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 pist ...

produced in small numbers in

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

in the closing stages of

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

. 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 to d ...

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 compressor is a mechanical device that increases the pressure of a gas by reducing its volume. An air compressor is a specific type of gas compressor. Many compressors can be staged, that is, the gas is compressed several times in steps o ...

. 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 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.Dyer, pp. 73–74 The Tsu-11 was also selected to power the Yokosuka MXY9 ''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) is a Japanese World War II rocket-powered interceptor aircraft close ...

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 The National Air and Space Museum (NASM) of the Smithsonian Institution is a museum in Washington, D.C., in the United States, dedicated to history of aviation, human flight and space exploration. Established in 1946 as the National Air Museum, ...

Washington, DC Washington, D.C., formally the District of Columbia and commonly known as Washington or D.C., is the capital city and Federal district of the United States, federal district of the United States. The city is on the Potomac River, across from ...

. 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