Note on page No 589 * Large tables which do not appear with the text will be found at the end of the Paper.

Note on page No 590 * (Here it is my pleasant duty to acknowledge the help, assistance and encouragement which I have received from so many hands. In particular I want to thank my two colleagues, Mr. J. G. Simms, O.B.E., M.A., and Mr. P. W. Brooks, B.Sc, A.C.G.I., A.F.R.Ae.S., who have both been untiring in compiling data, in constructive criticism, and in discussion of problems thrown up during preparation of the Paper. They have both contributed materially to it. In addition I gratefully acknowledge the help, advice and data so freely accorded to me by Airspeed Ltd., Sir W. G. Armstrong Whitworth Aircraft Ltd., the Bristol Aeroplane Company Ltd., British European Airways, the British Overseas Airways Corporation, the de Havilland Aircraft Company Ltd., Mr. C. Jackson, B.Sc., A.C.G.I., A.F.R.Ae.S., Mr. C. Dykes, M.A., Captain A. G. Lamplugh, C.B.E., F.R.Ae.S., Captain H. Spry ation, the Ministry of Civil Aviation, the Ministry of Supply, Olley Air Services Ltd., Rolls-Royce Ltd., Vickers-Armstrongs Ltd., Mr. A. H. Watson, M.A., F.S.S., and Captain J. Laurence Pritchard, Hon.F.R.Ae.S., Mrs. Joan Bradbrooke. A.R.Ae.S., and other members of the Staff of the Royal Aeronautical Society. In the preparation and checking of the manuscript, tables and figures I am grateful for the assistance of the Misses J. E. Bagshaw, P. E. Copland, V. Hart, J. Gwilliam and D. Stansfield and of Messrs. R. E. G. Davies and R. V. Easy. Although I take full responsibility for the opinions expressed in this Paper, none of which necessarily reflects any official views, without these and many other persons and bodies, the Paper could not have been written.)

Note on page No 600 * METO = Maximum except take-off.

Note on page No 610 * As an example of increased complexity the number of sparking plugs in a well-known “vintage” civil aeroplane is 56 compared with 224 in a modem successor. Turbine transports will improve this particular feature.

*1 This introduces a small error with pistonengined types, although it is not as serious as at first appears, because there is considerable flexibility in the relatively slow cruise-climb performance assumed. With turbine-powered types, the error is smaller still, as the lighter the aircraft, the greater the operating height. The more rapid climb will then be largely balanced by the greater height to be reached.

†2 Still-air distances to alternate airports are assumed to be as follows for the seven types of aircraft considered:—

Rapide 100 miles Constellation 500 miles

Dove 170 miles Orion I 500 miles

Dakota 300 miles Brabazon I 500 miles

Ambassador 420 miles

Note on page No 633 * A commentary on the handicap imposed on turbine-powered aircraft by the need for diversion and stand-off reserves is provided by the fact that the Brabazon IB will require more fuel to' divert to an alternate airport (covering 500 still-air miles at 3,000 feet on six engines at 200 m.p.h.) than it will to climb to operating height on eight engines and descend on six engines at an average of 260 m.p.h. (210 m.p.h. climb speed, 290 m.p.h. descent speed). The relative figures for fuel are:—

Taxi, climb and descent (2.36 hours), 11,900 lb.; diversion to alternate (2.5 hours), 13,630 lb.