Having analyzed the current state and prospects of the American aviation, a group of designers led by R. Wood began developing a heavy fighter-interceptor. It was supposed to create an aircraft with powerful cannon weapons and high flight data. Such a machine could intercept enemy heavy bombers or escort their bombers. Advertising materials on the project talked about creating a completely new concept for the aircraft: a mobile anti-aircraft platform. In the light of the composition of the armament of the new aircraft, such a term was partially fair.
In 1936, the command of the US Air Corps received a package of documents describing the new project. The Bell FM-1 Airacuda aircraft (which can be translated as “Air barracuda”) interested the potential customer, although its appearance looked too bold and original. Nevertheless, Bell received a contract for the construction and testing of the first prototype of the new aircraft with the designation XFM-1. At this stage there was a slight hitch of the nomenclature character. If adopted, the new fighter should have received the designation FM-1, but this index was supposed to be assigned to the Grumman F4F-3. Some time allowed to postpone the decision of this issue for the future.
The Bell Airacuda aircraft was a twin-engine midplane with a small sweep wing. The fuselage section, close to the oval, was intended to accommodate part of the crew and part of the weapons. In the nose of the fuselage placed workplaces of the pilot and navigator. In the middle - the workplace arrow-radio operator. On the wing of the aircraft provided two engine nacelles of characteristic shape. Since the main objective of the project was to ensure maximum firepower, the original layout decision was made. In front of the two engine nacelle placed the shooters and guns. The engines thus had to be installed in the rear of the nacelles.
As a power plant, the first prototype of the Airacuda aircraft used two piston engines Allison V-1710-13 with the power of 1133 hp. with three blades pushing screws. These engines could provide good flight characteristics, but during the tests it turned out that the power plant of the aircraft needs to be improved.
The basic one weapons The XFM-1 Airacuda interceptor has become two 37-mm automatic guns M4. The gun and the ammunition for it (110 shells) was in the blister wing gondola. An interesting feature of the fighter’s weapons was the fact that the main task of the shooters who were in the gondolas was to load the guns, although if necessary they could direct their weapons and fire. Nevertheless, the guns were considered as course weapons and were controlled by a navigator, whose workplace was equipped with special controls. Also in the gondolas were 7,62-mm machine guns. In the side blisters of the fuselage, it was proposed to mount two installations for large-caliber machine guns. With their help, the gunner-radio operator could protect the aircraft from attacks from the rear hemisphere.
The design of the fuselage allowed to leave some volume in which it was possible to transport bombs. In this case, the plane could take on board up to 270 kg fragmentation bombs of small caliber.
Despite its purpose, the Bell XFM-1 Airacuda fighter turned out to be large and heavy. The total length of the aircraft exceeded the 13,6 meter, the wingspan was 21,3 m. The weight of the empty aircraft was equal to 6060 kg. With crew, ammunition and normal fueling, take-off weight exceeded 7850 kg. The maximum allowable take-off weight was 9800 kg.
Experience in the construction of aircraft allowed the company Bell Aircraft quickly enough to assemble the first prototype of the new fighter. In mid-July 1937, the prototype aircraft rolled out of the assembly shop and began to test it. At this time, the US military issued a press release, which noted the mass of the positive aspects of the new project. It was noted that none of the previous projects caused such a stir as Bell XFM-1 Airacuda. In addition, the armament complex and the convenience of the crew have been commended. According to the plans of the time, the new aircraft was supposed to perform the functions of a heavy interceptor and an escort fighter. In the latter case, FM-1 could be accompanied by Boeing B-17 Flying Fortress bombers, whose construction began at that time.
In the last days of August 1937, test pilot B.S. Kelsey made the first flight on a new aircraft. During the tests, it was possible to establish sufficiently high flight characteristics of the new aircraft. The maximum speed up to 440-445 km / h made it possible to accompany the bombers that were available at that time and effectively fight modern fighters. With a cruising speed of 390-395 km / h, the flight distance reached 4180 kilometers. The practical ceiling reached 9300 meters.
In general, good flight characteristics were accompanied by a number of specific features. So, the XFM-1 could not fly with one engine running. With a significant difference in the engines of the aircraft broke into a tailspin. In addition, the fighter turned out to be quite difficult to control and reacted disproportionately to the movements of the steering wheel during pitch control. The audit showed that the cause of such problems was an unfortunate combination of engine power and screw placement. Using less engine power did not lead to a significant improvement in handling, although it lowered the speed of flight.
Great criticism caused the architecture of the power plant and auxiliary systems. As test pilot E. Schilling recalled, engine start-up depended on an auxiliary power unit (VSU), which was a backup source of electric power. To restart the engines in flight, it was necessary to turn on the APU and carry out a rather complicated procedure. In case of failure of the APU, the aircraft could not start the engines, which made it impossible to use electric and hydraulic systems. Later it was supposed to solve this problem with the help of a fundamental change in the aircraft systems.
It should be noted that during the flight tests engine failure in the air was quite common. Due to the not very good location of the radiators, the V-1710-13 engines regularly overheated. Because of this, in particular, the prototype model of the Airacuda aircraft was taken to the runway with the help of a tractor and only then started the engines. In the future, it was planned to equip the FM-1 fighter with turbo-compressors, ensuring the performance of engines at high altitudes.
The weapon test also ended with negative testers reviews. When firing cannons and machine guns located in gondolas, smoke quickly filled the cockpit of the shooter and interfered with its normal operation. In addition, the work of shooters was associated with a different risk. When leaving the plane with a parachute, the shooter risked falling under the propeller blades, because of which the designers of Bell Aircraft, together with colleagues from related enterprises, had to invent an emergency release system for the blades.
Some changes and design modifications allowed the prototype XFM-1 to go through factory tests. In 1938, he was handed over to the Air Corps for further work. Military test pilots evaluated the aircraft and made their decision. They found the Airacuda to be interesting and worthy of attention, but noted insufficient maneuverability, even for a heavy fighter. In addition, the claims were caused by the installation of guns and machine guns, which could degrade the accuracy and accuracy of shooting. However, according to the test results of the first aircraft, the Air Corps ordered the construction of a pre-production batch of ten units.
Nine new aircraft were built in accordance with the updated project YFM-1 (Mod.7). The modified project implied the use of V-1710-23 engines with 1150 horsepower. with turbochargers and larger area radiators. Refinement of the power plant helped to eliminate some problems, but the maneuverability and controllability of the aircraft did not become suitable for operation. During the tests of the YFM-1 fighter aircraft, two accidents happened. So, in September 1939, one of the turbocharger parts collapsed in flight, which led to an engine explosion. The crew could not save the burning car and left it. The second pre-production aircraft was lost due to poor handling. During the tests, the pilot J. Strykler could not in time bring the fighter with the engines off from the corkscrew. The remaining height was not enough to start the engines, which is why the commander ordered the crew to leave the car. Using the remaining margin, Strykler coped with the plane and landed it on the field. The pilot was still alive, but the plane had to be written off.
On the basis of the project YFM-1 (Mod.7) was created aircraft YFM-1A (Mod.8). The main difference of this version of the fighter from the others was a three-post chassis with a front support. A total of three such aircraft were built, all of which were seriously damaged during the tests. One of these incidents led to the death of the pilot. On the test aircraft YFM-1A due to vibrations of the fuselage collapsed gas line, which led to a fire. Two pilots left the plane, but one of them died while jumping. The result of the investigation of this accident was a recommendation to limit the flights of new types of aircraft due to constant maintenance and piloting difficulties.
From 1938 to 1940, 13 aircraft of several modifications were assembled. These were the first prototype of the XFM-1 and several YFM-1, YFM-1A and YFM-B. The latest version (YFM-1B) was a YFM-1A with other engines and modified cab glazing. Despite many problems, the first Airacuda fighter squadron was still assembled and handed over to the military. Initially it was assumed that after completion of the tests, the Air Corps would order at least two squadrons of new aircraft in addition to those already transferred, but the signing of this contract was constantly postponed and as a result did not take place.
By the beginning of official use in the military, the Bell YFM-1 Airacuda aircraft had a specific reputation and therefore did not cause any enthusiasm among the pilots. In addition, all the transferred aircraft did not meet the requirements for flight speed - none of the YFM-1 could not achieve the performance of the prototype XFM-1. For obvious reasons, there was no longer any talk of combat work. In the middle of 1940, the US Air Corps command decided to distribute the existing YFM-1 across several air bases to give combatant pilots the opportunity to master another combat vehicle. The pilots of the four bases located in the states of Virginia, California and Ohio, showed interest in the new machine, but, flying on it, lost all interest due to the complexity of piloting and incomprehensible prospects.
At the end of the 1940 of the year, Bell Aircraft launched a project for the deep modernization of the heavy fighter YFM-1, which should have resulted in a significant increase in flight and combat performance. In 1941, the project was ready, but the operating experience of the existing aircraft caused the completion of work. For almost the entire 1941 year, all the Airacuda aircraft that were available at that time stood idle in the hangars. They were remembered only after the USA entered the Second World War. At the very beginning of 1942, the remaining nine aircraft were sent to the Shanut Field Training Center. There the planes were assembled in the 10 training squadron and were used for crew training until the end of the year. By the middle of 1942, all nine YFM-1 aircraft were written off.
From the beginning of the tests in the 1937 year to the decommissioning of the 1942 in Bell Airacuda aircraft constantly pursued problems of a very different nature. As in the old adage, the “first pancake” of Bell Aircraft came out unsuccessful. Probably, a large number of new original technical solutions, applied even at the stage of the project concept itself, became the cause of numerous flaws and problems. As a result, instead of a heavy fighter or a “mobile anti-aircraft platform” capable of effectively fighting enemy bombers, the American military pilots received only a few training aircraft. Traction to the use of bold technical solutions has become a characteristic feature of the work of Bell Aircraft in the late thirties. For example, several original ideas were applied in the design of the P-39 Airacobra fighter. In this case, they did not prevent the testing, fine-tuning and use of aircraft in the army, but this is another история.
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