Allied emergency fighters


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31 December 2008
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There is a lot of info out there on Axis, especially German, prototypes and projects for emergency fighters--generally small, simple, easy-to-mass produce alternatives to exisiting fighters often using non-strategic materials like wood and mild steel. I'd like to learn more about Allied emergency fighter prototypes and projects, especially those conceived or built during the early years of WWII when things were looking pretty grim. I am not talking about desperate expedients like arming light trainers, I mean aircraft designed as emergency fighters.

Off the top of my head I can think of two (not counting the Commonwealth Boomerang, which actually entered production):

1) The British Miles M.20 (1940-41, two prototypes) used the same Merlin engine as the early Hurricane and Spitfire (actually the firewall-forward "power egg" from a Lancaster or Beaufighter) and managed to be faster than the Hurricane and a little slower than the Spifire despite the fixed gear. With thick wings and no undercart to stow it had room for twice the fuel and ammo of the other designs, which would have made for an excellent combat radius or long loiter time on patrol. Its wooden construction (based mostly on Master advanced trainer components) did not compete for the limited alloy suppy. But once the Battle of Britain was won and production of other fighters had caught up, there was little need. The second prototype to a shipboard fighter specification was also not picked up, perhaps because of naval suspicion of wooden construction and because the outmoded Spits and Hurricanes were already being converted for naval use.


2) The American Bell XP-77 (1941-44, two prototypes) was a lighweight, low-powered fighter designed to use non-strategic wood in its construction. It had racy lines and good ground handling thanks to the retractable tricycle gear, but the two prototypes proved overwieght, underpowered and tricky to fly, one being lost when the pilot bailed out unable to recover from a spin.


Does anyone have any more Allied emergency fighter projects? Perhaps paper or prototype competitiors to the XP-77 to start?


There was this one:,1338.0/highlight,percival+mew+gull.html
Thanks, guys, though I did say in my original post...

I am not talking about desperate expedients like arming light trainers, I mean aircraft designed as emergency fighters.

Off the top of my head I can think of two (not counting the Commonwealth Boomerang, which actually entered production)....


The MB2 is certainly in the right ballpark, does anyone know of any more?
Mole, there were only two posted, and you accepted the MB2 .
That was designed as a private venture to Specification F5/34, along with half a dozen other fighter designs none of which were
small, simple, easy-to-mass produce alternatives to existing fighters often using non-strategic materials like wood and mild steel.
MB2 fiirst flew in 1938, but after modification it was abandoned in 1939 with no interest from the RAF, so it doesn't fit your early wartime time slot either.

Did you actually read the thread I suggested?
I should have said that what I already know is from The British Fighter since 1912 Peter Lewis 1965
the single-seat Percival P.33AB with a 1300hp Merlin and four .303 Brownings - which was expected to have a top speed of 352mph and would have resembled an enlarged Mew Gull fitted with a retractable undercarriage.
Silvester's Percival and Hunting Aircraft says
based on the aerodynamic configuration of the Mew Gull but somewhat larger
and that the Merlin XX was to be used.
The design was in competition with the Miles M20
I was hoping someone might know how much larger, and perhaps even have a drawing.
Which drawing Lark provided. At 6300lb, the P33 was a tad bigger than the Mew Gull.


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You forgot the Miles Master Fighter, a one place version of the Miles Master Mk1a trainer, armed with six Browning machinguns
alternatives to exisiting fighters often using non-strategic materials like wood
DH Mosquito? ::)
It was designed as a bomber, after all, and the Beaufighter was a bit slow as a night fighter.
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A great subject Mole
Thanks for bringing it up.

Thankfully for the poor pilots, we didn’t need to resort to such second rate aircraft.
But it was wise to have investigated such basic designs, when all seemed so bleak, as apposed to just giving up!

I wonder if any of the these prototypes – such as the Miles M.20 and Bell XP-77 were ever put up against the then standard fighters of the day – i.e. ‘dissimilar air combat’ to see how they faired?
Would be interesting to find out!!!!!!!!!!!!!

as ever a superb contribution by Justo Miranda , but ı think the PZL 50 was a regular project and there might be others as well
An excellent contribution Justo..
I just knew that you had a few beauties in your files.
Thanks a lot.
Thankyou Justo - fascinating posts!

May I ask what is the Chinese fighter with the forward swept wing?

Also the VEF Irbitis I-19 seems to be powered by an X block engine. Is it a DB 604? Or perhaps a Kamm Gruppenmotor?
May I ask what is the Chinese fighter with the forward swept wing?

It is the Yench'ü (Experimental Pursuit, XP-1) fighter prototype built by the No.1 Aircraft Factory in Canton. It was completed in 1943 but crashed during the first test flight (autumn that year). Design started by C L Zakharchenko as the D-2 in 1942. Engine: Wright Cyclone.

Source: A History of Chinese Aviation until 1949. Lennart Andersson. AHS of ROC.

Justo's image is slightly different from illustrations and photo in the book. Probably it depicts the intended production configuration?

BTW, who was C L Zakharchenko?
Karl Irbitis proposed building a composite engine MI-02 connecting three D.H. Gypsy Six to each other to make an inverted "Y" 6-bank ,36 cylinder air cooled power plant.
Thankyou Pometablava!

Justo, so a very similar concept to the Kamm Gruppenmotors then? Three Gypsy 6 would only give about 600 hp and have 18 cylinders though. Do you mean three Gypsy XIIs? That would have 36 cylinders and about 1300 hp.
Skyblazer said:
From Race with the Wind: How Air Racing Advanced Aviation, by Birch Matthews (MBI, 2001):

"With the war already waging in Europe, race pilot Harry Crosby turned his attentions to a lightweight interceptor for the Air Corps. The design was influenced by his CR-4 race plane. Unlike the all-metal CR-4, however, Crosby's CIP-5 proposal was based upon wood, a nonstrategic material. The CIP-5 was to be powered by an air-cooled Ranger V-770. The Air Corps was not interested."

Another source states that Mattson Compton helped Crosby with the design.

Non-strategic materials, Ranger V-770... This seems like an obvious contender for the Bell XP-77 to me!

Pioneer said:
Thankfully for the poor pilots, we didn’t need to resort to such second rate aircraft.
But it was wise to have investigated such basic designs, when all seemed so bleak, as apposed to just giving up!

I wonder if any of the these prototypes – such as the Miles M.20 and Bell XP-77 were ever put up against the then standard fighters of the day – i.e. ‘dissimilar air combat’ to see how they faired?

I think the M.20 has to come close to the top of the list for "emergency aircraft we'd like to have seen in combat". If nothing else, it might have allowed diversion of strategic materials from Hurricane to Spitfire production and could have replaced the Hurricane in the anti-bomber role.

As for dissimilar combat, no doubt there are number crunchers among us who would love to play with figures, and those who put rare or never-built aircraft into expansion packs of air combat simulators have the same problems to solve. Just how do you compare them? Straight-line speed and climb rate are the obvious indices (ideally both plotted against altitude), but there are equally important considerations such as turn rate and radius, and acceleration. This means you need good guesses as to drag coefficient, power available at height and so forth, and it can all get rather complicated rather quickly.

Then of course there are the quirks of individual designs - unpredictable behaviour near the stall, tendency to shed bits under heavy combat structural loadings (or conversely the idiosyncratic* ability of a particular design to survive massive amounts of combat damage), long cowling lengths leading to poor gunnery in high-angle turning dogfights and so forth.

* = Ultimately traceable IMO to the peculiarities of detail design: how the control runs are arranged, structural redundancies where applicable in this generation of fighters, position of fuel tanks and armour, and so forth; but all this is so dependent on what sort of fire is being taken from what angle and at what range that the variables are impossible to predict. Add to that the issue of QC from the factory and you're up for some real fun debating the ins and outs of how well they would have worked.
From Tony Buttler’s ‘British Secret Projects, Fighters and Bombers 1935-1950.

Prototype Defiant K8310 eventually had its turret removed and in August 1940 was flown as an unarmed flying demonstrator for a fixed-gun version called P.94, which was intended for rapid production using many complete Defiant components. The P94 had the turret replaced by 12 0.303” MG disposed in each side of the wing centre section in nests of six – 4 20mm cannon replacing 8 of the 0.303” in two nests of two each were an alternative while the MG could also be depressed 17 degrees for ground attack work. P.94 had a 1,100hp Merlin XX, which offered a maximum speed of 360mph at 21.700ft, a sea level climb of 3,250ft.min and would get to 25,000ft in 8.1 minutes. To allow the type to act as a long range fighter two 30-gallon auxiliary tanks could be carried and in production the aircraft would use standard Defiant jigs. The P94 was never ordered but Boulton Paul also proposed to convert the now single seat Defiant prototype into a 4 cannon fighter demonstrator. The Air Ministry’s rejection of this idea was recorded at a company board meeting on 26th September 1940.
Both the recent “WW2” US “secret projects” book and the recent revamp/ new addition of the equivalent British “secret projects” book have details on such aircraft.
Both strongly recommended.
Most of these rushed airplanes are detailed in Justo Miranda’s latest book: “Enemy at the Gate, Panic Fighters” published in late 2019. It contains dozens of 1/72 scale drawings of all these airplanes, plus a few I have never heard of before.
I strongly recommend this book for those of us fascinated by obscure airplanes.
Also look at the “Panic Fighter 1938” thread over on
More of a general question ....
Why did so few WALLIED fighters have motor-kanons?

Hispano-Suiza pioneered the concept during WW1 with a .303 Lewis light machine gun firing nestled between the V cylinder banks and hrough the propeller speed reduction un
By 1938, their 12y engine - with a 20 mm cannon firing through the PSRU - was being manufactured for the French Air Force. H.S. widely exported engines and cannons. Even Klimov (USSR) bought a license.
Germany developed a couple of inverted V engines - with 20 mm motor-cannons - for the Me-109.
The only true WALLIED motor-cannon was the Bell XP-77, but it never progressed beyond the prototype stage. It’s 20 mm cannon was mounted above the crankcase of its inverted V engine. This configuration improved visibility and reduced undercarriage length.
The next best was Bell’s P-39 Airacobra with its 37 mm cannon firing through the PSRU, but the engine was behind the cockpit and needed a long drive shaft.
Why so few WALLIED motor-cannons?
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...Why did so few WALLIED fighters have motor-kanons?...

A clunky explanation might be space allocation by priority for the various engine designers.

In the case of the early Rolls-Royce Merlin, the intake manifold from the single-stage supercharger took up the same 'real estate' as the HS 12Y's moteur-canon. That was further complicated with two-stage Merlin superchargers which also introduced an intercooler into that space.

In the case of the Allison V-1710, responsibility seems to rest with the Planning Section of the USAAC's Equipment Division. For whatever reason, a down-draught version of the Bendix Stromberg PD-12 carburettor was stipulated for the supercharged Allison V-1710.* That placed the P-40B's PD-12K1 carb exactly where the breech of an HS 404 would have sat.

Of course, it could be argued that with its internal-spur reduction gear, the early 'C model Allison couldn't have easily accommodated a motor gun anyway. That would have been solved by the higher thrust-line, external-spur 'F model. But, by then, Allison faced wartime urgency and retaining the same PD-12K1 carbs was a time-saver. Of course, it also needs to be said that, the US had no reliable 20 mm gun in production at that point anyway.

* OT but US officialdom also rejected Allison's recommendation to introduce a two-stage supercharger.
wonder if any of the these prototypes – such as the Miles M.20 and Bell XP-77 were ever put up against the then standard fighters of the day – i.e. ‘dissimilar air combat’ to see how they faired?

The M.20 was flown against a Hawker Hurricane by test pilot Eric Winkle Brown during suitability trials for its potential as a single-seat carrier fighter for the Admiralty. The following is from Brown's excellent recollection Wings of the Weird and wonderful Volume One (Airlife, 1983):

"The initial rate of climb was surprisingly good, for I had rather expected it to be sluggish on account of the fixed undercarriage and the all-up weight being in excess of that of the contemporary Hurricane and Spitfire. The even bigger surprise was its level flight turn of speed, which was in excess of the [Grumman] Martlet at 335 mph."

"The harmony of control was quite good but the controls were all heavier than those of the Hurricane, Martlet or Spitfire."

"For the test, a Hurricane flown by [Flt Lt J.R.] Tobin had come up to dog fight with me and it was obvious the Hurricane was more manoeuvrable and had a much smaller turning circle. In attempting to follow the Hurricane in a steep turn I flicked out of control at 140 mph without any warning. The Hurricane could also change direction faster and accelereated faster, although the M.20 was itself no slouch."

"Half a dozen more landings had convinced me that this would not be an ideal deck landing aircraft"

"In essence my report to the Admiralty, which apparently was considering the M.20 to meet Naval Staff Requirement N.1/41, expressed the view that the M.20, although surprisingly nippy in performance, could not match the Martlet, Hurricane, or Spitfire for manoeuvrability, and did not offer enough speed performance superiority over the Martlet or Hurricane to give an offsetting advantage."
Why did so few WALLIED fighters have motor-kanons?

One thing you have to consider, for the UK especially, and France and the US to a lesser extent, is that we went directly from requiring two rifle-calibre guns with the Gladiator, to eight rifle-calibre wing guns with Spitfire and Hurricane. Some of the French and US designs stuck with two or three guns in the nose, but there was a relatively rapid escalation in required firepower, and a single motor-cannon, even in 20mm, just isn't putting a whole lot more lead in the air. Once we'd gone the wing-gun route, why go for a motor-cannon, with all the installation complications, when you can stick two or more in the wings (or initially under them).
It's worth remembering that it took the Germans some time to get it right with the Daimler Benz engines, one of the prototype Bf 109s that was sent to Spain was fitted with a motor cannon, but it overheated and although experimentation was carried out with later engines, the first production Bf 109 to be fitted with motor cannon was the Friedrich of late 1940, early 1941. There are misconceptions that earlier prewar variants were fitted with motor cannon, but the likes of the Bf 109C-2 was a project only and was not put into production, likewise no production variants of the infamous Bf 109E was fitted with a motor cannon despite many books, cutaway illustrations and so forth depicting the model as fitted, despite the original intent.

This is the cockpit of a surviving Bf 109G (G-2 Black 6 at RAFM Cosford) and the big lump in the middle is the cover of the gun breech. The Bf 109's cockpit is a small space as it is and the gun makes it even more claustrophobic.

Motor cannon
According to the book “Race with the wind” inter-War racers almost spawned a few American “panic fighters.”
General Billy Mitchel suggested a militarized version of the Wedell-Williams racer as an interceptor.
In 1940, racer Harry Crosby proposed his CIP-5 lightweight interceptor. It was based on Crosby’s CR-4 racer, but powered by the same Ranger V-770 engine as Bell’s prototype. Both Crosby and Bell proposed wooden airframes.
The Wedell-Williams racer-turned-interceptor is almost certainly the XP-34.

Yes, Wedell-Williams XP-34 was developed from their pre-war racers number 44 and 45. The number 45 had a cantilever wing and retractable main wheels. It was powered by a Pratt & Whitney R-1340 engine and first flew in 1933. In 1934, it qualified at more than 300 mph, but stability problems forced WW to withdraw it from competition. Sadly, both Jimmy and Walter Wedell along with financial backer Harry P. Williams died in flying accidents. With the death of chief test pilot John Worthen in 1936, the last principle contributor vanished.

In 1935, the US Army Air Corps ordered a full set of drawings for the XP-34. WW proposed a Pratt & Whitney R-1535 Twin Wasp engine producing 700 horsepower, but was rejected. When the USAAC requested an X-1830 engine (900 hp.) WW concluded that re-design was too much of a hassle.
The widow Williams proposed the XP-34 to the US Army Air Corps, but it was soon over-taken by faster airplanes. Since installing a larger engine would require a major re-design … and their designer was dead - Mrs. Marguerite Clark Williams dropped the proposal.
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The Ranger SGV-770 engine was also proposed for the Douglas XP-48. It resembled the Bell XP-77 except for its high aspect ratio wing with a span of 32 feet.
However, Ranger continued suffering development problems and the USAAC cancelled the project in 1940. No prototype was built.
Tucker XP-57 resembled Bell’s P-39 Airacobra, but was lighter with only a 3,000 pound empty weight. The Miller, 8-cylinder engine was mounted behind the pilot. A single .50 machine gun or 20 mm cannon would fire through the propeller hub. Unfortunately Tucker Aircraft went bankrupt in February 1941 and the project never got off the drawing board.

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