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Aviation History
1921
1921 - 0314.PDF
Angle of Incidence , •O.00O4-4 -2 0 4 6 8" 10 R I* l& 18 frngic of Incidcncc.dsg 0155 1510 MB 20 40 60 60 ^ g 90 10! i/Z< CHARACTERISTIC CURVES AND SECTION ORDINATBS FOB las HI WING SECTION MAY 5, 1921 flaps had been determined, the other tests were run at accurateangles with respect to this standard ; but the standard varied slightly from the original wing. Since the envelopecurve is the ultimate goal, this minor error, while annoying, is relatively unimportant. The Glenn Martin No. 4F, which was the No. 4 sectionwith flaps added, was run first. The test demonstrated clearly that at very low angles of lift coefficient a negative angleis best for both front and rear flaps ; but that at any speed ordinarily reached, the front flap only should be raised fromthe normal position. At liigh values of lift the front flap could profitably be in its normal position, and the rear flapshould be down about 450 to 50°. It is only at the burble point and beyond that there is any noteworthy gain fromthe lowering of the rear flap. The Glenn Martin No. 2F gave better results than theNo. 4F, as expected. The conclusions drawn in regard to the use of flaps are almost identical. An angle of — 50 for the frontflap is beneficial at all values of lift up to the burble point of the original wing. At very small lifts,- the front-flap canbe raised even to — io° with additional gain. In this latter region, also, the rear flap should be lifted to — 50. As theburble point is reached, the front flap apparently should come to o°, and from there on the rear flap should be broughtdown by successive stages to about + 55 °. The qualities of the wings with flaps, as indicated by thesetests, remain to be considered. The maximum lift increased .25 per cent, for the No. 4F and 29 per cent, for the 2F, overthe original wing. These new maxima,* 0.00484 and 0.00516, constitute the highest lift coefficients yet attained as faras I am aware.f The drag at this extreme lift is, however, very high. It is interesting to note that for the No. 2F theL/D is 15.1 at 25 per cent, of Lc maxima, and 8.4 at 11 per cent.t These values of Lc correspond to speeds of twiceand three times the minimum respectively. It would, therefore, appear that for racing machines the use of a wingwith flaps is highly desirable. For heavy weight-carrying planes, the drag would be high at low speeds ; and theperformance would resemble that of the Fokker-Junkers, which seems to be slow in pulling up from the ground, butclimbs well when a good flying speed is attained. The effect of an increase in speed and scale is uncertain,since experiments on thick wings with flaps have not been made. There is, however, no reason to believe that thewing characteristics would not improve to an appreciable extent. In any event, full-flight tests can soon settle thequestion. * If a correction is applied for the reduction of chord and area with theflaps at large angles, Lc would approach o 00575 in the case of the No. 2F. t The largest value, I have noted elsewhere is that recorded for the R.A.F.19in Report and Memorandum No. 648, published by the Advisory Committee for Aeronautics (Great Britain). That report records O = 0*93, or Lc —o'00474. The Handley Page apparently only reached Ci = o'8, or Lc = o '00408. [This paper was read before Mr. Hanscom had seen the diagramsfrom Mr. Handley Page's lecture, hence he was judging the H.P. slotted wing on the figures relating to the R.A.F. 6 tested with and without slot atthe N.P.L. Since then, however, other sections and better shaped slots have given better results, while a section fitted with six slots showed as high amaximum lift coefficient as 1*96 (absolute). This lift, however, occurred at an angle of incidence of about 45 degrees and, in practice, it would be almostimpossible to make use of it, owing to the large angle.—ED. FLIGHT.] J The corresponding values for the R.A.F.15 obtained from NationalPhysical Laboratory tests are 14^5 and J-J per cent. Honours WAZIRISTAN AIR AWARDS.—The King has approved ofthe following rewards for gallantry and distinguished service in Waziristan, 1919-20 :—Bar to the D.F.C.—Flying Officer J. R. Swanston, D.F.C., R.A.K (since killed).D.F.C.—Observer Officer (Hon. Flight Lieut.) D. Craik, R.A.F. ; Pilot Officer N. Fielden, R.A.F. ; Observer OfficerB. A. Foord, M.C., R.A.F. ; Trying Officer H. C. Hawkins, R.A.F.M.B.E. Military Division) .—Pilot Officer B. W. Wright, R.A.F. Examinations for Aviation Ground Engineers CANDIDATES desirous of becoming certified GroundEngineers (Aircraft or Engines) under Section 4 of the Air Navigation Directions, 1919, may, until further notice,be examined at the Air Ministry (Alexandra House), Kings- way, London, W.C. 2, on alternate Wednesdays, commencingas from May 4, 1921, and monthly at Birmingham, Leeds or Bristol as required. Candidates desiring to be examined can secure applicationforms from the Secretary (C.A.L.), Air Ministry, London, W.C 2, and should submit their completed forms'of applica- tion, accompanied by a fee of 55., at least seven days priorto the date on which the examination is desired. Candidates should also state at which of the above places they wish tobe examined. " R. 33's " Night Flight LAST week the experiments with night-flying lights onthe Croydon-Paris air route were continued, the airship " R. 33 " leaving her mooring mast at Pulham at 9.19 p.m.on April 29, arriving over Waddon aerodrome at 10.30 p.m. Cruising slowly over and around the aerodrome the airshipconducted a number of experiments with the different lights at Waddon, afterwards continuing her cruise to Lympneand the coast in order to test the efficacy of the lights on the route.Crossing the Peruvian Andes THE Peruvian Andes were crossed by aeroplane forthe first time on May 2, when Giovanni Ancillatto, an Italian aviator, left Lima at 10.45 and reached Cerro dePasco at noon, crossing the Andes at an elevation of 16,000 ft. in an Ansaldo machine equipped with a 300 h.p.Fiat engine. Ancillatto made a previous attempt the day before, but, after reaching the high plateau region, wasturned back by fog. 314
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