Editing Area rule (section)

==Applications==
The first aircraft where the area rule was consequently implemented was the German bomber [[Testbed aircraft|testbed]] [[Junkers Ju 287|Junkers Ju-287]] (1944).<ref>{{Citation | first = Hans-Ulrich | last = Meier | language = de | title = Die Pfeilflügelentwicklung in Deutschland bis 1945 | year = 2006 |trans-title=The swept-wing development in Germany until 1945 | isbn = 3-7637-6130-6 | pages = 166–99| publisher = Bernard & Graefe }}.</ref> Other corresponding German designs were not completed due to the end of the war or even remained in the planning stage.

When the area rule was re-discovered by Whitcomb, it was made available to the U.S. aircraft industry on a secret basis for military programs from 1952<ref>{{Cite web|url=https://archive.org/details/Aviation_Week_1955-09-12|title = Aviation Week 1955-09-12|date = 12 September 1955}}</ref> and it was reported in 1957 for civilian programs.
<ref name="Aviation-1957">{{cite web |url=https://archive.org/details/Aviation_Week_1957-08-12 |title=Aviation Week: August 12, 1957 |date=12 August 1957 |page=29 |publisher=McGraw-Hill |access-date=4 November 2022}}</ref>
Convair and Grumman, with Whitcomb's help, used it concurrently to design the [[Grumman F-11 Tiger]] and to redesign the [[Convair F-102]].<ref name="Aviation-1955">{{cite web |url=https://archive.org/details/Aviation_Week_1955-09-12 |title=Aviation Week: September 12, 1955 |date=12 September 1955 |page=12 |publisher=McGraw-Hill |access-date=4 November 2022}}</ref> The [[Grumman F-11 Tiger]] was the first of the two aircraft to fly and had been designed using the area rule from the outset.<ref>Design For Air Combat, Ray Whitford,{{ISBN|0 7106 0426 2}}, p.156</ref> The Convair [[F-102 Delta Dagger]] had to be redesigned as it had been unable to reach Mach 1 although its design speed was Mach 1.2. The expectation that it would reach design speed had been based on optimistic wind-tunnel drag predictions.<ref>The World's Fighting Planes Fourth and completely revised edition, William Green 1964, MacDonald & Co.(Publishers) Ltd., Gulf House,2 Portman Street, London W.1, p.136</ref>{{Sfn | Wallace | 1998 | p = 144}} Modifications which included indenting the fuselage beside the wings and adding more volume to the rear of the aircraft, reduced the transonic drag significantly and the Mach 1.2 design speed was reached. The reason for using the area rule on these fighter aircraft was to reduce the peak value of the drag which occurs at Mach 1 and so enable supersonic speeds with less thrust than would otherwise have been necessary.

In 1957 a modified area rule was available for raising the subsonic cruise speed of transport aircraft by 50&nbsp;mph.<ref name="Aviation-1957"/> The cruise speed is limited by the sudden increase in drag which indicates the presence of local supersonic flow on top of the wing. Whitcomb's modified rule reduced the supersonic speed before the shock, which weakened it and reduced the drag associated with it. The [[Convair 990]] had bumps called [[Anti-shock body|antishock bodies]] added to the top surface of the wing with the intent of achieving the required cruise speed. However, the area distribution in the channels formed by the nacelle/pylon/wing surfaces also caused supersonic velocities and was the source of significant drag. An area-rule technique, so-called channel area-ruling, was applied to achieve the required cruise speed.

Designers at [[Armstrong-Whitworth]] took the sonic area rule a step further in their proposed M-Wing, in which the wing was first swept forward and then to the rear. This allowed the fuselage to be narrowed in front of the root as well as behind it, leading to a smoother fuselage that remained wider on average than one using a classic swept wing.

The extension behind the flight deck on the [[Rockwell B-1 Lancer]] and [[Boeing 747]] was added to improve the cross-sectional area distribution according to the area rule.{{Sfn | Wallace | 1998 | p = 147}}

Aircraft designed according to Whitcomb's area rule (such as the [[F-102 Delta Dagger]] and the [[Northrop F-5]]) looked odd when they first appeared and were sometimes dubbed "flying [[Coke bottle]]s", but this became an expected part of the appearance of some transonic aircraft. Visually-apparent indications that the area rule has defined the shape of an aircraft are fuselage "waisting" and tip-tank shaping as on the [[Northrop F-5]], and rear fuselage thinning on business jets with rear engines such as the [[Bombardier Global Express]]. The rule also requires careful positioning of parts, like the boosters and cargo bay on rockets and the shape and location of the canopy on the [[F-22 Raptor]].

The supersonic area rule was applied, at Mach 2, to the prototype [[Concorde]]. The rear fuselage was extended by 3.73m on the production aircraft and reduced wave drag by 1.8%.<ref>A Case Study By Aerospatiale And British Aerospace On The Concorde By Jean Rech and Clive S. Leyman, AIAA Professional Study Series, Fig. 3.6</ref>