Issue No 22 THE AVIATION HISTORIAN 57
formal concession to supersonic flows, this big
two-seater slipped through Mach 1 smoothly.
Sadly, mechanical flaws and a high-profile
tragedy at the 1952 SBAC show at Farnborough
obscured the artistry of this late 1940s design.
Clarkson, Bishop, Tamblin and Smith were all of
the “old guard”, schooled in the ongoing research
on both sides of the Atlantic, and had engaged
with interference reduction in their work since
the 1930s, shaping high-speed aircraft from the
D.H.88 Comet racer and D.H.91 Albatross airliner
through to the military Mosquito and Hornet.
In more recent times there has been a renewed
industry focus on this area. In June 2017 Airbus
announced the A380plus, with root fairings
reshaped by the Airbus UK team to reduce the
giant airliner’s drag. It is perhaps no coincidence
that the team can trace its heritage back to the
original de Havilland team at Hatfield. The
related patents being filed for Airbus for shock-
reducing fillets (which the company insists on
calling “upper belly fairings”) refer to the “art”
of seeing where adverse pressure gradients and
transonic shocks will occur for any given aircraft
and its wing-roots.^19The teardrop expires
Area ruling — or the “Coke bottle” or “wasp
waist” — was the first real departure from the
teardrop since streamlining began. It wasn’t
invented by American aerodynamicist Richard
T. Whitcomb, but a theory as to why it worked
was properly codified by his confidential paper
A Study of the Zero-Lift Drag-Rise Characteristics of
a Body Near the Speed of Sound in 1954, and some
manufacturers immediately grasped the principle
and built accordingly.^20sported various shapes and sizes of additional root
filleting and fairing since the 1970s, among many
aerodynamic tweaks made with compressibility
as a consideration at speeds of 500+ m.p.h.
A lost art?
By 1945 the knowledge was in place. Designers
knew to avoid the natural junction of a teardrop-
shaped fuselage and an aerofoil. High-speed
aircraft were perfectly honed for minimum drag
— at least as far as they could be while clinging
to the teardrop.
A collection of everything NACA knew about
aerodynamics at the end of the war was published
in the unexcitingly-titled Summary of Airfoil Data,
which stated: “The main problem of interference
is considered to be that of avoiding boundary-
layer separation resulting from rapid flow
expansions caused by the addition of induced
velocities about bodies and the boundary-layer
accumulations near intersections. This effect may
be kept to a minimum by the use of bodies with
low induced velocities, by separation of interfering
bodies to the greatest possible extent and by such
selection and arrangement of combinations that
the points of maximum induced velocity for each
body do not coincide.”^18 There is no longer any
mention of “differing airflows”.
Back in the UK, under the oversight of the
company’s chief designer R.E. Bishop and
aerodynamicist Richard Clarkson, de Havilland’s
Bill Tamblin and J.P. “Phil” Smith began work on
a “heavy” all-weather fighter. What eventually
emerged from the drawing board was the D.H.110
— the epitome of the pre-Richard Whitcomb/
area-ruled high-speed aircraft. Without a bad
intersection anywhere and yet with no deliberate
This fascinating graph from
the Aeronautical Research
Council’s R&M 2222 shows
the sudden drag rise brought
on by various aircraft
approaching the speed
of sound (Cof sound (Cof sound (Cpppp = pressure = pressure
coefficient). That this does
not necessarily happen at
critical Mach for the wing is
demonstrated by the Meteor
I (short nacelles) and IV
(long nacelles) curves. The
intriguing mention of
a spoiler on the Mustang I
appears to refer to an
extendable deflector plate
fitted just forward of the
aircraft’s radiator intake,
which improved its transonic
performance, for then-
unknown reasons.High-speed comparison research at the RAE, 1942–45
VIA AUTHOR