Dr Richard Whitcomb was already famous for the discovery of the "area rule" - the "coke bottle" fuselage shaping that allowed aircraft to go supersonic more efficiently - when I came to work for him at NASA. The discovery had won him the Collier Trophy, the USA's highest award for aircraft design.
My first task, in 1962, was to assist Dick in the development of a supersonic transport known as SCAT 4. In other words, Dick said draw a line here, and I drew the line. After several weeks of this, I told him I didn't mind the drawing but I would appreciate him explaining what he was doing. From then on, Dick took me under his wing.
In 1964, he began working on a new concept, the "supercritical aerofoil", which was to be as significant an aerodynamic contribution as the area rule. I was privileged to be his associate on this work.
The journey began with Dick's idea for a fixed, single-slotted flap that was deployed in the cruise. With this concept, he successfully delayed the supersonic drag rise for commercial transports and increased their cruise speeds by 10-15%. The slotted supercritical aerofoil was difficult to optimise aerodynamically, however, as theoretical design codes were in their infancy. The aerofoil was also difficult to build.
The superior aerodynamics of the slotted supercritical aerofoil were demonstrated in the windtunnel in 1964. But the aspect ratio of the model was lower than that being considered for the Boeing 747, so the wing span was extended. To simplify the extension, we closed the gap between the main part of the aerofoil and the plain flap. To our amazement, the "unslotted supercritical aerofoil" worked as well as the slotted version.
Dick recognised the importance of this discovery and today's supercritical aerofoil was born. It differed from previous shapes by being flat on top and having the camber concentrated in the aft part of the aerofoil. Since their development, supercritical flow principles have been applied to all new aircraft designs.
Another major contribution he made was the development of winglets. Industry wanted higher aspect-ratio wings for commercial aircraft, but airport parking spaces limited wing span. Dick had the idea of putting "end plates" on the wing. They were supposed to increase the effective aspect ratio, but were never as efficient as theory said they should be.
Dick's discovery was that you had to camber and twist the endplate, or winglet, so that it would be highly loaded at the aircraft's cruise angle of attack. The camber and twist allowed the wing and winglet to achieve the optimum span loading for minimum induced drag. Today, you see winglets on most new corporate, commercial and military transports.
Dick was the greatest intuitive aerodynamicist I have known. Such was his concentration that many times I passed his office and saw him gazing into the sky, thinking through a problem, one cigarette burning in his hand and another parked in the ashtray. Many have said Dick could put a saddle on an air molecule and ride it over a wing to see where it went.
His understanding of aerofoil shaping was extraordinary. Many nights, I would watch him modifying the wing shape on a 4ft-span commercial transport model using the touch of his fingers and a file to cut the stainless steel.
When he finished one wing, he could duplicate the shape on the other wing by touch to within a few thousandths of an inch.
Dick was married to his work. He would rest during windtunnel runs by napping on a lawn chair behind a set of manometer boards while other engineers ran the tests. Many was the time when I got into Dick's old Volvo coupe and saw his NASA salary cheque tossed on the floor. Rumour had it the government accounting office called Dick and demanded he cash his cheques so they could close out the year's books.
While intuitive, Dick was keenly aware of the potential of theoretical aerodynamics. In designing the supercritical aerofoil, we made extensive use of the new Lockheed subsonic viscous aerofoil analysis code.
He sponsored the first NASA contract for transonic aerfoil analysis, which was given to General Dynamics. It took hours on the best computers we had to compute a solution.
The kick-start given by Dick in sponsoring some of the initial transonic aerofoil analysis work resulted in an explosion of activity and led to today's capability to perform viscous transonic analyses of the most complex shapes in seconds.
Beyond all doubt, Dick Whitcomb has proved himself to be an extraordinary aerodynamicist.
Source: Flight International