The Nakajima Kikka
By Mike Bennighof, Ph.D.
January 2009

Our Leyte Gulf game has a number of fine Japanese aircraft that never actually entered combat, some of which we’ve seen in an earlier installment. One of the most interesting of these is sure to be the Japanese jet bomber and its near-sister, the jet fighter.

Japanese interest in jet combat aircraft intensified in September 1944, when the Japanese air attaché in Berlin forwarded a number of detailed reports on the German Me262 jet program. The naval staff directed Nakajima to design a similar jet bomber, with faily modest requirements of speed, range and bomb load.

American engineers inspect a very lonely Kikka after the war.

A direct copy of the Me262, the Ki201 “Karyu,” (“Fiery Dragon”) began development work at Nakajima as well, but this project did not have official sanction. The Kikka (“Orange Blossom”), designed by Kazuo Ohno and Kenichi Matsumura, was smaller and less capable than the Me262, but within Nakajima’s capabilities to design and produce. A pair of disassembled Me262 fighters left Germany in March 1945 aboard the submarine U-234 for Japan, but the U-boat and its cargo surrendered to the U.S. Navy on 13 May 1945, after Germany capitulated. Thus Ohno and Matsumura’s plane, while superficially very similar to the Me262, was pretty much an original design.

The plane needed to use a minimum of skilled labor and strategic materials, have folding wings to allow it to be hidden in caves, and take off from a very short runway (no more than 1,150 feet). The Japanese design team met these objectives in rapid order, but Japanese industry could not at first supply workable jet engines. The first pair of engines specified for the plane, Tsu-11 turbojets based on an Italian Campini design, only produced 441 pounds of thrust each (by contrast, the Junkers Jumo 004B engines that powered the Me262 put out 1,980 pounds apiece).

Japanese-designed Ne-12 turbojets could put out 750 pounds, but this still left the Kikka far short of meeting its requirements and the Navy began to lose interest. But the embassy in Berlin came up with photographs of a cutaway model of the BMW 003B engine that powered the Heinkel 162 single-engine jet fighter. The Japanese copy, designated Ne-20, delivered 1,047 pounds (vs. 1,830 for the German original) but that was enough to bring the Kikka up to spec. Though the Ne-20 was not nearly as good an engine as the original, building a working jet engine of any sort just by looking at a photograph was a serious achievement.

Another view of the Kikka.

The first Kikka was ready for flight in August 1945, with Navy Lt. Cdr. Susumu Tanaoka serving as test pilot. To make the short take-off possible (felt necessary because of heavy American bombing then smashing all Japanese airfields), the Kikka would use a pair of “rocket bottles” to give 992 pounds of extra thrust each. These would drop away right after take-off. The first flight, on 7 August 1945, went well. The next went poorly when ground crew mounted the rcket bottles at the wrong angle, damaging the plane. The first prototype was put aside, but before the second could be made ready for a test flight Japan surrendered. Anywhere from a dozen to 45 pre-series Kikkas were in various states of construction (the numbers vary by source, probably depending on how parts for unassembled Kikkas are counted), but only the first flew under Japanese control.

As an attack bomber, the Kikka was to have a top speed of 440 miles per hour; only slightly faster than the best Japanese piston-engined aircraft and considerably slower than the fastest American fighter to see action over Japan, the P-51H Mustang. Range was specified as only 127 miles, with a bomb load of 1,100 pounds; the final product greatly exceeded this with an estimated range of 586 miles. The Navy did not see short range as a problem; the Kikka would dart out of its mountain bases, strike American ships offshore, and dart back again. The Kikka carried no armament other than its bomb load.

A fighter version, which did not leave the drawing board (but of course made it into our game) would have had two 30mm cannon. With a pair of Ne-130 engines delivering 1,980 pounds each, it likely would have developed much greater speed (the Me262 A1a reached 540 miles per hour with similar engine power).

It’s not likely that this wonder weapon would have had much of an effect on the war’s outcome. Japan faced the same problems in this regard as Nazi Germany, only moreso: a shortage of fuel and skilled pilots. Germany produced over 1,400 Me262 jets and only put a hundred or so into action. Japan had no hope of matching that performance, and had even fewer pilots to man the cockpits.

Maintenance would have been another problem; the Germans lost dozens of their jets to engine failures and landing-gear collapse. With no service data, it’s impossible to say if the Japanese engines would have done any better, but given their origins as copies made from photographs, the odds are they would have been even more prone to break down with heavy use.

Leyte Gulf has three Kikka aircraft counters, two bombers and one fighter. They’re powerful craft, but not particularly better than the good American conventional fighters like the P-51D, P-47D or F4U.

This piece originally appeared in August 2005.

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