Richard T. Whitcomb, Jet Age Aeronautical Pioneer

by Dr. Richard Stimson

in Others

The First Flight Society inducted NASA retired aeronautics engineer Richard Whitcomb, who made supersonic flight possible, into the Paul E. Garber First Flight Shrine at the Wright Brothers National visitor’s center in Kill Devil Hills, NC, during celebration activities commemorating the 104th anniversary of flight on Dec. 17, 2007.

His portrait will be displayed in the flight room of the visitors’ center where it will join those of other aviation pioneers. The tradition began in 1966 with the portrait of the Wright brothers.

Whitcomb followed in the best tradition of the Wright brothers, who when confronted with the claim of experts that man could never fly, showed them that they were wrong.

Whitcomb was also faced with the claim that man could never fly faster than the speed of sound. Many in the aeronautical experts in the 1930s and 1940s believed in the existence of an invisible barrier in the sky that prevented aircraft from flying faster than the speed of sound, which was approximately 700 mph.

Government researchers at McCook Field in Dayton and others first identified the problem on aircraft propellers in the 1920s. When the tips of a whirling propeller approached the speed of sound, it lost efficiency because of a drastic loss of lift. They simply could not turn any faster.

The big problem seen by the experts was the problem of overcoming drag. Both the Wrights and Whitcomb used their intellect and wind tunnel tests to solve the problem of drag. Tom Crouch, senior curator at the Smithsonian’s air and Space Museum noted that “Whitcomb battled the enemy of drag and won.”

The problem of drag facing the designers of supersonic aircraft was the large increase in drag associated with the formation of shock waves that occurred at speeds just below and above the speed of sound (transonic speeds). An airplane can experience severe instability at these speeds.

When an aircraft moves at the speed of sound, shock waves build up in front of it creating a single, very large shock wave. During transonic flight, a plane must pass through this large shock wave as well as contending with the instability caused by air moving faster than sound over parts of the wing and slower in other parts. The phenomenon is explained by the Bernoulli principle.

One day late in 1951 Whitcomb relates that he was thinking about the problem and trying to visualize the air passing over a body at transonic speed when he came to the startling realization that the air passing over a body at transonic speed behaved in a different way than the experts thought. He concluded that what really caused transonic drag was not the diameter of the fuselage alone, rather it was the drag rise created by the total cross-sectional area of the fuselage, wings and tail.

Since wings added most to this area, drag could be reduced significantly by tucking in or narrowing the fuselage where the wings attached and then expanding the fuselage at their trailing edges. Using this configuration the air would be displaced less violently, the waves and drag would diminish, thus enabling an airplane to pass more easily through the transonic zone.

He concluded that the same amount of air had to be replaced to get out of the way to make room for the plane, but with the trimmed down “wasp waist,” the air would not be displaced in such violent shock patterns. The configuration became known as the “area rule.” It was shaped more like an old-fashioned soda bottle.

His discovery was particularly timely because at that moment virtually all military fighters aimed at sustained level supersonic flight was doomed to remain below Mach 1 because of the incapability of the jet engines of the time to overcome the tremendous drag rise.

On August 1954, his ideas were confirmed in practice when a Grumman F9F-9 successfully breezed through sonic speed in level flight without the use of an afterburner, the first time this had been done.

Whitcomb was awarded the prestigious Collier trophy for his achievement and many other awards.

He continued to refine and extend his basic concept for commercial jets and well as military planes.

In the 1960s he conceived the “supercritical airfoil,” an airfoil whose primary attribute was improved performance at high subsonic speeds.

In the 1970s he developed what is called “winglets.” These are devices placed at the wingtips, normal to the wingspar, extending both upward and downward. The devices reduce wingtip vortices and the induced drag such vortices create. The aerodynamic efficiency of the wing is improved and fuel consumption reduced as well.

Tom Crouch notes that “Dick Whitcomb’s intellectual fingerprints are on virtually every commercial aircraft flying today.”

Whitcomb’s personality was in many respects similar to that of the Wrights. He was a conservative and shy and didn’t like administrative duties. In the laboratory he was a creative radical and in some respects management didn’t know quite know how to deal with him, so they pretty much let him do what he wanted.

Previous post:

Next post: