The Republic P-47 Thunderbolt - Development, Variants, and Service
by
Daniel
“If it can be said that the P-38s struck the Luftwaffe in its vitals and the P-51s are giving it the coup de grace, it was the Thunderbolt that broke its back,” wrote Major General Bill Kepner, commander of VIII Fighter Command in May 1944.[1] The Republic P-47 Thunderbolt was the heaviest single-seat single-engine fighter of World War Two, with the long-range N-models weighing over 20,000lbs gross.[2] The P-47 was powered by a turbocharged 18-cylinder Pratt & Whitney R-2800 Double Wasp air-cooled twin-row radial engine, with maximum outputs ranging from 2,000hp to 2,800hp depending on the subtype.[3] The P-47 provided the American heavy bombers with protection from German fighters when flying over Nazi territory, something that they desperately needed in 1942. Capable of flying at over 429mph in level flight, and able to out-dive all non-jet German fighters, the P-47 was one of the best high-altitude fighters of the war thanks to the turbocharged Double Wasp that powered it.[4] The P-47 was also the most-produced American fighter of all time, with a total production of 15,683 aircraft, 12,602 of them D-models, which is the largest production of any subtype of an American fighter aircraft.[5]
In 1940, the United States Army Air Corps (USAAC) issued a requirement for new fighter designs. The Republic P-43 Lancer, powered by a turbocharged Pratt & Whitney R-1830 Twin Wasp radial engine, possessed good performance at high altitude, although overall it was inferior to other modern fighters such as the Supermarine Spitfire and Messerschmitt Bf-109E. This necessitated a new, more capable fighter to be designed. Republic initially responded with the AP-10, which was to be powered by a 1150hp Allison V-1710-39 liquid-cooled engine. The AP-10 was designated XP-47 and XP-47A, with the main difference being that the XP-47 guns in its wings and nose, while the XP-47A only had nose-mounted guns. Neither type was met with approval from the USAAC, prompting Republic to develop a new prototype, the XP-47B. The XP-47B first flew on May 6, 1941, with a gross weight of 12,086lbs, more than twice weight of some contemporary fighters.[6] It was powered by the most powerful engine available at the time: a turbocharged Pratt & Whitney R-2800-21 Double Wasp radial engine, which produced 2,000hp. The XP-47B attained a maximum speed of 412mph, in spite of its size and weight.[7] The first delivery of the P-47B occurred on December 21, 1941, and in late 1942, 200 P-47Cs had shipped to Britain for use as escort fighters.
In early 1942, the 8th Air Force suffered losses of 13.6% of its bomber strength when attacking targets in Western Europe.[8] The Allied bombers needed an escort fighter to protect them from German fighters. This need was initially satisfied by the P-47, which possessed adequate range, superior high-altitude performance to the Bf-109 and Fw-190, and unparalleled diving ability.[9] From 1942 through 1943, the P-47 was the primary USAAF fighter in the European Theater of Operations (ETO). The Messerschmitt Bf-109 was the Luftwaffe’s primary fighter and the P-47’s main opposition in the skies over Western Europe. The American B-17 Flying Fortress and B-24 Liberator bombers flew at approximately 25,000 feet and above, meaning that the Thunderbolt would be near its optimal altitude for maximum performance. Initially, the Thunderbolt pilots were reluctant to engage German fighters that attacked the bombers, although this quickly changed and by 1944 the Luftwaffe was running out of experienced fighter pilots, as many of them had been shot-down by Thunderbolts.[10]
The P-47B/C models were capable fighters at high altitude; they could fly at 429mph and were unmatched in a dive.[11] The P-47C differed from the P-47B primarily by its 2,300hp power output, 300 more than the P-47B. The P-47C also had the capacity to carry a 200gal drop-tank, its fuselage was lengthened by 10.5in, and had modifications made to its rudder and elevator balance systems to improve its flight characteristics.[12] However, both of these early versions of the Thunderbolt had some significant weaknesses. The P-47B and P-47C had poor acceleration and climbing ability: it took 20 minutes for the Thunderbolt to climb to 30,000ft, compared to 11 minutes for a Bf-109G and 14 minutes for an Fw-190A. While the Thunderbolt was a capable fighter once it reached high speeds and altitudes, “To try to engage Bf 109s and Fw 190s in dogfights below 15,000ft could be suicidal,” said Col. Hubert “Hub” Zemke of the 56th Fighter Group.[13] The P-47B and P-47C were not perfect, however their appearance in the ETO increased the pressure on the Luftwaffe by both inflicting losses on their fighters and enabled the USAAF to continue its daylight bombing raids.[14]
The early P-47Ds improved over the P-47C as the P-47C had improved over the P-47B. The early D-models featured moderate upgrades over the C-models: improved pilot armor, improved fuel systems, improved hydraulic systems, the addition of water injection, and later-on provisions for two 1,000lb bombs or three 500lb bombs. Water injection helped regulate the Thunderbolt’s engine temperature, which allowed the P-47 to maintain War Emergency Power (WEP, maximum possible output) for longer periods of time. The greatest improvement stemmed from the synergy of the water injection with the paddle-blade propellers, which were introduced on the later D-models. The improved Thunderbolt had a top speed of 433mph and could now climb to 30,000ft in 13 minutes instead of 20.[15]
The P-47M was a variant of the P-47 designed to intercept the V-1 flying bombs. The P-47M was similar to the D-model, except that it had an R-2800-57(C) engine fitted with a high-output CH-5 turbocharger, producing a total output of 2,800hp.[16] Although it was initially plagued by reliability issues, the P-47M was capable of 475mph,[17] making it arguably the fastest piston-engined fighter in World War Two. The P-47’s development culminated in the P-47N, which was conceived as a long-range version of the P-47. Although it arrived too late to fly in the ETO, the P-47N served in the Pacific as a fighter-bomber and escorted B-29s. The P-47N had 42’6” wings, versus the usual 40’9” wings, a difference of 21 inches; and could carry 1170 gallons of fuel in total, giving it a cruise range (not ferry radius) of 2190 miles.[18] The P-47N was also the heaviest Thunderbolt, frequently being flown at gross weights near 22,500lbs.[19] Surprisingly, the P-47N was able to roll 20% faster than the P-47D (98 degrees/second @ 300mph vs. 78 degrees/second @ 300mph). The P-47N had a top speed of 467mph thanks to its R-2800-57(C) engine, making it the second-fastest production Thunderbolt variant, bested only by the P-47M.[20]
The Thunderbolt was armed with six or eight Browning AN/M2 .50cal heavy machine guns, which combined with provisions for up to 2,500lbs of bombs and rockets made the Thunderbolt a powerful ground-attack aircraft. The Thunderbolt was also highly durable, given its sturdy wings, armor plating, and air-cooled engine. The air-cooled engine was less vulnerable than liquid-cooled engines because air-cooled engines did not have coolant which could leak when the engine was damaged. All of the top ten Thunderbolt aces in the ETO survived the war in spite of six of them having been shot down.[21]
While the P-51 Mustang possessed superior range and dogfighting ability to the P-47 Thunderbolt, the Thunderbolt continued to serve after the Mustang’s introduction, and following D-Day, the Thunderbolt was undertaking an increasing number of low-altitude missions, which led to some difficulties for the Thunderbolt pilots. However, due to mounting German losses, the Thunderbolt pilots saw an increase in their number of victories following the Battle of the Bulge in December 1944.[22]
The P-47 Thunderbolt flew nearly twice as many sorties as the P-51 Mustang, 423,435 versus 213,873, and Thunderbolts destroyed 4.6 enemy aircraft for every Thunderbolt that was lost from aerial combat.[23] While not as tight-turning as the German fighters, the Thunderbolt excelled as an energy fighter; diving from a high altitude to attack its enemies, and then escaping with a zoom-climb using the airspeed it had gained from the dive.[24] The 56th Fighter Group had accumulated more aerial victories than any other group in the ETO by VE-Day, and had the two highest-scoring American aces in the ETO, Lt. Col. “Gabby” Gabreski and Captain Robert S. Johnson, with 28 and 27 kills respectively. The 56th was also the only remaining fighter group in the Eighth Air Force that was still equipped with P-47 Thunderbolts by the end of the war, offering testimony to the Thunderbolt’s effectiveness.[25]
Sources
Footnotes
[1] Martin Bowman, P-47 Thunderbolt vs Bf 109G/K (Oxford: Osprey Publishing, 2008), 62.
[2] Warren M. Bodie, Republic's P-47 Thunderbolt: From Seversky to Victory, ed. Jeffrey L. Ethell (Hiawassee: Widewing Publications, 1994), 403.
[3] Ibid., 387-404.
[4] Martin Bowman, P-47 Thunderbolt vs Bf 109G/K (Oxford: Osprey Publishing, 2008), 58.
[5] Ibid., 15.
[6] Ibid., 10.
[7] Ibid., 9-10.
[8] Ibid., 4.
[9] Ibid., 58-59.
[10] Ibid., 60-61.
[11] Ibid., 58.
[12] Ibid., 22.
[13] Ibid., 59.
[14] Ibid., 37-39.
[15] Ibid., 13, 24-25.
[16] Ibid., 15, 26.
[17] Warren M. Bodie, Republic's P-47 Thunderbolt: From Seversky to Victory, ed. Jeffrey L. Ethell (Hiawassee: Widewing Publications, 1994), 401.
[18] Ibid., 387-403.
[19] Ibid., 402-403.
[20] Ibid., 403.
[21] Martin Bowman, P-47 Thunderbolt vs Bf 109G/K (Oxford: Osprey Publishing, 2008), 66.
[22] Ibid., 66.
[23] Ibid., 73.
[24] Ibid., 58-59.
[25] Ibid., 66.
In 1940, the United States Army Air Corps (USAAC) issued a requirement for new fighter designs. The Republic P-43 Lancer, powered by a turbocharged Pratt & Whitney R-1830 Twin Wasp radial engine, possessed good performance at high altitude, although overall it was inferior to other modern fighters such as the Supermarine Spitfire and Messerschmitt Bf-109E. This necessitated a new, more capable fighter to be designed. Republic initially responded with the AP-10, which was to be powered by a 1150hp Allison V-1710-39 liquid-cooled engine. The AP-10 was designated XP-47 and XP-47A, with the main difference being that the XP-47 guns in its wings and nose, while the XP-47A only had nose-mounted guns. Neither type was met with approval from the USAAC, prompting Republic to develop a new prototype, the XP-47B. The XP-47B first flew on May 6, 1941, with a gross weight of 12,086lbs, more than twice weight of some contemporary fighters.[6] It was powered by the most powerful engine available at the time: a turbocharged Pratt & Whitney R-2800-21 Double Wasp radial engine, which produced 2,000hp. The XP-47B attained a maximum speed of 412mph, in spite of its size and weight.[7] The first delivery of the P-47B occurred on December 21, 1941, and in late 1942, 200 P-47Cs had shipped to Britain for use as escort fighters.
In early 1942, the 8th Air Force suffered losses of 13.6% of its bomber strength when attacking targets in Western Europe.[8] The Allied bombers needed an escort fighter to protect them from German fighters. This need was initially satisfied by the P-47, which possessed adequate range, superior high-altitude performance to the Bf-109 and Fw-190, and unparalleled diving ability.[9] From 1942 through 1943, the P-47 was the primary USAAF fighter in the European Theater of Operations (ETO). The Messerschmitt Bf-109 was the Luftwaffe’s primary fighter and the P-47’s main opposition in the skies over Western Europe. The American B-17 Flying Fortress and B-24 Liberator bombers flew at approximately 25,000 feet and above, meaning that the Thunderbolt would be near its optimal altitude for maximum performance. Initially, the Thunderbolt pilots were reluctant to engage German fighters that attacked the bombers, although this quickly changed and by 1944 the Luftwaffe was running out of experienced fighter pilots, as many of them had been shot-down by Thunderbolts.[10]
The P-47B/C models were capable fighters at high altitude; they could fly at 429mph and were unmatched in a dive.[11] The P-47C differed from the P-47B primarily by its 2,300hp power output, 300 more than the P-47B. The P-47C also had the capacity to carry a 200gal drop-tank, its fuselage was lengthened by 10.5in, and had modifications made to its rudder and elevator balance systems to improve its flight characteristics.[12] However, both of these early versions of the Thunderbolt had some significant weaknesses. The P-47B and P-47C had poor acceleration and climbing ability: it took 20 minutes for the Thunderbolt to climb to 30,000ft, compared to 11 minutes for a Bf-109G and 14 minutes for an Fw-190A. While the Thunderbolt was a capable fighter once it reached high speeds and altitudes, “To try to engage Bf 109s and Fw 190s in dogfights below 15,000ft could be suicidal,” said Col. Hubert “Hub” Zemke of the 56th Fighter Group.[13] The P-47B and P-47C were not perfect, however their appearance in the ETO increased the pressure on the Luftwaffe by both inflicting losses on their fighters and enabled the USAAF to continue its daylight bombing raids.[14]
The early P-47Ds improved over the P-47C as the P-47C had improved over the P-47B. The early D-models featured moderate upgrades over the C-models: improved pilot armor, improved fuel systems, improved hydraulic systems, the addition of water injection, and later-on provisions for two 1,000lb bombs or three 500lb bombs. Water injection helped regulate the Thunderbolt’s engine temperature, which allowed the P-47 to maintain War Emergency Power (WEP, maximum possible output) for longer periods of time. The greatest improvement stemmed from the synergy of the water injection with the paddle-blade propellers, which were introduced on the later D-models. The improved Thunderbolt had a top speed of 433mph and could now climb to 30,000ft in 13 minutes instead of 20.[15]
The P-47M was a variant of the P-47 designed to intercept the V-1 flying bombs. The P-47M was similar to the D-model, except that it had an R-2800-57(C) engine fitted with a high-output CH-5 turbocharger, producing a total output of 2,800hp.[16] Although it was initially plagued by reliability issues, the P-47M was capable of 475mph,[17] making it arguably the fastest piston-engined fighter in World War Two. The P-47’s development culminated in the P-47N, which was conceived as a long-range version of the P-47. Although it arrived too late to fly in the ETO, the P-47N served in the Pacific as a fighter-bomber and escorted B-29s. The P-47N had 42’6” wings, versus the usual 40’9” wings, a difference of 21 inches; and could carry 1170 gallons of fuel in total, giving it a cruise range (not ferry radius) of 2190 miles.[18] The P-47N was also the heaviest Thunderbolt, frequently being flown at gross weights near 22,500lbs.[19] Surprisingly, the P-47N was able to roll 20% faster than the P-47D (98 degrees/second @ 300mph vs. 78 degrees/second @ 300mph). The P-47N had a top speed of 467mph thanks to its R-2800-57(C) engine, making it the second-fastest production Thunderbolt variant, bested only by the P-47M.[20]
The Thunderbolt was armed with six or eight Browning AN/M2 .50cal heavy machine guns, which combined with provisions for up to 2,500lbs of bombs and rockets made the Thunderbolt a powerful ground-attack aircraft. The Thunderbolt was also highly durable, given its sturdy wings, armor plating, and air-cooled engine. The air-cooled engine was less vulnerable than liquid-cooled engines because air-cooled engines did not have coolant which could leak when the engine was damaged. All of the top ten Thunderbolt aces in the ETO survived the war in spite of six of them having been shot down.[21]
While the P-51 Mustang possessed superior range and dogfighting ability to the P-47 Thunderbolt, the Thunderbolt continued to serve after the Mustang’s introduction, and following D-Day, the Thunderbolt was undertaking an increasing number of low-altitude missions, which led to some difficulties for the Thunderbolt pilots. However, due to mounting German losses, the Thunderbolt pilots saw an increase in their number of victories following the Battle of the Bulge in December 1944.[22]
The P-47 Thunderbolt flew nearly twice as many sorties as the P-51 Mustang, 423,435 versus 213,873, and Thunderbolts destroyed 4.6 enemy aircraft for every Thunderbolt that was lost from aerial combat.[23] While not as tight-turning as the German fighters, the Thunderbolt excelled as an energy fighter; diving from a high altitude to attack its enemies, and then escaping with a zoom-climb using the airspeed it had gained from the dive.[24] The 56th Fighter Group had accumulated more aerial victories than any other group in the ETO by VE-Day, and had the two highest-scoring American aces in the ETO, Lt. Col. “Gabby” Gabreski and Captain Robert S. Johnson, with 28 and 27 kills respectively. The 56th was also the only remaining fighter group in the Eighth Air Force that was still equipped with P-47 Thunderbolts by the end of the war, offering testimony to the Thunderbolt’s effectiveness.[25]
Sources
- Bodie, Warren M. Republic's P-47 Thunderbolt: From Seversky to Victory. Edited by Jeffrey L. Ethell. Hiawassee: Widewing Publications, 1994.
- Bowman, Martin. P-47 Thunderbolt vs Bf 109G/K. Oxford: Osprey Publishing, 2008.
- Image Credit: https://upload.wikimedia.org/wikipedia/commons/1/1b/P-47D-40_Thunderbolt_44-95471_side.jpg
Footnotes
[1] Martin Bowman, P-47 Thunderbolt vs Bf 109G/K (Oxford: Osprey Publishing, 2008), 62.
[2] Warren M. Bodie, Republic's P-47 Thunderbolt: From Seversky to Victory, ed. Jeffrey L. Ethell (Hiawassee: Widewing Publications, 1994), 403.
[3] Ibid., 387-404.
[4] Martin Bowman, P-47 Thunderbolt vs Bf 109G/K (Oxford: Osprey Publishing, 2008), 58.
[5] Ibid., 15.
[6] Ibid., 10.
[7] Ibid., 9-10.
[8] Ibid., 4.
[9] Ibid., 58-59.
[10] Ibid., 60-61.
[11] Ibid., 58.
[12] Ibid., 22.
[13] Ibid., 59.
[14] Ibid., 37-39.
[15] Ibid., 13, 24-25.
[16] Ibid., 15, 26.
[17] Warren M. Bodie, Republic's P-47 Thunderbolt: From Seversky to Victory, ed. Jeffrey L. Ethell (Hiawassee: Widewing Publications, 1994), 401.
[18] Ibid., 387-403.
[19] Ibid., 402-403.
[20] Ibid., 403.
[21] Martin Bowman, P-47 Thunderbolt vs Bf 109G/K (Oxford: Osprey Publishing, 2008), 66.
[22] Ibid., 66.
[23] Ibid., 73.
[24] Ibid., 58-59.
[25] Ibid., 66.