT Mustang
44-11953/12852 North American P-51K-10-NT Mustang

Mustang IV, P-51Ds in Foreign Service

The serial numbers of the Mustang IVs supplied to the RAF were as follows: KH641/KH670 (P-51D), KH671/KH870 (P-51K), KM100/KM492 (ex-USAAF P-51K), KM493/KM743 (ex-USAAF P-51D), KM744/KM799 (not delivered), and TK589 (Ex USAAF P-51D 44-13332).

RAF Mustang IVs based in England were kept busy during the latter part of 1944 by the V-1 "buzz bomb" threat, destroying 232 of these missiles by September 5.

On April 16, 1945, Mustangs of 611 Squadron were the first RAF aircraft to greet their Russian allies over Berlin.

At the end of the war in Europe, the RAF took delivery of 600 Mustang IVs in India for use against the Japanese in Burma and beyond. However, Japan surrendered before these could be put to use, and most of these aircraft were scrapped.

After the war, a large number of the RAF's Mustangs were returned to the USA, but a few continued to serve with the RAF as late as May of 1947 when they were replaced by British-built equipment.

In late 1944, the first French unit began its transition to reconnaissance Mustangs. In January 1945, the Tactical Reconnaissance Squadron 2/33 of the French Air Force took their F-6Cs and F-6Ds over Germany on photographic mapping missions.

The Italian-based Royal Australian Air Force (RAAF) No 3 Squadron had operated Mustang IIIs and IVs from November 1944 until VE Day. Most of the missions flown by this unit were ground support operations over northern Italy in pursuit of reteating German forces, and fighter sweeps over Yugoslavia.

In the Pacific theatre, the RAAF had been equipped with Spitfire VIIIs, but these possessed insufficient range for the missions that would now be required in the final push against Japan. 314 US-supplied P-51Ks were allocated to the RAAF, but the Commonwealth Aircraft Corporation (CAC) simultaneously made arrangements to produce the P-51D under license in Australia. NAA supplied 100 kits and Packard supplied 80 V-1650-3 engines in order to get CAC started.

Designated CA-17 Mustang 20, the first Australian-assembled Mustang flew for the first time on April 29, 1945. A total of 80 CA-17s were assembled, but all were too late to take any part in the war against Japan. After the war, CAC went on to produce 120 more Mustangs, all built from Australian-manufactured components. The first 40 examples were designated CA-18 Mustang 21, and were powered by the V-1560-7 engine. These were followed by 14 Mustang 22s with the RAF installation of an F24 oblique camera behind the cockpit. The CAC manufacture was completed by the production of 66 Mustang 23s which were powered by British-built Merlin 66 or 70 engines. Fourteen Mustang 21s were later converted to Mustang 22 standards. The RAAF also received 214 P-51Ds and 84 P-51Ks directly from the USA under Lend-Lease, but no RAAF Mustangs became operational until well after the end of the Pacific War.

The Mustang-equipped RAAF Squadrons No. 76, 77, and 82 participated in the occupation of Japan starting in 1946. They remained there until 1949, when Nos 76 and 82 Squadrons were withdrawn back to Australia, leaving only No. 77 Squadron still in Japan. No. 77 Squadron was in Japan when the Korean War began, and they immediately joined with the US Fifth Air Force, using their Mustangs as fighter-bombers in a desperate attempt to stem the North Korean advance. During the first six months of the Korean conflict, they flew 2600 sorties against tremendous odds. The Australian Mustangs were finally superseded by Gloster Meteors in 1951.

Thirty P-51Ds were supplied to the Royal New Zealand Air Force in 1945, but they were not introduced into service until a couple of years later. They were replaced by de Havilland Vampires in 1950.

In 1950, the South African Air Force received a batch of ex-USAF F-51D Mustangs as a result of their contribution to the United Nations forces in Korea. Mustangs serving with No 2 Squadron SAAF entered combat against North Korea in November of 1950. They remained in service with the SAAF until 1953 when they were replaced by Sabres.

The Royal Canadian Air Force received 100 P-51Ds shortly after the war ended. These served with the RCAF for some years, the last example not going out of service until 1956.

Early in 1945, there was a distinct possibility that Sweden might get involved in the war in Europe. In an effort to bolster its air defenses, Sweden purchased 50 P-51Ds from the USA. The Swedish government had been planning to introduce the homegrown SAAB-21A as its frontline fighter, but its entry into service was slow and 90 more Mustangs were purchased from the USA as an interim stopgap measure until the SAAB fighter could be available in greater quantity. Eventually, enough Swedish-built fighters became available, and the Swedish Mustangs were phased out of service or sold off as surplus.

The Swiss Air Force flew mainly German-built equipment during and immediately after the war. With the defeat of Germany, the Swiss had to look elsewhere for arms suppliers, and they ordered a batch of jet-powered de Havilland Vampire fighters from Britain. However, deliveries of the Vampires were slow. While awaiting the Vampire deliveries, Switzerland bought 100 surplus F-51Ds as an interim type. These were finally phased out of service in 1956.

The Chinese Air Force received three squadrons of P-51Ds in 1946. When Chiang Kai-shek's government was overthrown by Mao's Communists in 1949, most of the Nationalist P-51Ds fled to Formosa. However, a few were left behind and were incorporated into the People's Liberation Army Air Force. However, it is not known if these P-51Ds were ever used against United Nations forces in Korea.

The Netherlands forces fighting against the Japanese in the Pacific late in the war were equipped with P-51Ds. When the war against Japan ended, Dutch Mustangs were used in a futile attempt to suppress the Indonesian nationalists. When the sovereignty of Indonesia was at last recognized in June of 1950, the Netherlands East Indies Air Force was officially disbanded and the surviving Mustangs were transferred to the Indonesian Air Force. Indonesian Mustangs remained in service with the IAF until replaced by Russian fighters in 1959.

After Italy quit the Axis and joined with the Allies, the Italian air force was supplied with American equipment, including P-51Ds. By late 1948, Italy had 48 Mustangs in service, and they remained front-line equipment until replaced by Vampires and Sabres in 1953.

In spite of a Western-sponsored arms embargo, the new state of Israel managed to purchase 25 surplus F-51D fighters from Sweden in 1952. These replaced the Avia S.199 (Czech-built Bf-109G) fighters previously operated by Israel. The F-51Ds served with the Israel Defense Force/Air Force for several years. They saw action against Egypt during the Suez incident of October-November 1956. They were finally replaced by jets in the late 1950s.

The Republic of Korea Air Force were supplied with F-51D Mustang fighters in 1950 for use in opposing the North Korean attack. At first, they were used for defensive purposes, but they eventually went over to the offensive ground attack role. They were finally replaced by Sabres in 1960.

Under the terms of the Rio Pact of 1947, Cuba was supplied with F-51D Mustangs. These were still in service when Fidel Castro seized control of Cuba in 1959, and they served with the Cuban air force until they were replaced with Russian-built equipment in the early 1960s.

Dominica purchased 32 surplus P-51Ds from Sweden in 1952, and these were still in service in 1962.

Guatemala purchased a small number of P-51Ds just after the war ended, but no spares were available and were allowed simply to go out of service as parts begin to wear out.

Haiti purchased six P-51Ds just after the war, and some of them remained in service well into the 1960s.

Nicaragua took delivery of a few F-51Ds in 1947, and some of them remained in service well into the 1960s.

Uruguay also got a few P-51Ds just after the war, and these remained in service until the 1960s.

The Philippine Air Force received a number of P-51Ds in 1946, and they served until 1960.

Lightweight Mustangs: XP-51F, XP-51G, XP-51J

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. 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.

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.

The project was given the company designation NA-105. Resemblance to the previous Mustang was only coincidental, since the structure of the aircraft was almost completely redesigned. Most of the changes were made in an attempt to save weight. The main landing gears were redesigned and the wheels and tires were greatly reduced in size. New disc brakes were fitted to the wheels. The wing was larger in area, having 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 wing tanks were reduced in capacity to 102 US gallons and the fuselage tank was eliminated entirely. The engine mounting was simplified, the "integral" engine cradle saving over 100 pounds of weight and improving 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, 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. 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 moulded plastic parts.

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 powerplant of the P-51D. Maximum speed was 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.

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 first XP-51G flew by Ed Virgin on August 9, 1944, the second machine following on November 14. The engine was the Rolls-Royce Merlin 145M engine of 1910 hp., driving a Rotol propeller with five wooden blades (almost identical to the propellers of the Spitfire XIV). It was readily apparent that this was the hottest Mustang yet --- 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.

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.

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.

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.

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.

P-51H

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 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 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. However, the profile of the canopy was quite 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 fuselage was modified in order to raise the cockpit to give an 8-degree gunsight deflection angle looking down along the top line from gunsight 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. 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.

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.

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, these being designated P-51M. 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.

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 had been completed.

Also cancelled was an order for 1700 P-51Ls. 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.

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

One Packard Merlin V-1650-9 twelve-cylinder Vee liquid cooled engine rated at a war emergency power of 2218 hp at 10,200 feet with water injection. 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 were 6585 pounds empty, 9500 pounds normal loaded, and 11,500 pounds maximum. 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

PA-48 Enforcer

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 Mustang aircraft both in the US and overseas. In 1967 and again in 1972, the USAF procured additional batches of Mustangs from Cavalier. 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 underwing hardpoints. 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 (67-22579/22582 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.

The US Army purchased a couple of F-51Ds from Cavalier in 1968 for use at Fort Rucher as chase planes in the Lockheed Cheyenne armed helicopter program. These planes had wing-tip fuel tanks and were unarmed. For several years since 1967, the US Army also used a "genuine" F-51D (44-72990) as a chase plane.

Cavalier believed that the Mustang design still had potential for further development. 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, 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 Cavalier 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 Cavalier.

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.

Later in 1971, Piper Aircraft acquired the rights to the Enforcer from Cavalier. 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 underwing hardpoints were fitted. The fixed wing-mounted guns were removed, and all gun armament was carried within underwing 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.

Sources:

Classic Warplanes: North American P-51 Mustang, Bill Gunston, Gallery Books, 1990.

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.

Fighting Mustang: The Chronicle of the P-51, William N. Hess, Doubleday, 1970.

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.

Joe Baugher