The Aviation Historian — January 2018

58 THE AVIATION HISTORIAN Issue No 22

Without getting into arcane supersonic aero-

dynamics, the explanation for supersonic

shocks is ironically much closer to the collision

of “airstreams” that is so often erroneously

given as the cause of subsonic interference drag.

Whitcomb’s “lightbulb moment” came in 1951

when he visualised rigid pipes of air running along

the airframe, a useful working image first used

in a lecture to the NACA team by Dr Ing Adolf

Busemann, who suggested that aerodynamicists

should think like pipefitters. Whitcomb’s idea

was to smooth the outer shape of the bundle of

pipes by adjusting the shape of the aeroplane.

This smoothing was a transonic version of fixing

Ower’s local venturi choke over the wing with

Klein’s expanding fairing, or improving the

Whirlwind’s tail with a “Coke bottle” fairing, in

that it was still about minimising the abruptness

of longitudinal pressure changes.

Aeroplane designers were not necessarily

immediately grateful. Alexander Kartveli, chief

designer at Republic, “wasn’t happy. He liked his

airplanes to look sleek” recalled Whitcomb.^21 The

tunnel jockeys had established all the connections

beyond doubt; in any “classic” streamline design

the wing root would always start to put the brakes

on before the wing did. This was stated in black-

and-white for the first time in NACA confidential

report L5G31, A Simple Method for Estimating

Terminal Velocity Including Effect of Compressibility

on Drag, which states: “The critical speed was

arbitrarily taken as that of the wing-root section

... [this] is justified on the grounds that the wing-
root section usually has a lower critical speed
than any other component part of the airplane”.
The importance of this statement never had a
chance to become recognised. The wing alone
was blamed by the textbook for limiting speeds,
right up until the point at which Whitcomb meta-
phorically threw the textbook away.
In 1953 Robert T. Jones at NACA’s Ames facility,
who had (independently of German science)
identified wing sweepback as a key to supersonic
flight, said:
“In this [subsonic] range, there exists no
possibility of either favourable or adverse inter-
ference on the pressure differentials themselves.
If one body is so placed as to receive a drag from

LEFT Richard Whitcomb, who
formulated the area-rule theory
of aerodynamics in the early
1950s, had already made a name
for himself at NACA as an “ideas
man” with a restless intellect. The
concept, arrived at independently
by Whitcomb, had also been a
subject of much discussion among
German wartime aerodynamicists.
BOTTOM Before Muttray, Ower,
Klein et al — or even the Short
Mussel — was the German Pfalz
D III biplane fighter of 1917, which
was fitted with what would become
established as the “right” fillet.
Was this glimpse of the future
incorporated by accident or
design? If readers have any more
NASA information, do contact the Editor!

PHILIP JARRETT COLLECTION