de Havilland D.H.86 Express

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.


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
1934–1937

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
the accidents other than perhaps adding to the aircraft’s lack of inherent
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).

The Royal Air Force's Aeroplane and Armament Experimental Establishment tested
the D.H.86A design in 1936 following three fatal crashes in Europe. It would be
forty years before the report was published – one of the most damning
indictments ever written on the design of a commercial airliner put into series
production. The D.H.86 had been rushed from design concept to test flight in a
record four months to meet the deadlines set by the Australian airmail
contracts, and a lot of attention to detail had been ignored. It was a big
aircraft for its power, and as a result very lightly built. There was poor
response to control movements in certain speed ranges, the wings were inclined
to twist badly if the ailerons were used coarsely and, most seriously, the
vertical tail surface was of inadequate area. The result was an aircraft that,
although quite safe under normal conditions, could rapidly get out of control
under certain flight regimes.

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. The mid-air break-up of Qantas' VH-USE Sydney in a
thunderstorm near Brisbane on 20 February 1942 with the loss of nine lives, was
possibly unavoidable; however, the fin was found almost a mile away from the
main wreckage, which was burnt without an investigation being carried out. The
accident involving MacRobertson Miller Airlines’ ex-Qantas aircraft VH-USF at
Geraldton on 24 June 1945 most likely was entirely avoidable had the AaAEE
report been communicated to Australia. On its first commercial flight for its
new owners after military service, the pilot and a passenger were killed in a
classic loss-of-control accident while taking off with a heavy load in gusty
conditions.

Following the first three fatal Australian D.H.86 accidents, and a forced
landing by VH-USW Lepena on 13 December 1935 (a Friday) when the pilot believed
his aircraft was about to break up in mid-air, the Australian Government
temporarily suspended the type's Certificate of Airworthiness. This caused
outrage in Britain as it reflected on the whole British aircraft industry. In
fact, the D.H.86 had approached the limits to which traditional "plywood and
canvas" aircraft construction could be taken, and was obsolete compared to
all-aluminium stressed-skin aircraft like the Boeing 247 and the Douglas DC-1
that were already flying before it was even designed, and the Douglas DC-3 that
had its first flight just four days after the forced-landing of VH-USW. Under
pressure from Holymans and other companies, the Australian Government rescinded
its ban on the import of American aircraft during 1936, and from then on, with
the exception of Viscounts, large airliners used in Australia were of American
or Dutch (F27s) manufacture.

Specifications (D.H.86A)

General characteristics
Crew: Two (pilot and co-pilot)
Capacity: 10–12 passengers
Length: 46 ft 1 in (14.04 m)
Wingspan: 64 ft 6 in (19.66 m)
Height: 13 ft 0 in (3.96 m)
Wing area: 641 ft² (59.6 m²)
Empty weight: 6,140 lb (2,791 kg)
Loaded weight: 10,250 lb (4,659 kg)
Powerplant: 4 × de Havilland Gipsy Six I inline engine, 200 hp (149 kW) each

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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