Assisted take off

Assisted take off

Assisted take off is any system for helping aircraft into the air (as opposed to strictly under its own power). The reason it might be needed is due to the aircraft's weight exceeding the normal maximum take off weight, insufficient power, or the available runway length may be insufficient, or a combination of all three factors. Assisted take off is also required for gliders, which do not have an engine and are unable to take off by themselves.

Catapults (CATO)

A well-known type of assisted take off is that using the aircraft catapult. In modern systems fitted on aircraft carriers, a piston, known as a "shuttle", is propelled down a long cylinder under steam pressure. The aircraft is attached to the shuttle using a tow bar or launch bar mounted to the nose landing gear (an older system used a steel cable called a catapult bridle; the forward ramps on older carrier bows were used to catch these cables), and is flung off the deck at about 15 knots above minimum flying speed, achieved by the catapult in a 4 second run.

The United States is replacing carrier steam catapults with linear induction motors. The system is called the Electromagnetic Aircraft Launch System (EMALS). An electromagnetic wave travelling through the motor propels the armature along its length, pulling the plane with it. With this system, it will be possible to match launch power and aircraft weight more closely than with the steam system, causing less wear on the aircraft.

The catapult approach is also used for towing gliders into the air. This can be accomplished using an elastic bungee arrangement, or more commonly using a cable wound onto a winch, powered by a large diesel engine. The bungee approach is rarely used for man-carrying gliders, as the acceleration is uncontrolled and can yield very high G-forces. It is commonly used to launch model gliders however. Manned gliders are commonly launched simply by towing them aloft behind a powered aircraft.


JATO stands for 'Jet-assisted take off' (and the similar RATO for 'Rocket-assisted take off'). In the JATO and RATO systems, additional engines are mounted on the airframe which are used only during take off. After that the engines are usually jettisoned, or else they just add to the parasitic weight and drag of the aircraft. However some aircraft such as the Avro Shackleton MR.3 Phase 2 and Convair B-36 Peacemaker (which gained a quartet of jet engines in mid-life), had permanently attached JATO engines.

During WW2 the German Arado 234 and the Messerschmitt 323 "Gigant" used rocket units beneath the wings for assisted take off. Such systems were popular during the 1950s, when heavy bombers started to require two or more miles of runways to take off fully laden. This was exacerbated by the relatively low power available from jet engines at the time - for example the B-52 Stratofortress required 8 turbojet engines to yield the required performance, and still needed RATO for very heavy payloads ( a proposed update of the B-52 replaces these with half the number of much more powerful engines).In a Cold War context, RATO and JATO bottles were seen as a way for fighter aircraft to utilize the undamaged sections of runways of airfields which had been attacked.

Gravity assistance

Early pioneers in powered and unpowered flight used gravity to accelerate their aircraft to a speed which allowed its wings to generate enough lift to achieve independent flight. These included attempts to achieve flight from towers, city walls and cliffs. Generally more successful were attempts in which speed was built up by accelerating down hill and mountain slopes, sometimes on rails or ramps.

Carrier aircraft

Probably the ultimate form of gravity assistance is when an aircraft is released from a larger mother ship or mother craft. This may be because the daughter craft is incapable of taking off normally e.g. the atmospheric flight tests of the Space Shuttle..

In the interwar years in order to achieve long ranges with the technology of the time, trials were undertaken with float planes piggy backed atop flying boats. With the float plane carried part of the way to its destination and freed from having to use any of its own fuel in the initial climb these combinations could deliver light but time critical cargos faster and farther than a single individual aircraft.

Hot air balloons have acted as "motherships" to hang gliders and para gliders in altitude and distance record attempts.

"Jet Donkeys"

An unusual assisted take off scheme was partially developed during the 1950s which consisted of a jet powered truck or dolly which ran either on rubber tires or rails, used to push a heavy aircraft into the air. Once airborne, the dolly would instantly detach. Because the dolly did not need to fly itself, it was not constrained by the need for low weight, and so could be fitted with very large and powerful engines. The system only reached the early stages of development. The same company was also drawing up plans for a flyable version of the dolly launch system, which it called "jet donkeys". The idea was that a small powerful secondary aircraft could push the heavy main aircraft into the air, detach in flight and return to the airfield to be reused. Sketches of the proposed system show a strange canard-layout aircraft with its cockpit in the tail, pushing the main aircraft via a long extended nose. The system was never developed, it was not long before the further development of the jet engine meant that most of these assisted take off schemes became unnecessary.

ee also

*Aviation history for the work of the early pioneers.
*Colditz glider for an example of gravity assistance.
*Silbervogel a long range bomber proposal, utilising a rail mounted captive rocket booster.

Wikimedia Foundation. 2010.

Игры ⚽ Нужно сделать НИР?

Look at other dictionaries:

  • assisted take-off — noun A take off in which the full power of an aircraft s normal engines is supplemented by eg turbojet, rocket motor units, or liquid rockets • • • Main Entry: ↑assist …   Useful english dictionary

  • Catapult Assisted Take Off But Arrested Recovery — Katapultunterstützter Start einer F 18 Die Abkürzung CATOBAR (Catapult Assisted Take Off But Arrested Recovery) bezeichnet ein System des Starts und der Wiederaufnahme von Flugzeugen auf Flugzeugträgern und bezieht sich auf Flugzeuge, die nach… …   Deutsch Wikipedia

  • Take-off — rsp. Takeoff (englisch: take off, take off oder takeoff) bezeichnet: das Abheben eines Luftfahrzeuges, siehe Start (Luftfahrt) Take off Modell, ein Modell in der Entwicklungstheorie, siehe The Stages of Economic Growth: A Noncommunist Manifesto… …   Deutsch Wikipedia

  • Conventional Take-Off and Landing — CTOL: Eine Junkers Ju 52 beschleunigt vor dem Start Conventional Take Off and Landing (CTOL) ist die konventionelle Start und Landeweise von Flugzeugen durch Beschleunigen bis zum Erreichen der Startgeschwindigkeit bzw. Ausrollen auf einer… …   Deutsch Wikipedia

  • Computer-assisted web interviewing — Sociology …   Wikipedia

  • NASA spin-off — Science and technology in the United States African American contributions Discoveries …   Wikipedia

  • Computer-assisted dispatch — The central idea is that persons in a dispatch center are able to easily view and understand the status of all units being dispatched. CAD provides displays and tools so that the dispatcher has an opportunity to handle calls for service as… …   Wikipedia

  • JATO — may also refer to the group Jews Against the Occupation. JATO Dynamics, the automotive market intelligence worldwide company. Rato was the Japanese name of Luodong, Taiwan. JATO is an acronym for Jet fuel Assisted Take Off. The term is used… …   Wikipedia

  • B-47 Stratojet — Infobox Aircraft name=B 47 Stratojet type=Strategic bomber manufacturer=Boeing caption=Boeing B 47E 65 BW (AF Serial No. 51 5257) during rocket assisted takeoff test. designer= first flight=17 December 1947 introduced=June 1951 retired=1966, B… …   Wikipedia

  • Rocket — This article is about vehicles powered by rocket engines. For other uses, see Rocket (disambiguation). A Soyuz U, at Baikonur Site 1/5 A rocket is a missile, spacecraft, aircraft or other vehicle which obtains thrust from a rocket engi …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”