de Havilland DH.91 Albatross

https://en.wikipedia.org/wiki/De_Havilland_Albatross

The DH.91 was designed in 1936 by A. E. Hagg to Air Ministry specification 36/35
for a transatlantic mail plane.

The aircraft was remarkable for the ply-balsa-ply sandwich construction of its
fuselage, which was later made famous in the de Havilland Mosquito bomber.
Another unique feature was a cooling system for the air-cooled engines that
allowed nearly ideal streamlining of the engine mounting. The first Albatross
flew on May 20, 1937. The second prototype broke in two during overload tests
but was repaired with minor reinforcement, and it and the first prototype were
operated by Imperial Airways.

Although designed as a mailplane, a version to carry 22 passengers was
developed; the main differences being extra windows and the replacement of split
flaps with slotted flaps. Five examples formed the production order delivered in
1938/1939. When war was declared all seven aircraft were operating from
Bristol/Whitchurch to Lisbon and Shannon.

Role
Mail plane and transport aircraft

Manufacturer
de Havilland

Designer
A. E. Hagg

First flight
20 May 1937

Introduction
October 1938

Retired
1943

Primary users
Imperial Airways/British Overseas Airways Corporation
Royal Air Force

Number built
7 (including two prototypes)

As normal for the Imperial Airways fleet of the time, all were given names
starting with the same letter, and the first aircraft's name was also used as a
generic description for the type overall, as "Frobisher Class". This tradition,
which came from a maritime and railway background of classes of ships and
locomotives, lasted well into postwar days with BOAC and BEA.

The first delivery to Imperial Airways was the 22-passenger DH.91 Frobisher in
October 1938. The five passenger-carrying aircraft were operated on routes from
Croydon to Paris, Brussels and Zurich. After test flying was completed, the two
prototypes were delivered to Imperial Airways as long-range mail carriers. The
only significant season of their operation was the summer of 1939, when they
were the main type on the two-hourly London Croydon-to-Paris Le Bourget
passenger route.

With the onset of World War II, the Royal Air Force considered their range and
speed useful for courier flights between Great Britain and Iceland, and the two
mail planes were pressed into service with 271 Squadron in September 1940,
operating between Prestwick and Reykjavik but both were destroyed in landing
accidents in Reykjavík within the space of 18 months: Faraday in 1941 and
Franklin in 1942.

The five passenger aircraft were used by Imperial Airways, (BOAC from September
1940) on Bristol–Lisbon and Bristol–Shannon routes from Bristol (Whitchurch)
Airport.

One aircraft (Frobisher) was destroyed during a German air raid on Bristol in
1940, one (Fingal) was destroyed in a crash landing following a fuel pipe
failure in 1940 at Pucklechurch, another (Frobisher) was destroyed in an air
raid on Whitchurch, and one more (Fortuna) crashed near Shannon Airport in 1943.

This accident was found to be due to deterioration of the aircraft's plywood
wing structures. In view of the two surviving aircraft's vulnerability to
similar problems, and for lack of spares parts, Falcon and Fiona were scrapped
in September 1943.

Specifications (DH.91)

General characteristics
Crew: four (pilot, copilot, radio operator and steward)
Capacity: 22 passengers
Length: 71 ft 6 in (21.80 m)
Wingspan: 105 ft 0 in (32.01 m)
Height: 22 ft 3 in (6.78 m)
Wing area: 1,078 ft² (100.2 m²)
Empty weight: 21,230 lb (9,650 kg)
Loaded weight: 29,500 lb (13,380 kg)
Powerplant: 4 × de Havilland Gipsy Twelve 12-cylinder inverted V piston engine,
525 hp (392 kW) each

Performance
Maximum speed: 195 kn (225 mph, 362 km/h)
Cruise speed: 183 kn (210 mph, 338 km/h)
Range: 904 nmi, (1,040 mi, 1,675 km)
Service ceiling: 17,900 ft (5,455 m)
Rate of climb: 700 ft/min (3.5 m/s)
Wing loading: 27 lb/ft² (134 kg/m²)
Power/mass: 0.07 hp/lb (120 W/kg)





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