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Subject: de Havilland D.H.86 Express
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https://en.wikipedia.org/wiki/De_Havilland_Express
The de Havilland Express, also known as the de Havilland D.H.86, was a
four-engined passenger aircraft manufactured by the de Havilland Aircraft
Company between 1934 and 1937.
During 1933, talks between the governments of United Kingdom, India, Malaya, the
Straits Settlements and Australia resulted in an agreement to establish an
Empire Air Mail Service. The Australian Government called for tenders on 22
September 1933 for the Singapore-Australia legs of the route, continuing as far
south as Tasmania. On the following day Qantas, anticipating success in
contracting for the Singapore-Brisbane leg, placed an order with de Havilland
for an as-yet non-existent aircraft to be designated the de Havilland 86, the
prototype to fly by the end of January 1934. This order was soon followed by one
from Holyman's Airways of Launceston, Tasmania to operate the Bass Strait leg of
the service. The D.H.86 was initially styled the Express or Express Air Liner,
although the name was soon discontinued.
The D.H.86 was conceptually a four-engined enlargement of the successful de
Havilland Dragon, but of more streamlined appearance with tapered wings and
extensive use of metal fairings around struts and undercarriage. The most
powerful engine made by de Havilland, the new 200 hp (149 kW) Gipsy Six, was
selected. For long-range work the aircraft was to carry a single pilot in the
streamlined nose, with a wireless operator behind. Maximum seating for ten
passengers was provided in the long-range type, however the short-range Holyman
aircraft were fitted with twelve seats.
The prototype D.H.86 first flew on 14 January 1934, but the Qantas
representative Lester Brain immediately rejected the single pilot layout because
he anticipated pilot fatigue over long stretches, and the fuselage was promptly
redesigned with a dual-pilot nose. Only four examples of the single-pilot D.H.86
were built, and of these the prototype was rebuilt as the dual-pilot prototype.
When she entered service in October 1934 the first production aircraft,
Holymans' single-pilot D.H.86 Miss Hobart, was the fastest British-built
passenger aircraft operating anywhere in the world. Despite de Havilland's
predictions to the contrary, the dual pilot type with its lengthened nose proved
to be even faster.
Investigations in 1936 following a series of fatal crashes resulted in late
production aircraft being built with additional fin area in the shape of
vertical "Zulu Shield" extensions to the tail planes to improve lateral
Role
Passenger transport / trainer
Manufacturer
de Havilland
First flight
14 January 1934
Introduction
1934
Primary users
Imperial Airways
Qantas
Royal Air Force
Royal Australian Air Force
Produced
Number built
62
A total of 15 D.H.86s, D.H.86As and D.H.86Bs operated commercially within
Australia and New Guinea up to the outbreak of World War II. Eight D.H.86A and
D.H.86B aircraft were impressed into the Royal Australian Air Force and served
as A31-1 to A31-8 during the War. Some served as air ambulances in the Middle
East, while others did sterling work as transport aircraft and air ambulances in
Australia and New Guinea.
A total of 62 D.H.86s of all types were built. Most of those still flying in
Europe at start of World War II, except for the Railway Air Services aircraft,
were taken into military service, mostly for communications and radio
navigational training. A few Expresses survived the war and were used by UK air
charter operators until the last example was burnt out in 1958.
Seriously lacking in directional stability, the D.H.86s were frequently in
trouble. On 19 October 1934 Holyman's VH-URN Miss Hobart was lost in Bass Strait
with no survivors. Flotsam that may have been wreckage from the aircraft was
seen from the air three days later but surface ships failed to locate it in
rough seas; the aircraft had effectively vanished. At the time Miss Hobart
disappeared the design of the aircraft was not suspect, and it was thought that
an accident may have occurred when Captain Jenkins and the wireless
operator/assistant pilot Victor Holyman (one of the proprietors of Holyman
Airways) were swapping seats in mid flight. However, following the loss of
Qantas' VH-USG near Longreach four weeks later while on its delivery flight, it
was found that the fin bias mechanisms of the crashed aircraft and at least one
other were faulty, although it is doubtful that this had any direct bearing on
stability. Further investigation revealed that VH-USG had been loaded with a
spare engine in the rear of the cabin, and that one of the crew members was in
the lavatory in the extreme aft of the cabin when control was lost. It was
theorised that the aft centre of gravity condition that thus existed resulted in
loss of control at an altitude insufficient for recovery (the aircraft was at an
estimated height of 1,000 ft (300 m) prior to the crash).
Although the control problems were overcome on later-manufactured D.H.86Bs by
the fitting of a new spring in the elevator control and the fitting of auxiliary
fins, the results of these tests do not appear to have been communicated to
Australia and the D.H.86s already in use were never modified in this way to
improve their safety. This lack of communication may have caused a number of
later accidents, including at least one of two further fatal disasters in
commercial service.
Specifications (D.H.86A)
General characteristics
Crew: Two (pilot and co-pilot)
Length: 46 ft 1 in (14.04 m)
Wingspan: 64 ft 6 in (19.66 m)
Height: 13 ft 0 in (3.96 m)
Empty weight: 6,140 lb (2,791 kg)
Loaded weight: 10,250 lb (4,659 kg)
Performance
Maximum speed: 166 mph (144 knots, 267 km/h)
Cruise speed: 142 mph (123 knots, 229 km/h)
Range: 760 mi (661 nmi, 1,223 km)
Service ceiling: 17,400 ft (5,300 m)
Rate of climb: 925 ft/min (4.7 m/s)
*
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