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American long-range, single-seat fighter
The North American Aviation P-51 Mustang is an American long-range, single-seat fighter and fighter-bomber used during World War II and the Korean War, among other conflicts.
The Mustang was designed to use the Allison V-1710 engine, which had limited high-altitude performance in its earlier variants. The aircraft was first flown operationally by the RAF as a tactical-reconnaissance aircraft and fighter-bomber (Mustang Mk I). Replacing the Allison with a Rolls-Royce Merlin resulted in the P-51B/C (Mustang Mk III) model, and transformed the aircraft’s performance at altitudes above 15,000 ft (4,600 m) (without sacrificing range), allowing it to compete with the Luftwaffe’s fighters. The definitive version, the P-51D, was powered by the Packard V-1650-7, a license-built version of the two-speed, two-stage-supercharged Merlin 66.
Merlin Engine
In fact, in December 1943 the first Merlin-engined P-51B/C Mustangs entered combat in Europe. These P-51s provided sorely needed long-range, high-altitude escort for the US bombing campaign against Germany.
The P-51D arrived in quantity in Europe in the spring of 1944, becoming the USAAF’s primary long range escort fighter.
Thanks to its ability to excel in long-range escort duty, the Mustang was the first single-engine plane based in Britain to penetrate Germany, first to reach Berlin and first to go with the heavy bombers over the Ploiesti oil fields in Romania.
How was the iconic Mustang able to perform such long-range escort missions? Not because of its drop tanks.
‘Lots of planes could carry drop tanks: P-47, P-40, P-38, etc.,’ says James Gibson, former MP&P Engineer at Boeing, says on Quora.
The secret behind P-51B/C/D Mustang range
‘The real secret to the Mustang’s range was not the laminar flow control wing, or the Merlin engine. It was the addition of a fuselage tank behind the cockpit halfway through production of the P-51B. This additional internal tank increased fuel capacity by 85 gallons: original P-51Bs only had 184 gallons in the wings. The addition increased total fuel to 269 gallons or some 30%. Further adding two 75 gal drop tanks you reached 419 gallons. The later D&H models carried 110 gal drop tanks for 489 gallons.
‘But when you carried so much fuel you had to be aware of which tanks you were using at which point in the flight. On take-off you used the rear fuselage tank. This tank effected the center of gravity of the plane. You didn’t want to tangle with a 109 or a Focke Wulf when carrying fuel in the rear tank. So you burned it first and then switched to the drop tanks about halfway to Berlin.’
Gibson concludes;
‘You would then burn off the drop tanks, hopefully before engaging enemy fighters. But if they struck early you could drop those tanks and thus be clean and maneuverable. This was the fight profile that allowed the Mustangs maximum range and best performance when over target.’
Photo credit: U.S. Air Force
