The North American P-51 Mustang has gone down in the history books as one of the greatest World War Two fighters. It was originally designed to fulfill an RAF urgent request for a new long-range fighter plane to help combat the German Luftwaffe (in addition to the RAF Supermarine Spitfire and Hawker Hurricane). The prototype NA-73X airframe was finished on September 9th, 1940 (just 102 days after the contract was signed by the British Purchasing Commission) and the first Mustang flight was on October 26th, 1940. By 1942 the Mustang was established in RAF and USAAF squadrons. The Brits initially used the Mustang for reconnaissance and as a fighter-bomber but ultimately the Allison V-170 engined P-51A Mustang Mk.I/II wasn’t that great and although it operated reasonably well at lower levels, it performed poorly at higher altitudes (not ideal given it was intended to be a primary fighter, hence the RAF using it in alternate roles).
Then by 1943 the idea had come up to put the legendary Rolls Royce Merlin engine (used in the Spitfire and Hurricane) in the P-51B/C models (RAF Mustang Mk.III). Suddenly the Allies had a high performance fighter that performed well above 15,000 feet, with an extremely long-range that could strike deep into enemy territory and escort bombers all the way to continental Europe and back whilst being able to match and beat the best of the Luftwaffe fighters thrown up against them. The somewhat of a lame duck soon became the “Cadillac of the Sky” and helped change the face of air combat in World War Two (predominately operated in Europe but also saw service in China and the Pacific Theatre).
From mid 1944 the ultimate variant of the single seat Mustang was the P-51D (RAF Mustang Mk.IV) which changed significantly in design from the earlier “razorback” configuration to a bubble canopy to improve all round visibility for the pilot. The P-51D was fitted with 6 x 0.50 caliber machine guns for plenty of firepower and a supercharged liquid cooled V-12 Packard V-1650-7 Merlin engine (licence built Rolls Royce Merlin 60 series engine) with a top speed of 703 km/h / 437 mph. The range of the P-51D was a massive range of 2,755 km / 1,650 miles when fitted with external drop tanks. The combination of speed, range and an excellent fighter to boot enabled the Allies to gain air superiority over Europe.
16,766 Mustang’s were built and over 8,000 of these were the D model (later models also included the P-51H and P-51K). Once they started to be retired many were put up for private sale. We are lucky that so many were built as the P-51 has become one of the most prolific warbirds in museums and on the air show scene today.
During World War Two the USAAF is said to have shot down 4,950 enemy aircraft over Europe in the Mustang with an impressive kill ratio of 11:1. That victory tally equates to approximately half of all USAAF air to air victory claims in the European theatre. The P-51 was indeed a game changer.
The brilliance of this pairing of engine and machine is proven in the success and longevity of the design. The Later model P-51D Mustang’s were still a front line fighter into the 1950’s and at the start of the Korean War (1950-1953) were the primary fighter-bomber of a number of nations involved on the United Nations side (including the USAF, RAAF, ROKAF, SAAF). By that time most were re-designated as the F-51 Mustang. It was only time and the advent of the jet age in the 1950’s that saw the twilight of the Mustang’s career as a primary fighter and switch to ground attack. Even then it still soldiered on in reserve units and in many smaller nations for many years to come.
Despite being well and truly obsolete many Latin American air forces were still operating World War Two era combat aircraft well into the 1960’s and beyond. The Dominican Republic retired their last P-51 in 1984 after operating them since the late 1940’s!
The last known air combat between piston engine fighters was the “Football War” of 1969 which was a brief conflict between El Salvador and Honduras following economic, political unrest and disputes over immigrants from El Salvador owning Honduran property. Mud was being slung from both sides of the border and immigrants were expelled but things started to get ugly during World Cup Qualifying football (soccer) matches in the Honduras between the two countries when violence broke out at the games and also on the streets. People were killed and many El Salvadorans fled back to their home country. Diplomatic ties were ceased and war ended up breaking out on July 14th, 1969 when the El Salvador air force attacked targets and their army invaded Honduras. The invasion slowed quickly though as their supply line was disrupted by air attacks as the Honduran Air Force had been very effective in quickly knocking out the El Salvador oil and fuel supplies (as well as attacking airfields). A cease-fire was announced on July 18th, 1969 (yes just 4 days later) but sporadic fighting apparently continued and troops did not withdraw back to El Salvador until early August.
El Salvador operated around 7 North American / Cavalier (rebuilds) F-51D Mustang (a number of which were clandestinely obtained in the United States from private owners to get around arms embargoes) and 12 Goodyear FG-1D Corsair fighters that were pitted against 12 to 14 Honduran Vought F4U Corsair fighters. El Salvador suffered with a shortage of pilots and actually hired some mercenaries to help fly combat missions (although I have read some of these guys would disengage from air combat!). During the official period of the war despite army losses on the ground the Honduran pilots were able to establish air superiority over their country and a number of El Salvadoran aircraft were shot down for no loss (El Salvador losses: 4 Corsairs and 1 Mustang shot down, a TP-51 Mustang forced landed in Guatemala and was interned for the war, 2 F-51’s collided on a runway and were both badly damaged, and at least one other F-51 was damaged on the ground during a Honduran air attack – the Air Combat Information Group has a lot of great information on this conflict).
So in this battle the Corsair proved superior to the Mustang but the quality and availability of pilots probably had a lot to do with the one-sided results. Losses may have been higher for El Salvador if the Honduran Government had not ordered their air force to only conduct defensive operations following the earlier successful air strikes in El Salvador.
During the recent Aviation Nation 2014 at Nellis Air Force Base in Nevada I got to see a couple of P-51D Mustang’s put through their paces. Nothing better than seeing that beautiful gleaming metal soar through the sky and hearing that Merlin purr!
Aces Flying High 
Nice write up a beautiful and important airplane. Although I might take some issue with calling the Allison Mustang a lame duck; they (both Rolls Royce and North American in separate projects) put a Merlin on it because they saw a brilliant air frame with tons of potential, not because anyone was ready to write it off.
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Emphasis on “somewhat of a lame duck” especially when compared to what it became with the Merlin. The Allison really limited the Mustang’s value as a fighter (great for low-level recon and low level ground attack but not really what they wanted the Mustang for) 🙂
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Reblogged this on Aviation Trails and commented:
A fabulous aircraft made even better by the Merlin engine. A real stunner in every aspects of the word.
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