The Bell Airacuda could best be described as an expensive mix of innovations and oddities.
During the mid-1930s the idea of the heavy fighter was taking hold. Bomber technology was advancing
at a terrific pace, and although many subscribed to the idea that “the bomber always gets through”,
many also thought that fighter protection would remain a necessity.
Heavy fighters would be contemplated by many nations as both bomber escorts and bomber hunters.
In 1936 this very concept was being considered in the United States.
Development of the Boeing B-17 was underway, and an operational requirement was issued for
a long-range escort fighter; two manufactures would submit designs for this requirement:
Lockheed and Bell. The Bell Aircraft Corporation was a new player on the highly competitive field
that was the American aircraft industry, and the company needed to make a name for itself.
The two manufacturers were awarded preliminary design contracts,
and both submitted their proposals to the Army Air Corps by the deadline of March 15th 1936.
Bell’s proposal was the XFM-1, which would become known as the Airacuda. It was a curious
design and the brainchild of Robert Woods and Art Fornoff. At a casual glance it resembled
a medium bomber more than a heavy fighter, and many people in fact referred to it simply as a
“bomber hunter” rather than a fighter at all. It had an all-metal structure that was built
around a pair of Supercharged Allison V-1710 engines and a powerful offensive armament.
The wings were of box spar cantilever construction and comprised of central and outer sections.
The front and rear of the fuselage were joined at the front spar of the wing for added stability
and the rear section was of a semi-monocoque construction.
The V12 liquid-cooled Allison engines put out 1090hp each, and they drove a pair of three-blade
pusher propellers. They were arranged in such a way that the forward section of each engine
nacelle could be dedicated as a gunner’s compartment, albeit a fairly noisy one.
Speaking of gunners. The proposed armament, by 1930s standards was…well,
impressive. It was to be equipped with a pair of 30 calibre machine guns – which was
fair enough – but it was also equipped with a pair of 37mm automatic cannons.
These would be mounted in a pair of flexible cones that were on the front of each engine nacelle.
Each nacelle would house a gunner, however their primary purpose was to feed the guns rather than
fire them, though they could still do that in an emergency. The aircraft featured an innovative
fire-control system - developed by Sperry Instruments - which would allow the navigator
to operate the cannons remotely, with the gunners making minor corrections to their aim. In essence,
what Bell had designed was a flying anti-aircraft battery that could engage enemy bombers beyond
the range of their own defensive guns. In a pinch it could also be used as a
fighter bomber, and could carry up to twenty 30lb bombs in bays installed in the wings,
but this was considered more as an afterthought. A meek defensive armament came in the form
of two 50 calibre machine guns that were mounted in side blisters on the fuselage.
The Airacuda had a crew of five: a pilot, a co-pilot and navigator, a radio operator gunner,
and two dedicated gunners. The aircraft was designed to provide excellent frontal visibility.
A Plexiglas enclosed cabin extended from the nose all the way aft of the navigator’s station,
and the engine nacelles offered good visibility for the gunners as well. There was however a
notable pair of blind spots in the early design, the aircraft lacked any dorsal viewing ports or
defensive armament, and the direct rear-view visibility was almost non-existent. Though
this would be somewhat rectified later on, for now it remained an otherwise ignored design flaw.
After a wooden mock-up had been built and basic wind tunnel testing had been completed,
construction of the prototype began in May of 1936. Work was completed by the end of
summer in 1937 and on the 1st of September it would take off for the first time.
When completed, the XFM-1 had a wingspan of 69ft 10 in, a length of 44ft 10 in,
and a height of 13ft 7 in. This, combined with its mass, gave it both the looks and the feel of a
medium bomber. It had an empty weight of 13,400lb and a loaded weight of 17,333lbs – not exactly a
featherweight. Its twin Allison engines gave it a top speed of 270mph, a cruising speed of 244mph
and a normal operating range of 800 miles. Unfortunately, things would immediately begin
to go wrong. During take-off, the port engine backfired and blew in the air ducts as well as
the intercooler. Another incident occurred during the second flight, this time during landing,
when the starboard undercarriage refused to lock and thus collapsed upon impact.
The aircraft was subsequently repaired, and after 10 more test flights where it proved that it could
take off and land without trying to kill the test pilot, it was accepted at Wright Field
for further testing on the 21st October. It then went to Langley Field for further testing in 1938
where it made itself increasingly unpopular with the ground crew responsible for keeping it in
flying condition. What had looked good on paper was quickly becoming a nightmare in practice,
and the Airacuda was plagued with all sorts of maintenance problems.
The engines, for example, were usually considered reliable and easy to maintain. However,
when installed in the pusher configuration aboard the Airacuda, they had insufficient
cooling systems that failed to counter the lack of propwash that often helped to cool engines.
As such they overheated incredibly easily, to the point that the aircraft could not taxi on its own,
and had to be towed from the hangar to the runway. The engines, though supercharged,
were meant to be turbo-supercharged, but these developed a nasty habit of blowing up and so
the first prototype was supercharged only. The armament, though powerful, proved to be both
lacklustre and dangerous. The 37mm cannons had a low shell velocity, proved difficult to aim,
and had the unfortunate tendency of filling the engine nacelle holding the gunner with smoke. This
all reduced the effective range of the Airacuda’s guns, meaning that if it were to successfully hunt
and shoot at enemy bombers, it would probably be doing so within the range of their defensive guns,
which leads on to the next problem – it was about as manoeuvrable as a brick.
The Airacuda suffered severe flight limitations. It couldn’t make immelman turns, fly inverted or
even complete basic rolls. It also took extreme offense to any sort of pitch input when under
power, with even the slightest movements requiring immediate correction lest the aircraft continue
moving in the original input direction. Perhaps the worst of its flaws was the
electrical system. It featured an independent auxiliary power unit;
this powered the aircraft’s electrical systems as well as both the fuel pumps and the engines…yeah
I think you can see where I am going with this. If said power unit were to fail,
and fail it did, then the unlucky pilot would have no fuel pressure and thus no engines, and
also no hydraulic pressure for the gears or the flaps. This happened on more than one occasion,
and Ben Kelsey, who did many of the first test flights was very lucky that he could either land
the plane safely, or his crew could restart the APU before the plane lost total control.
Despite repeated attempts at killings the pilots, hotboxing the gunners,
and driving the ground crew to tears, the XFM-1 was put on display alongside several other Air
Corps prototypes – including the Bell XP-39 - at the Bolling Field Exhibition in January 1940.
During this time, a new version of the aircraft was being built.
Back in 1938, not long after the first prototype was completed, the War Department had given a
contract for 13 XFM-1s for service testing and, 9 of these would be completed as the YFM-1.
These were powered by improved versions of the Allison engines that produced 1150hp,
and many changes were made to address the long list of deficiencies with the first prototype.
The engines were now housed in modified cowlings and the air intakes were moved into the wing
leading edge in an attempt to address the overheating issue. The engine supercharges
were now built into the nacelles themselves and propeller spinners were added. The issue
of defensive blind spots was finally revisited. The fuselage was lengthened and re-designed,
with a periscope being fitted under the nose to detect threats from the underside. Along
with this, the side blisters were replaced with hatches, and the machine guns were repositioned
in ventral and dorsal hatches near the wing trailing edge to provide a better field of fire.
The first YFM-1 made its maiden flight on the 28th of September 1939. Three of the delivered
aircraft were completed as the YFM-1A, which had a nosewheel undercarriage added to improve
its take-off and landing characteristics. Unfortunately, this rather backfired as they
quickly developed a horrific nosewheel wobble that was only solved after numerous tests involving
a car fitted with the Airacuda’s nosewheel as a sort of Frankenstein testing unit.
Despite the litany of problems, only two aircraft would be lost in accidents, with only one fatality
being recorded from the second. That being said, losing two aircraft from a batch of just twelve
still doesn’t represent a glowing safety record, and the thirteenth was never completed. Further
development of the Airacuda was discontinued for various reasons: it was slow, it was unreliable,
and it was becoming increasingly expensive. The remaining aircraft served operationally
in a squadron for a period of time, but this was short lived. In January of 1942,
the nine remaining Airworthy planes were dispersed to various training
schools throughout the country. Some would be used by mechanics as instructional airframes,
and some would be flown by pilots who wanted another odd plane to add to their log books.
The failure of the Airacuda could have been a serious disaster for Bell had their other design,
the P-39 Airacobra not succeeded. Eventually all of the Airacudas were scrapped and no examples
of this weird aircraft survive to this day. As far as first aircraft go, Bell certainly
chose to go with different, rather than safe. Anyway, I hope you all enjoyed today’s video,
thank you all so much for watching, and I’ll catch you all next time.