History
In the late 1930s, several nations began developing heavy fighters, twin-engine aircraft designed for long-range escort, interception, and ground attack missions. Germany, France, the Netherlands, and the United Kingdom produced such types, including the Bf 110, Potez 630, Fokker G.I, and Bristol Beaufighter. At the time, the United States lacked its own heavy fighter. Aware of this gap, the US Army Air Corps (USAAC) issued specifications and launched a competition for a long-range, heavily armed twin-engine fighter that could also serve as an interceptor and light bomber. This concept became known under the designation FM: Fighter, Multi-place.
Bell promised performance figures of 300 mph, a 15,000 ft climb in 10 minutes, a service ceiling of 30,000 ft, and a 3,000-mile range. The XFM-1 made its maiden flight in September 1937, but early tests highlighted several shortcomings: it was slow, heavy, and challenging to fly. The prototype only reached 277 mph, falling short of the promised 300 mph.
Despite its issues, the XFM-1 performed well enough to secure a follow-up contract in May 1938 for 13 service-test aircraft designated YFM-1. These featured uprated 1,150 hp V-1710-23 engines with relocated B-1 turbo-superchargers beneath the nacelles to counter increased weight. Other improvements included a lengthened fuselage, replacement of the fuselage blisters with sliding panels, a revised flat windscreen, and a fully glazed nose. The 0.30 caliber coaxial guns were removed and replaced with telescopic rangefinders. These rangefinders were connected to a Sperry Instruments “Thermionic” fire control system, a gyro-stabilized autopilot that allowed the pilot or navigator to aim the cannons using an electrically actuated hand controller. The nacelle crew members were still required to manually reload five-round clips for the cannons. The removed 0.30 caliber guns were repurposed into a retractable dorsal turret and ventral tunnel mount. Engine air ducts were also moved to the wing leading edges, and a periscope-equipped underside gunsight allowed the pilot to monitor the rear lower quadrant. The YFM-1 could also carry twenty 30-pound fragmentation bombs on underwing racks. With these enhancements, Bell now promised 305 mph at 20,000 ft.
Development delays persisted, but the first YFM-1 flew on September 28, 1939. On its second flight, one of the turbo-superchargers exploded, sending shrapnel into the fuselage. Despite the setback, the aircraft was delivered to the Army on February 23, 1940. Nine more YFM-1s were completed by July 30, 1940. Two of them were modified into the YFM-1B configuration, using V-1710-41 engines without turbo-superchargers, though no notable improvement in flight performance was achieved. Between August and October 1940, one additional aircraft was built as the YFM-1A, while two others were converted to this variant, which included tricycle landing gear.
Flight trials continued into 1941, but the aircraft remained plagued by performance issues. One test flight ended in near-disaster when YFM-1 #38-942 entered an unrecoverable spin due to rudder lock. One of the test pilots bailed out, hitting the tail and suffering two broken legs before parachuting safely. The other pilot managed to regain control and land, but the damage rendered the aircraft a total loss.
By late 1941, it was clear the YFM-1 could not meet expectations. It was slower than its promised performance and even struggled to keep pace with a B-17. Engine cooling issues made it unreliable in warm conditions, often requiring ground towing. The aircraft’s dependence on a single auxiliary power unit meant electrical failures could render essential systems inoperable, including flaps and landing gear. The Airacuda was also unstable in pitch, and its rudder could lock during spins, posing serious risks. Pusher propellers further complicated bailouts for the nacelle crew and made general handling hazardous.
In January 1942, another YFM-1 was lost when an internal fire caused by a broken oil line forced the crew to abandon the aircraft. All but the pilot survived. Following the investigation, the remaining Airacudas were grounded.
Only 13 Airacudas were produced, and they equipped a single squadron between 1938 and 1940. Some airframes logged as little as 15 hours of flight time. After the US entered World War II, the YFM-1 was quickly outclassed. It proved that heavy fighters, such as the Bf 110, were too vulnerable against lighter, more maneuverable single-engine adversaries. Meanwhile, Lockheed’s P-38 Lightning entered service and demonstrated significantly better performance in the heavy fighter role. This led to the YFM-1 being retired to ground training duties before being scrapped entirely in late 1942.
Despite its failure, the Airacuda was not a total loss. It provided valuable lessons in aircraft systems integration, fire control technology, and heavy fighter design, all of which informed future US aircraft development and Bell’s engineering capabilities.
