The rapid development of aircraft construction in the thirties brought fame to the American firm Seversky. It was founded in 1928 by engineer and pilot Alexander Seversky who left Russia. The firm of this Russian emigrant was mainly engaged in the development and production of amphibious aircraft.
By the forties A. Seversky left the direct management of the company. And in the summer of 1939 it received a new name "Republic Aviation Corporation", or more simply - "Republic". American Alfred Marchev became its president. Alexander Kartvelli, a talented engineer and also a Russian emigrant, remained vice-president and chief designer. He worked with Alexander Seversky for a long period and preserved many of Seversky's ideas and handwriting in his cars.
In 1940, the company developed a new fighter P-43 "Lancer", which had a maximum speed of 570 km / h and had a range of up to 1000 km. However, the aircraft no longer met the requirements of the US Air Force. At that time, the American corporations Lockheed, Bell and Curtiss created the P-38, P-39, P-40 fighters, and they had much higher flight and technical characteristics.
However, among the large number of aircraft types in the US Air Force, there was no single-engine long-range, high-altitude and high-speed heavy escort fighter to protect long-range strategic bombers. In 1940, representatives of the US Air Force signed a contract with the firm for $ 62 million for the serial production of such an aircraft.
On May 6, 1941, an experimental prototype of the fighter, which received the designation XP-47B, took to the air. The flight characteristics of the car exceeded all expectations. In horizontal flight, it accelerated to 657 km / h, which was 50-70 km / h higher than that of all other fighters of that time, with the exception of the Soviet MiG-3, which had a speed of 640 km / h.
The aircraft was equipped with the latest Pratt-Whittney XR-2800-21 turbocharged engine (at maximum power its power reached 2000 hp). No other fighter in the world had such a powerful engine at that time. At that time, it was turbochargers that became the Achilles heel of all high-speed cars. The solid weight and technical imperfection of these devices, frequent failures negated all the advantages of such power plants.
Most of the designers did not manage to solve the problem of the reliability of the turbocharger drive with the red-hot exhaust gases of the engine, which quickly burned through its turbine. But Kartvelli found a rather original solution. He mounted the turbocharger not on the engine, as was customary, but in the aft fuselage. He stretched the air ducts and a long exhaust pipe almost through the entire fuselage. This, of course, led to a significant increase in the weight of the aircraft structure. But the turbocharger, which had already cooled down exhaust gases, worked without interruption. Managed to significantly reduce the length of the nose of the fuselage, which made it possible to somewhat improve the pilot's view from the cockpit.
Kartvelli also used an original exhaust system on the fighter. When the engine was operating in the nominal mode, the exhaust from each cylinder was discharged into a single manifold and expelled through two adjustable nozzles located on the sides in the nose of the aircraft. When the pilot needed to increase the power of the power plant, in addition to adding fuel, he blocked the nozzle flaps. In this case, the red-hot exhaust gases were redirected to the turbocharger, and then exited into a common nozzle, which was located under the tail assembly.
At the same time, another technical problem was solved. When compressed in a turbocharger, the air was quite hot, and it had to be cooled before being fed into the motor. And now a pipeline with hot air was led through a conventional air radiator, which was also located in the aft fuselage. The air required for the radiator entered through the frontal air intake located under the power plant. Then it passed through a long duct. He cooled the heated air passing from the turbocharger to the engine in the radiator and exited through two flat nozzles located on the sides of the fuselage in the tail section. A certain amount of heated air from the turbocharger was also directed in the plane of the wings to heat the lubricant for machine guns during high-altitude flights.
Cartwelli tried to improve the aerodynamics of the new aircraft. As the initial, they took an external form, similar to that of the Lancer fighter. The well-streamlined nose of the fuselage, despite its rather large cross-section, is very aerodynamically perfect. The cockpit canopy was distinguished by a pointed bow. Behind it, it passed into an elongated thin gargrot.
Kartvelli installed a wing with a relatively small area on the P-47. And if for almost all fighters of that time the specific wing load was about 150-200 kg / m2, then for the P-47 this value reached 213 kg / m2. And by the end of World War II, it even increased to 260 kg / m2. To place the main landing gear in a relatively small wing, the designers had to mount special devices on them that reduce the length of the landing gear at the time of cleaning.
However, despite the excellent altitude and speed characteristics, as well as good armament, the P-47 fighter showed insufficient maneuverability. This was primarily due to the very heavy weight of the airframe structure and the large volume of fuel tanks. The flight weight of even the prototype reached 5.5 tons (later increased to 9 tons). This came close to the weight of some twin-engined bombers and was practically twice that of most fighters of the time. The heaviest units, such as the engine, compressor, armament with ammunition, were located at a distance from the center of gravity, this also had an extremely negative effect on the maneuverability of the fighter.
In the spring of 1942, the first production vehicles with the designation P-47B for the US Air Force left the shops of the Repablic plant. In November 1942, they began to enter the combat units of the British Air Force.
The appearance of "thunderbolts" on the fronts of World War II allowed the Allied bomber aviation to gradually switch from night to day raids on the most important industrial centers of Nazi Germany.
In the winter of 1942, the Republican firm received a second order for the supply of P-47 fighters. Therefore, the company had to completely stop the production of other types of aircraft.
During the testing and operation of the R-47, one very serious drawback came to light. Despite the huge fuel supply of 1155 liters, the maximum flight range at a speed of 0.9 from the maximum was about 730 km. Naturally, such speeds were not required to escort the bombers, and the Thunderbolt flew up to 1500 km in the most advantageous mode of operation of the power plant. However, in the event of an air battle, fuel was consumed too quickly, and there was not enough fuel to return. This led to the creation of a new modification, which received the designation P-47C. This "Thunderbolt" could carry an additional outboard tank with a volume of up to 750 liters under the fuselage, and its flight range immediately increased to 2000 km. To ensure the normal operation of the engine for a long time, the volume of the oil tank was increased.
In 1942, the production of "thunderbolts" of the S-1 series began. On these machines, water was injected into the working mixture, which entered the engine cylinders. This allowed for a short period of 5 minutes to increase its power by 300 hp. This mode of operation of the power plant was called emergency. By increasing the power of the power plant, the R-47 aircraft of the S-1 - S-5 series, despite the increase in flight weight to 6776 kg, were able to fly at speeds up to 697 km / h at an altitude of 9000 m.
Due to the placement of a 57-liter water tank, the length of their fuselages increased by 20 cm. Since 1943, the production of the P-47D aircraft, the most massive version of the P-47 fighter, began. As a rule, they were equipped with a pair of additional underwing holders. They could hang two fuel tanks with a capacity of 568 liters. The total fuel supply reached 2574 liters. The flight range reached - 3000 km.
The US Air Force was in dire need of such aircraft: the squadrons of "flying fortresses" continued to suffer heavy losses from German interceptors. Therefore, in 1943, the US government transferred another state-owned plant in Evansville, Indiana, to the Republican company.
Codenamed P-47G, "Thunderbolts" were also produced by the Curtiss-Wright aircraft company at their plant in Buffalo, New York. The letters CU were added to the designation of these machines (the first two letters of the company name). The fighters produced at the factories of the Republican company (in the cities of Farmingdale and Evansville) additionally received the letters RE and RA in the designation, respectively.
In 1944, one of the P-47D-10RE fighters with the R-2800-63 engine was tested in the USSR. The design of the fighter was thoroughly studied at the Bureau of New Technology of TsAGI. The pilots of the LII and the Air Force Research Institute conducted tests of the Thunderbolt in the air, refined its flight performance, which, as was usually the case for American technology, turned out to be somewhat lower than those declared by the company.
Overall, the P-47 disappointed our test pilots. The famous engineer-pilot of the LII M. L. Gallay described his impressions of the Thunderbolt in the following way: “Already in the first minutes of the flight, I realized - this is not a fighter! Stable, with a spacious and comfortable cockpit, comfortable, but not a fighter. The P-47 had unsatisfactory maneuverability in the horizontal and especially in the vertical plane. The fighter accelerated slowly, was inert due to its heavy weight. This plane was perfect for a simple en-route flight without harsh maneuvers. But this is not enough for a fighter."
Thunderbolt fighters were not suitable for the Soviet Air Force. Designed to escort long-range high-altitude bombers, they were out of work in our country. At this time, almost all Soviet fighters were involved exclusively in performing tactical combat missions - providing air cover for ground forces from attacks by German bombers, escorting their front-line bombers and attack aircraft, and destroying enemy aircraft in the air. In addition, the Germans carried out almost all air operations on the Eastern Front at altitudes below 5000 m. Nevertheless, about 200 Thunderbolt fighters entered service with our Air Force.
The Americans used the P-47 like this. B-17 bombers walked in close formation and created dense defensive fire, reliably defending themselves. "Thunderbolts" also acted in rather large groups and drove off "Messerschmitts" and "Fockewulfs" on the distant approaches to the bombers, did not give the enemy the opportunity to attack effectively. The "Thunderbolts" did not have so many victories - one shot down or damaged enemy aircraft on 45 sorties, although some P-47 pilots still had a combat score of more than a dozen downed aircraft. The most productive were Francis Gabreski and Robert Johnson (each had 28 wins), David Schilling (22), Fred Christensen (21), Walter Mahuren (20), Walter Bescam and Gerald Johnson (18).
In 1944, a second front was opened in the West. Thunderbolts were used to attack ground targets from low altitudes. And this is not surprising. Indeed, in the US aviation there was no specialized attack aircraft, and the P-39, P-40, P-51 and, of course, the P-47 were rather widely involved in performing its tasks.
He turned out to be more adapted to this. The P-47 had a long range, it could reach the deep rear of the enemy. True, the speed at the ground, and especially with suspended bombs, turned out to be lower than that of the main Nazi fighters. But other dive bombers and attack aircraft were left far behind. In addition, the Thunderbolt could carry a fairly heavy bomb load. R-47 (series from D-6 to D-11, as well as G-10 and G-15) on the ventral holder instead of an additional tank took one 227-kilogram bomb or several bombs of lesser weight. A little later, starting with the D-15 series, two more were hung, 454 kg each. They were located on the underwing hardpoints. Thus, the total bomb load reached 1135 kg, which was comparable to the combat load of many bombers of that period.
The P-47 had powerful machine-gun armament. Of course, this did not allow him to effectively fire at enemy tanks, like the Il-2 or Ju-87C, on which 23 and 37 mm cannons were mounted. However, eight large-caliber machine guns turned out to be quite enough to destroy cars, steam locomotives and other similar equipment, to destroy manpower.
Many Thunderbolts carried six rocket launchers with bazookas. Such formidable P-47 squadrons, together with the British Typhoon and Mosquito attack aircraft, during the landing of the Anglo-American troops in Normandy, practically managed to disrupt the transport of Hitler's troops and did not allow the Germans to deliver reinforcements in time.
The Thunderbolt was a fairly tenacious machine. This was facilitated by the air-cooled radial motor and the absence of fuel tanks in the wing, which, due to their large area, were usually the first to be hit. The fuel tanks in the fuselage were sealed.
The pilot was additionally protected from the front with bulletproof glass and steel armor plate, and when attacked from behind - with an armored back plate, an intermediate radiator and a turbocharger, their damage did not lead to a fall of the aircraft. The air cooler tunnel, which ran under the fuselage, as well as the exhaust pipe and air ducts stretched along its sides, covered the pilot, tanks and other vital structural elements and assemblies.
The most interesting and unusual element in the design of the P-47 was a special steel truss ski located under the fuselage. She protected the fighter from destruction in the event of a forced landing with the landing gear retracted. In a word, the P-47 turned into a fighter-bomber.
Simultaneously with the serial production of the Thunderbolt, Republican was looking for ways to further improve the aircraft. Several experimental machines were created. In particular, a pressurized cockpit was installed on one of the R-47V fighters. On the other - a wing with a laminar profile, which had less drag compared to the usual one. These aircraft were designated XP-47E and XP-47F, respectively.
But the main emphasis was placed on experimental cars with other engines. One of them, the XP-47N aircraft, was the most different from all the P-47 variants. An experimental 16-cylinder liquid-cooled engine Chrysler XI-2220-11 with a takeoff power of 2500 hp was installed on this machine.
True, the XP-47N took a long time to finish. Its first flight took place only at the end of July 1945. The maximum speed did not exceed 666 km / h.
The experimental vehicle, which had the designation XP-47J, turned out to be more successful. It was a lightweight fighter with a takeoff weight of 5630 kg. The armament was standard - six machine guns. Air-cooled motor R-2800-57 with a takeoff power of 2800 hp. In July 1944, this aircraft reached a maximum speed of 793 km / h, then, in the fall of the same year, 813 km / h at an altitude of 10,500 m.
During flight tests, according to the US Air Force, the XP-47J reached a speed of 816 km / h. The rate of climb was almost 30 m / s. In terms of its high-altitude and speed characteristics, it surpassed all piston aircraft known at that time in the world.(The only confusing thing is that the official flight speed has never been registered as a world record.)
In 1944, another experimental XP-72 fighter was created under the leadership of A. Kartvelli. In fact, it was an ordinary Thunderbolt equipped with an R-4360 Wasp Major engine with a capacity of 3650 hp. (which led to a significant change in the shape of the nose of the aircraft). Two examples of the fighter were built. On one of them, a conventional four-bladed propeller was installed, on the other - two coaxial three-bladed ones. The maximum speed of the latter reached 788 km / h at an altitude of 6700 m.
Despite the high results achieved, the new cars did not go into series. The engines were not reliable, the aircraft required a lot of fine tuning, and the maneuverability became even worse. In addition, the Second World War was already coming to an end, and the board of the Republican company decided, without interfering with the rate of production of fighters, to carry out their evolutionary improvement.
Thus, a new large-diameter propeller with blades of a different configuration was installed on the P-47D series 22 fighter. The rate of climb increased by almost 2 m / s.
Since 1944, starting with the D-25 modification, the P-47 fighters began to be produced with a new drop-shaped cockpit canopy, which allowed the pilot to conduct a circular view. At the same time, the volume of the main intra-fuselage fuel tank was increased by another 248 liters. The volume of the water tank is from 57 to 114 liters.
Work on the creation of the experimental XP-47J was not in vain. From the end of 1944, the improved R-2800-57 engine began to be installed on serial "thunderbolts", which received the designation R-47M. In level flight, according to the company, their maximum speed at an altitude of 9150 m reached 756 km / h.
It is interesting to note that the P-47M fighters were designed specifically to combat the German V-1 cruise missiles, which the Germans fired at London.
The latest version of the "Thunderbolt" was the long-range high-altitude fighter of the super-heavy class P-47N. He had significant differences from the machines of earlier modifications. Like the R-47M, it was powered by an R-2800-57 engine with a capacity of 2800 hp. However, the volume of the fuel tanks was much larger. It became impossible to place additional fuel in the fuselage, and there were no wing tanks on the Thunderbolt. Therefore, the designers of the Republican company have designed a completely new wing. Increased its scope and area. A thinner profile and new endings were used. But the most important thing is that fuel tanks with a volume of 700 liters were still placed in the wing!
In addition, they provided for the suspension of two large additional tanks with a volume of 1136 liters each under the wing and one 416 liters under the fuselage. In total, the P-47N could take on board almost 4800 liters of fuel. The normal flight weight of the D and M series aircraft was about 6500 kg, and at full load it reached 9080 kg.
The car could fly at a distance of up to 3,780 km and stay in the air for almost 10 hours. This, in turn, required the installation of an autopilot on it.
In the shock version, instead of suspended fuel tanks under the wing of the R-47N, two bombs weighing 454 kg each and 10 missiles of 127 mm caliber could be suspended. The maximum speed reached 740 km / h at an altitude of 9150 m. The rate of climb, despite the large flight weight of 15, 25 m / s. However, these aircraft rarely operated against ground targets and were used at the final stage of the war mainly to escort the B-29 strategic bombers that flew to Japan.
Fighters "Thunderbolt" were mass-produced until the complete defeat of Japan. The Evansville plant was then closed and returned to the government.
During the war, the Republican firm built 15 329 P-47 fighters. Of these, P-47V - 171, P-47C - 60602, P-47D - 12600, P-47M - 130 and P-47N -1818. The firm produced a number of spare parts equivalent to about 3,000 aircraft. Almost 350 P-47G fighters were produced by Curtis. Thus, the P-47 "Thunderbolt" became the most massive American fighter during the Second World War.