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Aviation History
1937
1937 - 1973.PDF
Jl)LY 15: 1937- FLIGHT. fV*. The Outlooks Salaried Sluggishness F OR a number of years now transport pilots have usually been paid a fixed retainer with a bonus for flying hours. So long as the different machines in a company's fleet—or those of competing firms—had much the same cruising speeds all was well, but nowadays there are a number of complications. The pilot who is fortunate or unfortunate enough to be handling fast aeroplanes on his regular runs is automati cally paid less for work which is usually more difficult and responsible than that of his fellow pilots who are in charge of slower machines. An obvious solution is to adjust the flying pay so that it is based on mileage rather than on hourage. Meanwhile, it is possible that operators are losing quite a lot of money, both in fuel and salaries, because the average pilot does not worry too much about accurate navi gation. Why should he? If he takes five minutes more on the A to B run—because he hangs carelessly on to an initial compass course until radio bearings are eventually collected from B—his salary is so much greater. The fact that no complaints are ever made on this score says a good deal for the natural honesty and professional pride of cur transport pilots. Changes, nevertheless, will have to be made in the salary system. Probably they will take the form of a mileage arrangement with a purely nominal '' fine '' system for really unreasonable delays. Happily enough, pilots do not complain publicly about the inequities of the present ar rangements ; perhaps we shall hear more about it througn the new Association. The Human Engine T/'ERY provocative is the article by Mr. Granville Y Bradshaw which we publish this week. His ingenious combination of hand-and-foot operation may, and probably does, add something to the power which a man can produce; this should be possible by permitting the limbs to work in the most effective and efficient way. But when it comes to calculating the horse-power needed to change the sloping path of a glider into a horizontal flight path, it is to be feared that Mr. Bradshaw suffers from an excess of optimism. Taking as his starting point a glider with an L/D ratio of 30: 1, Mr Bradshaw comes to the conclusion that some thing like one-fifth of a horse-power will suffice to keep man and machine, weighing together 2301b., flying horizontally. If that were so, flight by human power would have arrived long ago, even with the airscrew propulsion which he casts aside. Unfortunately, the picture is not quite so rosy. In order to achieve a flying speed as low as 8 m.p.h., the wing loading would have to be a fraction of a pound and the wing span would probably be as great as that of the Empire flying boats! Such a glider could certainly not be built for a loaded weight of 230 lb. It is much more likely that the weight would be 300 lb. and the gliding angle 1 in 20. Even that would be an achievement of no mean order. If those figures are accepted, and a speed of 30 m.p.h. instead of 8 m.p.h. assumed, the power required for level flight would be nearly \\ h.p. It seems unlikely that a speed of much less than 30 m.p.h. could be expected, as the low, wing loading would mean a large and fragile machine. • • • - '.. ••-••• Mr Bradshaw estimates that in the University Boat Race the men develop more than 2 h.p. each for the duration of the race. Professor A. V. Hill, on the other hand, has stated that an athlete running uphill can probably exert about i| h.p., and that a sprinter running at top speed for 20 seconds can probably develop just over 7.\ h.p., but would be exhausted and unfit for further effort for 20 minutes. Towing tests on a boat with crew aboard have indicated that the average power output per man is about one-half horse-power for 20 minutes. This and more information on the subject is included in the note by Mr. Townend in the July issue of the R.Ae.S. Journal, to which we referred last week. Flapping Flight ALTHOUGH Mr. Bradshaw seems to have "come f-\ unstuck" on the questions of glider weights, speeds and the power which a man can develop, he appears to be in good company when it comes to his idea of using a form of flapping wing or rising and falling weight 1.0 imitate bird flight. Townend calls attention to the so- called " Katzmayr Effect " and to Cowley's R. & M. Note on this phenomenon. He comes to the conclusion that if the "Katzmayr Effect" is inverted by having the air- stream steady and the wing capable of both torsional and flexural oscillation, a very efficient aircraft might result. It seems to be largely a question of designing the wings to have a natural period of oscillation which would suit the natural speed of ' rowing'' which the human power plant would adopt. That a certain amount of energy can be extracted from a wind which is not uniform is agreed. Cowley, however, found that it was important that the wind '' waves '' should be long compared with the wing chord. This fact may have something to do with the apparent ease with which birds fly. It is to be hoped not only that Mr. Bradshaw will con tinue his interesting experiment, but that Mr. Townends final advice in the note referred to will be heeded. This reads as follows : " Even if the structural difficulties should appear great, it would seem to be worth while to know whether it is fundamentally possible to transfer the neces sary power by the mechanism in question without using the large amplitudes of oscillation generally associated with the usual proposals of flapping flight." Mr. Townend's suggestion is for a mathematical examination along lines similar to those involved in the study of flutter. Aeroplane Noises r HERE has been some discussion in the papers lately about the noise made by aeroplanes flying over' Oxford, and the disturbing effects it has upon serious study. It is, however, interesting to note that a Fellow of Ail Souls' College has written to a contemporary to say that, to his surprise, he finds himself getting accustomed to the noise, and thinking it less troublesome than the noises of a railway station. Nevertheless, Flight does not take the view that ao effort should be made to reduce aircraft noise. On the con trary, everything possible should be done to minimise its effects, not merely out of consideration for people on the ground but also for strategical reasons. A bomber flying silently at 20,000ft. would be extremely hard to detect. DIARY OF FORTHCOMING EVENTS—PAGE 74.
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