Last-minute adjustments are made to the Kikka's starboard engine

Designers Kazuo Ohno and Kenichi Matsumura created a plane that could be called a 2/3 rd or ¾ th-scale mimic of the Messerschmitt fighter. Whereas the Me 262 had a wingspan of about 40 feet and a length of around 34 feet, the Japanese aircraft was just a bit over 26 ½ feet long with a wingspan of just over 32 ¾ feet. Its wing was nicely swept, but the tail surfaces were not, and all control surfaces were, oddly enough, fabric-covered in an otherwise-all-metal airplane. The canopy was a three-piece sliding type, instead of the Messerschmitt’s three-piece hinged “coffin-lid” arrangement.

The twin turbojets were mounted beneath the wings in separate nacelles, allowing, with a minimum of changes, the installation of a variety of engines as they were developed. As it turned out, this feature was quite useful, as engine development fell behind that of the airframe. Initially, the plane was to have been powered by two Campini-type Tsu-11 engines, but these were replaced by a pair of 750-lb. thrust Ne-12 turbojets. But the future of the Navy Special Attacker Kikka (as it was designated) was made uncertain by the failure of the Ne-12 to develop its designed power during ground tests. By a stroke of luck, Engineer Eichi Iwaya of the Navy had obtained detailed photographs of the BMW 003 axial-flow turbojets used in the Me 262, and from those photos the Japanese were able to create a similar engine, designated Ne-20, with a theoretical power output of 1,047 pounds of static thrust. Everyone concerned felt the Ne-20 was perfect for the Kikka, and so the project’s pace was speeded up during the summer of 1945.

The Kikka's Ne-20 turbojet engine

At this point, a note about the aircraft’s designation would be in order. Although it was dubbed a "Special Attacker", this writer believes that the Kikka was not actually intended for kamikaze attacks, except in extremis (i.e., if the pilot were wounded or the airplane was damaged, and could not return to base). It seems very foolish to go to the trouble to design a very expensive jet-powered plane and then assign it to one-way missions. The Me 262 was notorious for requiring a skilled pilot to fly it, and even then the pilot, if he had previous experience in aircraft with reciprocating engines, had to unlearn a lot of habits which were all right for flying conventional fighters but which could be fatal in the 262. For example, the Me 262’s throttles could not be “chopped”, i.e., quickly brought from high power to a lower-power setting, or shoved forward swiftly, “balls to the wall” as American flying slang put it.

Jet throttles had to manipulated carefully and slowly, or else the jet engines would flame out, either from fuel starvation or fuel satiation. Thus, by analogy, only skillful pilots could fly the Kikka. Undoubtedly the Japanese were aware, from reports from their air attaché in Germany, of the unique problems involved in flying a jet as opposed to flying a more conventional aircraft. Thus, the Kikka could not have been intended as a kamikaze aircraft. Indeed, it was intended for other roles besides being a fast attack bomber, as will be seen. The term “Special Attacker” refers, in this writer’s opinion, to the special way the Kikka was powered (by jets) rather than to its being intended for “special”, i.e., suicide, attacks.

The Kikka's test pilot and a ground crewman look on as a technician makes sure all systems are 'Go'.

With its Ne-20 engines installed, the Kikka prototype was given its first ground tests on June 30, 1945. Late in July, it was dismantled and taken to Kisarazu Naval Airfield, where after re-assembly it was flown for the first time on August 7, with Lt. Cdr. Susumu Takaoka as test pilot. The Kikka taxied for a long time before it gained enough speed to lift off the ground; the flight itself lasted just 20 minutes, and the aircraft was never taken above 2000 feet. The slowness with which it gained take-off speed delayed the second flight until August 11, when it attempted to lift off with RATOG bottles beneath the wings. Unfortunately, the rocket bottles were not installed at the correct angle to lift the Kikka off the runway, and after the rockets burned out, the pilot aborted the take-off and crashed into the rough ground beyond the runway’s end. The second prototype was almost ready for its own first flight when the war ended on August 15. Eighteen additional prototypes and pre-production examples were left in various stages of construction on that date.

Aside from the basic attack bomber, there was a projected unarmed two-seat trainer, and the third Kikka was to be the prototype for this variant. An unarmed two-seat reconnaissance version and a cannon-armed single-seat fighter were also under development at the war’s end. The fighter variant was to have been powered by either a pair of 1,984-lb. thrust Ne-130 or a pair of 1,951-lb. thrust Ne-330 axial-flow turbojets, and armed with a pair of nose-mounted 30mm cannon.

The second prototype Kikka, seen just after the close of the war

Nakajima Kikka Technical Data