FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1932
1932 - 0097.PDF
January 29, 1932 Supplement to FLIGHT Edited by C. M. POULSEN January 29, 1932 CONTENTS Climb Relationship;. By \V. R. Andrews. A.F.R.Ae.S. . . Limits. Fits and Allowances. By R. Rodger.. Technical Literature— Summaries of Aeronautical Research Committee Reports Summaries of N.A.C.A. Technical Reports Mechanical Properties of N'okel Alloy Steels... Page 1 CLIMB RELATIONSHIPS By W. R. ANDREWS, A.F.R.Ae.S. Mr. IF. li. Andrews, who is on the Technical Staff of .1. V. Hoe d: Co., Ltd., at Manchester, will need no introduction to our readers, as he has already contri buted several articles to THE AIRCRAFT ENGINEER. In the present issue we publish the first instalment of an article on climb relationships, and by way of an intro duction we do not think we can do better than quote from the covering letter which Mr. Andrews sent with the article. " In this comic atmosphere of ours,'" Mr. Andrews ivrites, " it often happens that a flight test result shows a high figure for initial climb and a low figure for absolute ceiling, or vice versa. There is nothing more annoying than to find later that the climb curve drawn through the scattered points has a slope not in keeping with the results obtained under ideal weather conditions. " The suggested relationship between initial climb and ceiling gives an easy means of showing up this phenomenon, once the constant for the aircraft is known. It is surprising, too, what can be done with scattered, points once one has an indication of what the result should be. This, I believe, is known as ' judicious faking '—but in bad. weather one has to produce something, and the means justifies the end." IT often happens that time or environment does not permit elaborate calculations for the change in climb relationships attendant upon a change in weight. The tollowing notes have been compiled to facilitate the calculations in such cases. In all cases the relationships have been expressed as formulae for inclusion in the Engineer's Notebook. These are simple, and a slide-rule only is necessary for their computation. The chief use of the formulae is to estimate the change in climb conditions and ceiling for a change in the gross weight of an aircraft. For the purpose of the investigation, a hypothetical engine and aircraft have been chosen and the perform ance calculated for an increase in weight from 5,000 lb. to 9,000 lb. This change of weight would roughly repre sent the case of an aircraft flown with pilot and little fuel on the one hand and with the full load on the other. The range of the investigation is to determine :—- (1) The climbing speed at any particular weight, knowing the speed for any other weight. (2) The rate of climb off the ground for any weight, from the known conditions at another gross weight. (3) The absolute ceiling in terms of the ground level rate of climb, from the rate of climb and absolute ceiling for another weight. (4) The rate of climb and absolute ceiling in terms of the weight, engine output, airscrew effici ency and stalling speed, where test data are not available. The hypothetical example chosen for the investigation has the following characteristics : — 1. Engine. Normal airscrew r.p.m. ... 1,363 Normal b.h.p 675 Maximum airscrew r.p.m. ... 1,500 Maximum b.h.p 723 2. Wings. The wing area is the same for all cases, viz., 539 sq. ft. The following equivalent monoplane aspect ratios and the corresponding induced drag coefficients have been employed: — TABLE I. A = Aspect Ratio =3 6 KDI/KL2 = 0-216 0-111 1 9 0-076 The wing chosen has a mean thickness to chord ratio of 0.16 and a mean camber of centre line of 0.032 c. and a Kj, max. of 0.705. The estimated profile drag of such a wing is depicted in Fig. 1. 3. Gross Weights. The performance has been estimated at 5,000, 7,000 and 9,000 lb. gross weight. 96 a e2
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
