History and Development
The Republic P-47, known as the "Jug" by those who flew it between March 1943 and August 1945, had its beginning in 1935 when Seversky Aircraft Corporation entered an Army Air Corps fighter design competition. Were it not for a series of accidents, the evolution of the Thunderbolt might have ended at that point. The Curtiss Hawk 75 and the Northrop 3-A both were competitors; however, the fly-off had to be postponed until April 1936, giving Seversky enough time to develop the prototype SEV-1XP single seater with retractable landing gear. Seversky won the competition with an order for 77 aircraft to be designated as the P-35. A distinctive feature of the P-35 was its semi-elliptical wing plan-form. Soon Seversky was selling P-35s in Europe and elsewhere. However, due to financial difficulties the Seversky Aircraft Corporation was reorganized, and the name was changed to Republic Aviation Corporation, but Seversky's chief engineer and the designer of the P-35, Alexander Kartveli, remained.
As a result of a new fighter competition in 1939, Republic entered the XP-41, designated AP-4, with a turbocharger in the central fuselage and using the P-35 wing. When Republic filled an order in late 1940 and early 1941 for 13 AP-4s, they were delivered as YP-43 Lancers and were powered with Pratt & Whitney 1200 hp R-1830-35 Twin Wasp engines. These aircraft turned in speeds of 351 mph at 20,000 feet. As the demand for high performance fighters increased, the debate concerning in-line versus radial engines developed. Curtiss, Bell, and Lockheed all went to in-line; however, Republic in their proposal for the AP-4J specified the R-2800-7 Double Wasp radial. At the same time Republic submitted a proposal for the AP-10 using an Allison V-1710-39 in-line engine.
The P-47's large engine cowling obstructed the pilot's forward view. On a narrow pierced steel plank taxiway a ground crew situated on the wing helps taxi Maj. Glenn T. Eagleston back to his hardstand. The 353rd Thunderbolts carried all yellow cowling with black cowl flaps and winged skull and crossbones which would became one of the most memorable designs on a Thunderbolt.
After several modifications in the AP-10 proposal the aircraft was ordered under the designation of XP-47. The wingspan of the proposed XP-47 was 30 feet with an area of 165 sq. feet. Overall length was 27 feet 6 inches. Empty weight would be 4,790 pounds. The estimated performance of the aircraft was 400 mph at 15,000 feet. It would have four 30 cal. guns in each wing and two 50 cal. guns in the nose. Before construction could begin on the new fighter, combat reports from Europe indicated the design was deficient. The concern being centered on the vulnerability of the water-cooled engines and a need for much heavier armament. The Republic design team, under Kartveli, proposed a new radial-engine design with eight 50 cal. guns and a weight nearly twice that of the earlier design. The Army issued a revision to its original XP-47 contract based on Kartveli's proposed changes and ordered 171 P-47B and 602 P-47C fighters.
While Republic kept its assembly line operating by turning out P-43 Lancers, the P-47 was designed and the new Pratt & Whitney R-2800 Double Wasp engines were assembled. The supercharging system for the big fighter created many problems during the design stage. Because of the importance of a smooth airflow between the supercharger and the engine, this portion of the aircraft was designed first and the rest of the aircraft was designed to fit around it. Despite the fact that the supercharger was in the tail and the engine in the nose, the system proved quite successful and did not even suffer greatly from battle damage.
In keeping with the large proportions of the fighter, the engine turned over a twelve foot propeller. In order to mount the landing gear in the wing and have room for the eight machine guns, and still have ground clearance for the propeller, the designers used a telescoping strut which lengthened the landing gear nine inches when it was lowered.
On May 6, 1941 the XP-47B made its first flight. Weighing twice as much as its contemporaries, the P-47 was the largest, heaviest, single-engine single-seat fighter to reach the production line. Nearly two years of testing and refining were required before the huge fighter, now called Thunderbolt, was ready for combat. When it did arrive, it was met with mixed emotions by experienced fighter pilots used to the trim lines and light weight of the P-39 and P-40. But time would prove the wisdom of Kartveli's design and the Thunderbolt became one of the legendary fighters of World War II. It was the fighter pilots of the 4th Fighter Group, Eighth Air Force who, after entering combat in the Thunderbolt and comparing it to the Supermarine Spitfire which they had previously been flying, gave the aircraft the name "Juggernaut."
In their first combat sorties, flown in April 1943, the Thunderbolt pilots discovered that they could out-dive all of the opposing fighters, a definite advantage in aerial combat. Additionally, the superb ability of the P-47 to survive battle damage proved to be one of its most outstanding attributes.
During the course of the war the P-47 would go through many modifications to improve its combat efficiency. The P-47D saw the addition of water injection to boost engine power at higher altitudes, more powerful versions of the R-2800 engine, increased fuel capacity and "bubble" canopy for increased rearward visibility. The "Jug" also went into service in the Pacific Theater and 247 went to the R.A.F and 103 to the Soviet Union under the Lend-Lease program. The P-47N, developed specifically for operation in the Pacific, had an 18 inch greater wing span with two 93 gallon internal wing fuel tanks in addition to the two drop tanks and a 100 gallon belly drop tank. With a total fuel capacity of 1266 gallons, it had a range of 2,350 miles and very effectively flew escort missions with the B-29 Superfortresses attacking the Japanese mainland in the closing stages of the war.
Of the total 15,683 P-47s built, approximately two-thirds reached operational commands overseas, and 5,222 were lost in action, 1,723 in non-combat situations. The "Jug" flew over half a million missions, dropped over 132,000 tons of bombs and destroyed 7,067 enemy aircraft over half of which were in the air and the rest on the ground.
US Army Air Force designation: P-47 British name: Thunderbolt A standard high-altitude fighter in the USAAF, the Thunderbolt was employed primarily as a long-range bomber escort over Germany and enemy-occupied territory. Early in 1944, it went into service as a dive-bomber and ground-attack fighter in Italy and it became a foremost factor in the ground operations in the European invasion and subsequent operations in the Western Front. It was also in the Pacific theatre of operations both as a high-altitude bomber escort and as a low-altitude ground-attack fighter.
The specification to which the P-47 was designed was drawn up at Wright Field in June 1940. The original XP-47 design was for a lightweight interceptor fighter fitted with an Allision V-1710 liquid-cooled engine and an armament of one 50 mm cannon and one .30 caliber machine-gun with provision for two additional .30 caliber machine-guns mounted in the wings. This design was not carried forward.
The first experimental prototype of what became the Thunderbolt was the XP-47B which was first flown on May 6 1941. Production got under way the following November. The first production P-47B was delivered on March 18, 1942.
P-47s began to arrive in Britain in November 1942 and the first operational sortie with the 8th Air Force was made on April 8, 1943. The first mission with auxiliary fuel tanks took place in July and during the last few weeks of 1943 the first fighter-bomber missions with two 500 lb bombs were made. The first pairs of 1,000 lb bombs were carried by P-47s during the Italian campaign early in 1944.
The Thunderbolt, in addition to being a standard fighter in the USAAF (United States Army Air Force), was also supplied, under the Lend-Lease Act, to Great Britain, Russia, France and Brazil. The RAF used the Thunderbolt in India and Burma. The Brazilian fighter squadron which served in Italy was equipped with Thunderbolts.
The 10,000th Thunderbolt came off the assembly lines on September 20, 1944, just two and a half years after the first P-47B was delivered to the USAAF.
2,000 hp Wright R-2800-21 eighteen-cylinder radial air-cooled engine with exhaust driven turbo-supercharger. Curtiss Electric four-blade constant speed propeller 12 ft 2 in (3.7 m) in diameter. Self-sealing fuel tanks (307 US gallons capacity). Armour protection for pilot. Eight .50 caliber machine-guns. Length: 34 ft 10 in (10.6 m).
Similar to the P-47B but fitted with special shackles to carry one 200 US gallon auxiliary fuel tank under the fuselage. Length: 35 ft 7 in (10.8 m).
P-47D (Thunderbolt I and II)
First models similar to the P-47C but fitted with universal shackles under the fuselage for either droppable fuel tanks or 500 lb bombs and similar wing racks. Later models fitted with water injection, which added several hundred horsepower for emergency use; improved turbos; wide-blade propellers (13 ft (3.96 m) in diameter) which added 400 ft/minute to the climb; increased fuel capacity which increased the operational radius to 637 miles (920 km); jettisonable standard canopy and later a new jettisonable blister canopy with full bullet-proof windscreen. The bomb load was increased from two 500 lb bombs to two 1,000 lb and one 500 lb bombs and three auxiliary fuel tanks could be carried externally on the same racks. Various combinations of bombs and tanks could be carried to suit tactical requirements. After the introduction of the dorsal canopy in the P-47D-25, an extended dorsal fin was added to improve directional stability lost by the reduction of the rear fuselage. Length: 36 ft 1 in (11 m).
An experimental version of the P-47B fitted with a pressurized cabin. Only one aircraft was so fitted.
Another experimental version of the P-47B fitted with laminar flow wings.
Similar to the P-47C and early P-47D but built by Curtiss Airplane Division at Buffalo, New York. Progressive developments introduced in the P-47D, including water-injection and external racks were also added to the P-47G.
A modification of the P-47B to test the experimental Chrysler XIV-2200 inverted Vee liquid-cooled engine.
Similar to the P-47D but with many engineering changes. Weight reduced by 1,000 lbs (454 kg). Reduced diameter engine cowling with cooling fan. Redesigned wings. Many features of this experimental model were incorporated in the production P-47M and N.
A special model which went into service in Europe early in 1945. Fitted with a P-47D wing, P-47N fuselage and a 2,100 hp Pratt & Whitney R-2800-57 engine with larger supercharger and an improved water-injection system. Was claimed to be the fastest propeller-driven aircraft in service at the time and to be successful in combating German jet-propelled fighters.
A long-range fighter developed for bomber escort duties in the Pacific Theatre. Same fuselage and power plant as the P-47M but fitted with redesigned wings of 18 in greater span, 22 sq ft increased area and with squared wing tips and larger ailerons; increased fuel capacity with eight additional tanks, one in the leading edge of each wing and three near each wheel well; strengthened landing gear with wider tread. Armament the same as previous P-47s but with provision for two 500 lb bombs and ten 5-in rockets under the wings. Maximum weight over 20,000 lbs (9,080 kg).
Type: Single-seat interceptor fighter/fighter-bomber
Powerplant: One 2,535 hp (1,889 kW) Pratt & Whitney R-2800-59 Double Wasp turbo-supercharged eighteen-cylinder air-cooled two-row radial engine
Wing Span: 40 ft 9 in ( 12.4 m)
Length: 36 ft 1 in ( 11.03 m)
Height: 14 ft 2 in (4.3 m)
Wing Area: 300 sq ft (29 sq m )
Empty Weight: 10,700 lbs ( 4853 kg)
Maximum T/O Weight: 19,400 lbs (8,800 kg)
Maximum Level Speed: 428 mph at 30,000 ft (690 km/h at 9,000 m)
Initial Climb: 2,780 ft per min (834 m)
Service Ceiling: 40,000 ft (12000 m)
Range: Normal 1,000 mi (1600 km); Max Range: 1,900 mi (3060 km)
Armament: eight .50 caliber wing-mounted Browning machine-guns with 267 or 425 rounds per gun plus 2x 1,000lbs or 3x 500lbs bombs