AP 118 · No. 10 Section II · Aircraft Plate 208 / 297

Plate 208 of 297 · Early jet age · Ten-engined transatlantic flying-boat airliner prototype

Saunders-Roe Princess

SR.45 Princess, G-ALUN, painted as G-ALUN, the Saunders-Roe SR.45 Princess, the only Princess to fly, standing on its beaching gear on the slipway at East Cowes as photographed in 1953–54: the largest all-metal flying boat ever built, with a pressurised double-bubble hull on a two-step planing bottom, a 219 ft 6 in wing carrying ten Bristol Proteus turboprops in six nacelles (four coupled pairs driving contra-rotating propellers and a single engine in each outer nacelle), wing-tip floats retracted to form the wing tips, and a tall fin above a dihedral tailplane: bare aluminium hull sides, wings and nacelles, a white roof and white fin and rudder, a dark blue cheat line through the upper-deck windows with a white pinstripe below it, a grey planing bottom, a Union flag high on the fin with ‘G-ALUN’ in black below it and ‘G-ALUN’ under the port wing (no Princess survives; the shape was taken from a published three-view scaled to the published span, length and height and checked against some 20 photographs of G-ALUN; the colour of the planing bottom is inferred from black-and-white photographs, the beaching gear’s wheel sizes are estimated, and a small unreadable marking near the bow is left off).

3D model

Turn it over

A procedural model built in Blender from published dimensions, drawings and photographs, painted as G-ALUN, the Saunders-Roe SR.45 Princess, the only Princess to fly, standing on its beaching gear on the slipway at East Cowes as photographed in 1953–54: the largest all-metal flying boat ever built, with a pressurised double-bubble hull on a two-step planing bottom, a 219 ft 6 in wing carrying ten Bristol Proteus turboprops in six nacelles (four coupled pairs driving contra-rotating propellers and a single engine in each outer nacelle), wing-tip floats retracted to form the wing tips, and a tall fin above a dihedral tailplane: bare aluminium hull sides, wings and nacelles, a white roof and white fin and rudder, a dark blue cheat line through the upper-deck windows with a white pinstripe below it, a grey planing bottom, a Union flag high on the fin with ‘G-ALUN’ in black below it and ‘G-ALUN’ under the port wing (no Princess survives; the shape was taken from a published three-view scaled to the published span, length and height and checked against some 20 photographs of G-ALUN; the colour of the planing bottom is inferred from black-and-white photographs, the beaching gear’s wheel sizes are estimated, and a small unreadable marking near the bow is left off). Drag to orbit, scroll or pinch to zoom · download .glb (1.8 MB)

Data plate

Specification

First flight, number built and top speed are for the whole family (SR.45); engine, crew and dimensions are for the SR.45 Princess, G-ALUN modelled here.

History

The Princess

Before the war Britain’s long-distance air routes had been flown by flying boats, and in 1946 the Ministry of Supply ordered three very large ones from Saunders-Roe of East Cowes for British Overseas Airways Corporation’s services across the Atlantic. Henry Knowler’s design team drew the largest all-metal flying boat ever built: a pressurised double-deck hull with a double-bubble section, a wing spanning almost 220 ft, wing-tip floats that retracted to form the tips, and ten Bristol Proteus turboprops, eight of them coupled in pairs to drive contra-rotating propellers.

The Proteus took longer to develop than expected, and while the boats were being built the world moved on. Wartime runways meant that landplanes could now fly the long routes, and BOAC flew its last flying-boat service in 1950 and lost interest in the Princess. Only the first, G-ALUN, was finished. Saunders-Roe’s chief test pilot, Geoffrey Tyson, took it off the Solent for the first time on 22 August 1952, and it flew over the crowds at the Farnborough show in 1952 and again in 1953. It made some 47 test flights, totalling about 100 hours, before it was grounded in 1954.

No airline wanted it. The other two Princesses were never flown and were cocooned at Calshot, and G-ALUN joined them in storage after its test flying. Over the next decade they were offered for RAF trooping, studied as test-beds for nuclear-powered flight and considered as transports for American rocket stages, but none of these schemes came to anything, and corrosion was found inside the cocoons. All three were broken up by 1967. None survives.

This airframe

SR.45 Princess G-ALUN

G-ALUNThe airframe modelled

G-ALUN was the first of the three Princesses and the only one to fly. It was launched at East Cowes in 1952, first flew on 22 August that year and spent the next two years on test and demonstration flying before it was put into storage; it was broken up in the 1960s. No Princess survives, so the model shows G-ALUN as photographs record it in 1953–54, standing on its beaching gear on the slipway: bare aluminium hull sides, wings and nacelles, a white roof and white fin and rudder, a dark blue cheat line through the upper-deck windows with a thin white pinstripe below it, a grey planing bottom, a Union flag high on the fin with ‘G-ALUN’ below it and the registration under the port wing. Its shape was taken from a published three-view scaled to the published span, length and height and checked against some 20 photographs. The wing-tip floats are shown retracted. The colour of the planing bottom is inferred from black-and-white photographs, the wheel sizes of the beaching gear are estimated, and a small marking near the bow that no photograph shows clearly is left off.

Where to see one

Not on charge

Only G-ALUN ever flew. All three were cocooned at Cowes and Calshot and scrapped by 1967, so none survives.

All 297 plates

Profiles and models are procedural interpretations built in Blender from published dimensions, three-view drawings and photographs of each airframe. Treat the museum aircraft as the reference.