An article by Major Oliver Stewart M.C., A.F.C., that appeared in "The Navy" magazine back in June 1952.
ONE OF THE most courageous enterprises in the whole history of aviation is approaching its most critical stage as these words are written. It is the construction of the first of the 140-ton Princess class flyingboats. Three are being built, but the second and third are to suffer an officially imposed delay. The first is nearly ready and may make an initial flight this year. Before pointing to some of the extremely interesting features of the design, let an attempt be made to sum up the general objective. It is to produce an extremely large aircraft which can operate from natural runways. In spite of its size - and the Princess is a good deal bigger than the Brabazon - it makes no demands for huge agricultural acreages to be set aside for its use and for thousands of tons of concrete to be laid down; it does not ask that villages be razed in order to make way for its take-off run or for trees to be felled and amenities ruined. It combines, therefore, the quality of great size with the ability to operate from any stretch of sheltered water.
Great size in an aircraft is desirable for many reasons. If long journeys are to be made, large cabins are preferred by the passengers. And as air transport increases in popularity so aircraft operating companies call for larger size machines. The large size passenger aircraft not only gives its occupants greater comfort, but it also eases traffic control at airports and improves earning power. On the Service side (and the first Princess is to be used as a troop transport aircraft) the advantages of size are self-evident. If, then, it is decided that a very large aircraft should be built, the selection of the flying-boat formula instead of the landplane has some notable advantages.
The natural runway provided by water can carry any load. It can give a taking off and landing run of any required length. Then the big boat hull gives increased safety - a point well made by Sir Frederick Bowhill a short time ago. He pointed out that the view that flyingboats were safer than land planes was not just a vague impression; but a fact fully supported by statistics. The increased safety arises largely from the fact that whereas a landplane which is forced to "ditch" is in great danger, a flying-boat which is forced to come down on land is not. Flying-boats can be put down on land with little damage to the machine and almost no risk to the occupants. And comparatively small flying-boats have repeatedly shown their ability to alight in mid-Atlantic and to take off again. The general desirability of the flyingboat is therefore clear enough and when the points are enumerated it seems hard to discover why we in Britain, after pioneering this type of aircraft, lost interest in it. For the disadvantages are comparatively few.
Flying-boat designers will dispute the contention that flying-boats must by their form be slower than comparable landplanes. But the fact is that flyingboats have nearly always been somewhat slower than comparable landplanes. The difference, however, is small. It might be three per cent. But even this small difference must be held against the flying-boat. The other objection to this type of machine is less well supported. It is that most commercial air lines use landplanes; that in consequence the huge and expensive aerodromes with their enormously long and wide runways will be built in any case, so it behoves us to make use of them and not to introduce a type of aircraft which would require the setting up of additional bases - marine bases in this instance. This is the poorest possible argument for failing to develop a type of aircraft which is characteristically British and which has proved itself to be the safest kind and the most comfortable kind. In short, then, the case against the flying-boat has never been sound. It is to be hoped that the coming of the Princess boats will turn attention once more to this type of machine and stimulate further work on them in the future.
I turn now to some details of the Princess. The aircraft is being built at Cowes in the yards of Saunders-Roe, a firm with long experience of boats and boat building, and the chief designer is Mr.Henry Knowler who recently read a paper on flying-boats for the Louis Bleriot lecture in Paris. The Princess is a monoplane, with the wings sprouting from the top of the hull. The wing span is 219 ft. 6 ins. The overall length of the aircraft is 148 ft. and the height to the top of the tail is 55 ft. 9 ins. The hull is a beautiful piece of design and construction, having a ship-like appearance yet an aerodynamically satisfactory streamline form. It has a single step on which much research was done, for unless correctly formed, the step - essential for the unstick from the water - can be a source of drag in the air. The wing-tip stabilising floats are retractable. They fold upwards and outwards to form the wing tips when the aircraft is in flight.
Ten engines are disposed along the wings of the Princess, eight of them in coupled pairs and the other two in single nacelles. This is an unusual engine arrangement. The Brabazon has eight engines coupled in pairs, but it has not the additional, single-mounted, outboard engines. The engine itself is the Bristol Proteus, an advanced turboprop, or gas turbine driving an airscrew. The aircraft's design figures were largely worked out on power ratings which the Proteus Type 2 engines, which will be fitted to the first machine, will not be able to give. The performance of this first aircraft may therefore be slightly down on calculation. But the Proteus 3 which will be fitted to the other two Princesses when these are eventually completed, will give more power than was originally expected with a consequent increase in the overall performance. Design figures for the Proteus 2 Princess give a cruising speed of 380 miles an hour (610 kilometres an hour) and a range of more than 3,500 miles (5,500 kilometres). The aircraft, when used as a trooper, will take 200 men with their equipment. The cabin is pressurised and the control for pressure, temperature and humidity is automatic. The aircraft will thus be able to fly at heights of up to 12,000 metres (40,000 ft.), while the cabin pressure will remain high enough to give normal living conditions.
The control of an aircraft of this size is a special problem. An electrohydraulic system has been devised by Saunders-Roe and it is believed that this will give easy and accurate control throughout the range of air speeds. One related matter must be touched upon and that is the provision for mooring the aircraft. The opponents of the flying-boat have often argued that the provision of launches, mooring bays, slipways and the rest of it would make a marine base as costly as a big land airport; but the fact is that an automatic system of mooring flyingboats has been devised and will be used for the Princesses. It does away with a great deal of manoeuvring and manipulation which, in some conditions, can be lengthy and tedious.
No one who has followed the controversy about flying-boats over the years can doubt that these aircraft have many and powerful enemies. All those who favour American practice and think that British aviation should follow closely in the tracks of United States aviation and give up its own specialities are opposed to the flying-boat. But all those who played a part in or who followed closely the development of the system of Empire air routes are strong supporters of the flying-boat. It would be useless to deny, however, that the future of this machine is now almost entirely in the hands of the Princess. No other notable attempts are being made here to re-introduce the flying-boat. No other big flying-boats are being built. If the Princess is a great success, the whole situation will be transformed and it will be almost certain that Britain will return to her marine aircraft and develop them once again. But if the Princess proves unsatisfactory for any reason, the opponents of the flying-boat will seize their opportunity and the flying-boat, in spite of its great achievements, may become a museum piece.