de Havilland Albatross

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

The de Havilland DH.91 Albatross was a four-engine British transport aircraft
in the 1930s. A total of seven aircraft were built in 1938–39.

Development

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 notable for the ply-balsa-ply sandwich construction of its
fuselage, later used 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 20 May 1937.
The second prototype broke in two during overload tests but was repaired with
minor reinforcement. The first and second prototypes 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)

Operational history

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 9 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.

Frobisher was destroyed during a German air raid on Whitchurch in 1940, Fingal
was destroyed in a crash landing following a fuel pipe failure in 1940 at
Pucklechurch and Fortuna crashed near Shannon Airport in 1943. The latter
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.

Aircraft

Faraday
Mail-carrier variant was delivered to Imperial Airways in August 1939 as Faraday
and registered G-AEVV. It was transferred to BOAC when it was formed in 1940 but
was impressed into Royal Air Force service with serial number AX903 for
operation by No. 271 Squadron RAF. It was destroyed in a landing accident at
Reykjavik on 11 August 1941.

Franklin
Mail-carrier variant was delivered to BOAC as Franklin and registered G-AEVW.
Impressed into Royal Air Force Service with the serial number AX904 for
operation by 271 Squadron. It was destroyed when the landing gear collapsed on
landing at Reykjavik on 7 April 1942.

Frobisher
Passenger variant was registered G-AFDI and delivered to Imperial Airways (later
BOAC) as Frobisher in 1938. It was destroyed on the ground during a German air
attack on Whitchurch Airport on 20 December 1940.

Falcon
Passenger variant was registered G-AFDJ and delivered to Imperial Airways (later
BOAC) as Falcon in 1938. It was scrapped in September 1943.

Fortuna
Passenger variant was registered G-AFDK and delivered to Imperial Airways (later
BOAC) as Fortuna in 1939. Destroyed in a crash landing near Shannon Airport,
Ireland on 16 July 1943.

Fingal
Passenger variant was registered G-AFDL and delivered to Imperial Airways (later
BOAC) as Fingal in 1939. Destroyed in a crash landing near Pucklechurch,
Gloucestershire, England on 6 October 1940.

Fiona
Passenger variant was registered G-AFDM and delivered to Imperial Airways (later
BOAC) as Fiona in 1939. It was scrapped in September 1943.

Specifications (DH.91)

General characteristics
Crew: 4 (pilot, copilot, radio operator and steward(ess))
Capacity: 22-30 passengers
Length: 71 ft 7 in (21.83 m)
Wingspan: 105 ft 0 in (32.01 m)
Height: 22 ft 3 in (6.78 m)
Wing area: 1,077.9 sq ft (100.14 m2)
Airfoil: RAF-34 mod
Empty weight: 21,300 lb (9,662 kg)
Max takeoff weight: 29,500 lb (13,381 kg)
Fuel capacity: airliner 440 imp gal (528 US gal; 2,000 l) in two under-belly
tanks ; mailplane 1,320 imp gal (1,585 US gal; 6,001 l) in four main cabin fuel
tanks
Powerplant: 4 × de Havilland Gipsy Twelve V-12 air-cooled inverted geared and
supercharged piston engines, 415 hp (309 kW) each at 2450 rpm at 8,000 ft (2,438
m)
510 hp (380 kW) at 2,600 rpm for take-offPropellers: 2-bladed de Havilland
constant-speed propellers

Performance
Maximum speed: 225 mph (362 km/h, 196 kn)
Cruise speed: 210 mph (340 km/h, 180 kn) with 77% power at 11,000 ft (3,353 m)
193.5 mph (168 kn; 311 km/h)with 65% power at 11,000 ft (3,353 m)200 mph (174
kn; 322 km/h)with 65% power at 15,000 ft (4,572 m)Range: 1,070 mi (1,720 km, 930
nmi) in still with maximum fuel
Service ceiling: 18,700 ft (5,700 m)

Absolute ceiling: 20,500 ft (6,248 m)
Absolute ceiling on one engine: 12,300 ft (3,749 m)
Rate of climb: 1,018 ft/min (5.17 m/s)
Time to altitude:

5,000 ft (1,524 m) in 7 minutes
10,000 ft (3,048 m) in 14 minutes
15,000 ft (4,572 m) in 26 minutes
Wing loading: 27.4 lb/sq ft (134 kg/m2)
Power/mass: 0.0719 hp/lb (0.1182 kW/kg)




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