FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1931
1931 - 0198.PDF
uSUPPLEMENT TO FLIGHT FEBRUARY 27, 193; THE AIRCRAFT ENGINEER mail services general. The value of night air mail services has been appreciated by the Department of Commerce, and in order to make it practicable 14,000 miles of lighted airways have been installed. During the first half of 1930, the internal airlines of the U.S.A. carried 3,571,956 lb. (1,600 tons) of air mail, for which was paid $4,737,441. The most important service apparently being the San Francisco-Chicago (1,932 miles) (Boeing Air Transport), which accounted for 925,485 lb. (413 tons) for the six months. The second in importance is the Chicago-New York (717 miles) (National Air Transport), which accounted for 809,141 lb. (361 tons) for the six months. The latest figures to hand indicate that on November 15, 1930, the miles of airway operating mails in U.S.A. were 41,601 miles out of a total of 49,529 miles, and the average daily mileage schedules having a contract for mail was 75,370 miles out of a total of 116,605 miles for all services. The United States began their Transcontinental Air Mail Service from New York to San Francisco on a joint basis. i.e., the mails went by air during the day and by train at night. However, it was soon realised that if air mail was to have its fullest advantage it must fly on a 24-hour day basis. In consequence, the Central West was equipped with a lighted airway, and by this means it is possible for planes to leave New York at daylight, fly through the Central region at night and complete the journey by air the next day. Four years ago, when the Post Office Department of U.S.A. turned over the air maU services to the Aeronautics Branch of the Department of Commerce, there were 2,000 miles of lighted airways on a line between New York and Salt Lake City. To-day, there are 14,000 miles of airways fully equipped for night flying. A substantial portion of them have complete radio equipment for direction and communica- tion, and practically all have comprehensive weather report- ing service. The program in hand calls for 25,000 miles of trunk line airways. An idea of the progress being made in the U.S.A. will be apparent from the above few facts, but it is just as well to remember that at the present time the Post Office of America is not making a profit, and the deficit on Air Mails last year amounted to something like £1,400,000, which represents the subsidy necessary to air line operators during the experimental period. (To be continued.) TECHNICAL LITERATURE SUMMARIES OF AERONAUTICAL RESEARCH COMMITTEE REPORTS These Reports are published by His Majesty's Stationery Office, London, and may be purchased directly from H.M. Stationery Office at the following addresses : Adastral House, Kingsway, W.C.2 ; 120, George Street, Edinburgh; York Street, Manchester ; 1, St. Andrew's Crescent, Cardiff ; 15, Donegall Square West, Belfast; or through any bookseller. WIND TUNNEL EXPERIMENTS WITH CIRCULAR DISCS. By L. F. G. Simmons, M.A., A.R.C.Sc, and N. S. Dewey, M.A. R. & M. No. 1334 (Ae. 467). (6 pages and 10 diagrams.) February, 1930. Price9d.net. In continuation of the development of methods for photographing airflow a series of photographs of eddying motion were taken, with smoke used to render the flow visible, and an electric spark to serve as the source ofillumination. The flow selected for examination was the wake behind thin, circular discs, which wag known to undergo a marked transformation fromlaminar to eddying motion, within the VI)/r range available in the 1-ft. wind tunnel. Thus, by such a means an unsteady type of flow could bereadily produced and emp oyed as a subject for testing the photographic technique, from the results of which a judgment could be formed of theprobable value of the method for purposes of boundary layer investigation. The photographs appended to the report show that the method adoptedis capable of revealing satisfactorily the characteristics of eddying motion in the wake of a disc up to a wind speed of about 5 ft./sec, At higher speedsthe method fails owing to the rapid diffusion of the smoke and the consequent reduction in opacity. The results provide an interesting comparison with those of T.2884(revd.).* It is shown that at the lowest Reynolds numbers a permanent * To be published shortly. T.2884 (revd.). " On the Eddy System inthe Wake of Flat Circular Plates in Three-Dimensional Flow." T. F. Stanton and D. Marshal]. vortex exists at the rear of the disc closely resembling that recorded in thewater experiments. A change from this condition of flow to another tyno occurs, as in the water experiments, but at a lower value of VD/o; ;• jgsuggested that this lack of correspondence may be due to turbulence pro'-ont in the free stream of the air flow. THE STRESSES IN A RADIALLY SPOKED WIRE WHEEL TOI^R LOADS APPLIED TO THE RIM. PART II.—SIMPLIFIED FORMU- LA AND CURVES. By Prof. A. J. Sutton-Pippard, M.B.E D.Sc. M.Inst.C.E., and W. E. Francis, M.Sc. R. & j£ No. 1337 (Ae. 468). (10 pages and 11 diagrams.) July, 1930* Price 9rf. net. An analytical and experimental investigation of the stresses in a radiallv-spoked wire wheel when acted upon by a radially-applied load, described in an earlier paper,* led to certain formula! for the calculation of spoke loadsand rim reactions in such wheels. These formulae arc based on the assump- tion of a large number of spokes, but it was shown that reasonable accuracywas obtained when the number was as low as twenty-four. A more detailed arithmetical investigation has shown that they can beconsiderably simplified at the expense of a very small loss of accuracy, and in the present paper these simplified formulae and curves plotted from themare presented in a form suitable for design purposes and for further investi- gations which it is proposed to carry out. * The stresses in a radially-spoked wire wheel under loads applied to therim. A. J. Sutton Pippard and W. F. Francis. STALLED FLIGHT TESTS ON A BRISTOL FIGHTER FITTED WITH AUTO CONTROL SLOTS AND INTERCEPTORS. By R, p. Alston, B.A., and Pilots of Aerodynamics Flight. R.A.E. Communicated bv the Director of Scientific Research, Air Ministry. R. &"M. NO. 1338 (Ae. 469). (3 pages and 1 diagram.) June, 1930. Price 4d. net. An " interceptor " consists of a narrow plate which may be raised to aposition approximately normal to the upper surface of a wing. It is placed close behind an open slot, and nullifies the effect of the slot, producing anincrease in drag and reduction in lift. The interceptor Is arranged to come up when the aileron on that wing is raised. In the course of their experi-ments Messrs. Handle?- Page found that the most effective position o( the interceptor was very close behind the trailing edge of the slat; this necessitatesthe interceptor being housed in a recess, which is covered by the slat when the latter is lying against the wing as in normal flight. A D.H! Moth fitted with autoslots and interceptors was tested in stalledflight by R.A.E. pilots in November, 1929,* and the control was reported to be very good. On that aeroplane the interceptors were operated directlyby the ailerons through a lost motion device, thus allowing small aileron movements for normal flight without causing the interceptor to come intoaction. On the Bristol Fighter the slat, interceptor and aileron are inter- connected by a mechanism which only allows the interceptor to come upwhen the slat is forward ; when the slat is back, as in normal flight, full aileron may be applied witout causing any fouling of the slat and inter-ceptor. The lateral control at the stall of the Bristol Fighter fitted with thiscontrol is very good. The mechanism in its present form does not permit the interceptor to have sufficient movement to affect the motion in a spin.A three-axis rate of turn recorder has now been fitted, and measurements of the motions resulting from the use of the control at the stall are beingmade. * R. & M. 1292. Stalled flight tests on a Moth fitted with slots andinterceptors, Jones, Maitland and Purdin. FILL SCALE EXPERIMENTS ON HIGH TIP SPEED AIRSCEEWS. THE EFFECT OF THICKNESS OF SECTION ON AIRSCREW PER- FORMANCE. By W. G. Jennings, B.Sc, and A. Ormerod, B.Sc. Communicated by the Director of Scientific Research, Air Ministry. R. & M. No. 1339 (Ae. 471). (6 pages and 8 diagrams.) August, 1930. Price 6d. net. Full-scale experiments on high tip speed airscrews are described in R. andM. Nos. 1173 and 1282*. The latter report deals with comparative per- formance tests of three airscrews of different sections, with thickness/chordratios varying from 0-12 to 0 10. The present report continues the investi- gation of the effect of high tip speeds on airscrew performance, and (1«Uswith full-scale comparative tests of airscrews with different thiekness/chord ratios. Performance tests of three conventional section airscrews with meanthickness/chord ratios of 0 10, 0 08 and 0 06 respectively, have been carried out in a single-seater aircraft. The first two airscrews were testedat various pitch settings of the blades. The results have been compared with wind tunnel tests on similar airscrews working at low and at higntip speeds. The 0 • 10 thick airscrews show a serious drop in efficiency when the tipspeed exceeds the velocity of sound. For a pitch/diameter ratio of 0-56 this decrease in efficiency is of the order of 20 per cent. The 0 08 and (••06thick airscrews both show a decrease in efficiency of about half this amount. A direct comparison of the 0 10 thick airscrew with a high-speed modelairscrew of similar thickness appears to indicate that there is no serbus scale effect on maximum efficiency or torque coefficient. The wind tunnel experiments will be extended shortly by tests of an air-screw of 0 06 thickness'chord ratio, and by some further tests of the (08 suction. A fuller comparison of tunnel and flight results will then aepossible. * &. and St. 1173 and 1282. Full-scale experiments on high tipairscrews, by W. G. Jennings. ENGINES AT PARIS SHOW The tables of engine data which accompanied Captain Swa.. s article on engines at the Paris Aero Show, and which had to be hi Id over last month, will be found on the following two pages.—ED 1QA f
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
