In 1927 the
Soviet research and development laboratory
Gas Dynamics Laboratory developed
solid-propellant rockets to assist aircraft take-off and in 1931 the world's first successful use of rockets to assist take-off of aircraft were carried out on a
U-1, the
Soviet designation for a
Avro 504 trainer, which achieved about one hundred successful assisted takeoffs. Successful assisted takeoffs were also achieved on the
Tupolev TB-1. and
Tupolev TB-3 Heavy Bombers. The official test of the Tupolev TB-1 in 1933 shortened the takeoff by 77% when using the rockets. The British system used fairly large solid fuel rockets to shoot planes (typically the
Hawker Hurricane) off a small ramp fitted to the fronts of merchant ships, known in service as
Catapult armed merchantmen (or CAM Ships), in order to provide some cover against
German maritime patrol planes. After firing, the rocket was released from the back of the plane to fall into the water and sink. The task done, the pilot would fly to friendly territory if possible or parachute from the plane, hopefully to be picked up by one of the escort vessels. Over two years the system was only employed nine times to attack German aircraft with eight kills recorded for the loss of a single pilot. Blitz fitted with
Starthilfe RATO units in Virginia. The
Luftwaffe also used the technique with both liquid-fueled units made by the
Walter firm and BMW – and solid fuel, themselves made both by
the Schmidding and WASAG firms – as both firmly attached and jettisonable rocket motors, to get airborne more quickly and with shorter takeoff runs. These were used to boost the takeoff performance of their medium bombers, and the enormous 55-meter wingspan
Gigant,
Messerschmitt Me 321 glider, conceived in 1940 for the invasion of Britain, and used to supply the Russian front. The enormous Me 321s originally had air tow assistance from up to three
Messerschmitt Bf 110 heavy fighters in a so-called
Troika-Schlepp arrangement into the air with loads that would have made the takeoff run too long otherwise, but with much attendant risk of aerial collision from the trio of
vee-formation Bf 110s involved in a simultaneous
towplane function, meant to be greatly eased with the substitution of the trio of Bf 110s with a single example of the unusual, twin-fuselage
Heinkel He 111Z purpose-designed five-engined towplane. The use of rocket-assisted takeoff methods became especially important late in the war when the lengths of usable runways were severely curtailed due to the results of Allied bombing. Their system typically used jettisonable, self-contained
Walter HWK 109-500 Starthilfe ("takeoff-help"), also known as "Rauchgerät" – smoke generator, unitized liquid-fuel monopropellant rocket booster units whose engines driven by chemical decomposition of "
T-Stoff", essentially almost pure
hydrogen peroxide, with a
Z-Stoff catalytic compound. A
parachute pack at the blunt-contour front of the motor's exterior housing was used to slow its fall after being released from the plane, so the system could be re-used. First experiments were held in 1937 on a
Heinkel He 111, piloted by test-pilot
Erich Warsitz at
Neuhardenberg, a large field about 70 kilometres east of
Berlin, listed as a reserve airfield in the event of war. Other German experiments with JATO were aimed at assisting the launch of interceptor aircraft such as the
Messerschmitt Me 262C, as the
Heimatschützer special versions, usually fitted with either a version of the
Walter HWK 109-509 liquid fuelled rocket engine from the
Me 163 Komet program either in the extreme rear of the fuselage or semi-"podded" beneath it just behind the wing's trailing edge, to assist its
Junkers Jumo 004 turbojets, or a pair of specially rocket-boosted
BMW 003R combination jet-rocket powerplants in place of the Jumo 004s, so that the Me 262C
Heimatschützer interceptors could reach enemy bomber formations sooner. Two prototypes of the
Heimatschützer versions of the Me 262 were built and test flown, of the three designs proposed. In contrast to
the wide variety of aircraft types that the HWK-designed
Starthilfe modular liquid monopropellant booster designs were tested with, seeing some degree of front-line use; the aforementioned solid-fueled RATO booster designs from both the Schmidding and WASAG firms remained almost strictly experimental in nature, with the
Schmidding 500 kg thrust solid-fueled booster units intended to see service, a quartet mounted per airframe for use with the radical
Bachem Ba 349 VTO rocket interceptor design in 1945, for its vertical launch needs. The strictly experimental, HWK 109-501
Starthilfe RATO system used a similar bi-propellant "hot" motor to that on the
Me 163B Komet rocket fighter, adding a 20 kg mass of a combination of
B-stoff hydrazine, mixed with "Br-stoff" (
ligroin hydrocarbon distillate) for a main "fuel" to the
T-Stoff monopropellant still destabilized with the
Z-Stoff permanganate for ignition as the oxidizer, tripling the 109-500's thrust figure of 4.95 kN (at 14.71 kN/1,500 kgf) with a burn of 30 second duration. Due to the "hot" system's similar risks demanding similar special fueling and handling procedures to that of the Komet's 509A rocket motor, the 109-501 seems to have remained a strictly experimental design, only being used for the test flights of the
Junkers Ju 287 V1 prototype jet bomber. In early 1939, the
National Academy of Sciences in the United States provided $1,000 to
Theodore von Kármán and the Rocket Research Group (including
Jack Parsons,
Frank Malina,
Edward Forman and
Apollo M. O. Smith) at the
Guggenheim Aeronautical Laboratory at the California Institute of Technology (GALCIT) to research rocket-assisted take-off of aircraft. This JATO research was the first rocket research to receive financial assistance from the U.S. government since World War I when
Robert H. Goddard had an Army contract to develop solid fuel rocket weapons. In late 1941 von Kármán and his team attached several 50-pound thrust, solid fuel
Aerojet JATOs to an
Ercoupe, and Army Captain
Homer Boushey took off on test runs. On the last run they removed the propeller, attached six JATO units under the wings, and Boushey was thrust into the air for a short flight, the first American to fly by rocket power only. Both armed services used solid fuel JATO during the war. ==Post WWII==