The North American P-51 Mustang was one of the more successful and iconic fighter planes of the Second World War.
Despite its very American origins, the P-51 was designed in response to a specification from the British government and a request from the Royal Air Force to build North American Aviation planes under license.
Although altitude problems designated it to RAF army-cooperation roles, the P-51 was known for its incredible speed and fast production output.
Origins of the P-51 Mustang
The development process for the P-51 Mustang began in Great Britain and was prompted by a purchasing commission call by British civil servant Sir Henry Self in 1938. Self was tasked with buying American military equipment to bolster the British armed forces, particularly in response to growing rearmament in Nazi Germany.
However, in the late 1930s, there were no American-manufactured fighter aircraft that met European specifications. The Curtiss P-40 was identified as the fighter that came closest to meeting the standards required, however, these were in short supply at the time.
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Self asked the North American Aviation (NAA) company if they could build the P-40 under license as he was concerned by the fact NAA had not designed a fighter plane before.
However, NAA executive James Kendelberger stated their company could design and build a superior fighter plane in a shorter time, rather than modifying their production line to build the P-40.
P-51 Mustang Development
NAA began work on drawing designs for the aircraft in January 1940. Kendelberger found inspiration for the design by studying aircraft produced in Britain and Germany. NAA also purchased design blueprints of the experimental Curtiss XP-46 which they factored into their own design.
The NAA prototype was named the NA-73X and the process was overseen by designer Edgar Schmued. Some of the design was lifted from the T-6 Texan trainer NAA had produced but improvements were made to the wings to reduce drag. NAA also fitted the powerful turbocharged Allison V-1710 found in the P-40.
The NA-73X completed its maiden flight in October 1940, which was considered a short development period as the plane had been commissioned only 149 days before its first flight.
Production was given the green light and the plane was given the name Mustang.
Test pilots noted that the NA-73X showed good handling and economical fuel consumption. However, while the Allison engine produced an incredible speed, it was also found to be underpowered at a higher altitude which the RAF feared could make the aircraft unsuitable for use during dogfights above Europe which took place at a high altitude.
British RAF test pilots also reported that below fifteen thousand feet, the Mustang showed incredible speed but expressed a reluctance to fly the aircraft any higher as the handling would grow weaker.
NAA felt that developing and fitting a new engine would take time and money. In May 1942, British test pilot Ronald Harker suggested switching the Mustang’s engine to the Rolls-Royce Merlin that had been fitted to the Supermarine Spitfire.
As a result, the Mustang Mk X was produced featuring the Merlin engine at Rolls-Royce’s facility in Hucknall, England in October 1942.
American production of the Mustang replicated the Merlin engine under license as the Packard V-1650-3 Merlin engine.
P-51 Mustang in British Service
Although conceived in America, the RAF became the first operators of the Mustang and the first Mustang squadron, No. 26 Squadron was formed in October 1942 and in May that year, the Mustang was sent for its first mission over occupied France.
Due to the altitude performance issues, many Mustangs ended up with the RAF’s integrated Army Cooperation Command to perform observational, ground attack and light but long-range bombing duties.
While it was deemed unsuitable as a dogfighter in European airspace, the Army Cooperation Command exploited its power and range to make the Mustang a dependable aircraft for performing high-speed missions over occupied Europe and sometimes Germany itself.
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Between 1943 and 1944, the Army Cooperation Command used the Mustang to locate V-1 missile launching sites.
Prior to the Second World War, the United States Airforce placed a lesser emphasis on fighter escort of bombers, believing that a large and tight formation of bomber aircraft would combine enough firepower to ward off attacking enemy fighters.
However, existing evidence and aircrew reports from RAF and Luftwaffe daylight bombing raids showed that unescorted bombers were vulnerable to both air and ground fire.
The creation of the Allied Combined Bomber Offensive (CBO) in 1943 was intended to pave the way for a full-scale Allied invasion of Europe through preemptive bombing raids from above.
US Army Air Forces (USAAF) daylight bombing raids encountered stiff Luftwaffe air defense over Germany and lost significant amounts of Boeing B-17, including seventeen B-17s lost in October 1943 during a bombing raid over Schweinfurt in October that year.
As a result, the USAAF began exploring options for a bomber escort plane. The P-51 was deemed the most suitable option with its efficient range enabling it to escort B-17 bombers to their target and then back to American bases in England.
The Mustang was deployed alongside USAAF bombers in 1944 and quickly proved effective in air-to-air combat with Luftwaffe fighters.
In February 1944, Allied air forces launched what was known as the “Big Week” which consisted of a week-long bombing offensive against German aircraft manufacturing facilities.
During the raids, USAAF P-51 Mustang squadrons depleted the Luftwaffe of an estimated seventeen percent of their most skilled fighter pilots. Nazi military chief Hermann Goring allegedly stated during the war that he knew German air superiority was lost once the Mustang entered the fight.
In April 1944, USAAF Mustangs took part in Operation Jackpot which involved direct strikes on Luftwaffe fighter airfields. The attacks proved successful and decimated much of the Luftwaffe’s fighter capabilities.
In part due to the P-51’s abilities in the air and its success against Luftwaffe fighters, the RAF began to perform daylight bombing missions again over the German mainland from 1944 onwards.
However, the operations also exposed certain flaws with the Mustang’s design. The Mustang was found to be more vulnerable to defensive fire from the ground when taking part in strafing and ground attacks due to the engine being more exposed compared to other fighter planes.
The external fuel tanks on the wings were sometimes known to destabilize the aircraft and cause the P-51 to enter a spin when it was performing a dive manoeuvre.
Rather than risk losing more pilots to accidents, USAAF Lieutenant Colonel Thomas J. Hitchcock (then serving as an air force attaché at the American Embassy in London) decided to investigate the problem himself. Although not a frontline combat pilot during the Second World War, Hitchcock was an experienced pilot and a World War One ace who had played a role in the Mustang’s development.
To work out the problem, Hitchcock took a test flight in a Mustang in April 1944 but was unable to pull the plane out of a controlled dive and was killed when it crashed near Salisbury, England.
Although considered a tragic incident, the Mustang remained in service and continued to help the Allies gain air superiority over Europe which laid the groundwork for the successful D-Day landings in 1944.
By 1945, three P-51 USAAF squadrons claimed to have shot down 4,950 enemy aircraft, one of the most successful scores recorded by a fighter type.
The P-51 saw less action in the Pacific Theatre compared to other American-made aircraft due to its heavy demand in Europe. But as the Allies established total superiority in European airspace and land forces closed in on Germany, Mustangs began to be deployed more steadily against Japanese forces.
The Mustang first saw action in the Pacific War in 1945 when a number were donated to the Chinese Air Force as part of air defence against Japan.
After US forces successfully captured Iwo Jima in March 1945, the USAAF stationed Mustang squadrons on the island to escort Boeing B-29 bombers on raids against the Japanese mainland.
P-51 Mustang Role Post-war
Unlike other fighter aircraft, the Mustang continued to be used for frontline sorties in the immediate post-war period.
At the start of the Korean War in 1950, the P-51 served a frontline role as a ground attack strike aircraft and for photo reconnaissance.
Both the post-war United States Air Force, US Navy and the South Korean Air Force used the Mustang extensively during the Korean War, with US forces responding to South Korea’s invasion by exploiting the Mustang’s range as a long-distance bomber to attack North Korean targets.
However, with the jet age approaching, both the US and South Korea opted to replace their Mustang units with jet fighter aircraft such as the Grumman F9F Panther.
The Australian, South African and combined British Commonwealth Air Forces both deployed the Mustang as an attack aircraft in Korea. However, heavy losses prompted the Australian and South African militaries to switch to the F-86 Sabre jet while the British replaced their P-51 units with the Gloucester Meteor.
The Legacy of the P-51 Mustang
The Mustang became known as one of the fastest planes to take to the skies during the Second World War. It proved versatile in all theatres during the war, and military historians have credited the Mustang with destroying over five thousand enemy aircraft in total.
In doing so, it is credited with helping the Allies gain European air superiority.
The Mustang was also notable for achieving other significant records during its service: it was the first American-built fighter plane to achieve a speed of over 400 miles per hour and held the record for the fastest climb to 20,000 ft, which it managed in just over four minutes.
Perhaps most notably, American flying ace Chuck Yeager piloted a Mustang during the Second World War before he would go on to become the first pilot to break the sound barrier in 1947.
Specifications of the P-51 Mustang
- Crew: 1
- Length: 32 ft 3 in (9.83 m)
- Wingspan: 37 ft 0 in (11.28 m)
- Height: 13 ft 4.5 in (4.077 m) tail wheel on ground, vertical propeller blade
- Empty weight: 7,635 lb (3,463 kg)
- Max takeoff weight: 12,100 lb (5,488 kg) 5,490
- Powerplant: 1 × Packard (Rolls-Royce) V-1650-7 Merlin 12-cylinder liquid cooled engine, 1,490 hp (1,110 kW) at 3,000 rpm; 1,720 hp (1,280 kW) at WEP
- Maximum speed: 440 mph (710 km/h, 383 kn)
- Range: 1,650 mi (2,660 km, 1,434 nmi) with external tanks
- Service ceiling: 41,900 ft (12,800 m)
- Rate of climb: 3,200 ft/min (16 m/s)