Hello, and welcome to Aviation Deep Dive. Japanese designs in the Second World War are
generally remembered for their excellent manoeuvrability, and their dominance during the early years
of the war. Many would say however, that the numerous
aviation companies in Japan would produce their best designs with their backs up against
the wall during the later years of the war. When the Boeing B-29 undertook their first
raids on the Japanese home islands in June 1944, the home industry immediately realised
the need for a high altitude, fast and heavily armed interceptor capable of taking down the
enormous American bombers. Nakajima was amongst the first to start work
on this concept, the fruit of which would be the largely forgotten Ki-87, a turbo-supercharged
heavily armed fighter designed for extreme speeds at high altitudes. The roots of this aircraft however, actually
go back to long before B-29s even flew in early 1942. Nakajima and the Technical Division of Imperial
Army headquarters had been experimenting with fitting a large radial engine with an exhaust-driven
turbo-supercharger, the results of which were eventually poured into development of the
ill-fated Tachikawa Ki-94. Nakajima, mean whilst, was instructed to work
on their own design that would be based off the technology developed from the research
- their design would be a Plan B, a fall-back if the Ki-94 project turned out to be a failure. Meanwhilst, Japanese officials were getting
increasingly spooked at the prospect of American aircraft technology. It had become known by 1943 that the B-29
could fly at altitudes of up to 10,000 metres, but when it appeared over Tokyo at that altitude
in the same year, it was flying so fast that the Ki-44 - an interceptor introduced into
Japanese service less than a year before - could not even come close to catching up. The J2M4, J2M5 and N1K5 fighters that were
designed to counter the threat were not even close to production. Nakajima, mean whilst had put together a design
- outlining a low-wing, fairly large interceptor - with an externally mounted turbo-supercharger
- and a deadly proposed armament of twin 30mm cannons and twin 20mm cannons. The aircraft would also have a central bomb
rack capable of carrying up to a single 250 kg bomb for multi-role capabilities. Construction of the aircraft - dubbed the
Ki-87 - began in July 1943, but immediately ran into issues. The starboard externally mounted turbo-supercharger
was favoured by Nakajima engineers, as it was considered that placing it ventrally would
risk putting it in contact with fuel, which would be an enormous fire risk. The Imperial Japanese Army, mean whilst, apparently
disagreed, and insisted on the ventral placement. Ultimately, after many delays and disagreements
between Nakajima and the IJA, the engineers were proved right and the turbo-supercharger
was moved back to it’s original place - but precious months had been wasted, especially
when considering their were many other issues to contend with. The technology was new and extensive testing
had to be done. By March 1944, the B-29 raids on Japan were
imminent, and the Tachikawa Ki-94 had been a disappointment. The pressurisation system had turned out to
be extremely heavy and complicated, both compromising the expected performance of the design and
creating a maintenance nightmare for ground crews. Desperate attention was turned to the Ki-87,
with slightly relaxed requirements and a request for a simplified and lighter pressurisation
system. Nakajima was awarded a contract to build three
prototypes and seven pre-production aircraft, to be completed between November 1944 and
January 1945 - with the expectation that serial production would begin around February 1945. Construction would be fairly protracted however,
issues with the electrical undercarriage retracting system as well as with continued disagreement
as to the optimal position of the turbo-supercharger delaying final assembly. The engine decided on powering the aircraft
would be the Nakajima Ha219 Ru, although of course like most Japanese equipment it was
given a different designation by the manufacturer, and different military branches - so it was
also known as the Ha-44 Model 11. This late war Japanese 18-cylinder engine
would give 2,400 horsepower at sea level for takeoff power, and paired with the turbo-supercharger
would still be pumping out over 1,850 horsepower at 10.5 kilometres of altitude. The engine was certainly powerful, but would
present its own issues - being maintenance heavy and ultimately only around ten were
actually built. The four-bladed constant speed propellor was
also very large, necessitating pretty large gear legs for ground clearance. Regardless, the Ki-87 prototype was finally
finished, fully constructed by February 1945 - and after some ground testing, underwent
its first flight in April at the Nakajima testing facility. One issue that had yet to be fully resolved
however, was to do with the undercarriage. Operated electrically, they were plagued by
failures and simply were not reliable enough to trust for the aircrafts maiden flight,
and thus were left in the locked down position. The aircraft demonstrated generally good flying
characteristics, considering the Gear was down, although at 5,600 kg (or 12,400 lbs) when fully loaded, the Ki-87 was
quite heavy for an aircraft of it’s role - indebted no doubt to the large turbo-supercharging
system. The interceptor was also projected to have
a maximum speed of 706 km/h at 11,000 metres - although it would take 14 minutes to climb
to that altitude. The preliminary tests were considered generally
succesful, apart from the undercarriage issues, and full production for 500 of the aircraft
was planned. However, at this point the war was in dire
straits for Japan - the Battle for Okinawa was raging but the US were getting closer
and closer to mainland Japan - and bombing raids on the Japanese mainland had been catastrophic
for the native industry. The Japanese had needed these 500 Ki-87s,
piloted by experienced crews, a year earlier. The single prototype was simply too little
too late. Over the course of the next few weeks the
Ki-87 underwent a further four test flights, none of them long, and all of them with the
unreliable undercarriage extended. Further upgrades of the Ki-87 had been planned
by Nakajima, namely the II variant - which would be powered by a 3,000 horsepower Ha-46
engine, but this never left the design stages. As it was, the Ki-87 had not reached readiness
stage for serial production by the time of the Japanese surrender on the 2nd September,
and had in fact been grounded for months beforehand. Left abandoned at the Chofu Airbase in Japan,
the sole prototype was discovered by the Americans, where it was photographed - and this is unfortunately
where all the information that I can find dries up. There doesn’t appear to be any evidence
of evaluation by the Americans, and I can only assume it was scrapped shortly thereafter. This photo shows the aircraft on the tarmac
at the abandoned airbase in Chofu. The Ki-87 is a pretty fascinating glimpse
into late-war Japanese aviation industry. It’s got the sleek lines of a late war fighter,
with armament to match, though ultimately with just one prototype produced and without
even being close to seeing service - this aircraft has been almost completely forgotten,
and relegated to barely a footnote in history - I could only find one historical book that
even mentioned it. A huge thanks to my Patrons, on screen now,
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