North American P-51* "Mustang"

The development

The P-51 was one of the best Allied fighters of WWII. From the technical point of view, it is recognized as the best piston-engined fighter ever. Its success comes from the unique combination of properties that made it unique. There were 15,675 P-51's built altogether, and it occupies the second place on produced planes after the P-47 Thunderbolt.
The P-51 project started just few months before World War II. The first plane was built in a very short period of time, and it performed its first flight on 26/10/1940. We assume that some of P-51 developers had once worked for Willy Messerschmitt and the "Mustang" was built under the influence of Bf-109 (The best German and World War II fighter). The truth is unknown but the North American manager (and chief designer) H. "Dutch" Kindelberger is known to have visited German factories before the war to take new ideas.

From the very beginning "Mustang" was a good plane. Its low altitude performance was good, and it could carry four 0.5 inch (12.5 mm) and four 0.3' (7.5 mm) machine guns - heavy and efficient weapons for that period. Unfortunately, "Mustang's" airframe design was too modern for the engines of that time, and the plane failed to achieve good high altitude performance. The main reason was its Allison V-1710 Vee engine, which had 1100 hp. power, and as it had no supercharger, the plane's weight-to-power ratio became too poor. The air combats in Europe in those days were held from medium to high altitudes, and therefore it was decided that the "Mustangs" would be used for low level tactical reconnaissance and ground attack. About 20 aircraft (the name "Mustang" was devised from a popular song, and combined with the English tradition of designation it became "Mustang I") were passed to RAF (Royal Air Force) through the Lend-Lease agreement. Their first combat mission was on 10/5/1942. They were considered unhelpful, and no one then knew that it would become one of the best fighters of World War II.

Picture 2.2: Another P-51 in flight. This aircraft was restored.

Mustang series

Later a new version of "Mustang", "Mustang IA" appeared. Its designation was P-51 and the official name was both "Apache" and "Mustang" but finally the name was defined as "Mustang". Its weapons changed to four 0.5 inch (12.5 mm) guns or four 20 mm cannons. Next version was denominated "Invader" . It was a version of P-51 with lower performance but it could carry six 0.5' (12.5 mm) guns and two 500 lb. (226.8 Kg.) bombs. The planes were better than the original version, but the V-1710 still made them sluggish.
The "Mustangs" served as escort* fighters in attacks in the Far East. During this period there was a serious need in escort fighters, because of the bombing of Axis's strategic targets. The "Spitfires and Hurricanes ran out of fuel within the first hours. In this case B-17s B-24s remained exposed to enemy fire. An attack German interceptors like FW-190 could lead to tragedies.

"Mustangs" with "Merlin" engine

On 30/4/1942 Ronald W. Hawker a Rolls-Royce test pilot piloted RAF "Mustang". He was impressed by it because Mustang's speed was larger in 30 mph. than Spitfire's and it could carry 3 times more fuel. He reported that the plane would be adequate for the new "Merlin" engine models. Rolls Royce decided to try to put a new engine in "Mustang". After long research they decided that the "Merlin 68" engine was the best for "Mustang". "Packard" bought a license to build it under the designation "V-1650-3". A problem related to high engine temperatures (200 degrees centigrade) was solved by putting an intercooler. That way the P-51B/C was created. The only difference between P-51B and P-51C is the factories where the planes were produced. The P-51B was made in Inglewood, California (1988 built) and P-51C was made in Dallas, Texas (1750 built).The speeds at all altitudes were about 50 mph. higher than the P-51As'.
The new P-51B/C was used in 15 fighter groups. The groups were in the 8^th and 9^th Air Forces in England and in 12^th and 15^th Air Forces of USAAF* in Italy the European Theater December 1943. They also entered service China-Burma-India (CBI) September March 1943 Mustangs were used as escort fighters to B-17 "Flying Fortress" and B-24 "Liberator" bombers bomb Berlin. They took part in other large bombing missions too. About 59 planes were passed to Royal Australian Air Force Allied forces. 100 supplied Chinese years 1943-1944. One of special uses was shooting down V-1 "buzz bombs". V-1s were German primitive ground-to-ground cruise missiles that were used to terrify some cities (mainly London). Typical flew at 370 mph. a P-51 fueled with high octane fuel able get 420 2000 feet. January 1945 F-6Cs (the reconnaissance version) for photo-mapping purposes. P-51B/C renamed F-51B/C 1948 out 1949.

Graph 2.1 P-51A-10-NA, P-51B-1-NA and P-51C-10-NT comparison. Based on materials taken from Internet (see the bibliography). As you can see, the difference between P-51B,C and D is very small but there is a raise of speed of about 50 mph. at all altitudes relatively to P-51A.

P-51 D/K and the further history

Then, finally, the P-51D/K appeared. It is the most known version of "Mustang". There was an opportunity to improve the disadvantages of the P-51B/C version, for example its limited firepower. Finally three 0.5 inch (12.5 mm) machine guns were installed in each wing. The inboard guns had 400 rounds each and the other guns had 270 rounds each. There was also an option to remove two of the guns, and retain just four with 400 rounds each. There were additional modifications of the landing gear and wing design. The problem with installation of another fuel tank was fixed in some planes too. 7956 planes of this type were produced (6502 in Inglewood and 1454 in Dallas). The difference between K and D versions was in the armies they arrived: P-51K was built for the United Kingdom, while P-51D was built for USAAF. Another minor difference was in the propeller (it did influence the performance, though). The P-51D began to arrive in Europe in March 1944. This version was better than most of Luftwaffe's (German air force) piston-engine fighters. German pilots considered that the P-51 was not so vulnerable to cannon, but Mustang's liquid-cooled engine could be put out of action by one hit. On July the 18,1944 Mustangs met a pair of Me-163 "Comets" (a German fighter with rocket engine). They tried to shot it down, but they didn't succeed. On August 5, 1944 a Me-163 group destroyed three "Mustangs" and three bombers. On August the 16, A "Mustang" piloted by Lt. Col. John. B. Murphy finally managed to shot down a Me-163. Although Me-163 gained much publicity and the Allied high command was scared, the plane was dangerous to fly on and its endurance was low (it was one of the first jets and its rocket engine was both dangerous and a fuel-hog). The Me-262 appeared in July 1944. It had a real turbojet (not rocket) engine. It was better than Me-163 and its speed was 100 mph higher than Mustangs'. Its disadvantages were the low endurance, and the difficult piloting technique. The safe method to shoot Me-262 down was to dive on it when its speed was low (usually at the takeoff). Young Captain, Charles "Chuck" Yeager, the man who first flew at speeds higher than sound's, distinguished himself by shooting down a Me-262. Though Me-262 was fast, its reliability and mean time between failures were low. As a result of Me-262s' technical unreliability, "Mustangs" could have a descent fight against them. Because of the higher priority of the war in Europe, "Mustangs" arrived to the Far East later in 1944 and operated on close-support work. On 4/7/1945 "Mustangs" escorted B-29s on bombing ride to Japan. "Mustangs" were also used to bomb Japan. During the Korean War, "Mustangs'" high payload and reliability were utilized, and "Mustangs", though technically obsolete as fighters, were used as tactical bombers. In 1946 the P-51D designation was changed to F-51D. The last "Mustangs" went out of service in USAF in 1957. Israeli Air Force used "Mustang" in the Independence War, Operation "Kadesh" and other small operations mainly as a light bomber.

Table 2.1 Mustang's description and specifications.

Table 2.2 Mustang's propulsion and performance.