Aviation of World War II

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SR.45 Princess

Long-Range Passenger Seaplane



Despite the large number of concrete strips built around the world, Saunders-Roe believed in flying boats after World War II. The development of gas turbine engines made it possible to create a power plant for such an aircraft with a high power density in comparison with those previously available. This encouraged Saunders-Roe to design an even larger flying boat than what was already available, although in the end providing truly suitable and powerful engines proved to be one of the main challenges in the development of the final SR.45.

However, in 1944, based on research on a six-engine (84,823 kg) flying boat, Knowler and Arthur Gouge made three fundamental decisions: using gas turbine engines as a power plant, increasing the size of a flying boat as well as the introduction of a sealed enclosure. During the spring of 1945, Saunders-Roe prepared a proposal for the construction of the SR.45 as an important part of the future communications of the British Overseas Airways Company (BOAC).

The most advanced aspects of the SR.45 were a pressurized cab, a powerful air-conditioning system with bleed air from the engines and irreversible control of the steering surfaces using hydraulic boosters.

10 Bristol Proteus 600 turboprop engines were chosen as the final version of the power plant, eight of which worked on coaxial propellers rotating in different directions, while the power of the power plant was 32,000 hp.

However, with the development of jet aircraft and the airport network, the bright prospects for the use of heavy flying boats on transoceanic flights no longer seemed so obvious. Land-based vehicles were faster, and they did not have the problem of corrosion of hulls in sea water. In addition, jet aircraft were faster than turboprop. In light of these circumstances, the customer of the aircraft - BOAC - in 1951 abandoned the plans for the passenger operation of the Princess. The aircraft with the G-ALUN index was the only one of the three Princess built aircraft that performed flights - a total of 46 flights (100 flight hours). The other two vehicles were mothballed. All three aircraft were subsequently dismantled for scrap in 1967. So the attempt to use long-range passenger seaplanes on commercial flights ended ingloriously.

SR-45 Princess
Crew 3-4
Length, m 45.11
Height, m 7.39
Wing span, m 66.90
Wing area, m² 384.60
Weight, kg
Empty 86,184
Gross weight 156,490
10×TJE Bristol Proteus 600, h.p. 10×3200
Maximum speed, km/h 625
Cruising speed, km/h 580
Service ceilling, m 6,200
Service range, km 9,200
Pay load, passengers, normal/max 105/200
Photo Description
Drawing SR.45 Princess

Drawing SR.45 Princess

SR.45 in flight

SR.45 in flight

March 03, 2019.
It can be assumed that from the point of view of the safety of transantlantic flights, it was an absolutely safe plane. In case of emergency situations, fires, engine failures, etc. the plane was able to land in the ocean and wait for help indefinitely :-)

March 13, 2019.
Regarding the "absolutely safe aircraft". S.8 Calcutta G-AADN "City of Rome", built in March 1929. On October 26, 1929, returning from another flight, the plane got into a storm and was forced to splash down near La Spezia (near Genoa). The commander gave an SOS signal, but the rescuers arrived too late. The plane sank along with all four passengers and three crew members.


  • "Flying Boats of the World. Saro Princess"
  • "The Saunders-Roe SR.45 Princess" /Flight/
  • British warplanes of World War II /under cor. Daniel March/