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Subject: Avro Tudor
Date: 11 Sep 2017 07:32:11 -0700
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https://en.wikipedia.org/wiki/Avro_Tudor
The Avro Type 688 Tudor was a British piston-engined airliner based on Avro's
four-engine Lincoln bomber, itself a descendant of the famous Lancaster heavy
bomber, and was Britain's first pressurised airliner. Customers saw the aircraft
as little more than a pressurised DC-4 Skymaster, and few orders were
forthcoming, important customers preferring to buy US aircraft. The tailwheel
undercarriage layout was also dated and a disadvantage.
Avro began work on the Type 688 Tudor in 1943, following Specification 29/43 for
a commercial adaptation of the Lancaster IV bomber, which was later renamed
Lincoln. The specification was based on recommendations of the Brabazon
Committee, which issued specifications for nine types of commercial aircraft for
postwar use.
Avro first proposed to build the Avro 687 (Avro XX), which was a Lincoln bomber
with a new circular section pressurized fuselage and a large single fin and
rudder in place of the predecessor's double ones. During the design stage, the
idea of a simple conversion was abandoned and the Avro 688 was designed, which
retained the four Rolls-Royce Merlin engines. It was designed by Roy Chadwick
who, due to wartime restrictions, could not design a completely new aircraft,
but had to use existing parts, tools and jigs. Using the Lincoln's wing,
Chadwick, who had worked on the Lancaster, designed the Tudor to incorporate a
new pressurized fuselage of circular cross-section, with a useful load of 3,765
lb (1,705 kg) and a range of 3,975 mi (6,400 km).
The Tudor was a low-wing cantilever monoplane with four engines, a single fin
and rudder and a retractable tailwheel undercarriage (in its original
configurations).
The circular cross-section fuselage was an all-metal semi-monocoque structure,
of 10 ft (3.0 m) diameter, fitted with kapok-filled inner and outer skins above
floor level. The hydraulically operated main-wheel units were similar to those
of the Lancaster, had single Dunlop wheels and retracted rearward into the
inboard engine nacelles. The twin tailwheels retracted rearward into the
fuselage and were enclosed by twin longitudinal doors.
Role
Airliner
Manufacturer
Avro
Designer
Roy Chadwick
First flight
14 June 1945
Primary users
B.S.A.A
BOAC
Produced
Number built
38
Developed from
Avro Lincoln
Developed into
Avro Ashton
Tudor I
The Tudor I was intended for use on the North Atlantic route. At the time, the
United States had the Douglas DC-4 and Lockheed Constellation, which could both
carry more passengers than the Tudor's 12, and also weighed less than the
Tudor's weight of 70,000 lb (32,000 kg). The Tudor's tailwheel layout was also a
drawback. Despite this, the Ministry of Supply ordered 14 Tudor Is for BOAC, and
increased the production order to 20 in April 1945.
The Tudor I suffered from a number of stability problems, which included
longitudinal and directional instability. The problem was handed over to the
Royal Aircraft Establishment at RAE Farnborough, where an extensive programme of
testing was carried out, the test pilot being Eric Brown. Following the RAE's
recommendations, a larger tailplane was fitted, and the original finely curved
fin and rudder were replaced by larger vertical surfaces. BOAC added to the
delays by requesting more than 340 modifications, and finally rejected the Tudor
I on 11 April 1947, considering it incapable of North Atlantic operations. It
had been intended that 12 Tudors would be built in Australia for military
transport, but this plan was abandoned.
Twelve Tudor Is were built, of which three were scrapped, while others were
variously converted to Tudor IVB and Tudor Freighter Is.
Tudor IV
To meet a BSAA requirement, some Tudor Is were lengthened by 5 ft 9 in (1.75 m),
powered by 1,770 hp (1,320 kW) Rolls-Royce Merlin 621s and 1,760 hp (1,310 kW)
Rolls-Royce Merlin 623s. With 32 seats and no flight engineer position, these
were known as Tudor IVs, and when fitted with a flight engineer's position and
28 seats, as Tudor IVBs.
BSAA's new flagships received mixed reviews from pilots. Some greeted it with
enthusiasm, such as Captain Geoffrey Womersley, who described it as "the best
civil airliner flying." Others rejected it as an unsound design. BSAA's chief
pilot and manager of operations, Gordon Store, was unimpressed:
"The Tudor was built like a battleship. It was noisy, I had no confidence in its
engines and its systems were hopeless. The Americans were fifty years ahead of
us in systems engineering. All the hydraulics, the air conditioning equipment
and the recircling [sic] fans were crammed together underneath the floor without
any thought. There were fuel-burning heaters that would never work; we had the
floorboards up in flight again and again.
Specifications (Avro 688 Tudor 1)
General characteristics
Crew: 5 (two pilots, flight engineer, radio operator, navigator)
Capacity: 24 passengers
Length: 79 ft 6 in (24.23 m)
Wingspan: 120 ft 0 in (36.58 m)
Height: 22 ft 0 in (6.71 m)
Loaded weight: 66,000 lb (30,000 kg)
Max. takeoff weight: 76,000 lb (34,500 kg)
kW) each
Performance
Maximum speed: 320 mph (512 km/h) at 8,000 ft (2,440 m)
Cruise speed: 283 mph (453 km/h) at 12,000 ft (3,660 m)
Range: 3,630 mi (5,840 km)
Service ceiling: 30,100 ft (9,180 m)
Rate of climb: 990 ft/min (5 m/s)
*
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