FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1933
1933 - 0412.PDF
FLIGHT, AUGUST 24, 19SS THE ECONOMICAL CRUISING SPEED OF THE BURNELLI ALL-WING MONOPLANE By F. WERTENSON We have on previous occasions (THE AIRCRAFT ENGINEER, August 29, 1930 and September 25, 1931) published articles on the aerodynamic characteristics of the Burnelli semi all-wing aeroplanes. In the following article Dr. Wertenson deals with the advantages claimed for the type as a commercial machine with high cruising speed. Readers interested in the Burnelli designs may obtain further information from Air Commodore J. A. Chamier, of Chamier, Gilbert-Lodge & Co., of 47, Victoria Street, London, S.W.i. S 11]—HE economics of air transport have recently been (3 I receiving extensive theoretical and practical con- 111 sideration in the United States and abroad. It is generally recognised that air transport must advance sufficiently in the near future to make possible unsubsidised operations at a profit in competition with fast surface transportation before far greater expansion can be expected. How to accomplish this is a matter of varied opinion. It is logical that the main attention has been directed towards the design of the flying equipment, since the aeroplane constitutes the major expense item. In drawing a parallel to surface transportation, the aeroplane combines vehicle and road expenditures, and therefore it has great leverage in influencing operating costs. In regard to equipment requirements, the subject of one of the principal controversies is the effect of higher power loading versus higher speed. In some quarters it is main tained that large transports with increased pay load per horse-power and of moderate speeds will bring the required reduction in cost per ton-mile. This would make possible rates at the level required for competition with surface transport and to draw traffic therefrom, thereby greatly in creasing volume. The opposite view is that air transport should Strive for higher speeds and, thereby, cater to special patronage, which will pay rates in excess of those of fast surface transportation and sufficient to cover the cost of operation plus the essential profit. It is contended that new methods of travel develop new channels of traffic, and that this would particularly apply to super-speed air ways operations. One requirement is definitely agreed upon by both groups: With either method general improvements in the efficiency of air transport equipment are required, in addi tion to adapting it to traffic needs in order to bring about the desired advancement. The fundamental of equipment design is aerodynamics. Aerodynamic considerations directed attention to the so- called " all-wing " design, because in this regard it affords the highest efficiency possible with fixed wings. Due to structural reasons, and due to the general assumption that to house power plant, cargo and passengers in the wing necessitates unusually large thickness, chord and span, consideration of this trend of design has been applied only to types of large capacity and rather low speed, notwith standing that a plane composed entirely of lifting surface would be void of parasite drag and, therefore, capable of attaining the highest speed possible. The Burnelli plane is an all-wing plane in which only the central section is of increased thickness and chord to accommodate power plant, cargo and passengers. The outer wings are of normal thickness ratio. Investigation of the speed best adapted to present commercial needs of this design indicates that cruising speeds of 170 m.p.h. and higher are practical and economical. Types : Power Gross weight : lb. Wing loading : lb. per sq. ft. Lifting area : sq. ft. .. Lifting fuselage area : Wing panel area Drag distribution : Area X drag coefficient Wing Fuselage Pontoons or wheels Wing Fuselage Pontoons or wheels Tailplanes Bracing Total Top speed m.p.h. 2,600 6,000 40 150 150x0 0000212 7-5X0 000273 11-5x0-000230 0-00318 0-00205 0-00265 0-00031 0-00340 2,600 5,400 30 180 180X0-0000212 7-5x0-000273 4x0-00030 0-00383 0-00205 0-00120 0-00037 0-00290 2,600 5,400 37-5 144 144x0-0000286 7-5x0-000273 0-00412 0-00205 0-00040 0-01159 407 0-01035 422 0-00657 490 2 x 2,600 10,800 37-5 288 110 178 178x0-0000286 27x0 00026 0-00505 0-00700 0-00080 0-01285 495 Above table compares on a basis of equal power loading the ultimate high-speed performance obtain able by present practical designs. All types are assumed to have the same power plant, i.e., the Rolls-Royce " R " racing engine of 2,600 b.h.p. The wing loading of the seaplane is assumed heavier than for the landplane to account for pontoon weight, both using thin, wire-braced wing design. A heavier wing loading is allowed for the cantilever wing designs in proportion to the lift coefficient in crease compared to the thin-wing types, for equiva lent landing speeds. The research results indicate the aerodynamic superiority of the thick cantilever wing types with retractable undercarriage. Relative structural advantages and possible weight savings are not taken into account. The twin-engine design is assumed at double the weight of the single-engmeo types. 854
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
