The Ishikawajima Tsu-11 was a

motorjet A motorjet is a rudimentary type of jet engine which is sometimes referred to as ''thermojet'', a term now commonly used to describe a particular and completely unrelated pulsejet design. Design At the heart the motorjet is an ordinary pis ...

produced in small numbers in Japan in the closing stages of

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...

. It was principally designed to propel the Japanese Yokosuka MXY7 Ohka flying bomb, a

kamikaze , officially , were a part of the Japanese Special Attack Units of military aviators who flew suicide attacks for the Empire of Japan against Allied naval vessels in the closing stages of the Pacific campaign of World War II, intending t ...

weapon.

Design and development

The Tsu-11 used a four-cylinder inverted inline

Hitachi Hatsukaze The Hitachi Hatsukaze (初風, Hatsukaze - fresh wind), also known as the Hitachi GK4 (short Navy), Hitachi Army Type 4 110hp Air Cooled Inline (Army long), Hitachi Ha47 (Army Hatzudoki) and Ha-11 model 11 (unified), was Hitachi's fourth design i ...

''Toku'' Model 13 piston engine — a license-built version of the German

Hirth HM 504 The Hirth HM 504 is a four-cylinder air-cooled inverted inline engine. The HM 504 was a popular engine for light aircraft of the 1930s-1940s, and it was used to power a number of Germany's trainer aircraft of World War II. The engine featured a ...

inverted, inline-four cylinder air-cooled engine, with the "model 13" version indicating its adaptation to drive a single-stage compressor. A fuel injection system was fitted behind the compressor. In operation, fuel would be mixed with the compressed air and the resulting mixture ignited, creating thrust. The engine was designed to overcome the major shortcoming of the Ohka Type 11 weapons, that of limited range. The Type 11 was powered by solid-fuel rocket motors, which provided tremendous acceleration, but had a very short burn time. The upshot of this was that the Ohka's carrier aircraft would have to fly very close to the target, making it vulnerable to interception. In practice, most Ohka-carrying bombers were shot down before they ever had the opportunity to launch their weapons. It was reasoned that a jet engine would provide high speed as well as enough range to keep the carrier plane safe long enough to release the Ohka and leave the area. The engine was first tested hung underneath a

Yokosuka P1Y The Yokosuka P1Y ''Ginga'' (銀河, "Galaxy") was a twin-engine, land-based bomber developed for the Japanese Imperial Navy in World War II. It was the successor to the Mitsubishi G4M and given the Allied reporting name "Frances". Design and d ...

bomber sometime in 1944 and was deemed successful enough to order into production. The Ohka was adapted to accommodate the engine in a lengthened fuselage with jet intakes added at the sides. This configuration was designated Ohka Type 22. The Tsu-11 was also selected to power the

Yokosuka MXY9 The Yokosuka MXY9 ''Shuka'' (秋花, "Autumn flower") was a projected development of the MXY8 training glider, adding a small motorjet engine, the Tsu-11. It was intended to provide further training for pilots who were to fly the Mitsubishi J ...

''Shuka'' ("Autumn Fire") - a trainer intended to prepare pilots for the

Mitsubishi J8M The Mitsubishi J8M ''Shūsui'' ( Japanese: 三菱 J8M 秋水, literally "Autumn Water", used as a poetic term meaning "Sharp Sword" deriving from the swishing sound of a sword) was a Japanese World War II rocket-powered interceptor aircraft clo ...

rocket-powered interceptor. Neither of these aircraft entered service, however, as their development took place too late in the war. A single example of a Tsu-11 engine exists, preserved at the National Air and Space Museum in

Washington, DC ) , image_skyline = , image_caption = Clockwise from top left: the Washington Monument and Lincoln Memorial on the National Mall, United States Capitol, Logan Circle, Jefferson Memorial, White House, Adams Morgan ...

. In 1997 it was installed in the museum's Ohka 22 during its restoration. Engineering analysis of the engine during the restoration process suggested that the fuel injection and combustion probably contributed little to the power of the engine, with most of the thrust actually being produced by the compressor.

Design and development

Applications

See also

References

Bibliography