The zero-length launch system or zero-length take-off system (ZLL, ZLTO, ZEL, ZELL) was a method whereby jet

fighters Fighter(s) or The Fighter(s) may refer to: Combat and warfare * Combatant, an individual legally entitled to engage in hostilities during an international armed conflict * Fighter aircraft, a warplane designed to destroy or damage enemy warplan ...

and

attack aircraft An attack aircraft, strike aircraft, or attack bomber is a tactical military aircraft that has a primary role of carrying out airstrikes with greater precision than bombers, and is prepared to encounter strong low-level air defenses while pre ...

could be near-vertically launched using

rocket motor A rocket engine uses stored rocket propellants as the reaction mass for forming a high-speed propulsive jet of fluid, usually high-temperature gas. Rocket engines are reaction engines, producing thrust by ejecting mass rearward, in accordance ...

s to rapidly gain speed and altitude. Such rocket boosters were limited to a short-burn duration, being typically solid-fuel and suitable for only a single use, being intended to drop away once expended. The majority of ZELL experiments, which including the conversion of several front-line combat aircraft for trialling the system, occurred during the 1950s amid the formative years of the

Cold War The Cold War is a term commonly used to refer to a period of geopolitical tension between the United States and the Soviet Union and their respective allies, the Western Bloc and the Eastern Bloc. The term '' cold war'' is used because t ...

. As envisioned, the operational use of ZELL would have employed mobile launch platform to disperse and hide aircraft, reducing their vulnerability in comparison to being centralised around established airbases with well-known locations. While flight testing had proved such systems to be feasible for combat aircraft, no ZELL-configured aircraft were ever used operationally. The emergence of ever-capable

missile In military terminology, a missile is a guided airborne ranged weapon capable of self-propelled flight usually by a jet engine or rocket motor. Missiles are thus also called guided missiles or guided rockets (when a previously unguided rocket ...

s had greatly reduced the strategic necessity of aircraft for the

nuclear strike Nuclear warfare, also known as atomic warfare, is a theoretical military conflict or prepared political strategy that deploys nuclear weaponry. Nuclear weapons are weapons of mass destruction; in contrast to conventional warfare, nuclear w ...

mission, while questions over practicality had also played a role.

History

During the second world war, Germany experimented with the

Bachem Ba 349 The Bachem Ba 349 Natter ( en, Colubrid, grass-snake) was a World War II German point-defence rocket-powered interceptor, which was to be used in a very similar way to a manned surface-to-air missile. After a vertical take-off, which eliminate ...

, but due to them losing the war, development was cut short. According to aviation author Tony Moore, the concept of the ''zero-length launch system'' became popular amongst military planners and strategists during the early years of what is now known the

. Conventional aircraft, reliant on large and well-established airbases, were thought to be too easily knocked out in the opening hours of a major conflict between the

superpower A superpower is a state with a dominant position characterized by its extensive ability to exert influence or project power on a global scale. This is done through the combined means of economic, military, technological, political and cultural ...

s, thus the ability to remove this dependence upon lengthy runways and airbases was highly attractive. During the 1950s, various powers began experimenting with a diverse range of methods to launch armed fighter jets, typically using some arrangement of

s. In some concepts, such a fighter could be launched from a trailer from virtually any location, including those that could be

camouflage Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the b ...

d or otherwise concealed up until the moment of launch.Moore 2008, p. 72. The primary advantage of a zero-length launch system is the elimination of the historic dependence on vulnerable

airfield An aerodrome (Commonwealth English) or airdrome (American English) is a location from which aircraft flight operations take place, regardless of whether they involve air cargo, passengers, or neither, and regardless of whether it is for publ ...

s to facilitate air operations. In the event of a sudden attack, air forces equipped with such systems could field effective air defenses and launch their own airstrikes even with their own airbases having been destroyed by an early

nuclear attack Nuclear warfare, also known as atomic warfare, is a theoretical military conflict or prepared political strategy that deploys nuclear weaponry. Nuclear weapons are weapons of mass destruction; in contrast to conventional warfare, nuclear ...

. Although launching aircraft using rocket boosters proved to be relatively trouble-free, a runway was still required for these aircraft to be able to land or else be forced to crash. The mobile launching platforms also proved to be expensive to operate and somewhat bulky, typically making them difficult to transport. The security of the mobile launchers themselves would have been a major responsibility in and of itself, especially in the case of such launchers being equipped with

nuclear Nuclear may refer to: Physics Relating to the nucleus of the atom: *Nuclear engineering *Nuclear physics *Nuclear power *Nuclear reactor *Nuclear weapon *Nuclear medicine *Radiation therapy *Nuclear warfare Mathematics *Nuclear space *Nuclear ...

-armed strike fighters. F-84 Thunderjet ZELL

The

United States Air Force The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army Si ...

, the ''Bundeswehr's''

Luftwaffe The ''Luftwaffe'' () was the aerial-warfare branch of the German '' Wehrmacht'' before and during World War II. Germany's military air arms during World War I, the '' Luftstreitkräfte'' of the Imperial Army and the '' Marine-Fliegerabt ...

, and the Soviets' VVS all conducted experiments in zero-length launching. The first manned aircraft to be ZELL-launched was an

F-84G The Republic F-84 Thunderjet was an American turbojet fighter-bomber aircraft. Originating as a 1944 United States Army Air Forces (USAAF) proposal for a "day fighter", the F-84 first flew in 1946. Although it entered service in 1947, the Thun ...

in 1955. The Soviets' main interest in ZELL was for point defense-format protection of airfields and critical targets using

MiG-19 The Mikoyan-Gurevich MiG-19 (russian: Микоян и Гуревич МиГ-19; NATO reporting name: Farmer) is a Soviet second generation, single-seat, twinjet fighter aircraft, the world's first mass-produced supersonic aircraft. It was the ...

s. The American tests with the F-84s started with using the Martin MGM-1 Matador solid-fuel boost motor of some 240

kilonewton The newton (symbol: N) is the unit of force in the International System of Units (SI). It is defined as 1 kg⋅m/s, the force which gives a mass of 1 kilogram an acceleration of 1 metre per second per second. It is named after Isaac Newton in r ...

(52,000 lbf) thrust output, which burned out seconds after ignition and dropped away from the manned fighter a second or two later.Holder 2007, p. 138. Tests of the larger F-100 Super Sabre and SM-30 (MiG-19) (with the SM-30 using the Soviet-design PRD-22R booster unit) used similar short-burn solid fueled boost motors, albeit of a much more powerful 600 kN (135,000 lbf) thrust-class output levels.Greg Goebel's Air Vectors' "The Zero-Length Launch Fighter" page
/ref>Khurana 2009, p. 126. Testing proved that the F-100 was capable of a ZELL launch even while carrying both an external fuel tank and a single

nuclear weapon A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission bomb) or a combination of fission and fusion reactions ( thermonuclear bomb), producing a nuclear explosion. Both bomb ...

mounted on its

hard point A hardpoint is an attachment location on a structural frame designed to transfer force and carry an external or internal load. The term is usually used to refer to the mounting points (more formally known as a weapon station or station) on the ...

s. The conceived mission profile would have been for the pilot to have launched a retaliatory nuclear strike against the attacker before attempting to return to any available friendly airbase, or having to eject from the aircraft if a safe landing site could not be reached. Despite the extremely high thrust generated by the rocket motor, the F-100 reportedly subjected its pilot to a maximum of 4g of acceleration forces during the takeoff phase of flight, reaching a speed of roughly 300 mph prior to the rocket motor's depletion.Moore 2008, pp. 72-73. Once all fuel had been exhausted, the rocket motor was intended to slip backwards from its attachment points and drop away from the aircraft. However, testing revealed that this would sometimes fail to detach or cause minor damage to the aircraft's underside when doing so.Moore 2008, pp. 73-74. Despite such difficulties being encountered, the F-100's ZELL system was considered to be feasible, but the idea of its deployment had become less attractive as time went on.Moore 2008, pp. 74-75. Eventually, all projects involving ZELL aircraft were abandoned, largely due to logistical concerns, as well as the increasing efficiency of

guided missile In military terminology, a missile is a guided airborne ranged weapon capable of self-propelled flight usually by a jet engine or rocket motor. Missiles are thus also called guided missiles or guided rockets (when a previously unguided rocket ...

s having rendered the adoption of such aircraft to be less critical in the eyes of strategic planners. Furthermore, the desire to field combat aircraft that lacked any dependence upon relatively vulnerable landing strips had motivated the development of several aircraft capable of either vertical takeoff/landing (

VTOL A vertical take-off and landing (VTOL) aircraft is one that can take off and land vertically without relying on a runway. This classification can include a variety of types of aircraft including helicopters as well as thrust-vectoring fixed-wi ...

) or short takeoff/landing (

STOL A short takeoff and landing (STOL) aircraft is a conventional fixed-wing aircraft that has short runway requirements for takeoff and landing. Many STOL-designed aircraft also feature various arrangements for use on airstrips with harsh condi ...

) flight profiles; such fighters included production aircraft such as British

Hawker Siddeley Harrier The Hawker Siddeley Harrier is a British military aircraft. It was the first of the Harrier series of aircraft and was developed in the 1960s as the first operational ground attack and reconnaissance aircraft with vertical/short takeoff an ...

and the Soviet Yak-38, as well as experimental prototypes such as the American

McDonnell Douglas F-15 STOL/MTD The McDonnell Douglas F-15 STOL/MTD (Short Takeoff and Landing/Maneuver Technology Demonstrator) is a modified F-15 Eagle. Developed as a technology demonstrator, the F-15 STOL/MTD carried out research for studying the effects of thrust vectori ...

.Khurana 2009, p. 147.

Manned aircraft involved in ZELL testing

Lockheed F-104G DA 102 ZELL tests Edwards AFB 1963 (mfr LA 3183 via RJF) (16929987577)

* Republic F-84G Thunderjet * North American F-100D Super Sabre *

Lockheed F-104 Starfighter The Lockheed F-104 Starfighter is an American single-engine, supersonic air superiority fighter which was extensively deployed as a fighter-bomber during the Cold War. Created as a day fighter by Lockheed as one of the "Century Series" of fi ...

Mikoyan-Gurevich MiG-19 The Mikoyan-Gurevich MiG-19 (russian: Микоян и Гуревич МиГ-19; NATO reporting name: Farmer) is a Soviet second generation, single-seat, twinjet fighter aircraft, the world's first mass-produced supersonic aircraft. It was the ...

SM-30

References

Citations

Bibliography

* Holder, William G. ''Lost fighters: a history of U.S. jet fighter programs that didn't make it''. SAE, 2007. . * Khurana, K.C. ''Aviation Management: Global Perspectives''. Global India Publications, 2009. . * Moore, Tony. ''X-Plane Crashes: Exploring Experimental, Rocket Plane, and Spycraft Incidents, Accidents and Crash Sites''. Specialty Press, 2008. . * Polmar, Norman and Robert Stan Norris. ''The U.S. Nuclear Arsenal: A History of Weapons and Delivery Systems Since 1945''. Naval Institute Press, 2009. .

External links