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.
Trying to find delineations from foreign designs is fascinating and often - as you mention - influenced by some chauvinism. For sure in the 30's aircraft engineers watched closely what others did. It was the time of a paradigm change in aviation technology. And they also often acquired potential rivals for comparison (or should I say blueprints to copy?). The Gloster F.5/34 could also be a forefather of the Fiat G.50 and Macchi C.200, couldn't it?
I guess many of these propositions contain a grain of truth, but in the end there are so many more features than the outward shape that make a successful combat plane, e.g. the Zero's 20mm canon and above all its superb range and carrier suitability.
To reiterate some other popular suggestions: The A5M was a copy of the Boeing P-26, and plans for the Reggiane Re 2000 were stolen from Seversky (P-35). Strange that the 'copies' were much more successful than the 'originals'.
Thanks Michael. Agreed. But as I have blogged there were more connections involved than just the outward shape and those connections did not apply to the Fiat and the Macchi. So I'd put it slightly more than a popular suggestion based only on superficial similarity. And I do wonder if Gloster had an eye to carrier operation for the F.5/34 given their pedigree.
Interesting! With the Mk I eyeball alone, the Gloster seems far more likely than The Usual Suspects from Hughes and Northrop to have influenced Horikoshi's design, yet I've never noticed that or seen it mentioned. Since I never owned Putnam's "Gloster Aircraft Since..." or subscribed to English aircraft magazines, I hardly remember the design. The junction of the rear wing and fuselage, canopy setup, and the look of the cowling particularly resonate set next to the Zero; and more than the other airplanes usually mentioned, the wings, though stubbier, seem similar. I agree with Michael that it calls to mind Italian prewar designs as well, especially the empennage. An excellent article, especially with the information about Lord Sempill's connection. Put author Ben MacIntyre on to this, Nick, and together you two might dig it all out! Thanks for this one, Nick.
Though they are mostly all gone now, here in America many WWII-era servicemen still held to the idea that the Zero was largely derivative of American design. Most of the ones I heard mention it (usually talking to them as a teenager or young man, when they realized I was interested in the subject) had no reason to doubt what they had heard, and it had become accepted gen.
USN fighter pilot Bill Leonard's memories of the Zero, as one who flew Koga's captured Zero several times and certainly a person with a vested interest in knowing all about it (he finished with six kills in World War II), remain the most interesting for me. In essence they contradict the notion, though he noted the American origin of its propeller, some instruments, and other items. He also recorded how among all the USN and USAAF aircraft gathered for testing against the Zero, the Zero was the most mechanically reliable! Those of you with a copy of Jim Rearden's "Cracking the Zero Mystery" will find his accounts there of interest.
Technical espionage is a common occurrence. Why not? And no one will ever admit it.
Yes, of course Alex. But I was writing about specific connections, albeit speculatively, rather than technical espionage in general. A 'nothing to see here, move on" response which dismisses those connections is perhaps less brutal than "so what?" but equally discouraging to further exploration and endeavour.
Thank you Mark for expressing your appreciation of the article.
Responses may not have given proper credit to your research, Nick, which is as meticulous and stimulating as ever. The spontaneousness of reactions, however, proves that the blog gave us food for thought.
I wasn't aware of the Gloster design in the first place - so it's interesting in itself - and the connections you uncovered seem to point at more influence on the Zero's development than any previous assumptions of its heritage.
My point was simply that the result counts and for that Mitsubishi deserves the praise of originality. You certainly didn't question this.
I'm not sure if this is comparable but the He 100 may have been a similar milestone in the design of the Hien.
Keep up your highly appreciated research for us! Best, Michael
I happen to be in the middle of building the Planet kit, which I found on eBay for $20 (the original price was something like $60).
It is a very good kit of the first aircraft, which by the way was not armed. The resin is super hard with corrections needed to the wing join and cowling. It comes with two canopy's which you need to be careful with due to its hard plastic which is prone to shattering. It is a handsome design.
What an interesting article! I've never heard of the Gloster plane, and the connections between Mitsubishi and Lord Sempill are certainly thought-provoking. Thanks for presenting this!
Thanks for your time & effort on this posting, Nick.
Very interesting article Nick, especially with the factual connections stitching it all together.
With lookalike designs in mind, the Polish PZL P.50 also comes to mind. It even has the nose guns, but the canopy was more traditional with poor visibility to the rear. It actually looks a bit like the fighter variants of the NA-16 series, which spawned the famous T-6, which of course is often abused as a Zero lookalike :)
It's not unusual for aircraft designed around the same time to superficially appear similar. The designers are using similar technology, similar data, designing to similar requirements, using the same engineering equations and similar materials, so they are coming up with similar solutions (and constantly inspiring each other at the same time). It's a bit like convergent evolution, whereby unrelated species independently evolve similar features or traits to adapt to similar environmental challenges.
Look at the generation of fighters designed in the late 1960s and early 1970s. The F-14, -15, -16, YF-17/FA-18 and the Mig-29 and Su-27 all to varying degrees share similar design features, like LERX, bubble canopies etc. (they don't look like Mirages).
Yes, of course I understand that 'comrade harps', but the article suggests additional known factors as food for thought beyond the conventional wisdom which you have belaboured. Factors which you appear to have disregarded in favour of a rather patronising comment. Also worth reading Horikoshi's account as he makes little or no mention of the cross-cultivation you belabour and notwithstanding F-14s, MiG-29's and the modern internet of images and a plethora of pundits, the world was a very different place in 1937.
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