JATO

For other uses, see JATO (disambiguation).
America's first "rocket-assisted" take-off, an ERCO Ercoupe fitted with a GALCIT booster, in 1941, performed at March Field, California

JATO (acronym for jet-assisted take-off), is a type of assisted take-off for helping overloaded aircraft into the air by providing additional thrust in the form of small rockets. The term JATO is used interchangeably with the (more specific) term RATO, for rocket-assisted take-off (or, in RAF parlance, RATOG for rocket-assisted take-off gear).

Early experiments and World War II

Early experiments using rockets to boost gliders into the air were conducted in Germany in the 1920s (Lippisch Ente), and later both the Royal Air Force and the Luftwaffe introduced such systems in World War II.[1] 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.

A German Walter Starthilfe liquid-fueled RATO pod

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 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. This 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 or -501 Starthilfe ("takeoff-help") liquid-fuel monopropellant rocket engines driven by chemical decomposition of "T-Stoff", essentially almost pure hydrogen peroxide, with a Z-Stoff catalytic compound.

The sole surviving Ar 234 Blitz, with Walter Starthilfe RATO units fitted.

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 an 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.[2] 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 early 1939, the United States National Academy of Sciences 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 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 Goddard had an Army contract to develop solid fuel rocket weapons.[3][4][5] In late 1941 von Kármán and his team attached several 50-pound thrust, solid fuel Aerojet JATOs to a light Ercoupe plane, 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.[5]:329

Post WWII

LC-130 cargo plane RATO takeoff from snow

After World War II JATO became particularly common owing to the low slow-speed thrust of then-current jet engines or for assisting heavy aircraft; the prop-engined Avro Shackleton used Armstrong Siddeley Viper turbojets for takeoff. As the take-off thrust of jet engines has grown, JATO has fallen from favor. It is still used, however, when heavily-laden aircraft need to take off from short runways or when operating in "Hot and high" conditions.[6]

Two similar zero-length launch experimental programs were carried out by the US Air Force and by the Soviet VVS at around the same time in the late 1950s, both using high-thrust, short burn duration booster designs of very similar appearance and function. The US Air Force used a modified Republic F-84, designated EF-84G, which used the MGM-1 Matador cruise missile's solid fuel booster. The Soviet VVS used a modified MiG-19 fighter, designated SM-30, launched from a special launcher, and using a nearly identical solid-fueled rocket booster design to that of the EF-84G. The F-100 and F-104 were also used for zero-length launch experiments.[7]

Operation Credible Sport was a United States military operation plan in late 1980 to rescue hostages held by Iran using C-130 cargo planes modified with rocket engines to enable a very short take off and landing. The plan was canceled after an accident occurred during a test landing when the forward-facing JATO units designed to slow the aircraft fired before the downward-facing units (designed to cushion the landing) did, causing the aircraft to crash-land.

The JATO Junior was an attempt by Aerojet Engineering to introduce smaller JATO units to small commercial aircraft, but was blocked by the U.S. Navy Bureau of Aeronautics. Aerojet claimed that the smaller JATO bottle, delivering 250 pounds of thrust for 12 seconds could help a light private plane, that normally requires almost 900 feet of runway to clear a 50 foot high obstacle, could do the same with 300 feet of runway with a JATO Jr unit.[8]

The Boeing 727 had provision for Aerojet JATO assist for use in "hot and high" situations.[9]

Urban legend

The JATO Rocket Car is an urban legend that relates the story of a car equipped with JATO units that is later found smashed into a mountainside. This story is often given as an example of a Darwin Award; it appears to be apocryphal, with no basis in fact.[10]

The legend has been examined several times on the Discovery Channel show MythBusters. For the first attempt, in a 2003 pilot episode, the crew replicated the scene and the thrust of the JATO with some commercially available amateur rocket motors. The car did go very fast, outrunning the chase helicopter, but nowhere near the 300 mph (500 km/h) reported in the original story, and failed to become airborne. The myth was revisited in 2007, using a different configuration of rockets in an attempt to make the car fly; it exploded before reaching the end of its launch ramp. The myth was again revisited in 2013 in the 1st Episode of Mythbusters Series 12 - as a celebration for the 10th year on air.

A JATO-equipped 1958 Dodge Coronet car on the El Mirage dry lake was used for a TV advertisement to demonstrate the power of their 'total contact' brakes. This was broadcast during The Lawrence Welk Show in the late 1950s. [11]

References

Notes

  1. ↑ "For operations from small flight decks with heavy loads, rocket-assisted take-offs were necessary." http://uboat.net/allies/aircraft/swordfish.htm
  2. ↑ Warsitz, Lutz: THE FIRST JET PILOT - The Story of German Test Pilot Erich Warsitz (p. 45), Pen and Sword Books Ltd., England, 2009
  3. ↑ Malina, Frank J. (1967). "Memoir on the GALCIT Rocket Research Project". l'Observatoire Leonardo pour les Arts et les Techno-Sciences.
  4. ↑ "Orders of Magnitude - A History of the NACA and NASA, 1915-1990, Ch. 2". NASA. 1989.
  5. 1 2 Lehman, Milton (1988). Robert H. Goddard. New York: Da Capo Press. pp. 91–5.
  6. ↑ "Booster Kick Off Civilian Planes" Popular Science, June 1955, p. 50.
  7. ↑ Archived June 13, 2012, at the Wayback Machine.
  8. ↑ "Baby" Jet unit boost light plane into air Popular Mechanics, February 1950, p. 163.
  9. ↑ http://www.boeing-727.com/Data/type%20cert/typecert200ser.html
  10. ↑ "Carmageddon". snopes.com.
  11. ↑ Dodge presents The Lawrence Welk Show on YouTube, segment begins at 30:00
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