P-47D / P-47G and XP-47K / XP-47L Refinements of the Thunderbolt continued, leading to the P-47D, which was the most produced version with 12,602 built. The D model actually consisted of a series of evolving production blocks, the last of which were visibly different from the first. The first P-47Ds were actually the same as P-47Cs. Republic could not produce Thunderbolts fast enough at its Farmingdale plant on Long Island, so a new plant was built at Evansville, Indiana. The Evansville plant built a total of 110 P-47Ds, which were completely identical to P-47C-2s. Farmingdale aircraft were identified by the -RE suffix after the block number, while Evansville aircraft were given the -RA suffix. The P-47D-1 through P-47D-6, the P-47D-10, and the P-47D-11 successively incorporated changes such as the addition of more engine cooling flaps around the back of the cowl to reduce the engine overheating problems that had been seen in the field. Engines and engine subsystems saw refinement, as did the fuel, oil and hydraulic systems. Additional armor protection was also added for the pilot. The P-47D-15 was produced in response to requests by combat units for increased range. The internal fuel capacity was increased to 375 U.S. gal (1,421 l) and the bomb racks under the wings were made wet (equipped with fuel plumbing) to allow a jettisonable drop tank pressurized by vented exhaust air to be carried under each wing, in addition to the belly tank. Five different auxiliary tanks were fitted to the Thunderbolt during its career: 200 U.S. gallon (758 l) ferry tank, a conformal tub-shaped jettisonable tank made of paper, which barely cleared the ground on grass airfields, was used as an interim measure between 30 July and 31 August 1943; 75 U.S. gal (284 l) drop tank, a standardized teardrop-shaped steel tank initially produced for the P-39 Airacobra, was adapted to the P-47 beginning 31 August 1943, initially carried on a belly shackle but used in pairs in 1944 as underwing tanks and adopted as a standard accessory in the US inventory; 108 U.S. gal (409 l) drop tank, a cylindrical paper tank of British design and manufacture, used as a belly tank beginning in September 1943 and a wing tank in April 1944; 150 U.S. gal (568 l) drop tank, a steel tank first used as a belly 20 February 1944, and an underwing tank 22 May 1944; 215 U.S. gal (810 l) belly tank, a wide, flat steel tank developed by VIII Service Command that allowed performance-degrading wing pylons to be removed, was first used in February 1945. The tanks made of plastic-impregnated (laminated) paper could not store fuel for an extended period of time, but they worked quite well for the time it took to fly a single mission. These tanks were cheaper, lighter, and were useless to the enemy if recovered after being dropped—not only did they break apart, but they did not provide the enemy with any reusable materials that could be scavenged for their own war effort. With the increased fuel capacity, the P-47 was now able to perform escort missions deep into enemy territory. A drawback to their use was that fighters could not land with the tanks in place because of the hazard of rupture and explosion. Fighters recalled from a mission or that did not jettison for some reason were required to drop paper tanks into a designated dump area at their respective fields, resulting in substantial losses of aviation fuel. The P-47D-16, D-20, D-22 and D-23 were similar to the P-47D-15 with minor improvements in the fuel system, engine subsystems, a jettisonable canopy, and a bulletproof windshield. Beginning with the block 22 aircraft, the original narrow-chorded Curtiss propeller was replaced by propellers with larger blades, the Evansville plant switching to a new Curtiss propeller with a diameter of 13 ft (3.96 m) and the Long Island plant using a Hamilton Standard propeller with a diameter of 13 ft 2 in (4.01 m). With the bigger propellers having barely 6 in (152 mm) of ground clearance, Thunderbolt pilots had to learn to be careful on takeoffs to keep the tail down until they obtained adequate ground clearance, and on landings to flare the aircraft properly. Failure to do so damaged both the propeller and the runway. A modification to the main gear legs was installed to extend the gear legs via an electric motor (un-extending before retract) to accommodate the larger propeller diameter. The P-47D-25 was a model with increased range, firepower, and maneuverability. Even with two Republic plants rolling out the P-47, the USAAF still was not getting as many Thunderbolts as they wanted. Consequently, an arrangement was made with Curtiss to build the aircraft under license in a plant in Buffalo, New York. The Curtiss plant experienced serious problems and delays in producing Thunderbolts, and the 354 Curtiss-built fighters were relegated to stateside advanced flight training. The Curtiss aircraft were all designated P-47G, and a -CU suffix was used to distinguish them from other production. The first P-47G was completely identical to the P-47C, the P-47G-1 was identical to the P-47C-1, while the following P-47G-5, P-47G-10, and P-47G-15 sub-variants were comparable to the P-47D-1, P-47D-5 and P-47D-10 respectively. Two P-47G-15s were built with the cockpit extended forward to just before the leading edge of the wing to provide tandem seating, designated TP-47G, essentially to provide a trainer variant. The second crew position was accommodated by substituting a much smaller main fuel tank. The Doublebolt did not go into production but similar modifications were made in the field to older P-47s, which were then used as squadron hacks (miscellaneous utility aircraft). r/max
Posted on: Sat, 13 Dec 2014 21:00:00 +0000
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