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Aviation History
1920
1920 - 0451.PDF
APRIL 22, 1920 '42 *4S MAX/MUM SECTION full Sue NORMAL TO CHOffO Chor</= 3' ---, Fig. 10 air flow that is common in many thick sections. At certainangles of incidence there may be two or even more types of flow. This condition is somewhat analogous to a super-saturated solution, as a given type of flow can be carried beyond its normal point of breaking if the angle of incidenceis changed slowly and carefully, but if jarred or left for a considerable time will revert to its stable value. This in-stability is lessened and in some cases disappears with an increase in velocity to 40 m.p.h. This instability of flow isalso associated with aspect ratio, for even the R.A.F. 6 shows a break in the lift curve at very low aspect ratios. Drag.—The minimum drag decreases with the thicknessof the centre section, reaching the rather low value of 0-0048 for No. 44. The thinner sections, however, show a pronouncedincrease in drag at high angles, 14° to 200, in fact, exceeding the drag of the thicker wings. Thinning the tips decreasesthe drag at all angles.- L/D.—The L/D increases at all angles as the wing is thinneddown. With reference to Plot 8, the thickest wing, No. 43, gives a comparatively poor performance, while the thinnest,No. 44, is shown to be most excellent in this respect; the other sections falling between them. The max. L/D rangesfrom 13 to 18-2, increasing progressively as the wing.is thinned. Centre of pressure.—The centre of pressure travel becomesless, and the C.P. is slightly farther to the rear as the thick- ness is increased. The travel on No. 40 lies 28 per cent,from the leading edge at 120 and 51 per cent, at o°, while on No. 43 it moves, between the same angles, from 35 to 47 percent. Air Ministry Loses its Secretary THE Minister of Health has appointed Sir William Arthur Robinson, K.C.B., C.B.E., the Secretary of the Air Ministry, to be First Secretary of the Ministry of Health, in succession to the late Sir Robert Morant. ^....... . ... Advisory Committee Reports ' ~" " ••THE following reports of the Advisory Committee for Aeronautics were published by H.M. Stationery Office duringthe month of March, 1920 :— 24 v. Investigation of the Fracture of Exhaust Springs.(Revised). (With diagrams.) March, 1916. Price \d. 256. Wing Forces on Aeroplane Struts and Wires. (Withdiagrams.) June, 1916. Price 15. 627. Design of a Recording Three-dimensional Accelero-meter for use in Aeroplanes. Price 3d. 638. Longitudinal Stability of an Aeroplane. September,1919. Price 6d. Previous lists appeared in FLIGHT, July 3, 1919;October 23, 1919 ; February 19, 1920. Air Ministry Workers' ConditionsTHE Air Ministry Industrial Whitley Council have now approved draft constitutions for Works, Department, andShops Committees. It is intended to proceed with the formation of such Committees at Air Ministry industrialestablishments as rapidly as circumstances permit, and re- presentatives of the Council will visit the principal establish-ments to assist in the matter. The Council have appointed a committee to consider draft regulations governing em-ployment of civilians at Air Ministry industrial establishments. This test shows that a thin flat-bottomed wing (No. 40)may be thickened in the centre until an h/c ratio of 0-158 is reached (No. 42), with an increase in maximum lift of 50 percent, and a decrease in the maximum L/D of 18 per cent, and in the L/D at one-ninth maximum Lc of 30 per cent. If at the same time the tip is thinned to an h/c ratio of — 25(No. 46), the maximum lift is increased 32 per cent., the maxi- mum L/D is reduced 12 per cent., and the L/D at one-ninthmaximum Lc is reduced 18 per cent, as compared with No. 40. The thickness cannot be increased beyond this, for the maxi-mum Lc and L/D fall off rapidly. If a fiat-bottom section (No. 40) be thinned at the tips to an h/c ratio of one-twenty-fifth (No. 44) the maximum lift is unchanged, but the maxi- mum L/D is increased 6 per cent., and the L/D and one-ninth maximum Lc is increased 20 per cent. The wing is, of course, of no use for internal bracing, but is included inthis report to complete the series. There is no particular reason why these sections should becompared to No. 44, as this was simply a reduction of the master section to the thickness of an average wing. Ithappens to have a fairly good L/D and a rather low maxi- mum lift. For a more general comparison, section No. 46,the most practical section for internal bracing, can be com- pared with a high lift section, U.S.A. 2. Section No. 46has a 7 per cent, increase in maximum lift, and a 3 per cent, decrease in maximum L/D over the U.S.A. 2, and the L/Dat one-ninth maximum Lc is 30 per cent, higher on section No- 45- ;:- (To be Continued) Plying Between U.S. and CanadaTwo officers of the American Army Air Service, Col. H. E. Hartney and Capt. Douglas, arrived at Ottawa onApril 17 on a De H. machine after a direct flight from Washing- ton, which was made with one stop in two minutes over fourhours. Their mission was to confer with the Canadian AviationBoard on flying between the two countries, and they are the guests of the Canadian Government. Both officers areCanadians, and served in the Royal Air Force during the War, after which they joined the American Army. Capt. Matthews Crashes JUST when he seemed to have mastered his troubles andbe almost certain of reaching Australia, Capt. Matthews met with disaster. He was landing at Grokgak, near SinggaRadja, the capital of the Island of Bali (East Indies) when his machine crashed and was so hopelessly smashed, that thereseems to be no hope of repairing it. Capt. Matthews had still about 1,100 miles to go to reach Australia. The Rome-Tokyo FlightTwo of the competitors, Capt. Gordesco and Lieut. Grassi were killed in the crash of their machine whenattempting to land near the French Consulate at Bushire on April 13. Capt. Ranzi.and Lieut. Marzari arrived at Baghdadon April 12 and left the next morning for Basra. Lieut. Ferrarin left Rangoon on April 14 for Bangkok, and the nextday he left there for Hanoi. Capt. Masiero arrived at Hanoi on Saturday and was preparing to go to Canton at thefirstopportunity. 451
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