Tuesday, March 3, 2015

Nakajima Experimental Ki-12 Fighter


Nakajima Experimental Ki-12 Fighter.



No sooner had production begun in France of the advanced Dewoitine D.510 fighter in 1935, than Mitsubishi imported two for study by September of that year. The outstanding appeal of this aeroplane was its new engine-mounted 20mm cannon which fired through the propeller shaft. Taking into consideration this and other features of the Dewoitine, Nakajima designed a comparable fighter but went a major step further by adding a retractable undercarriage, the first to be built in Japan.

Heading this project were two French engineers, Roger Robert and Jean Beziaud who were hired by Nakajima, with Shigenobu Mori as the chief Japanese designer. Although the D.510 served as a reference aircraft in creating the new Nakajima fighter, a number of details were further refined. Using the same 690hp Hispano-Suiza 12Xcrs engine with its 20mm engine-mounted cannon which was imported separately for this project, an oval-shaped radiator was mounted in front of the nose instead of beneath as on the D.510. This reduced the frontal area of this aeroplane as with the similar D.513. The hydraulically-operated undercarriage retracted inwards into the elliptically shaped wing which also had split flaps. The tailwheel was fully retractable. The headrest behind the open cockpit was extended aft to become part of the fin. The result was perhaps one of the most refined fighter airframes in the world at that time.

The aeroplane was completed in October 1936 and moved immediately into the flight-test phase. It was tested against the Mitsubishi Ki-18 which had been completed fourteen months previously, as well as the Mitsubishi Ki-33, Kawasaki Ki-28 and the Nakajima Ki-27, the last of these being finished about this time. The Nakajima Ki-12 was found to be inferior to all in manoeuvrability, a quality which the Japanese Army placed above all others. Failing this most important test, the design was doomed because it was not thought that a licence manufacturing agreement for the Hispano-Suiza 12Xcrs would be granted, and Japan did not want to rely upon imported engines for its combat aircraft. Consequently, the Ki-12 programme ended with but one prototype, and Nakajima's Ki27 won the Army's approval to become its next standard fighter. On a trial basis, two Hispano-Suiza 12Xcrs were tested in the normally radial-engined Mitsubishi A5M3a, greatly enhancing its fighter-like lines and adding a little more speed.

Single-engine low-wing cantilever monoplane fighter with retractable undercarriage. All-metal monocoque fuselage, with all-metal multi-spar stressed skin wing. Pilot in open cockpit.
610-690hp Hispano-Suiza 12Xcrs twelve-cylinder vee liquid-cooled engine, driving a fixed-pitch three-bladed metal propeller.
One 20mm engine-mounted cannon firing through propeller shaft, two 7.7mm machine-guns mounted in the Wing.
Span 11 m (36ft 1in); length 8.30m (27ft 2 3/4in); height 3.30m (10ft 10in); wing area 17sq m (182. 992sq ft).
Empty weight 1,400kg (3,086Ib); loaded weight 1,900kg (4,188Ib); wing loading 111.9kg/sq m (22.9lb/sq ft); power loading 2.75kg/hp (6Ib/hp).
Maximum speed 260kt (229.2mph); cruising speed 200kt (230mph); landing speed 65kt (74.8mph); climb to 5,000m (16,404ft) in 6min 30sec; service ceiling 10,500m (34,448ft); range 433nm (498sm).
One built in October 1936.

1 comment:

  1. Bomber interceptors needed high velocity 20mm+ stand-off cannons, more than tight turning prowess. Japan missed an opportunity with this French gift that would bite them later in the B-29 raids. The Army Ki 12 and Navy A5M3a both had the motor-cannon and both were denied production. At least Japan had the foresight to accept the Ki 44 and J2M programs in time. They could've used better firepower though. A late-war version of the motoe-cannon Ki 12 would've been most welcome in 1944, even from Kawasaki! Perhaps with the fast 30mm Ho-155-II hub-cannon. It beats the Luftwaffe 30mm Mk 108 and Mk 103 cannons. It had the speed and light weight plus high velocity the others lacked in one cannon. In other words, it had the best of both without their weaknesses. Japan had the ideal motor cannon to tackle B-29s but no inline interceptor mounting it in the spinner! The Luftwaffe had motor cannon armed Bf 109s by the legion with inferior 30mm cannons and no B-29s to intercept like Japan had! Ironic.

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