Tools of War: Republic P-47 Thunderbolt — The Military Historian (2024)

When thinking of aerial warfare, it is common to recall the glamorous and sleek fighters that engaged in tumbling dogfights high above the earth. Several such aircraft are remembered include the P-51 Mustang, the Me-109, the Spitfire, and the A6M Zero. However, the Second World War also saw the rise of fighter bombers, aircraft which would take on multiple roles, including that of supporting advancing ground troops. The best example from that war was the Republic P-47 “Thunderbolt”.

By Seth Marshall

In the late 1930s, as war clouds gathered on the horizon, leaders of the United States Army Air Forces (USAAF) recognized that their existing fighter aircraft were outdated and would be unable to compete with the modern fighters that were being developed and seeing early combat over Europe at the time. Their response was to ask multiple aircraft firms to submit their proposals for fighter designs. One of the many companies to answer the call was Republic Aviation. Though Republic’s name was a new one in the aircraft industry, it was actually the successor to the Seversky Aero Corporation. Seversky was founded in 1931 by a Russian emigre, Alexander de Seversky. Seversky had designed two fighter aircraft, the P-35 and the P-43.

The P-35, a stubby radial-engined fighter, was a notable step forward for the USAAC, with its all-metal construction, retractable landing gear, and enclosed co*ckpit. The P-43 Lancer was a follow-on to the P-35; designed by Seversky’s head engineer, a Georgian émigré named Alexander Kartveli, the P-43 was powered by a 1200-horsepower Pratt & Whitney which could allow the fighter to reach a maximum speed of 356 mph at 20,000 feet. However, the P-43 had primarily been marketed as an export fighter- of the 272 built, 51 were delivered to China, while still others were delivered to European countries.[1] Those that did see US service were considered obsolete almost from the time they were delivered. As a result, and in order to fulfill a 1939 USAAC request for a high-altitude interceptor, the Seversky design team began working on a new fighter which would incorporate the experiences gained from working on the P-35 and P-43.

By this time, Seversky Aero Corporation had been renamed Republic Aviation. The founder, Seversky himself, had been ousted while in Europe in 1939 by a company board vote. The new aircraft would be again designed by Kartveli. Kartveli’s creation featured many characteristics shared with the P-43- it would be powered by a large radial engine and feature a co*ke-bottle-shaped fuselage. Kartveli’s first design was actually finished before the USAAC request was issued- the P-47A would be powered by a 1,150-horsepower Allison engine and armed with two .50 caliber machine guns. The USAAC request called for an aircraft which could fly at 400 mph at 25,000 ft, carry an armament of six .50 caliber machine guns, carry armor-plating for pilot protection, be equipped with self-sealing fuel tanks, and be capable of carrying 315 gallons of fuel.[2] Based on these specifications, the existing P-47A design was already outdated. As a result, Kartveli had to immediately set about upgrading the new aircraft. After revisions, Kartveli’s P-47B was powered by a 2,000-horsepower Pratt & Whitney Double Wasp radial engine equipped with a turbo supercharger, a three-bladed propeller, and eight .50 caliber machine guns. Owing to the ducting required to drive the turbo supercharger at altitude, the P-47’s size was tremendous. When fully loaded, the new fighter would weigh over 12,000 lbs, far heavier than contemporary fighters. The new design seemed promising, enough so that the USAAC placed an order in September 1940.

The XP-47B first flew on May 6, 1941, with Lowry L. Brabham at the controls. The first flight did not go as planned- Brabham had to make an emergency landing because of exhaust fumes leaking into the co*ckpit. However, the performance of the enormous new aircraft was better than Kartveli had hoped for- the XP-47B could achieve 412 mph at over 20,000 feet, and it could climb to 15,000 feet in five minutes. However, in addition to the fume problem, there were other issues. After the first production P-47s began to be delivered to the USAAF in March 1942, one of the new fighters crashed into a golf course on March 26, 1942, killing the pilot. It was determined that the tail assembly had broken off in flight- further investigation found that at high altitudes, the fabric-covered control surfaces would burst, eliminating their effectiveness, and the canopy could not be opened, trapping the pilot. Eventually, the problem was solved by using all-metal construction for the control surfaces, reshaping them, and adding trim tabs for additional control.[3] The canopy was replaced with a new one which could be jettisoned by the pilot in the event he needed to bail out. In spite of a turbulent testing period, the USAAF placed an initial order for 171 P-47Bs and 602 P-47Cs.[4]

In mid-1942, the 56th Fighter Group, based at Farmingdale, New York, was chosen as the first fighter group to be equipped with the P-47. This decision was primarily made owing to the proximity of the group to the Republic Aviation factory. The 56th had a very difficult period of breaking in their new mounts- during training, 41 P-47Bs were lost and 13 pilots killed. Though pilot error was a problem in some cases, many crashes were caused by continual teething problems. One phenomena which was encountered by P-47 pilots was compressability, a previously unknown occurrence. During a high-speed dive, air moving across the control surfaces becomes more dense, preventing control surfaces from being effective. Additional, air can be traveling at supersonic speeds across various surfaces while the aircraft itself is subsonic. This can cause buffeting, and can potentially lead to the aircraft breaking up in flight.[5] Eventually, these problems were overcome with the installation of dive flaps, making the P-47 a safer aircraft.[6]

The 56th Fighter ultimately proved to be the first Thunderbolt-equipped fighter group to be sent overseas. Two other Fighter Groups, the 78th and the 4th, had preceded the 56th in deploying- both of these units converted to P-47s not long afterwards. This was done, in the case of the 78th, because it had lost most of the P-38s with which it had been formed to the North African theater. Pilots in the 78th and the 4th were unimpressed by their new aircraft, which they derided as “seven-ton milk bottles.” This would eventually lead the Thunderbolt’s nickname- the “Jug.”[7]

The P-47’s first operational missions occurred in March 1943 and were relatively uneventful. These flights were really training flights over German-occupied territory, intended more to give their pilots experience than to target German aircraft. However, with the Luftwaffe’s strength in the West being what it was at that time, these flights did not remain quiet for long. On April 15, 1943, a flight of P-47s from the 4th Fighter Group encountered a group of Focke-Wulfe FW-190s. Former Eagle Squadron pilot Don Blakeslee caught up with one of the German fighters in a dive and shot it down, scoring the Thunderbolt’s first victory. However, the former Spitfire pilot was not overly enthused with the aircraft, remarking, “It oughta dive, it sure can’t climb.”[8]

Blakeslee’s comment was not entirely wrong. At the high altitudes that it was built for, the P-47 would prove that it was generally superior to Luftwaffe aircraft. However, at lower altitudes, it was found that the German aircraft had both superior turn and climb rates. Owing to its weight and powerful engine, it was found that at lower altitudes, the P-47’s best tactic was diving. Despite its shortcomings, the Thunderbolt was quickly pressed into service as a bomber escort. The first escort mission took place on May 4, 1943, when 117 P-47s from all three P-47 groups escorted 8th Air Force B-17s and B-24s to bomb Antwerp and Paris.[9] On these early missions, early model P-47s had mixed results. When they did engage German fighters, they had modest success. However, these P-47s did not have the range to escort their bombers all the way to targets inside of German, and had to turn back near the German border. As a result, the Luftwaffe simply had to wait until the bombers’ escort had turned for home, then they would pounce. As 1943 went on, 8th Air Force bomber losses became appalling; two raids on Schweinfurt on August 17th and October 17th respectively resulted in the loss of 60 bombers each. Until fighters with longer range could be made more readily available, stopgap solutions with the P-47 would have to be found. The best option seemed to be the addition of drop tanks. The first Thunderbolt mission with drop tanks to extend range was on July 28th, 1943 to Oschersleben and Kassel. Initially, large 200-gallon ferry tanks were used, but these were unpressurized and could not be used at altitudes above 23,000 feet. This resulted in a switch to 75-gallon teardrop-shaped tanks, which were more suitable. A third version emerged in the fall of 1943 with a centerline 108-gallon tank. This configuration finally allowed Thunderbolts to escort the bombers all the way to the target on September 27th, when the 8th Air Force hit Emden.[10] Additional improvements to the fighter’s design were made to continually improve its performance. The P-47D-20-RE saw a number of improvements: the so-called “universal wing,” designed to carry a variety of ordnance (which would greatly enhance its lethality as a fighter bomber), a four-bladed “paddle” propeller to improve rate of climb (now up to 2,750 feet per minute), and the water-injection R-2800-21 engine, which had a war emergency rating of 2300 horsepower.[11]

Around the same time period that the first P-47 units were being sent to Europe, additional fighter groups were formed and sent to the Pacific. The first of these was the 348th Fighter Group, which was made a part of the 5th Air Force in the Southwest Pacific. Under the leadership of LTC Neel Kirby, this unit demonstrated the potential of the P-47 as a fighter bomber over New Guinea. Two additional groups, the 35th and 48th, replaced their P-40s and P-39s with Thunderbolts soon after. Just as in Europe, the P-47s range was found to be an issue, particularly given the distances involved in flying from island to island in the Pacific. Drop tanks were again used as the solution- eventually, 5th Air Force technicians developed 200-gallon tanks to help cope with the problem.[12] Additional help in the Pacific came in the form of aviation legend Charles Lindbergh. Lindbergh had been fulfilling the role of civilian consultant to the military by advising Pacific units on how best to maximize their aircraft’s range. He had previously worked with F4U Corsair and P-38 Lightning units.

Back in Europe, Thunderbolt escort missions continued. By early 1944, Thunderbolts were carrying 150-gallon tanks to escort their charges all the way to their targets in Germany. During the third week of February 1944, known as “Big Week”, P-47s were used extensively in escort missions. On February 20, 1944, for example, 668 Thunderbolts escorted over 1,000 heavy bombers. Combined with additional protection from P-38 Lightnings and P-51 Mustangs, Thunderbolts wreaked havoc on the Luftwaffe’s strength in western Europe, causing large losses which temporarily forced the Luftwaffe from the skies.[13] Improvements were continually made to the big fighter in an effort to better its performance. The P-47D-25 changed the shape of the aircraft- the framed canopy and raised rear fuselage was replaced by a tear-drop-shaped canopy and cut-down rear fuselage, greatly improving rear visibility for the pilot. In late 1944, the P-47M was debuted as a limited response to the introduction of the V-1. 130 of these aircraft, powered by a 2,500-horsepower engine pushing the Thunderbolt to a maximum speed of 473mph at 30,000 feet. These aircraft were specifically intended to counter V-1 flying bombs.[14]

Even as P-47s were being used as escort fighters, there was an increasing trend of using the aircraft as a ground-attack plane. This is perhaps inevitable, given the Jug’s immense payload capacity. It could carry up to 3,000lbs of external ordnance including general purpose bombs, M10 rockets, fragmentation bombs, napalm tanks, and later in the war 4.5-inch High Velocity Aerial Rockets (HVARs). One configuration even featured a 1,000lbs bomb on each wing.[15] Paired with eight .50 caliber machine guns with 3400 rounds stored in the wings, the P-47 would prove to be an outstanding fighter bomber. The first use of the Thunderbolt as a fighter bomber came on November 25, 1943. Aircraft from the 56th and 353rd Fighter Groups, armed with a single 500lbs bomb, struck airfields in the St. Omer area of France.[16] Several months later in March 1944, 8th Fighter Command leader Brigadier Genearl Bill Kepner ordered a squadron of P-47s to form and develop ground strafing techniques. These pilots first practiced over airfields in England before undertaking a number of operational missions over the Continent. At the end of March, the pilots were returned to their units to instruct others on low-level attacks.[17]

At around the same time as these early fighter bomber missions were taking place, the P-51 Mustang began arriving in large numbers in England. With the 8th Air Force focused on the strategic bombing of Germany, most of its fighter groups began converting to the Mustang and handing over their P-47s. These used Thunderbolts, along with new ones being shipped to the theater, were used to begin building up the 9th Air Force. Unlike the 8th Air Force, the 9th was intended to provide tactical air support to ground forces. The 9th Air Force did have a bomber component, but this was made up of medium bombers intended to be used against transportation and communication hubs. The larger elements were the Tactical Air Commands (TACs). The 9th had two TACs- IX TAC, which was equipped with three Fighter Wings (each made up of 3-4 fighter groups), and XIX TAC had two Fighter Wings. IX TAC, commanded by then-Brigadier General Elwood “Pete” Quesada, supported Lieutenant General Omar Bradley’s First Army, while XIX TAC, commanded by then-Brigadier General Otto Weyland, provided supported to Lieutenant General George S. Patton.[18]

Following the invasion of Normandy, these TACs would play a significant role in the forward progress of American armies. After D-Day, P-47 units would engage in armored column cover missions, a tactic devised by Quesada, which involved several flights of heavily armed P-47s flying overhead of a tank column as it advanced. A liaison on the ground with the tanks, frequently a fighter pilot in a specially modified tank, would radio the circling fighter bombers regarding targets impeding the advance.[19] The P-47s would then act as on-call heavy artillery, hitting the target with bombs, rockets, and heavy machine gun fire. An additional tactic, armed reconnaissance, saw fighter bombers roaming as much as 30 miles in front of advancing columns and attacking targets of opportunity. As the Allies expanded their beachhead in mainland Europe, engineers worked to establish airfields and shorten the distance fighter bombers would have to travel for support. Two weeks after D-Day, five airfields had been established in France to support the fighter-bombers. By the end of the month, Quesada’s IX TAC had flown 26,000 sorties on 800 missions, claimed 204 enemy planes destroyed, as well as the destruction of 24 bridges, 506 railroad engines and cars, and nearly 1300 vehicles.[20] Operations would increase even more when the breakout from Normandy began in late July.

When Operation Cobra commenced on July 25, 1944, P-47 ground attack missions increased tremendously as the tanks on the ground began to break out. P-47 units were quickly relocated to the Continent to support the advancing tanks. One, the 50th Fighter Group, reported a typical day’s operations for July 29th- its three P-47 squadrons flew a total of 23 missions, losing three aircraft to flak, another three damaged, and claiming the destruction of 46 tanks, 80 other vehicles, 8 towed artillery pieces, and an estimated 80 German soldiers killed.[21] By this point in the war, the Luftwaffe on the western front was but a shadow of its former self- the primary threat to fighter bombers supporting the American advance came in the form of flak. A typical German infantry division was equipped with 84 20mm AA guns, while a panzer division could be equipped with up to 21 self-propelled AA guns, 50 towed guns, and 32 truck or half-track-mounted guns.[22]

“Ground attack pilots often had to contend with formidable concentrations of small caliber flak that was very effective up to 3000 feet and the fire of which was not visible to them; therefore they were briefed to come below 3000 feet only when carrying out their attacks. Heavy caliber automatic flak (20mm-40mm) was effective up to 6000 feet and its explosions were easily seen by the pilots; fighter-bomber formations usually flew at 7500-8000 feet, which was just out of range.”[23]

With such heavy amounts of flak then, it is unsurprising that fighter bombers suffered a far higher rate of loss to ground fire than to hostile fighters. From the start of Operation Cobra on July 25 to August 7th, IX TAC lost 80 aircraft- 49% were lost to flak, 24% to small arms fire, 24% to unknown causes, and just 7% to enemy fighters.[24]

Despite the high losses, the fighter bombers continued their grim work against German ground forces. As Allied armor began exploiting the frail German defenses in the wake of Cobra’s opening salvoes, large German convoys began attempting to fall back, only to set upon by fighter bombers. During the last week of July alone, Quesada’s IX TAC flew 9000 close air support sorties, and his pilots had claimed destruction of 384 tanks, over 2200 vehicles, and almost 100 artillery pieces.[25] On a sortie which could be described as typical of the period, the 405th Fighter Group tore into a German convoy on July 29th:

“On the afternoon of 29 July P-47s of the American 405th Fighter Group observed this dense mass of German transport, including tanks, on the roads near Coutances and on the road between St. Denis-le-Vetu and Roncey they saw a column extending for over three miles blocked by American armor to east and west. Between 310 and 940 p.m. the P-47s of the 405th Group systematically bombed and strafed this column, returning to their base to rearm and refuel before returning to the attack. Two days later American ground forces found the road impassable, and discovered 66 German tanks, 204 vehicles, and 11 guns destroyed, and 56 tanks and 55 vehicles damaged. This destruction was the result of the combined firepower of P-47s and artillery and tanks of nearby American ground units.”[26]

As the German retreat from Normandy increased in desperation, their slaughter by fighter bombers such as the P-47 only increased. The apex of this bloodbath would come during the Allied attempt to close the Falaise Gap. During this period, as thousands of vehicles and tens of thousands of soldiers tried to escape encirclement, fighter-bombers wreaked havoc among the retreating Germans. German tank commander Hans von Luck recalled, “Enemy planes were swooping down uninterruptedly on anything that moved. I could see the mushroom clouds of exploding bombs, burning vehicles, and the wounded, who were picked up by retreating transports.”[27] Jack Dentz, a pilot with the 386th Fighter Squadron, later remembered, “We went in like flying artillery and just destroyed it all… It was hideous. It was the only time I actually came home feeling sick. I killed over 60 horses on just one mission; they had been pulling 88mm guns.”[28]

The ground-attack missions, while successful, were not without cost. German units put up a tremendous amount of flak. During the length of its European campaign, XIX Tactical Air Command lost nearly 600 pilots either killed or missing, an average of two per day. During the summer of 1944, an average of 227 fighters were shot down per month, most to flak.[29] Fortunately, the P-47 proved to be one of the most rugged aircraft of the Second World War. Eventual ace Robert Johnson, of the 56th Fighter Group, had a narrow escape from a formation of FW-190s on June 26, 1943. One FW-190 hit Johnson’s P-47 with 21 20mm cannon shells, cutting Johnson’s hydraulics and jamming his canopy shut, preventing him from bailing out. One shell had also set fire to his aircraft, and Johnson was temporarily blinded by spraying hydraulic fluid- he had also been wounded by shrapnel in the leg and nose. Regaining control of his holed aircraft, Johnson headed for the English Channel, only to be set upon by another FW-190, which pumped his aircraft full of 7.92mm machine gun rounds. Eventually the German aircraft ran out of ammunition, pulled alongside Johnson, saluted, then flew off. Johnson managed to return his aircraft to base, he gave up counting holes in his aircraft after numbering 200. Johnson would eventually go on to become one of the highest-scoring P-47 aces, shooting down 27 German aircraft by June 1944. [30] The highest-scoring P-47 ace was Francis Gabreski, who shot down 28 German planes. Gabreski’s 28 kills also made him the highest-scoring American ace in the European Theater. Despite the gradual replacement of the Thunderbolt as an escort fighter by the P-51 Mustang, during over 746,000 missions flown by the P-47 pilots claimed 3,752 enemy planes shot down.[31] The most successful P-47 unit was the 56th Fighter Group, which at the end of the war was the only fighter group in the 8th Air Force still flying the Jug- it claimed 647 aerial victories and 311 more planes destroyed on the ground. Against these claims, the 56th had lost 128 Thunderbolts.[32] 9th Air Force P-47 groups, while focused on their ground attack missions, also claimed aerial victories. The 368th Fighter Group claimed 143 enemy planes shot down and 98 more destroyed on the ground from March 1944 to May 1945. During the same period, that group also claimed the destruction of nearly 500 tanks, 3174 rail cars, 33 bridges, 31 barges, and 187 artillery pieces.[33]

The final variant of the Thunderbolt to be produced was the P-47N. The heaviest of all of the Jugs, weighing in at 21,200lbs, was designed specifically with escort duties in mind. With external tanks, the P-47N had a combat radius of 1000 miles. Over 1800 of these final Jugs were produced, but few saw action before the war finally ended in August 1945.[34] Final production of the P-47 totaled 15,683- 5,222 were lost in combat operations.[35] With the surrender of Japan, P-47 production was cancelled. Many Thunderbolts were scrapped, which was common occurrence with most warplanes at the end of the war. In 1948, the P-47 was redesignated the F-47 in keeping with a new nomenclature system. F-47s would equip numerous Air National Guard squadrons until well into the 1950s. Air Force leaders discussed using the F-47 in Korea for close air support- the F-51 (previously known as the P-51) was in widespread use there, but took heavy losses from ground fire because of their more vulnerable liquid-cooled engines. However, by this time, F-47s and spare parts were in relatively short supply, so the Mustang continued to be used as a ground support aircraft in Korea.[36] F-47s would soldier on with a number of foreign air forces into the 1960s before the last examples in service were finally retired.

Though the Thunderbolt was overshadowed by the Mustang as the eminent American fighter of World War II, the Thunderbolt proved to be a far more capable ground attack aircraft which came to be feared by German ground forces. Perhaps most importantly, the use of the Thunderbolt for ground attack was a precursor to the transition among the Air Force and Navy to fighter-bombers as the primary type of combat aircraft. The Thunderbolt remains arguably the best fighter-bomber aircraft of World War II.