The P-51 Mustang was mostly used as a long-range escort fighter because of its superb range and maneuverability
One of the best and most well-known fighters employed by the US Army Air Forces (USAAF) in World War II was the P-51 Mustang. The USAAF received the first batch of P-51A fighters in March 1942.
The first P-51B/C Mustangs powered by Merlin entered action in Europe in December 1943. These P-51s gave the US bombing campaign against Germany the desperately needed long-range, high-altitude escorts. The P-51D became the main long-range escort fighter for the USAAF when it began to arrive in large numbers in Europe in the spring of 1944.
The Mustang was the first single-engine aircraft based in Britain to enter Germany, arrive in Berlin, and fly with heavy bombers over the Ploiesti oil fields in Romania thanks to its prowess in long-range escort duty. How did the venerable Mustang manage to complete such distant escort missions? Its drop tanks are not the reason.
‘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 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 the 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 affected 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 by U.S. Air Force