# Bell XFM-1 Airacuda



## Wildr1 (May 17, 2018)

XFM-1 was developed by the Bell Aircraft Corp. during the mid-1930s. It was the first military aircraft produced by Bell. Originally designated the Bell Model 1, the Airacuda first flew on 1 September 1937. The Airacuda was marked by bold design advances and considerable flaws that eventually grounded the aircraft.

The Airacuda was Bell Aircraft's answer for a "bomber destroyer" aircraft. Although it did see limited production, and one fully operational s quadron was eventually formed, only one prototype and 12 production models were ultimately built, in three slightly different versions.

The Airacuda was plagued with problems from the start. The lofty performance estimates were unobtainable as, despite its sleek looks, the Airacuda was heavy and was slower than most bombers. In the event of interception by enemy fighters, the Airacuda was not maneuverable enough to dogfight. Even the 37 mm cannons were of less value than predicted. The cannons had a tendency to fill the gun nacelles with smoke whenever fired and, additionally, fears persisted as to how the gunners would escape in an emergency, with the propellers directly behind them. An emergency bailout would have required both propellers to be feathered, though additional provision was made with the use of explosive bolts on the propellers to jettison them in the event of a bailout.

Despite these problems, one fully operational Airacuda squadron was eventually assembled, and operated from 1938 until 1940. Funds were appropriated, but never released, for the purchase of two groups of Airacudas. Continuing problems gave the aircraft a reputation as "hangar queens".

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## swampyankee (May 17, 2018)

Interesting, innovative failures. 

Of course, part of the reason for failure was an intrinsically flawed specification, but a major part was poor design work by Bell.


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## Wurger (May 17, 2018)




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## Capt. Vick (May 17, 2018)

Why is there not a book on this aircraft?


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## Wildr1 (May 17, 2018)




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## Wurger (May 17, 2018)




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## Capt. Vick (May 17, 2018)

I love this plane. The absurdity of its design is so cool!

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## wuzak (May 17, 2018)

I wonder how it would have performed if the nacelle mounted guns were moved to fixed positions in the fuselage, and the gunners' positions removed?

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## Zipper730 (May 17, 2018)

swampyankee said:


> Of course, part of the reason for failure was an intrinsically flawed specification, but a major part was poor design work by Bell.


What specification should have been issued?


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## Shortround6 (May 17, 2018)

Capt. Vick said:


> Why is there not a book on this aircraft?


No crosses/swastikas on it, if it had those then the books would be over a dozen

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## Wildr1 (May 18, 2018)




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## swampyankee (May 18, 2018)

Zipper730 said:


> What specification should have been issued?



One that wouldn't result in the YFM-1 

To start, fixed main armament, crew of one or two, and speed within 5% of the single seat fighters to enter service at the same time.


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## Wurger (May 18, 2018)




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## Zipper730 (May 18, 2018)

swampyankee said:


> One that wouldn't result in the YFM-1


So simple, but I completely understand what you're saying.


> To start, fixed main armament, crew of one or two, and speed within 5% of the single seat fighters to enter service at the same time.


Okay, so that would yield

Top speed 325-380 mph
Crew either consisting of a pilot, or pilot & radio-operator/fire-control guy


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## Wildr1 (May 19, 2018)

It had a crew of 5, it would have needed better engines , it was to heavy and slow, some bombers were faster. Below is the exit plan.

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## Wildr1 (May 19, 2018)



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## wuzak (May 19, 2018)

I didn't quite realise how large the X/YFM-1 was.

A wing span of 69ft 10in is 16.5ft more than a Bf110.
Length is only 4ft longer the the Bf110.

Empty weight was nearly 3,500lb greater than the Bf110.

All on, roughly, the same power.

The wingspan was greater than a Martin B-26/B-26A, and only 14in less than the B-26B. The span was a little over 2ft more than a B-25.


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## GrauGeist (May 19, 2018)

The ideologies of the 1930's were of an entirely different mindset, mostly rooted in memories of the "Great War".
The Battleship was the ruler of the Seas and the Bomber was the arch-enemy of civilization.

As a new decade dawned, there came a shock of cold, harsh reality and the days of the Battlship, "heavy fighters", bomber destroyers and other such holdovers from an earlier time became irrelevant.


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## Wildr1 (May 19, 2018)

It was a different era, and dreams of designers were not realistic as these fanciful covers of magazines of the time show.

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## Wurger (May 19, 2018)




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## Zipper730 (May 19, 2018)

Wildr1 said:


> It had a crew of 5, it would have needed better engines , it was to heavy and slow, some bombers were faster. Below is the exit plan.


I feel sorry for the gunners... if they couldn't feather those props those guys were either going to go down with the plane or become salsa...

By the way what was that window in the nose?


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## wuzak (May 19, 2018)

Zipper730 said:


> I feel sorry for the gunners... if they couldn't feather those props those guys were either going to go down with the plane or become salsa...
> 
> By the way what was that window in the nose?



For aiming the bombs?


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## Shortround6 (May 19, 2018)

The alternative exit route was to go through a tunnel/crawlway in the wing root from the nacelle to the fuselage. 
A difficult journey for even a thin and agile fellow unencumbered by flying suit/parachute.


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## swampyankee (May 19, 2018)

wuzak said:


> For aiming the bombs?



The gunners didn’t aim the guns; maybe the nose glazing was for the fire control system


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## Zipper730 (May 19, 2018)

wuzak said:


> For aiming the bombs?


Like dropping them on bomber formations?


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## Gnomey (May 19, 2018)

Good shots!


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## Zipper730 (May 19, 2018)

swampyankee said:


> The gunners didn’t aim the guns; maybe the nose glazing was for the fire control system


What kind of fire-control?


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## swampyankee (May 19, 2018)

Zipper730 said:


> What kind of fire-control?



There was a Sperry fire control system that aimed and fired the guns. See Bell XFM Airacuda Bomber Interceptor / Bomber Destroyer / Heavy Fighter - United States


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## Zipper730 (May 20, 2018)

So it pulled lead-computation and maneuvered the aircraft?


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## swampyankee (May 20, 2018)

Zipper730 said:


> So it pulled lead-computation and maneuvered the aircraft?


I’m not sure, but I think it aimed and fired the 37 mm, which were flexibly mounted.


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## GrauGeist (May 20, 2018)

The thermionic director was mounted in the nose. It's optic looks like a light centered in the nose window.

The prototype/early production airframes weren't fitted with the system, so the nose is solid in some photos.


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## Wildr1 (May 23, 2018)



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## Wurger (May 24, 2018)




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## flypaper2222 (May 24, 2018)

From what I hasve read one of the main problems was enginge cooling. The engines would quickly overheat just ideling on the tarmac. One of the photos above shows a make shift attempt to solve this problem with blowers piping air into the cowling air intakes (7th photo from the top)


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## flypaper2222 (May 24, 2018)

From what I hasve read one of the main problems was enginge cooling. The engines would quickly overheat just ideling on the tarmac. One of the photos above shows a make shift attempt to solve this problem with blowers piping air into the cowling air intakes (7th photo from the top)


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## Capt. Vick (May 24, 2018)

You can say that again...


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## swampyankee (May 24, 2018)

flypaper2222 said:


> From what I hasve read one of the main problems was enginge cooling. The engines would quickly overheat just ideling on the tarmac. One of the photos above shows a make shift attempt to solve this problem with blowers piping air into the cowling air intakes (7th photo from the top)


Considering all the other problems, cooling was just one more symptom of an intrinsically flawed design.


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## special ed (May 26, 2018)

Are these pictures still available from Bell?


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## Wildr1 (Jun 5, 2018)

unknown, I've had these for 30 years, with a few ebay exceptions


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## Zipper730 (Jun 5, 2018)

flypaper2222 said:


> From what I hasve read one of the main problems was enginge cooling.


Was this due to the lack of a slipstream?


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## Gnomey (Jun 13, 2018)

Nice shots!


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## C.Warren (Jun 13, 2018)

Thanks Wildr1, very interesting aircraft.
On the power issue, the first versions XFM-1 had turbo superchargers and the later did'nt, any ideas why?
If the guns where to be linked via the Sperry Fire Control ( GrauGeist mentions a Thermionic Director = Valves?) why were the gunners in the front engine positions?
In many ways it is very advanced design, radiators in wings, tricycle undercart, retracting top turret and who knows what else.
Lovely photos of interior.


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## swampyankee (Jun 13, 2018)

C.Warren said:


> Thanks Wildr1, very interesting aircraft.
> On the power issue, the first versions XFM-1 had turbo superchargers and the later did'nt, any ideas why?
> If the guns where to be linked via the Sperry Fire Control ( GrauGeist mentions a Thermionic Director = Valves?) why were the gunners in the front engine positions?
> In many ways it is very advanced design, radiators in wings, tricycle undercart, retracting top turret and who knows what else.
> Lovely photos of interior.


The gunners were there mostly to reload the guns, and as backups if the FCS failed.

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## wuzak (Jun 13, 2018)

C.Warren said:


> On the power issue, the first versions XFM-1 had turbo superchargers and the later did'nt, any ideas why?



It may have been due to the reliability of those early turbochargers.


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## GrauGeist (Jun 13, 2018)

Zipper730 said:


> Was this due to the lack of a slipstream?


Many mid-engined aircraft (pusher or tractor) had in-flight heating issues at one point or another. Some had the problem corrected (J7W1, P-39, etc.), others didn't operate long enough to have the bugs worked out (Do335, R2Y1, etc.).

Idling on the ramp or holding in a que waiting to go is hard on any water-cooled type, which can easily overheat without airflow, like the P-40 for example.


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## wuzak (Jun 14, 2018)

GrauGeist said:


> Idling on the ramp or holding in a que waiting to go is hard on any water-cooled type, which can easily overheat without airflow, like the P-40 for example.



Any engine type, really?


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## GrauGeist (Jun 14, 2018)

wuzak said:


> Any engine type, really?


Go back and re-read my post.
I said "*Idling on the ramp or holding in a que waiting to go is hard on any water-cooled type*".

And in that regard, yes, really.


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## at6 (Jun 14, 2018)

In spite of all of the Airacuda's problems, it was still an impressive looking and attractive design.

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## wuzak (Jun 14, 2018)

GrauGeist said:


> Go back and re-read my post.
> I said "*Idling on the ramp or holding in a que waiting to go is hard on any water-cooled type*".
> 
> And in that regard, yes, really.



Sorry, I thought that "Idling on the ramp or holding in a queue waiting to go" is hard on any piston engine type.


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## Zipper730 (Jul 15, 2018)

GrauGeist said:


> The thermionic director was mounted in the nose. It's optic looks like a light centered in the nose window.


So the pilot flew the plane, and the GIB operated the FCS?


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## Zipper730 (Jul 25, 2018)

This might sound silly, but would it have been possible to have designed, from a production or (remotely) practical standpoint a twin-engine cannon-armed patrol-interceptor/escort plane (which could do the stuff the YFM-1 could do with more speed and agility) with either one crew-member and fixed forward-firing guns or, twin-crew, with a GIB operating the traversable gun?

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## swampyankee (Jul 25, 2018)

Zipper730 said:


> This might sound silly, but would it have been possible to have designed, from a production or (remotely) practical standpoint a twin-engine cannon-armed patrol-interceptor/escort plane (which could do the stuff the YFM-1 could do with more speed and agility) with either one crew-member and fixed forward-firing guns or, twin-crew, with a GIB operating the traversable gun?




Yes. In essence, this is what the Me110 could be considered. Maybe somebody other than Bell would have done better


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## Zipper730 (Jul 25, 2018)

swampyankee said:


> Yes. In essence, this is what the Me110 could be considered.


Well, what I was talking about was designing it so it could EITHER carry traversable turrets and two crew (pilot to fly the plane, and GIB to adjust the guns), or just one crew member (only a pilot) without traversable guns.

Also was there any other competitor? I've found little on this


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## swampyankee (Jul 26, 2018)

Zipper730 said:


> Well, what I was talking about was designing it so it could EITHER carry traversable turrets and two crew (pilot to fly the plane, and GIB to adjust the guns), or just one crew member (only a pilot) without traversable guns.
> 
> Also was there any other competitor? I've found little on this





Zipper730 said:


> Well, what I was talking about was designing it so it could EITHER carry traversable turrets and two crew (pilot to fly the plane, and GIB to adjust the guns), or just one crew member (only a pilot) without traversable guns.
> 
> Also was there any other competitor? I've found little on this



There was an entry from Lockheed, but I think it was never built.


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## Zipper730 (Jul 26, 2018)

swampyankee said:


> There was an entry from Lockheed, but I think it was never built


Wher would I go to fid more on this?


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## wuzak (Jul 26, 2018)

Zipper730 said:


> Wher would I go to fid more on this?



The archives?


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## Zipper730 (Jul 26, 2018)

wuzak said:


> The archives?


What archives?


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## YGBSM (Jul 26, 2018)

From what I can tell, the Airacuda was Bell's attempt to break into the fighter business and not a specific response to a "circular proposal" which is how the USAAC solicited design proposals in those days; therefore, there wouldn't have been a specific competing design per se. It may have inspired later designs (or certain features thereof), but I haven't seen any specific mentions.


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## wuzak (Jul 26, 2018)

Zipper730 said:


> What archives?



The United States National Archives.


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## Zipper730 (Jul 27, 2018)

YGBSM said:


> From what I can tell, the Airacuda was Bell's attempt to break into the fighter business and not a specific response to a "circular proposal" which is how the USAAC solicited design proposals in those days


There was something called Project C which was for this type of aircraft. I can't really find anything else under it.


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## YGBSM (Jul 27, 2018)

You're right. I can't find any designation for the circular proposal, but the idea appears to have been started by a letter written in early 1935 by Captain Harry A. Johnson to Major General Benjamin Foulis recommending a heavily-armed super fighter capable of destroying bombers. The new plane would have the new designation "FM" for "fighter, multi-place".

Both Bell and Lockheed were issued $25,000 contracts to submit preliminary designs with a deadline of March 15, 1936. Bell won the competition by four-tenths of a point, 72 to 71.6 out of a possible 100. The Airacuda was set ahead by its twin cannons to the Lockheed's one. The *Lockheed aircraft's designation was XPB-3* and later *XFM-2.

Interestingly, the designer of the Airacuda for Bell was a former project manager at Lockheed.
*
Another humorous note - before the war, Bell visited the Messerschmitt factory in Germany and questioned what a long line of prototype Me-109s were for - to which Willi Messerchmitt quipped, "What is the Airacuda for?"


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## YGBSM (Jul 27, 2018)

Also, I didn't know this was a thing - a tail-dragger version of the P-39 with a tailhook - officially the XFL Airabonita:






Source: Bell XFL Airabonita - Wikipedia


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## Zipper730 (Jul 27, 2018)

At least I've found a picture, though I have no idea of how it's performance would compare: Supposedly the FM-1 only narrowly beat the design out.




Frankly, the design seems to be the example of a camel being the product of a horse designed by a committee

Instead of wanting a fast-climbing fighter with high-speed for destroying bombers, some wanted an aircraft able to mount extending patrols and carrying heavier firepower.
For the escort-mission, they wanted long-range on internal fuel (they hated the idea of drop-tanks because they figure they'd be jettisoned at the start of combat), and a waist gunner (evidently the idea seemed to be for an airplane that could use it to augment the bombers defensive firepower, maneuvering only when necessary): I'm guessing the fighter & bomber guys were still butting heads like nobody's business because up to this point, fighter pilots generally had a dim view of this (the gunners were generally pinned under g-load and couldn't do anything).
Some had taken a shining to dropping bombs on bomber formations (the USN actually had a similar idea for awhile), and this might have also fed into the idea of a fighter-bomber (or an attack-bomber variant).


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## YGBSM (Jul 27, 2018)

It was a narrowly-won contest by the FM-1 - four-_tenths_ of a point on a 100-point scale. The FM-2 was rated higher in some aspects to the FM-1, but the twin cannons of the FM-1 edged out the victory.



> Bell won the competition by four-tenths of a point, 72 to 71.6, out of a possible 100 points. The clincher appearently was the big twin guns aboard the Airacuda. Lockheed's aircraft had two 1,000-horsepower Allison engines, as did the Airacuda, but it had only one cannon. Lockheed held the edge in engineering, but Bell scored 19.3 to 15.6 in military characteristics.


Source: Larry, a Biography of Lawrence D. Bell

The primary mission of the FM program was to intercept bombers - the idea being with the 37mm cannons to sit about 2 miles behind the enemy bomber formation and lob shells at will, well outside their defensive turret range. The Airacuda was doomed by its lackluster performance - it could barely outpace the bombers it was supposed to intercept, and it was expensive. By the time it was all said and done, and Airacuda was about twice the price of a B-17 at the time (I'm assuming a "D" model).

The design inspiration for the Neptune can be seen. Good find on the photos.


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## Zipper730 (Jul 27, 2018)

YGBSM said:


> It was a narrowly-won contest by the FM-1 - four-_tenths_ of a point on a 100-point scale.


That _is_ close...


> Lockheed held the edge in engineering, but Bell scored 19.3 to 15.6 in military characteristics.


So military characteristics means the planes ability to be used as a weapons platform, engineering means it was better designed and more rugged?


> The primary mission of the FM program was to intercept bombers - the idea being with the 37mm cannons to sit about 2 miles behind the enemy bomber formation and lob shells at will, well outside their defensive turret range.


Was the traversable gun a requirement on either design or was that simply a choice on behalf of Bell?


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## YGBSM (Jul 27, 2018)

I'm going out on a limb here because information regarding Army Air Corps acquisitions processes at the time is a bit sparse. I believe "military characteristics" is an evaluation of the prototype's ability to meet the performance specifications in the design requirements - speed, range, load, etc. Engineering as you said is probably a catch-all for overall design innovation and functionality.

I haven't seen any of the specific requirements other than the general call for a multi-seat heavy fighter. They are probably buried with the original documentation in an archive somewhere, or we haven't looked hard enough. It is a rather obscure corner of history we're delving into, so the documentation probably hasn't been digitized by anyone yet.

I've also seen mention of the fact that the official procurement procedures of the Army Air Corps were not always (or rarely) followed to the letter... so the reality of specific programs differed from what may be found regarding the procedures.

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## vikingBerserker (Jul 27, 2018)

YGBSM said:


> You're right. I can't find any designation for the circular proposal, but the idea appears to have been started by a letter written in early 1935 by Captain Harry A. Johnson to Major General Benjamin Foulis recommending a heavily-armed super fighter capable of destroying bombers. The new plane would have the new designation "FM" for "fighter, multi-place".



It actually started several years before that in 1933. On January 9th, 1933, a directive for a multi-seat fighter was submitted to the Pursuit Board at Wright Field and on March 22nd 1933, the Material Division at Wright Field issued Engineering Section Memorandum Report B-51-104 entitled “Modification of Martin B-10 Airplane To A Multi-Seat Fighter. One of the proposals was to have mounted forward firing machine guns and a retractable turret located below the fuselage. There would also be numerous gun ports/mounts where the gunners could move and remount the machine guns and was to carry 10 x 15lb bombs.

The modifications turned out to make the aircraft slower than the bombers it was to target and it was decided to go with a purposely designed aircraft. This led to the aircraft you mention.

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## jmcalli2 (Aug 2, 2018)

Wildr1 said:


> It was a different era, and dreams of designers were not realistic as these fanciful covers of magazines of the time show.
> 
> View attachment 493933
> View attachment 493961
> ...



Love those magazine covers!


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## Gnomey (Aug 3, 2018)

Nice shots!


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## Capt. Vick (Aug 3, 2018)

Great info. I never knew there was a competition and Bell actually won.


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## Zipper730 (Aug 3, 2018)

vikingBerserker said:


> It actually started several years before that in 1933. On January 9th, 1933, a directive for a multi-seat fighter was submitted to the Pursuit Board at Wright Field and on March 22nd 1933, the Material Division at Wright Field issued Engineering Section Memorandum Report B-51-104 entitled “Modification of Martin B-10 Airplane To A Multi-Seat Fighter.


They probably picked the Martin B-10 because it was faster than the operational fighters of the time. Still, the idea of an aerial-defense gunship is kind of a flawed idea unless perhaps you have lasers (YAL-1).


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## Zipper730 (Aug 3, 2018)

The aircraft, IIRC was able to carry 600 pounds of 30 x 20 pound bombs that could be dropped on enemy bomber formations or people on the ground.

I'm curious where the bay was located


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## johnbr (Jan 28, 2019)

643 Test 73 - XFM-1 (First setup) - NasaCRgis

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## johnbr (Jan 28, 2019)



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## johnbr (Jan 28, 2019)

643 Test 75 - XFM-1 (Second setup) - NasaCRgis

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## johnbr (Jan 29, 2019)

Bell YFM-1 model

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## Zipper730 (Jan 29, 2019)

GrauGeist said:


> The thermionic director was mounted in the nose. It's optic looks like a light centered in the nose window.


I'm not sure if this was touched upon before, but how did it work? Was it a lead-computation device, or did it somehow work by identifying light contrast (i.e. aircraft block out light presenting a dark spot), or some mix of both?


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## Zipper730 (Jan 29, 2019)

So, to understand the chronology of things here basically

3/22/33: Directive was submitted to the Pursuit Board at Wright Field to modify the Martin B-10 to a multi-seat fighter. Proposals included forward firing machine guns, and a retractible turret below the fuselage; there were also various mounts where the guns could be re-located within the "fighter's" fuselage. 10 x 15 pound bombs were to be carried to drop on bomber formations.
1934: There were war-games/combat-exercises carried out during this period. I'm not sure the exact details, but some included attempting to intercept bombers. For some reason, some people decided that the solution was not more speed, but heavier firepower that could be lobbed outside the defensive range of enemy bombers.
Early 1935: Captain Harry A. Johnson submitted a proposal to Major General Benjamin Foulois recommending a heavily armed super-fighter capable of destroying bombers. Bell & Lockeed were given $25000 to develop preliminary designs with a deadline of 3/15/36
I'm not sure when Bell wanted to get in on the fighter-aircraft business, but Bell was founded in July 1935 (so that could be the timeframe), and from 1928-1935 he worked for Consolidated, and when Consolidated moved to California, he stayed behind and set-up his own company.

I'm also not sure why the war-games exercises in 1934 lead to the conclusions that they did.


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## johnbr (Feb 2, 2019)

net

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## johnbr (Feb 2, 2019)




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## johnbr (Jul 26, 2019)

Bell XFM-1 Airacuda 36-351 prototype, first flight September 1, 1937. Note external turbosupercharger and fuselage gun blisters, as well as curved cockpit glazing, not included on YFM-1s. 
View attachment 546171
View attachment 546172
View attachment 546171
View attachment 546172


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## johnbr (Jul 26, 2019)

Bell Airacuda, possibly YFM-1B 38-489 or 490, one of two YFM-1s converted, re-engined with 1,090 hp V-1710-41 engines, both WFU January 1942.


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## fubar57 (Jul 31, 2019)

You could hold a barn dance in that cockpit


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