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Aviation History
1918
1918 - 0813.PDF
OSSJULY 18, 1918, THE FLIGHT OF AN AEROPLANE AT DIFFERENT ALTITUDES. By LOUIS DE BAZILLAC, Ingenieur (Eccle Superieure d'Aeronautique de Paris). . Translated by B. BRUCE-WALKER, B.Sc. " ^ ^ : v " "••-— ••• 7 Continued from page 781.) - • - »" . v '-i <____«'-• ~ : IF it is granil BforB&WCo/°e£cf ^eriments, that the — altitude and the altitude Z - 60,370 log f we have thrust of the propeller is reduced proportionally to the density according to the above equations :— of the air, the general formulce for the aeroplane at an altitude Z, defining the ratio (I) (2) = p' are as follows :— (12) V-V/-1. The equations indicate further that for the same speed J the thrust of the screw H., at zero altitude and H at the alti- tude Z - 60,370 log - are connected by the equation :— 900 goo 790 soo soo (13) H - The relations (12) and (13) enable us, knowing H - fc(V) and R - <fc(V), easUy to construct a system of these curves for different particular values of ^. *._.,», I (fc) By Reference to Powers. -*mmi If we solve the problem by reference to powers all the pre- ceding equations still remain. We have for the power available at the altitude Z, p being the efficiency :— 5 ; (2A) na-Tp-pP»3D\ - ;/• FIG.7. \ 300 i • *• 120 for the power required <)n ~so to To 3 and lastly, for horizontal nights at the altitude Z, (10) H = R. I- - ;-H; (11) Z = 60,370 log ^ . 1 a * A Construct the curves (Fig. 8) :— The graphical solution of these equations is effected ^_ ^(V)j without difficulty by calculating first of all for n - 1 :— Ul.««= <j>2(V), (1st) The different values of the thrust H of the propeller for „ _ t. <7), and, lastly, for horizontal flight at altitude Z (IOA) na«- nr. as a function of the speed of translation ; If v, and V are the speeds, and (nr)0 and n, the powers corre- (2nd) The different values of the resistance to motion R of sponding to the same angle of attack for zero altitude and tne the aeroplane as a function of the speed of translation. T -^ .. . Jt - _,_„.- Construct (Fig. 7) the curves spondin g altitude Z - 60,370 log -, we have according Lto 'the* above equations :— Pp 0=i. (MA) V«- for/*: 'These curves will enable us to study the flight of the aero- plane near the ground, that is to say, at zero altitude. If V. and V are the speeds giving the same resistance R for 8ll n, v
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