Since the YFM-1 Sucked...

[jcf]

The Martin Type 167 Maryland prototype was designated the XA-22, designed as
an attack aircraft, it was in competition with the Douglas DB-7 which became the A-20.








Originally the "turret" was retractable and covered by a sliding panel

[NARSES2]

Now that retractable turret is a detail I was unaware of. Some British types had turrets which could be partially retracted (I assume US, French designers etc had similar thoughts) but I've not seen a fully retractable one of that vintage before. The hatch is particularly interesting.

Cheers Jon 

[Madoc]

The Bell Airacuda was as much a "technology demonstrator" for the Army Air Corps as it was anything else.  Funds were beyond tight back during the Depression Era US so the Air Corps tended to load up on any prototype they did get money to try out.  Hence all the "cutting edge" features of the Airacuda.  And Bell was a natural for doing technology demonstrator work like that.  Hence why they got the Airacomet work and why the Army turned to Bell for the X-1.

Now, to make the FM-1 "work" there'd have to be some significant changes.  First off, those big canons would have to be replaced.  They were monstrously overpowered for their day.  They were, in fact, the same caliber weapons the US Army - and the rest of the world, for that matter - were using as the main armament for their tanks!  In today's terms that'd be like mounting two 120mm canon on an aircraft as its primary armament.

It would've been nifty had those 37mm guns were effective in operational use but they weren't.  The things tended to jam.  A lot.  They weren't capable of handling the Gs involved in aerial use so their components would get hung up as a result.  So we'd have to ditch the things and replace 'em with either Oerlikon 20mm guns or perhaps Bofors 40mm ones and assume that the Army had figured some way of making sure the feed mechanisms for the Bofors kept feeding while the plane was flying around.

Then there's the engines.  First off, we'd have to replace the early model Allison V-1710s at just 1,090HP for the 111/113 versions which put out 1,600HP.  Either that or go with Merlins or something similar.

And we'd have to do something with the cooling.  Bigger radiators, fan driven ones as well to ensure the airflow was sufficient over them even when the bird was still on the ground.

Of course, if you've swapped out your canons with ones that have a reliable belt feed mechanism then you don't need "gunners" in those nacelles.  Their real job was to have kept those 37mm guns fed and unjammed.  Better, more reliable guns, would obviate the need for those gunners to be there and that would clear the space in the nacelles for more ammo and for bigger radiators in place of the crew compartment there.

Then you'd have to replace the electrical drives of everything on the plane since that system was definitely not ready for prime time.  Yes, a standard hydraulic system would we some more but it'd be a lot more reliable.

The end result would be a faster and more effectively armed weapon system.  The weight on some aspects would've gone up but you could get weight savings by having reduced the number of crew and the total airframe volume required to house them.  Plus you've bumped up your horsepower by a lot.

So, in all likelihood, the FM-1"B" would then actually turn out a useful machine.

Of course, Curtiss already had all of this in hand with it's XP-71 design.  That thing didn't mess around with anything so "dinky" as mere 37mm canon for its main armament.  No, it sported a full-on 75mm artillery piece with which it'd be blowing Nazi bombers out of the skies!

[KJ_Lesnick]

zenrat

Public Relations?

Photo-Reconnaissance


Madoc

Funds were beyond tight back during the Depression Era US so the Air Corps tended to load up on any prototype they did get money to try out.

Was there any place at that point in time for a specialized proof of concept aircraft either NACA or the military?

Bell was a natural for doing technology demonstrator work like that.

Why if I may ask?

Now, to make the FM-1 "work" there'd have to be some significant changes.

Of course - basically, the idea would be to take as much of the specification as was reasonable, and produce an entirely new design around the specifications.  I'm working with a guy who's helping me out with that.

The YFM-1 as it was seemed to be affected from several concepts that the US Army had for aircraft, which were not always as straight laced as you'd think.  These included: Bomber Defense, Bomber Escort, and Ground Attack.

• Bomber Defense
  
  
  
  • Some people seemed favorable to the classic interceptor profile which revolved around being able to climb very fast, accelerate rapidly to high speed, usually with high altitude capability built in.
    
  • Others favored heavy firepower and, presumably standing patrols: The idea would be that you wouldn't need as much of a speed-margin to run-down enemy bomber aircraft as you're already up at altitude and cruising along.  You still need to be able to outrun the enemy bomber of course, and the heavy firepower would allow you to damage/destroy the aircraft very rapidly.
    
  • There was also an interest in dropping bombs on bombers from altitude so as to effectively destroy them: The idea works when you take the explosive charge, stuff it inside a streamlined projectile, load it with rocket fuel and a guidance system, and configure the guidance system to a set of moveable fins on the body of the projectile — otherwise, it's pretty stupid, and turns your interceptor into a bomber (interestingly, the USN tried the same thing with the F4U Corsair though, to their credit, they used smaller bombs, and probably, a smaller load).
    
• Bomber Escort
  
  
  
  • They were very opposed to the use of drop-tanks on their bomber-escort aircraft: They figured that, at the start of combat, pilots would just jettison them, and sacrifice all the range that came with it.
    
    
    
    • While this is, to an extent, true: The fact is, it isn't as bad as you'd except as from engine-start, taxi-takeoff, and climbing past the end of the runway, the aircraft were drawing from the internal tanks; from that point until the start of combat — the internal fuel-load wasn't touched, producing range nearly for free
      
    • The need to meet this kind of range on internal fuel alone requires a higher fuel-fraction than a plane with drop-tanks, which requires a more creative design (sufficient volume for strength) or a greater size (which often comes at a cost to weight, and their attitude on using two engines seemed to vary from either: "NO" to "Yes, but you'll require an extra crew-member" — either of which imposes performance limitations, the first by making the plane underpowered, the second by requiring added weight in a crew-member that is not physically required).
      
    • High altitude capability was desired by the USAAC/F than almost any other air-arm in the world: This required two-stage supercharging/turbocharging and intercooling (and, since almost all intercoolers are air-to-air, they can take up decent volume), and with a strong (i.e. borderline pathological) interest in turbochargers to the exclusion of nearly everything else, it meant there was little resources to develop any alternatives (two-stage superchargers) outside the USN.  While turbochargers aren't exceedingly heavy in weight, they do tend to be bulkier than a twin-stage supercharger because of the turbine and exhaust system (if you're trying to maximize fuel volume — this will undercut your efforts).
      
  • They had strange ideas such as the idea of a rear-gunner, or even multiple gunners, producing in essence, a flying gunship that could, in theory, maneuver well enough to be a fighter. 
    
    
    
    • A rear gunner takes up additional space in the aircraft which ends up intruding into fuel-space, requiring a larger aircraft, or both.  All of this serves to undermine fuel-fraction, reduce power-to-weight ratios, or both.
      
    • One proposal included a modified Martin B-10 series with extra guns mounted throughout the plane, so as to allow it to serve as a gunship.  The idea fell apart when it was realized it's performance would be less than the normal B-10 series.  Interestingly, this is one thing that gave rise to the YFM-1...
      
    • It's not a surprise with these unneeded specifications that they felt long-range bomber-escorts were economically unfeasible (that and they didn't feel that they were inherently needed for daytime bomber operations when air superiority did not exist — every air-arm worth its salt will try and knock the enemy air-force dead on the ground if they can).
      
  • Ground Attack
    
    
    
    • It seemed that the USAAC/F had little interest in dedicated attack aircraft in terms of the classic single-engine dive-bomber
      
    • They seemed to either want fighter-bombers (which could do the attack mission, but bombs-off, were basically fighters), a common frame that could be made into a fighter or attack plane (such as the P-30/A-11), or a heavily armed gunship with a whole lot of 20 lb blast fragmentation bombs.
      
  This aircraft was, in a sense, built to all of these specifications as it had the range to be an escort, the cannon armament to make it a bomber killer, and bomb-loads that were useful for their perceived CAS roles.
  

  First off, those big canons would have to be replaced.  They were monstrously overpowered for their day.  They were, in fact, the same caliber weapons the US Army - and the rest of the world, for that matter - were using as the main armament for their tanks!

  I thought they used larger armaments for tanks, but I do know there was a 37mm anti-tank round.  It however, from what I've been told, are not the same as the 37mm anti-aircraft round: It was longer and heavier, and probably had a bigger explosive charge.  It also had a higher muzzle velocity due to a bigger casing.  Basically they were largely two different rounds that used the same bore.  Later on, there would be a variant called the 37mm M9 that would use the anti-tank rounds in their design, but the gun would weigh 405 lbs vs 213 lbs (in comparison I'm around 162 pounds -- I'm almost 6'3").
  

  It would've been nifty had those 37mm guns were effective in operational use but they weren't.  The things tended to jam.  A lot.  They weren't capable of handling the Gs involved in aerial use so their components would get hung up as a result.

  I remember the bigger complaint was the slow muzzle-velocity and bullet-drop -- the fact that they would jam under g-load isn't a big shock however.
  
  Back when the design was being conceived the two options were either the 37mm M4 or the Madsen 23mm.  The Madsen 23mm was generally better in that it had a better refire and muzzle velocity, but it wasn't an all American design -- it was Danish.  Most people in the past (and correctly so) preferred to buy local if they could: That said, since the USN wanted to arm all their fighters with 20mm, it seems best to just arm the plane with 37mm from the start; then switch to the HS404 before 1942 :p
  

  Then there's the engines.  First off, we'd have to replace the early model Allison V-1710s at just 1,090HP for the 111/113 versions which put out 1,600HP.

  That would be a time-related issue, the first V-1710's only produced around that horsepower level, so you'd be kind of restricted to that until more powerful variants became available.  Otherwise, I'd agree with you.
  

  And we'd have to do something with the cooling.

  The problem with the cooling with the pusher designs was that they didn't have a propeller up front blowing air through the radiator, so a fan-driven device would work in that design.
  
  With the tractor-prop, that should probably fix the problem in it's entirety
  

  Then you'd have to replace the electrical drives of everything on the plane since that system was definitely not ready for prime time.

  Yup

[zenrat]

zenrat

Public Relations?

Photo-Reconnaissance

Are you sure?

[KJ_Lesnick]

zenrat

Are you sure?

Pretty-sure... I might have misspelled it though :p

[ysi_maniac]

Here's some simple profiles I did many years ago.  V1710 with tractor props and two different types of nose, a slightly modified streamlined nose and a stepped one.  I used the XFM-1 as a basis simply because I didn't have any other profile to base it on.

A very attractive design IMO.

[Mossie]

Thank you Carlos.

[jcf]

Lockheed XFM2 armament diagram.

Span: 79' 4"
Length: 57' 3"



Alternate armament schemes and roles were proposed, including attack
bomber. The two turrets were to be spherical and the top one retractable.

Details are in a number of Lockheed XFM2 documents on the American Aviation Historical
Society website in the Members area, so if ya want more, go join and you'll have access,
it's only $29 US per year for an e-membership that includes digital versions of the quarterly
journals and a very large percentag eof the past journals going back othe beginning are
available in digitized form.

[KJ_Lesnick]

Lockheed XFM2 armament diagram.

Span: 79' 4"
Length: 57' 3"

The wings kind of look like the P-38 in plan-view...

Alternate armament schemes and roles were proposed, including attack
bomber.

Fascinating

Details are in a number of Lockheed XFM2 documents on the American Aviation Historical
Society website in the Members area, so if ya want more, go join and you'll have access,
it's only $29 US per year for an e-membership

Sounds great!

[NARSES2]

zenrat

Public Relations?

Photo-Reconnaissance

Are you sure?

I'm back--- so stop it 

Re the Lockheed XFM2 armament diagram I do find the mix of calibres (3 of them ?) very much of the period. Could of been a bit of a nightmare in war time conditions ? Especially if being used as an attack bomber with a quick turnaround.

[zenrat]

zenrat

Public Relations?

Photo-Reconnaissance

Are you sure?

I'm back--- so stop it  ...

Spoilsport.

[jcf]

Amongst the alternate armament fits was replacing the
nose turret 20mm with one of the following options:
37mm Browning Automatic Cannon,
25mm Browning Automatic Cannon,
a pair of MGs, either .30 or .50 caliber.

Fitting fixed .30 MG in the upper fuselage behind and to either
side of the nose turret, the guns to be electrically fired by the
pilot or turret gunner.

Under wing bomb racks with full remote salvo control allowing
precise release of the bombs in the desired order, particularly
in the case of a mix of bomb types being carried.

Redesign of lower fuselage, equipment relocation to create an
enclosed bomb-bay, to carry one of the following load options:
8 - 100lb Mk. III demolition bombs
2 - 300lb Mk. III demolition bombs
2 - 600lb Mk. III demolition bombs
1 - 1100lb Mk. III demolition bomb
1 - 2000lb demolition bomb

[NARSES2]

Some fascinating info' there Jon, thank you 

The 37mm auto-cannon crops up in a lot of U.S. pre-war designs but I've not noticed the proposed use of the 25mm before. It really is a fascinating period of aircraft design. The available technology however didn't quite meet the designers ideas a lot of the time.

[KJ_Lesnick]

Amongst the alternate armament fits was replacing the
nose turret 20mm with one of the following options:
37mm Browning Automatic Cannon,
25mm Browning Automatic Cannon

I never knew they built a 25mm design.  I'm surprised the Madsen had a chance then...

Under wing bomb racks with full remote salvo control allowing
precise release of the bombs in the desired order, particularly
in the case of a mix of bomb types being carried.

Redesign of lower fuselage, equipment relocation to create an
enclosed bomb-bay, to carry one of the following load options:
8 - 100lb Mk. III demolition bombs
2 - 300lb Mk. III demolition bombs
2 - 600lb Mk. III demolition bombs
1 - 1100lb Mk. III demolition bomb
1 - 2000lb demolition bomb

Wow, that's some internal load, more than the YFM-1.

The YFM-1 carried it's bombs in the wings, right?