The similarity between Gloster's F.5/34 'Unnamed Fighter' (above) and the later Mitsubishi Zero is self evident. But pondering what aircraft designs, if any, might have influenced Jiro Horikoshi's sparkling fighter design is something of a speculative cliché, if not a conspiracy theory per se, and one which is unlikely to be unravelled now. There has always been an element of chauvinism in the idea that it was so good that it must have been copied from a Western design. In November 1985 the magazine Airpower published a rather sensationalised speculation by Warren M Bodie that in July 1935 the Northrop 3A prototype had been flown to a rendezvous with a Japanese aircraft carrier off the coast of California (the aircraft had disappeared over the Pacific ocean on its maiden flight) from whence it was used as the basis for designing the Zero. Whilst the Northrop 3A was touted as a rather improbable and chunky inspiration for the sleeker and more deadly Mitsubishi design, the author did not consider Gloster's F.5/34 in his collated suggestions for other possible inspirations, which included the Bristol Type 133 and Vickers Type 279 'Venom'. But wait one, is there perhaps an aspect to this story that has never been revealed? This slightly off topic if not unhinged flight of fancy, far too tenuous for Zero Aces, explores two avenues of intrigue.
In October 1937 (the same month that Horikoshi received the formal specifications for the 12 shi fighter that would become the Zero) the British Air Stories magazine* cover art by S R Drigin (as shown above) depicted the Gloster F.5/34 in speculative RAF 56 Squadron service to accompany a brief description of 'A New British 300 M.P.H. Fighter' and a feature on 'British Warplanes of To-Day' described and illustrated by A C Leverington (as shown below). The cover art depicts the aircraft in a somewhat similar composition to the box art for the original Airfix Zero by Roy Cross - the aircraft diving obliquely towards the viewer with a background of cumulus. Interestingly A C Leverington's illustration seems to include an opening like a gun muzzle aperture just behind the cowling which was not present on the Gloster prototype. Russell Mallinson's story 'The Zero Plan' tagged on the cover is a spooky coincidence but has no connection to the Japanese fighter. Air Stories undoubtedly touted the potential of Gloster's design, uncensored and widely available at many newsagents. If it had escaped the notice of the Japanese air attaché in London that would have been a miracle. But there is more.
From 1932 to 1936 the notorious Lord Sempill, who was being investigated for passing secrets to the Japanese, reportedly represented Mitsubishi in Europe. Sempill had been instrumental in acquiring the Gloster Sparrowhawk for the Imperial Navy when he had led he British Air Mission to Japan in 1921, a type that had continued successfully in IJN service until 1928. In 1927 the Imperial Japanese Navy, seeking a Sparrowhawk replacement, acquired the Fleet Air Arm rejected Gloster Gambet (a carrier-based version of the Gamecock with extended wingspan, flotation bags and arrestor hook) as a pattern aircraft with licence building rights. The Gambet design, with modification, then became the basis for the Nakajima A1N1 and A1N2 fighters and that type was just going out of service when Gloster began work on the F.5/34 as a much more advanced type.
Lord Sempill - Gloster - Mitsubishi - the Imperial Japanese Navy - those connections are a matter of historical fact. By June 1941, MI5 had intercepted messages between London and Mitsubishi and Field Marshal Yamagata's Tokyo headquarters indicating that payments were being made to Sempill: "In light of the use made of Lord Sempill by our military and naval attaches in London, these payments should continue". There is also strong evidence that Sempill was in contact with Makihara Satoru, head of the Mitsubishi Shoji Company's London office. It is quite possible that Sempill had also maintained contact with the Gloster Aircraft Company and when the Air Ministry rejected their F.5/34 design there was perhaps an aspiration to try to sell the design to the Imperial Navy for licence building, to repeat the Sparrowhawk and Gambet successes through Sempill's contacts with Mitsubishi. Horikoshi was unlikely to have admitted being influenced in any way by general arrangement drawings and data from the F.5/34 project, especially if acquired covertly through espionage and intelligence channels or more prosaically via the Air Stories magazine.
The Gloster F.5/34 design project began in early 1935 under H P Folland in collaboration with H E Preston and two prototypes were built, K5604 being flown for the first time in December 1937 and shown at the Hendon Air Display in 1938. The second prototype was K8089 and both were experimentally flown at the Royal Aircraft Establisment under Air Ministry charge until May 1941 when they became the ground instructional airframes 2231M and 2232M. The armament in keeping with the Air Ministry specification was eight wing-mounted Browning .303 machine guns with 2,000 rounds of ammunition - but there was that distinctive hump above the cowling that in the Zero housed the two 7.7mm machine guns synchronised to fire through the propeller and plenty of armanent weight capacity in the wings for two 20mm cannon, 102 lbs vs 188 lbs.
1/72 scale kits for the F.5/34 have been released by Magna Models as 7572 in cast resin and white metal and by Planet Models as PLT258 in cast resin in 2014. The Planet Models kit (shown above and below in completed form) is a neat and crisply moulded production which does the original justice and makes up into an interesting comparison piece to the Mitsubishi A6M2. Potential 'what ifs' include an example in IJN markings with cowling guns and cannon wing armament, or an RAF production version replacing the Brewster Buffalo and squaring up to the Mitsubishi fighter in a fantasy dogfight double.
* Air Stories: Flying Thrills and Aerial Adventure in Fact and Fiction, Volume 5, No.4, October 1937, published by George Newnes Ltd., Tower House, 8-11 Southampton Street, Strand, London.
Image credit: Heading photograph via web: Air Stories magazine cover & excerpts author collection; Airfix box art © 1976 Airfix Products Ltd.:3-view plan via web; Magna box art © Magna Models date unknown; Model photograph © 2014 Planet Models/Special Hobby s.r.o.