Aeroplane September 2017

(Brent) #1
AEROPLANE SEPTEMBER 2017 http://www.aeroplanemonthly.com 85

Development


Technical Details


In Service


Insights


TECHNICAL DETAILS DE HAVILLAND DRAGON


T


he DH84 Dragon had
an all-wooden
structure. The fuselage
was built up as a
plywood box, supported by
spruce longerons and
stringers. The biplane wings
and tail were made of wooden
spars (solid spruce routed to
L-sections) and ribs, the wings
and control surfaces were
fabric-covered, and the
fuselage and fixed empennage
had a ply covering, with fabric
overall. Access to control runs
beneath the fuselage was
provided by zip fasteners or
lacing in the underside of the
fuselage. The fixed horizontal
tail was adjustable for trim by
a screw-jack on the front spar.
The rudder was balanced. The
whole structure was covered
with a nitro-cellulose finish,
and the rear fuselage
longerons with three-ply
covering were treated with
bitumastic paint to protect
against condensation.
The divided undercarriage,
with its 12ft span, was fixed. It
had a tailwheel and usually
had light alloy spats covering

the mainwheels for
streamlining and as
mudguards — as well as for
aesthetic purposes. Bendix
brakes were used. The
suspension’s only moving part
was one telescoping section,
with a rubber in-compression
shock absorber per
mainwheel. It was
recommended that the
Dunlop low-pressure 8.5in x
26.5in tyres be pumped up to

nacelles. A jury strut, fitted to
the front of the outer wing
cellule when the wings were
folded, was telescoped shorter
and could be clipped to the
underside of the upper wing
when not required. Wing
folding was by hand. The
lower centre section had no
dihedral, with just over 2° on
the upper. The upper wing
root had intakes for the cabin
air vents, and a 12-volt

instruments were on the
nacelles. A V-type windscreen
was made of safety glass, as
were side windows that could
be lowered into the fuselage
side “for ventilation and in
misty weather”, according to
the manual. The remainder of
the glazing was celluloid.
The cabin was usually
configured for one pilot and
six passengers, plus a
50-square foot baggage
compartment (with an access
door on the starboard side)
and lavatory, but these could
be removed and the cabin
extended to take eight
passengers. The theoretical
maximum load was 10
passengers. The normal cabin
dimensions were 9ft 9in long,
4ft 6in wide, and 4ft high. An
executive-type layout was
designed around one pilot
and four passengers
accommodated in relative
luxury. Standard cabin
equipment was sold separately
for £95, and weighed 100lb.
All Dragons had a single entry
door aft of the wing on the
port side, and an

Sturdy and utilitarian


The cabin was usually configured for one pilot
and six passengers, but the theoretical maximum
load was 10 passengers

a pressure of 28lb per square
inch (higher at maximum load).
The fully castoring tailwheel
also had a low-pressure tyre
and rubber in-compression
suspension.
The equal-span, two-bay
wire-braced biplane wings had
a 3° dihedral on the outer
planes. The incidence of 3°
and a very minor degree of
stagger, 7.5°, was to facilitate
outboard folding of the engine

dynamo could be fitted to the
outboard port lower wing
centre stub. The struts were of
steel tube, while the ailerons
on all four wings were linked
by struts and had the standard
DH-type differential action.
The single-pilot cockpit was
entered via an open bulkhead
from the main cabin. Standard
flying controls, a trim wheel
and a Reid & Sigrist turn
indicator were fitted. Engine

ABOVE: Wartime Australian Dragon manufacturing showing the fuselages being built up in the Mascot factory. THE COLLEC TION VIA G. GOODALL AND R. JAHNE

81-94_AM_DATABASE-Sept17_cc C.indd 85 31/07/2017 11:12

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