Anti-shock body is the name given by Richard T. Whitcomb to a pod positioned on the upper surface of a wing. Its purpose is to reduce

wave drag In physics, mathematics, and related fields, a wave is a propagating dynamic disturbance (change from equilibrium) of one or more quantities. Waves can be periodic, in which case those quantities oscillate repeatedly about an equilibrium (re ...

while travelling at

transonic Transonic (or transsonic) flow is air flowing around an object at a speed that generates regions of both subsonic and supersonic airflow around that object. The exact range of speeds depends on the object's critical Mach number, but transoni ...

speeds ( Mach 0.8–1.0), which includes the typical cruising range of conventional

jet airliner A jet airliner or jetliner is an airliner powered by jet engines (passenger jet aircraft). Airliners usually have two or four jet engines; three-engined designs were popular in the 1970s but are less common today. Airliners are commonly clas ...

s. 'The Cambridge Aerospace Dictionary' defines shock body (also known as Whitcomb body, Küchemann carrot or speed bump) as a streamlined volume added to improve

area rule The Whitcomb area rule, named after NACA engineer Richard Whitcomb and also called the transonic area rule, is a design procedure used to reduce an aircraft's drag at transonic speeds which occur between about Mach 0.75 and 1.2. For superson ...

distribution. The anti-shock, or shock body, was one of a number of ways of implementing what was then the recently developed area rule. Another was fuselage shaping.

Theory

The theory behind the anti-shock body was independently developed during the early 1950s by two aerodynamists, Richard Whitcomb at

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeedin ...

and

Dietrich Küchemann Dietrich Küchemann CBE FRS FRAeS (11 September 1911 – 23 February 1976) was a German aerodynamicist who made several important contributions to the advancement of high-speed flight. He spent most of his career in the UK, where he is b ...

at the British

Royal Aircraft Establishment The Royal Aircraft Establishment (RAE) was a British research establishment, known by several different names during its history, that eventually came under the aegis of the UK Ministry of Defence (MoD), before finally losing its identity in me ...

.Barnard and Philpott 2010, p. 254. The anti-shock body is closely associated with the

, a recent innovation of the era to minimise wave drag by having a

cross-sectional Cross-sectional data, or a cross section of a study population, in statistics and econometrics, is a type of data collected by observing many subjects (such as individuals, firms, countries, or regions) at the one point or period of time. The analy ...

area which changes smoothly along the length of the aircraft. The extension beyond the trailing edge was considered secondary to the body on the wing surface which slowed the supersonic flow to give a weaker shock and acted as a fence to prevent outward flow. The extension was only long enough to prevent flow separation. Whitcomb stated that the anti-shock body was no longer required on the top surface of a wing when the

supercritical airfoil A supercritical airfoil (supercritical aerofoil in British English) is an airfoil designed primarily to delay the onset of wave drag in the transonic speed range. Supercritical airfoils are characterized by their flattened upper surface, highly ...

was introduced because they both decreased the strength of, or eliminated, the shock and its attendant drag.

Applications

Aircraft that have used anti-shock bodies are the

Convair 990 The Convair 990 Coronado is an American narrow-body four-engined jet airliner produced between 1961 and 1963 by the Convair division of American company General Dynamics. It was a stretched version of its earlier Convair 880 produced in respo ...

airliner and

Fokker 100 The Fokker 100 is a regional jet produced by Fokker in the Netherlands. The Fokker 100 is based on the Fokker F28 with a fuselage stretched by to seat up to 109 passengers, up from 85. It is powered by two newer Rolls-Royce Tay turbofans, ...

aircraft. So-called "Küchemann carrots" were added to the

Handley Page Victor The Handley Page Victor is a British jet-powered strategic bomber developed and produced by Handley Page during the Cold War. It was the third and final '' V bomber'' to be operated by the Royal Air Force (RAF), the other two being the Avr ...

to provide volume for carrying chaff. They did not improve the performance of the aircraft and when they became redundant for their intended purpose they were left in place to save the cost of removing them. Boeing tested the effect of adding similar bodies to a wind tunnel model of the Boeing 707. Although the speed beyond which the drag rose abruptly was increased the additional friction drag on the surface area of the bodies cancelled out any advantage.The Road To The 707 The Inside Story of Designing the 707,William H.Cook,, p.259 File:Convair 990 on ramp EC92-05275-30.jpg, NASA

with antishock bodies on the top of the wings File:Austrian Arrows Fokker F100 (1) (cropped).jpg,

with anti-shock bodies on top of the wings

Alternative

Modern jet aircraft use supercritical airfoils to minimize drag from shockwaves on the upper surface.

References

Citations

Bibliography

* ap Rees, Elfan. "Handley Page Victor: Part 2". ''Air Pictorial'', June 1972, Vol. 34, No 6., pp. 220–226. * Barnard, R. H. and D. R. Philpott. ''Aircraft Flight: A Description of the Physical Principles of Aircraft Flight.'' Pearson Education, 2010. . {{refend Aerodynamics Aircraft wing design