Republic P-47 Thunderbolt
The Republic P-47 Thunderbolt is a World War II-era fighter aircraft produced by the American company Republic Aviation from 1941 through 1945. One of the main United States Army Air Forces fighters, it found success in the European and Pacific theaters as an escort fighter well-suited to high-altitude air-to-air combat. It also served as the foremost American fighter-bomber in the ground-attack role.
The P-47 was noted for its firepower: its primary armament was eight.50-caliber machine guns, and it could carry 5-inch rockets or a bomb load of. When fully loaded, the aircraft weighed up to 8 tons, making it one of the heaviest fighters of the war. It was also noted for its ability to remain airworthy with battle damage.
The P-47 was designed around the powerful Pratt & Whitney R-2800 Double Wasp 18-cylinder radial engine, which also powered the U.S. Navy/U.S. Marine Corps Grumman F6F Hellcat and Vought F4U Corsair. An advanced turbosupercharger ensured the aircraft's eventual dominance at high altitudes, while also influencing its size and design. The armored cockpit was relatively roomy and comfortable and the sliding bubble canopy introduced on the D variant offered good visibility.
The P-47 also served with the air forces of France, the United Kingdom, and the Soviet Union, and with Allied Mexican and Brazilian squadrons. It is the namesake of a later U.S. ground-attack aircraft, the Fairchild Republic A-10 Thunderbolt II.
Development
The P-47 Thunderbolt was designed by Alexander Kartveli, a man of Georgian descent. It was to replace the Seversky P-35 developed earlier by a Russian immigrant named Alexander P. de Seversky. Both had fled from their homeland, Tbilisi, Georgia, to escape the Bolsheviks. In 1939, Republic Aviation designed the AP-4 demonstrator powered by a Pratt & Whitney R-1830 radial engine with a belly-mounted turbocharger. A small number of Republic P-43 Lancers were built, but Republic had been working on an improved P-44 Rocket with a more powerful engine, as well as on the AP-10 fighter design. The latter was a lightweight aircraft powered by the Allison V-1710 liquid-cooled V-12 engine and armed with two.50 in M2 Browning machine guns mounted in the nose and four.30 in M1919 Browning machine guns mounted in the wings. The United States Army Air Corps backed the project and gave it the designation XP-47.In the spring of 1940, Republic and the USAAC concluded that the XP-44 and the XP-47 were inferior to Luftwaffe fighters. Republic tried to improve the design, proposing the XP-47A, but this failed. Kartveli then designed a much larger fighter, which was offered to the USAAC in June 1940, which ordered a prototype in September as the XP-47B. The XP-47A, which had little in common with the new design, was abandoned. The XP-47B was of all-metal construction with elliptical wings, with a straight leading edge that was slightly swept back. The P-47's airfoil section was developed by A. Kartveli and was designated as Republic S-3. The air-conditioned cockpit was roomy, and the pilot's seat was comfortable—"like a lounge chair", as one pilot later put it. The canopy door initially hinged upward. Main and auxiliary self-sealing fuel tanks were placed under the cockpit, giving a total fuel capacity of.
Power came from a Pratt & Whitney R-2800 Double Wasp two-row, 18-cylinder radial engine producing — the same engine that powered the prototype Vought XF4U-1 fighter to just over in October 1940—with the Double Wasp on the XP-47B turning a four-bladed Curtiss Electric constant-speed propeller of in diameter. The loss of the AP-4 prototype to an engine fire ended Kartveli's experiments with tight-fitting cowlings, so the engine was placed in a broad cowling that opened at the front in a "horse collar"-shaped ellipse. The cowling admitted cooling air for the engine, left and right oil coolers, and the turbosupercharger intercooler system. The engine exhaust gases were routed into a pair of wastegate-equipped pipes that ran along each side of the cockpit to drive the turbosupercharger turbine at the bottom of the fuselage, about halfway between cockpit and tail. At full power, the pipes glowed red at their forward ends and the turbine spun at 21,300 rpm. The complicated turbosupercharger system with its ductwork gave the XP-47B a deep fuselage, and the wings had to be mounted in a relatively high position. This was difficult, since long-legged main landing gear struts were needed to provide ground clearance for the enormous propeller. To reduce the size and weight of the undercarriage struts, and so wing-mounted machine guns could be fitted, each strut was fitted with a mechanism by which it telescoped out while it extended.
The XP-47B was very heavy compared with contemporary single-engined fighters, with an empty weight of, or 65% more than the YP-43. Kartveli said, "It will be a dinosaur, but it will be a dinosaur with good proportions". The armament was eight.50-caliber "light-barrel" Browning AN/M2 machine guns, four in each wing. The guns were staggered to allow feeding from side-by-side ammunition boxes, each with 350 rounds. All eight guns gave the fighter a combined rate of fire around 100 rounds per second.
The XP-47B first flew on 6 May 1941 with Lowry P. Brabham at the controls. Although minor problems arose, such as some cockpit smoke that turned out to be due to an oil drip, the aircraft proved impressive in its early trials. It was lost in an accident on 8 August 1942, but before that mishap, the prototype had achieved a level speed of at altitude and had demonstrated a climb from sea level to in five minutes.
Though the XP-47B had its share of shakedown troubles, the newly reorganized United States Army Air Forces placed an order for 171 production aircraft, the first being delivered in December 1941.
Operational history
US service
By the end of 1942, P-47Cs were sent to England for combat operations. The initial Thunderbolt flyers, 56th Fighter Group, were sent overseas to join the 8th Air Force. As the P-47 worked up to operational status, it gained a nickname: "Jug". Two fighter groups already stationed in England began introducing the Jugs in January 1943 - the Spitfire-flying 4th Fighter Group, a unit built around a core of experienced American pilots who had flown in the RAF Eagle Squadrons prior to the US entry in the war; and the 78th Fighter Group, formerly flying P-38 Lightnings.File:Francis Gabreski color photo in pilot suit.jpg|thumb|P-47 pilot Lt Col Francis S. "Gabby" Gabreski, 56th Fighter Group, leading ace of the 8th Air Force
Beginning in January 1943, Thunderbolt fighters were sent to the joint Army Air Forces – civilian Millville Airport in Millville, New Jersey, to train civilian and military pilots.
The first P-47 combat mission took place 10 March 1943 when the 4th FG took their aircraft on a fighter sweep over France. The mission was a failure due to radio malfunctions. All P-47s were refitted with British radios, and missions resumed 8 April. The first P-47 air combat took place 15 April with Major Don Blakeslee of the 4th FG scoring the Thunderbolt's first air victory.
By mid-1943, the Jug was also in service with the 12th Air Force in Italy and against the Japanese in the Pacific, with the 348th Fighter Group flying missions out of Port Moresby, New Guinea. By 1944, the Thunderbolt was in combat with the USAAF in all its operational theaters except Alaska.
Luftwaffe ace Heinz Bär said that the P-47 "could absorb an astounding amount of lead and had to be handled very carefully". Although the North American P-51 Mustang replaced the P-47 in the long-range escort role in Europe, the Thunderbolt still ended the war with an aerial kill ratio of 4.6:1 in over 746,000 sorties of all types, at the cost of 3,499 P-47s to all causes in combat. By the end of the war, the 56th FG was the only 8th Air Force unit still flying the P-47, by preference, instead of the P-51. The unit claimed 677-1/2 air victories and 311 ground kills, at the cost of 128 aircraft. Lieutenant Colonel Francis S. Gabreski scored 28 victories, Captain Robert S. Johnson scored 27 aerial victories, and 56th FG Commanding Officer Colonel Hubert Zemke scored 17.75 kills. Despite being the sole remaining P-47 group in the 8th Air Force, the 56th FG remained its top-scoring group in aerial victories throughout the war.
With increases in fuel capacity as the type was refined, the range of escort missions over Europe steadily increased until the P-47 was able to accompany bombers in raids all the way into Germany. On the way back from the raids, pilots shot up ground targets of opportunity, and also used belly shackles to carry bombs on short-range missions, which led to the realization that the P-47 could perform a dual function on escort missions as a fighter-bomber. Even with its complicated turbosupercharger system, its sturdy airframe and tough radial engine could absorb significant damage and still return home.
The P-47 gradually became the USAAF's primary fighter-bomber; by late 1943, early versions of the P-47D carried bombs underneath their bellies, midproduction versions of the P-47D could carry bombs and M8 4.5 in rockets under their wings or from the last version of the P-47D in 1944, High Velocity Aircraft Rockets. From D-Day until VE day, Thunderbolt pilots claimed to have destroyed 86,000 railroad cars, 9,000 locomotives, 6,000 armored fighting vehicles, and 68,000 trucks. During Operation Cobra, in the vicinity of Roncey, on 29 July, early in the US break out, the 405th Fighter Group hit a German column trapped between Roncey and St-Denis-le-Vetu by elements of the US 2nd and 3rd Armoured Divisions. The group attacked this column from 3:10pm to 9:40pm. Ground investigations found 66 tanks, 204 vehicles and 11 guns destroyed in this attack.
Medal of Honor recipients
Two P-47 pilots received the Medal of Honor during World War II:- USAAF Col. Neel E. Kearby of the 348th Fighter Group was awarded the Medal of Honor for his action during a fighter sweep over the Japanese base at Wewak, New Guinea on 11 October 1943, flying P-47D, serial number nicknamed "Fiery Ginger III". Encountering 40 Japanese planes, Kearby led his flight of four P-47s and in the ensuing combat, he shot down six Japanese planes. After the mission, Kearby would score a total of 22 aerial victores before he was shot down and killed over Wewak in 5 March 1944.
- USAAF 1st Lt. Raymond L. Knight of the 346th Fighter Squadron of the 350th Fighter Group was posthumously awarded the Medal of Honor for his actions during missions over northern Po Valley, Italy on 24 and 25 April 1945, flying P-47D, serial number nicknamed "OH JOHNNIE". On 24 April, he repeatedly volunteered to lead attacks on enemy air bases and exposed his P-47 to intense hostile fire in low-altitude reconnaissance and strafing missions. During a mission on the following day, his P-47 was badly damaged by anti-aircraft fire. Knowing that his unit was short on aircraft, he decided against parachuting to safety and instead attempted to fly his P-47 back to his home airbase, but crashed in the Apennine Mountains and was killed.