The North American P-51 Mustang proved an invaluable addition to the Allied cause in the latter half of World War 2. The system was designed and flown in a matter of months and made such an impact that it could clearly be considered the war-winning design for the Allies. Mustangs primarily assisted in escorting bombers on long range sorties but were able to attack ground targets with bombs and machine guns and outperform any of the German fighters that were matched against it. The Mustang exuded "classic warbird" in every sense of the phrase and went on to be one of the most recognized piston engine fighters of all time.
The British RAF need for more Curtiss P-40 production fighters led them to consider North American Aviation's manufacturing capabilities. North American designers Edgar Schmued and Raymond Rice, seeing this as an opportunity to market a new fighter altogether, seized the moment and produced a design for British review. The design was accepted under a new 1940 specification which required a heavily-armed fighter of considerable speed with the capability to operate at high altitude - all this with a flying prototype to be made available within a 120 day window. Development ensued and inevitably produced the NA-73X prototype within the allotted timeframe (some sources state the aircraft was completed in just 102 days whilst others say as many as 117 days). The NA-73X took to the skies on October 26th, 1940 with its 1,100 horsepower Allison V-1710-F3R (V-1710-39) inline engine and showed off its tremendous potential. The design was accepted by the British as the "Mustang" becoming an initial production model batch of 320 Mustang I's.
Mustang I's were first flown by British pilots on May 1, 1941 - these with 1,100 horsepower Allison V-1710-39 inline engines. As tactical reconnaissance platforms, these aircraft were modestly-armed with 4 x 0.50 caliber heavy machine guns. The type exhibited good response and its performance at low level was exemplary, outmatching even that of the fabled Spitfire Mark V's. Though the design proved quite functional, it was soon found that performance capabilities of the system dropped off significantly at altitudes higher than 15,000 feet. As a result, British Army Cooperation Squadrons were assigned the type and utilized them in both low-level reconnaissance and high-speed ground attack roles with its primary function being the former. The first Mustang I mission was accomplished on May 10th, 1942 with No. 26 Squadron. These Mustangs successfully strafed aircraft hangars at Berck sur Mer in German-held French territory. As more and more Mustangs became available, the aircraft would eventually field some 14 total Allied squadrons by the end of 1942 - 10 RAF, 3 RCAF and 1 Polish air group. Most early production Mustangs went to Britain as Mustang Mk.IA (4 x 20mm cannons) and Mustang Mk.II models, numbering some 620 total combined examples.
The USAAF (United States Army Air Forces) took notice of the aircraft and received two evaluation models (from the aforementioned British 620 order total) with the designation of XP-51. The type excelled in tests but the USAAF passed on an order commitment at the time. It was not until General Hap Arnold intervened that no fewer than 55 British-bound Mustangs were reserved for use in American service. These Mustangs became photo-reconnaissance models designated as F-6A and served with the 111th and 154th Observation Squadrons. These squadrons would be the first Mustang operators for the USAAF and see deployment to North Africa in early 1943.
Purchases of USAAF XP-51's full production models began with an initial block of 150 base model P-51's in March of 1942 (note that there was no model letter assigned to these). Aircraft were armed with 4 x 20mm cannons and were utilized for their inherently good low-level operational qualities thanks to their excellent airframes and under-performing Allison engines. These early-form Mustangs were utilized in the Southeast Asia Theater where most of their action took place at these optimal low altitudes.
The A-36A (known unofficially to some as "Invader") represented a dedicated ground-attack / dive-bomber version of the P-51 and was ordered by the USAAF in April of 1942. The aircraft were armed with 6 x 0.50 caliber heavy machine guns, with two to a wing and two in the upper nose portion of the fuselage. Underwing bomb racks also complimented the offensive punch. The system - with their Allison engines - first flew in September of 1942, production eventually totaling some 500 examples. A-36As were assigned to the 27th and 86th Bombardment Groups (Dive) and the first A-36A models were put into action in June of 1943. The 311th Fighter Bomber Group stationed in India also took deliveries of the type.
P-51 base models were similar to these attack aircraft and were also utilized in the low-level ground attack role, though these were built with 4 x 20mm Hispano-Suiza long-barrel cannons instead of machine guns and underwing bomb shackles for bombs. The similar P-51A models represented a total of 310 examples and were fitted with 4 x 0.50 caliber heavy machine guns instead of cannons.
Despite its usefulness as a low-level intruder, the Mustang had not lived to the high-altitude specifications originally laid out in the 1940 British requirement. As such, Britain and the United States individually began testing the airframe out with the Rolls-Royce Merlin engine common to the superb Supermarine Spitfire (along with a new four-blade propeller). Results of these tests yielded tremendous performance gains to the extent that the Mustang was clocked at 441 miles per hour at nearly 30,000 feet -100 miles per hour faster than the preceding Mustang production models could ever hope to achieve. These new Merlin-powered Mustangs emerged as the Mustang Mk.III (RAF use), P-51B and the P-51C (the major difference for the American models being in place of origin - P-51B's were constructed at the Inglewood, California plant whilst the P-51C's at facilities in Dallas, Texas). Deliveries began to the 354th Fighter Group in December of 1943. Reconnaissance versions of the P-51C's were appropriately designated as F-6C models.
Having the benefit of seeing design work and production through an on-going war, changes relayed from pilots with operational experience of Mustangs could easily be incorporated in future Mustang models. Such was the result with the development of the P-51D, the most definitive in the Mustang series as a whole - inevitably giving the Mustang its classic warbird appearance. Visibility out of the "razorback", framed cockpit was noted as inadequate for the rigors of dogfighting. This was addressed with the implementation of the "tear drop" canopy (sometimes referred to as the "Bubble-Top" or "Bubble" canopy) and instantly allowed for near 360 degrees of visual awareness from the cockpit. With the loss of the razorback upper portion of the fuselage, the fuselage itself was cut down at the rear. Armament now increased to 6 x 0.50 caliber heavy caliber air-cooled machine guns (three guns to a wing) with an improved and simplified ammunition feed system to help iron out a consistent jamming issue. The P-51D incorporated the new K-14 gunsight as well, in an effort to help improve gunnery accuracy. Power was derived from the Packard-produced Merlin inline engine of 1,590 horsepower. P-51D models were produced in two major batches as P-51D-NA of which 6,502 were produced from Block 1 through Block 30 with the new bubble canopy and the P-51D-NT of which 1,454 examples were produced from Block 5 through Block 30 with 6 x 0.50 caliber heavy machine guns. The P-51D also existed as a 2-seat dual-control trainer and numbered 10 examples in the form of the TP-51D-NT (TP-51D-NT). A reconnaissance platform existed as the F-6D. RAF P-51D models were Mustang Mk.IV's.
The XP-51F (the P-51E designation was reserved but never used) was produced in three examples as a "lightened" light weight test model. This led to two of the aircraft being fitted with a new engine and becoming the XP-51G. Ultimately, both of these designs led to the P-51H production model.
The P-51H (P-51H-NA) appeared as a "lightened" Mustang - proving some 1,000lbs lighter than the P-51D - and improved the overall top overall speed an astounding 487 miles per hour. This particular model never saw combat due to the end of the war, though production of the type had begun before the cessation of hostilities, totaling 555 examples. Two examples of the XP-51J model followed, these based on the XP-51F with a new engine.
The P-51K (P-51K-NT), of which 1,337 were produced, represented an "improved" D-model and fitted with an Aeroproducts propeller. Production of this model encompassed Blocks 1 through 15. A reconnaissance version of this model existed in the F-6K.
P-51L (P-51L-NA) became a single example model and represented an "improved" H-model with a new engine. Similarly, the P-51M (P-51M-NT) existed as one example based on the H-model and fitted with a different engine.
Australia became just the second Mustang producer, building the aircraft under license in the late 1940's. These Mustangs were designated simply as Mustang Mk.20, Mustang Mk.21, Mustang Mk.22, Mustang Mk.23 and Mustang Mk.24.
The type did, in one other Mustang form, fight on in Korea - this becoming the F-82 Twin Mustang. The system melded two P-51 airframes to one wing assembly with 6 x 0.50 caliber heavy machine guns mounted in the center wing chord. A rectangular tailplane joined the two airframes at the rear. Each Mustang fuselage retained its respective cockpit positions with dual controls with a pilot manning the primary portside cockpit and a pilot / navigator in the starboard cockpit. The Twin Mustang concept originated in 1943 with the design being acted on in January of 1944. The system was intended for use as a long-range escort fighter in the Pacific Theater during World War 2 but the end of the war canceled the initial order of 500, leaving just 20 operational production models complete. 1947 brought about renewed interest in the design, this time as a night-fighter and the system went into production once more, just in time for use in the Korean War.
Production of all 15,469 Mustangs was completed in 1946. With the creation of the USAF in 1948, all remaining P-51 Mustangs in American service now became F-51's - the "P" for "Pursuit" dropped in favor of "F" for "Fighter". The F-51 soldiered on in the newfound air force branch though the type was slowly being relegated to supportive roles behind the new-fangled jets arriving on the scene. A limited production run of Mustangs occurred in 1967, creating a turboprop-powered variant for use in the counter-insurgency role.
Despite utilizing a traditional design approach consistent with the times, the P-51 Mustang developed a distinct look about itself by the time the design was finalized in the classic P-51D model. Early-form Mustangs were fitted with a "razorback"-type fuselage just aft of the cockpit. Couple this with the framed canopy and one can imagine vision out of the cockpit a little obstructed especially when viewing to the rear. The introduction of the bubble canopy naturally changed all this, but also shortened the fuselage somewhat to compensate.
Overall, the P-51 exhibited a clean and sleek design approach thanks to its choice of in-line engine. The pilot sat at the center of the design, just above and aft of the low monoplane straight-wing assembly. The distinct air scoop was positioned to the rear and below the pilot, giving the Mustang series its distinct look while eliminating drag in the process. All wing edges were relatively straight cuts and this design mentality continued on through the horizontal and vertical edges of the empennage. The wings themselves were of a new advanced laminar-flow design and housed the potent heavy armament. Internally, the engine coolant components were strategically placed just below and behind the pilots seating position, a deviation from traditional aircraft fighter construction philosophy. The undercarriage was consistent with the times, with two main single-wheeled landing gears recessing into the wing-root / lower fuselage and a retractable tail wheel.
Armament varied throughout the life of the Mustang. Initial versions were fitted with 6 x 0.50 caliber heavy machine guns - two in the nose and four in the wings. A battery of 4 x 20mm cannons, which made it ideal in the ground attack role, or the lighter armament load of 4 x 0.50 caliber heavy machine guns (two to a wing) for tactical reconnaissance were also alternatives. Eventually, the legendary D-models would introduce the potent array of 6 x 0.50 caliber heavy machine guns (three to a wing) with a simplified feed mechanism to cut down on weapon jamming. Underwing bomb racks and rocket pylons increased potency of the platform as well. These could be deleted in favor of fuel drop tanks for improved range on those long bomber escort sorties.
The cockpit of the P-51 was regarded as comfortable for smaller pilots and ergonomically-designed overall. Some American pilots found its European-designed origins obvious when their shoulders could touch both sides of the cockpit at the same time. The instrument panel was regarded as well thought-out with all major gauges readily apparent on the large flat main panel. The K-14A (beginning with the D-models) dominated a good portion of the top forward viewing with its noticeable "No Hand Hold" message staring back at the pilot. The control column was a simple cylindrical form with a pistol grip at the top, this adorned with a red gun button. The flap control lever was activated from a low-set position within easy reach. The throttle control was a thick cylindrical shape positioned to the natural left of the pilot, leaving his right hand free to concentrate on the aircraft control column. Fuel controls were set between the pilots legs, just forward of the control column. Views forward, to the side and above were generally good through the original framed canopy but improved substantially with the addition of the tear drop canopy. As a whole, the attention given to the P-51's cockpit design made it a good fighter to be in on those long range escort trips. Its tight fit made for a perfect melding of man and machine.
In their first action, A-36As struck at targets on the island of Pantelleria in the Mediterranean Sea. These aircraft were called upon to undergo a variety of sortie types including strafing runs, bomber escort and bombing runs. Despite its low-altitude effectiveness, new model Republic P-47 Thunderbolts and newer P-51 Mustangs eventually overtook this role from the A-36 series thanks to the addition of underwing bomb racks, formidable machine gun firepower and better performance at low altitudes.
RAF use saw the Mustangs utilized in ground attack and escort sorties. Mustangs could now escort strike aircraft into German held territories and support the low-level strikes by keeping German fighters at bay. Their utilization against German anti-shipping groups in Norway eventually took their toll on enemy forces, keeping Allied shipping lanes open for another day. At least 31 RAF (Royal Air Force) and RCAF (Royal Canadian Air Force) squadrons were dedicated to the Mustang aircraft.
Unescorted daylight bombing raids deep into German-held territories were producing disastrous results for American warplanners of the USAAF. German interceptors knew the approximate range of the Republic P-47 Thunderbolt and Lockheed P-38 Lightning escort fighters and simply waited for the aircraft to return home to refuel, leaving the bomber formations at the mercy of the bothersome German Messerschmitt BF-109 and Focke-Wulf Fw-190 fighters. Bomber formations tried to adapt by flying special "box" formations to bring their machine gun arcs to a more productive bear but losses continued to mount to the point that daylight bombing raids had to be suspended for a time.
The arrival of the Mustang, with its speed, firepower and - most importantly - its range, soon brought the daylight bombing raid element back to the forefront. The introduction of drop tanks improved fuel and range of these little aircraft and allowed them to reach distances well past Berlin itself (drop tanks inevitably improved the range of all other American escort fighters as well). It cannot be understated the effect that the introduction of the P-51 must of had on the war, particularly the D-models. The aircraft, for all intents and purposes, single-handedly changed the course of the war in Europe - at least in the air. The closest performing German aircraft produced in any quantity was the Fw 190, an aircraft to which famed American aviator Chuck Yeager himself admitted as being the P-51's closest rival, but not matching it outright.
With the amendments in the P-51D models in tow, the aircraft was fielded for the first time in the Europe Theater in early 1944. Instantly, the D-models were pressed into service as bomber escort fighters, fighter-bombers and reconnaissance platforms wherever they could be used. P-51D Mustangs took over the aerial playing field and created lopsided advantages when squaring off against her German-produced contemporaries. The tide of the air war in Europe had officially shifted and the end of Germany's Third Reich was now in sight.
While success of the D-models in Europe unfolded, P-51D's eventually found their way into the Pacific and South East Theaters by late 1944. The primary role of P-51's in the Pacific became escorting the new, high-flying, long-range B-29 Superfortresses on their way to Japan and back. Mustangs fought on all fronts throughout the end of the war in 1945.
Issues in the Dutch East Indies in 1946 forced the Dutch to eventually disperse from their colony, leaving P-51D and P-51K models to the Indonesian Air Force. Incredibly, these Mustangs would be in operational service up until the 1970's. Israel became another post-war combat operator of the Mustang, using it in anger during their 1948 War of Independence and, later, in the 1956 Arab-Israeli War.
The Korean War brought about a clash of aviation eras as the infant jet age was thrust into the aviation world once dominated by piston-engine aircraft. Like other World War 2-era airframes, the now "F-51" Mustang was thrown into the combat mix and would see action in the early and middle years of the conflict until replaced in quantity by more capable jet-powered types. Despite their age, their proven effectiveness at ground attack and long-range qualities made Mustangs a favored component of inland strikes - positions that were beyond the reach of the fuel-thirsty new jet fighters such as the Lockheed P-80 Shooting Star. Mustangs in service with Australia, South Africa and South Korea all played roles in this early period and even scored several air-to-air kills in the process. With the arrival of the capable F-86 Sabre jets -particularly the F-86F fighter-bomber in 1953 - the role of the Mustang was all but over in the war. F-82 "Twin Mustangs" went on to play an equally vital night-fighter and all-weather attack role across the peninsula and was credited with the first USAF air victory in the war (a Yakovlev Yak-9).
American F-51 Mustangs flew up until 1957 with Air National Guard and Air Force Reserve units before being completely removed from service. Thankfully, the aircraft still exists as a prize for aviation collectors and remains a favorite at air shows across the globe.
The impressive reach of the P-51 - both in performance and in the sheer number of operators - surely says a lot about the class of this aircraft. The Mustang exceeded all specifications and allowed for a definitive shift in the direction of the air war over Europe, forcing Germany to lose all hope of ever recovering her air support. The P-51 served with at least 55 operators across the globe and was in operational service even into the 1970's - well into the jet age - and produced in excess of 15,000+ units. At any rate, the P-51 was as important to the Allied cause in the later years of World War 2 as the Supermarine Spitfire was in the early years, making her one of the most important and successful fighter aircraft platforms of all time. Her involvement in other global wars - from the Korean War to the Middle East and beyond - sure was a testament to both aircraft and pilot.