Tsu-11
Encyclopedia
The Tsu-11 was a primitive, motorjet
-style jet engine
produced in small numbers in Japan
in the closing stages of World War II
. It was principally designed to propel the Japanese Ohka
flying bomb
, a kamikaze
weapon.
The Tsu-11 used a four-cylinder inverted inline Hitachi Hatsukaze
Ha 11 piston engine 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
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 MXY-9 Shuka ("Autumn Fire") - a trainer intended to prepare pilots for the Mitsubishi J8M
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. 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 - in effect, an afterburning ducted fan
engine.
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 :...
-style jet engine
Jet engine
A jet engine is a reaction engine that discharges a fast moving jet to generate thrust by jet propulsion and in accordance with Newton's laws of motion. This broad definition of jet engines includes turbojets, turbofans, rockets, ramjets, pulse jets...
produced in small numbers in Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
in the closing stages of World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
. It was principally designed to propel the Japanese Ohka
Ohka
The Yokosuka MXY-7 Ohka was a purpose-built, rocket powered human-guided anti-shipping kamikaze attack plane employed by Japan towards the end of World War II...
flying bomb
Flying bomb
A flying bomb is a manned or unmanned aerial vehicle or aircraft carrying a large explosive warhead, a precursor to contemporary cruise missiles...
, a kamikaze
Kamikaze
The were suicide attacks by military aviators from the Empire of Japan against Allied naval vessels in the closing stages of the Pacific campaign of World War II, designed to destroy as many warships as possible....
weapon.
The Tsu-11 used a four-cylinder inverted inline Hitachi Hatsukaze
Hitachi Hatsukaze
-References:NotesBibliography* Bridgeman, Leonard. "The Bücker Bü 131B 'Jungmann'." Jane's Fighting Aircraft of World War II. London: Studio, 1946. ISBN 1-85170-493-0....
Ha 11 piston engine to drive a single-stage compressor
Gas compressor
A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume.Compressors are similar to pumps: both increase the pressure on a fluid and both can transport the fluid through a pipe. As gases are compressible, the compressor also reduces the volume of a gas...
. 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
Yokosuka P1Y
|-See also:-References:NotesBibliography* Francillon, Ph.D., René J. Japanese Aircraft of the Pacific War. London: Putnam 7 Company Ltd., 1970. ISBN 0-370-00033-1 ....
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 MXY-9 Shuka ("Autumn Fire") - a trainer intended to prepare pilots for the Mitsubishi J8M
Mitsubishi J8M
The Mitsubishi J8M Shūsui was a Japanese World War II rocket-powered interceptor aircraft closely based on the German Messerschmitt Me 163 Komet.Built as a joint project for both the Navy and the Army Air Services, it was designated J8M...
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
National Air and Space Museum
The National Air and Space Museum of the Smithsonian Institution holds the largest collection of historic aircraft and spacecraft in the world. It was established in 1976. Located in Washington, D.C., United States, it is a center for research into the history and science of aviation and...
in Washington DC. 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 - in effect, an afterburning ducted fan
Ducted fan
A ducted fan is a propulsion arrangement whereby a fan, which is a type of propeller, is mounted within a cylindrical shroud or duct. The duct reduces losses in thrust from the tip vortices of the fan, and varying the cross-section of the duct allows the designer to advantageously affect the...
engine.