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Subject: Saunders-Roe Princess
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https://en.wikipedia.org/wiki/Saunders-Roe_Princess
The Saunders-Roe SR.45 Princess was a British flying boat aircraft developed and
built by Saunders-Roe at their Cowes facility on the Isle of Wight. It has the
distinction of being the largest all-metal flying boat to have ever been
constructed.
The Princess had been developed to serve as a larger and more luxurious
successor to the pre-war commercial flying boats, such as the Short Empire. It
was intended to serve the transatlantic route, carrying up to 100 passenger
between Southampton, United Kingdom and New York City, United States in spacious
and comfortable conditions. To achieve this, it was decided early on to make use
of newly developed turboprop technology, opting for the in-developed Bristol
Proteus engine to power the aircraft. The project suffered delays due to
difficulties encountered in the development of the Proteus engine.
On 22 August 1952, the first prototype Princess, G-ALUN, conducted its maiden
flight. Between 1952 and 1954, the first prototype performed a total of 47 test
flights, including two public appearances at the Farnborough Airshow. This work
was carried out under a development contract for the Ministry of Supply, the
intention being that this would lead to a contract for the aircraft from British
flag carrier British Overseas Airways Corporation (BOAC). Although the initial
development contract had been successfully met, BOAC eventually decided to focus
on its land-based routes using the jet-powered De Havilland Comet instead. The
era of the large flying boat had effectively ended prior to the aircraft's
completion.
Work on the Princess was ultimately cancelled after having produced three
examples, only one of which flew. By the mid-1950s, large commercial flying
boats were being increasingly overshadowed by land-based jet airliners. Factors
such as runway and airport improvements had added to the viability of land-based
aircraft, which did not have to compromise to accommodate the additional weight
and drag of the boat hulls that were necessary on seaplanes, or the mitigating
measures needed against the corrosion caused by seawater. Following the
project's termination, the three airframes were stored with the intention of
selling them on; however, upon receipt of a promising offer for the aircraft, it
was found that corrosion had set in while in storage. As a result, all three
Princesses were scrapped.
Role
Flying boat airliner
Manufacturer
Saunders-Roe
First flight
22 August 1952
Number built
3 (1 flew, others cocooned)
Flight tests of the prototype revealed the reliability of the engines and
gearboxes to be problematic, but not to the extent that flight testing was
prevented. Evaluation of the flying boat continued into 1953, during which
particular attention was devoted towards addressing the difficulties uncovered.
During the 1953 Farnborough Airshow, the prototype was displayed. Flight tests
of the prototype continued up until 27 May 1954, by which point it had been
found that the Proteus engine, once perfected, would be capable of enabling the
type to achieve its envisioned performance figures. G-ALUN was the only model to
fly, performing 46 test flights in total during which 100 hours flight hours
were accumulated.
In 1964, the three Princesses were all purchased by Eoin Mekie on behalf of Aero
Spacelines, who planned to use them as heavy-duty freight aircraft for
transporting Saturn V rocket components for NASA. When the cocooning was
removed, it was found that they were badly corroded (the contract for
maintenance and inspection of the stored aircraft had been allowed to lapse,
which resulted in the airframes deteriorating rapidly), and all three Princesses
were broken up by 1967. They were the last fixed-wing commercial aircraft
produced by Saunders-Roe. The company constructed one more fixed-wing design,
the Saunders-Roe SR.53 mixed-power (rocket and turbojet) fighter design; aside
from that venture, the company primarily concentrated its efforts on helicopters
and hovercraft after this point.
Specifications
General characteristics
Crew: 2 pilots, 2 flight engineers, radio operator and navigator
Capacity: 105 passengers in tourist and first class cabins / 137,000 lb
(62,142.2 kg) disposable load
Length: 148 ft (45 m)
Wingspan: 219 ft 6 in (66.90 m) with wingtip floats retracted. 209 ft 6 in
(63.86 m) floats extended.
Height: 55 ft 9 in (16.99 m)
Wing area: 5,019 sq ft (466.3 m2)
Airfoil: "Saro-modified Goldstein section" to "modified N.A.C.A. 4415 Series" at
tip
Empty weight: 190,000 lb (86,183 kg)
Gross weight: 330,000 lb (149,685 kg)
Max takeoff weight: 345,025 lb (156,501 kg)
Fuel capacity: 14,000 imp gal (63,645.3 l; 16,813.3 US gal) in four integral
inner wing tanks.
composed of two Proteus), 2,500 hp (1,900 kW) each + 820 lbf (3.65 kN) residual
thrust at 10,000 rpm at sea level.
Maximum continuous power: 2,050 hp (1,529 kW) + 700 lbf (3.11 kN) residual
thrust at 9,500 rpm at sea level.
+ 820 lbf (3.65 kN) residual thrust at 10,000 rpm.
Maximum continuous power: 2,050 hp (1,529 kW) + 700 lbf (3.11 kN) residual
thrust at 9,500 rpm at sea level.
Propellers: 4-bladed de Havilland constant speed, quick-feathering Duralumin
propellers., 16 ft 6 in (5.03 m) diameter
Performance
Maximum speed: 380 mph; 611 km/h (330 kn) at 37,000 ft (11,000 m)
Cruise speed: 360 mph (579 km/h; 313 kn) at 32,500 ft (9,900 m)
Stall speed: 113 mph; 181 km/h (98 kn) flaps and floats down
Range: 5,720 mi (4,971 nmi; 9,205 km)
Endurance: 15 hours
Service ceiling: 39,000 ft (12,000 m) absolute
Rate of climb: 1,900 ft/min (9.7 m/s) at 184 mph (296 km/h; 160 kn) at sea level
*
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