Talking Proud Archives --- Military

Bell Airacuda: Too bold a design, advanced technologies not yet ready

By Ed Marek, editor

December 5, 2017
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YFM1Airacuda


WoodsBob
It's 1936 and the US Army Air Corps (USAAC) needed a long range escort fighter. It said it wanted a twin-engine multi-purpose platform. The requirement was for 300 mph maximum speed, a 30,000 ft. service ceiling, and a range of 3,000 miles. The AAC wanted the aircraft to defend large fleets of new B-17 "Flying Fortress" heavy bombers. The Army wanted it to fulfill a variety of battlefield roles including bomber, bomber escort, and ground attack.

Bell and Lockheed competed, and Bell won. Robert Woods, shown here, supported by Art Fornoff designed the XFM-1 which stood for Experimental Fighter Multiplace. XFM-1 was the name given to the prototype. The development aircraft was called the YFM-1. The aircraft was named the Airacuda.

Work on the aircraft began in 1936. Woods attempted to include many innovations in the design. One result was the aircraft endured many problems. The required a host of changes be made to the aircraft throughout its development. I'll mention only a few.

AiracudaTailDragger

The design for this fighter was unusual. She was a large aircraft with a 70 ft. wing span, about the size of a medium bomber. It had two supercharged Allison V-1710-9 engines which pumped out 1,090 horses. The engines were later upgraded to Allison V-1710-13 engines which raised the horsepower to 1,150. The engines were in streamlined nacelles on the trailing edge of the wing near the fuselage. The engines powered two three blade pusher propellers. This pusher design was untraditional. She was a tail-dragger as is shown in the photo.

AiracudaM4M2guns

She had a 37 mm M4 cannon and .30 cal Browning M2 machine gun in each nacelle, which at the time was formidable firepower. The web site "Gun Tables" said "The Bell XFM-1 Airacuda had remote-controlled 37mm M4 cannon, (right) mounted with a coaxial .30 Browning M2 (left) … (The M4) was a slow-firing cannon, with a low muzzle velocity and a limited ammunition capacity, but for its calibre it was light. It was intended to destroy bombers from a distance, but its performance was not sufficient for the task." The M4s and M2s were mounted in each of the two nacelles, and each had a dedicated gunner.

The aircraft required a five-man crew: a pilot and co-pilot also operating as a navigator in tandem, a gunner in each of the two nacelles, and a radio operator. The fighter also had small bomb bays and could carry 20-30 lb. fragmentation bombs. Underwing bomb racks could be fitted.

I have found a Russian web site with some very interesting photos of the YFM-1 aircraft:

YFM1WasteBlisterGun

The radio operators was tasked to defend both sides of the aircraft armed with two .50 cal Browning M2 heavy machine guns. These two guns were placed out both sides of the aircraft in what was known as a “waste blister” to enable the operator to attack aircraft coming from the rear.

30mmgunside

This shows the .50 caliber gun installation on the YFM-1, September 1939.

YFM1VentralGun

The .50 caliber guns were later replaced with one .30 caliber machine gun for the sides and another .30 caliber gun placed in a ventral tunnel to help defend the lower rear quadrant of the aircraft.

YFM1BTurret

The YFM-1B had a turret on top, mid-fuselage

YFM1TurretRetracted
Upper turret retracted

YFMTurretExtended
Upper turret extended

KelseyBenjamin
First Lieutenant Benjamin Scoville Kelsey took up the XFM-1 prototype on September 1, 1939. The aircraft was plagued with problems. Kelsey had a difficult time controlling the aircraft on a single engine. He found the aircraft began to spin.

There were a host of other problems, such as stability and pitch.
Test pilot Erik Schilling said this:

“Flying the Bell Airacuda was a new experience for me, since it was the first pusher aircraft I’d ever flown. Its handling characteristics were foreign to anything I had ever had my hands on. Under power it was unstable in pitch, but stable with power off. While flying straight and level, if a correction in pitch was required, a forward push on the control resulted in the airplane wanting to pitch over even more.

"Pitch control became a matter of continually jockeying the controls, however slightly, even when the aircraft was in proper trim. The same applied if pulling back on the control. It would tend to continue pitching up, requiring an immediate corrective response. The same happened in a turn with power off, the Bell became stable in pitch.

"This was fortunate because during approach and landing, it was very stable, and a nice flying airplane.”

The Airacuda was too slow, unable to achieve 300 mph, in some cases unable to keep up with the bombers it was to escort. It lacked maneuverability, could not survive a dog-fight, and was fraught with electrical problems. The nacelle-mounted M4 cannons had aiming problems. A specialized device was installed to improve the aiming which enabled the pilot to fire the weapons. The gunners in the nacelles were retained to keep loading, but they did not fire the weapons. A periscope was installed under the nose to permit the crew to search for fighters behind and below.

Nonetheless, the USAAC ordered 13 YFM-1 development aircraft. A lot of systems were moved around. The first YFM-1 made her maiden flight on September 28, 1939, two years after the XFM-1 first flew.

AiracudaFrontNosewheel

Only nine YFM-1s were completed in the newer configuration, with three more getting a nose-wheel instead of a tail wheel. The photo shows the nose wheel configuration.

By January 1942 there were nine airworthy aircraft left. I believe only two aircraft were lost. One pilot was lost as the result of bailing out. WWII for the US began in December 1941 after the Japanese attack on the Hawaiian Islands. The Airacudas were expensive, the Army was returning to single-engine, more agile fighters, and the P-38 "Lightning" was a twin engine fighter that proved much better.

The airworthy aircraft went to Chanute Field in Illinois, used as instructor airframes, and then scrapped. All aircraft were scrapped by early 1942.

Larry Bell admitted the aircraft was too advanced and the technologies not developed well enough. For example, the aircraft had gyro stabilized weapons sighting and a thermionic fire control system.

Bell lost out on a great opportunity as other companies were rushing out fighter and bomber aircraft far more capable. Frankly, the aircraft as it evolved became too complex, trying to do too many things.

The USAAC was also beleaguered with its own problems, borne out of a distrust of aviation and outdated rules and regulations governing new aircraft. It asked for a multi-purpose aircraft and that’s what it got. Then it started adding things to it, driving up cost, weight etc. It was considered a bomber destroyer and evolved into a “heavy fighter.” Others called it a flying gunship.

All this said, MilitayFactory.com said:

"The Bell XFM Airacuda bomber destroyer became a failed design for the new company but set the stage for more promising ventures to follow."