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Development Charges

Development Charges Aircraft Engineering TH E MONTHL Y SCIENTIFIC AND TECHNICAL ORGAN OF TH E AERONAUTICAL ENGINEERING PROFESSION VOL XXIV No 282 AUGUST 1952 Development Charges But if, on the other hand, for test purposes he sets out in search of them, fortified and pre-armed with the best possible advice from E have on occasion published articles on the design devel­ forecasters it is notorious that then, fly where he will, they tend to opment of certain types of aeroplane which have given an elude him. And so weeks, and even months, of precious time at what W overall picture of the many-sided facets that go to make up should be near the end of a newly born aeroplane's test flights may the complete modern aeroplane. Covering, however, as they have be wasted. Pitiable indeed is the lot of the development engineer. done, a wide range of subjects, passing rapidly perforce from one to If only to confirm our faith in the essential reliability of human another, it has not perhaps been too easy to realize the amount of nature, we would welcome further descriptions of the ebb and flow work that has had to be put in to bring to its final form any individual of the tide of progress in the development of other details of aero­ item. plane design. This gap, if such it be, is filled in this issue with MR . NEWBIGIN'S account of the gradual evolution of the de-icing system eventually Modern Manoeuvrability arrived at for the production models of the Airspeed Ambassador One of the concomitants of the great increases in the speed at aeroplane, whose identity has to some extent become obscured by which modern military aeroplanes fly and the altitudes at which the pseudonym of the Elizabethan class given to it by B.E.A.C. future combats will in all probability take place is the reduction in Vitally important as the subject is to the operator of commercial manoeuvrability from which the pilot finds his mount suffers. We aircraft, quite obviously de-icing is to the designer merely one of thought it would be interesting to readers to have a reasoned ap­ hundreds of the detailed components that have to be considered praisement of the causes of this unwelcome phenomenon and the from the drawing office to the production stage and fitted into the effects resulting from them and therefore invited MR YATES of the composite whole that is an aeroplane. In view of this, one cannot COLLEGE OF AERONAUTICS to look into the matter; with the results help being struck by the quite astonishing amount of time and effort that are to be found in the article which appears on later pages. that had to be put into the development of this comparatively minor It appears that the reason is in reality very simple. It is due to the piece of equipment. now familiar fact that with altitude there is a decrease in lift and a One point that did not tend to make the work easier was the diffi­ consequent increase in stalling speed. Indeed, at 62,000 feet, in the culty, amounting in fact almost to impossibility, of reproducing example taken, the stalling speed has reached 134 knots while, further­ flight conditions in a ground test rig—in, for instance, the supply of more, a state of affairs has arrived when either a decrease or an air in such conditions as to make a combustion heater operate satis­ increase in speed results in a stall—terrifying thought. factorily. 'It was only,' writes M R NEWBIGIN, 'after ten months of testing on the ground and in the air, involving many unsuccessful Closing the Gap experiments, innumerable shattered theories, and a good deal of While the stalling speed is creeping up, the limiting speed, or maxi­ political activity (whatever this may imply) that the end of this road mum available speed, is at the same time coming down. Whether was reached.' We have never read a sentence that more forcibly emphasizes the patience and pertinacity that is called for in the or not the Gilbertian situation can arise where the stalling speed has development engineer. so increased as to exceed the limiting speed—a pleasant reflexion on which it is tempting to dwell—we would not like to say. Fortunately— Another indication of the amount of detail that went to the evolu­ or unfortunately according to the point of view—before that position tion of this quite minor aspect of the design of the aeroplane is given is reached, or not as the case may be, buffeting will develop owing to by the description of the instrumentation that had to be used merely the aeroplane attaining its maximum permissible Mach number; to measure wing-surface temperatures. No less than six operations, which will be enough to prevent the pilot seeking a precise answer to for example, were found necessary for the satisfactory cementing of the conundrum we have propounded. As the author well puts it, by the thermocouples to the wing, which took four days to effect and this time 'an intriguing situation can be envisaged'. even then might be rendered nugatory by twenty minutes' flight in We have only dealt with the simpler and more obvious combined hail or heavy rain. effects of speed and height on the aeroplane's performance. M R First Catch Your Ice YATES also deals with the extreme case where the pilot may to all Another source of irritation and frustration irresistibly reminds intents and purposes be unable to effect a turn, which would de­ one of the initial piece of advice popularly attributed to the authoress generate into something more accurately described as a wide sweep of a famous cookery book when giving instruction on the art of pre­ of scores of miles in diameter, and such things as maximum diving paring a hare for the table. As every commercial pilot knows there speed and what he perhaps euphemistically describes as 'the maxi­ is no meteorological phenomenon so unexpectedly and undesirably mum speed for comfortable cruising'. encountered as icing conditions when he has a full load of passengers Altogether, we feel that M R YATES is to be thanked for explaining aboard in circumstances that force upon him flying at some height. so clearly some rather puzzling phenomena and the causes of them. S.B.A.C. DISPLAY • FARNBOROUGH • SEPTEMBER 1—7 • STAND NO. 30 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Aircraft Engineering and Aerospace Technology Emerald Publishing

Development Charges

Aircraft Engineering and Aerospace Technology , Volume 24 (8): 1 – Aug 1, 1952

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Publisher
Emerald Publishing
Copyright
Copyright © Emerald Group Publishing Limited
ISSN
0002-2667
DOI
10.1108/eb032185
Publisher site
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Abstract

Aircraft Engineering TH E MONTHL Y SCIENTIFIC AND TECHNICAL ORGAN OF TH E AERONAUTICAL ENGINEERING PROFESSION VOL XXIV No 282 AUGUST 1952 Development Charges But if, on the other hand, for test purposes he sets out in search of them, fortified and pre-armed with the best possible advice from E have on occasion published articles on the design devel­ forecasters it is notorious that then, fly where he will, they tend to opment of certain types of aeroplane which have given an elude him. And so weeks, and even months, of precious time at what W overall picture of the many-sided facets that go to make up should be near the end of a newly born aeroplane's test flights may the complete modern aeroplane. Covering, however, as they have be wasted. Pitiable indeed is the lot of the development engineer. done, a wide range of subjects, passing rapidly perforce from one to If only to confirm our faith in the essential reliability of human another, it has not perhaps been too easy to realize the amount of nature, we would welcome further descriptions of the ebb and flow work that has had to be put in to bring to its final form any individual of the tide of progress in the development of other details of aero­ item. plane design. This gap, if such it be, is filled in this issue with MR . NEWBIGIN'S account of the gradual evolution of the de-icing system eventually Modern Manoeuvrability arrived at for the production models of the Airspeed Ambassador One of the concomitants of the great increases in the speed at aeroplane, whose identity has to some extent become obscured by which modern military aeroplanes fly and the altitudes at which the pseudonym of the Elizabethan class given to it by B.E.A.C. future combats will in all probability take place is the reduction in Vitally important as the subject is to the operator of commercial manoeuvrability from which the pilot finds his mount suffers. We aircraft, quite obviously de-icing is to the designer merely one of thought it would be interesting to readers to have a reasoned ap­ hundreds of the detailed components that have to be considered praisement of the causes of this unwelcome phenomenon and the from the drawing office to the production stage and fitted into the effects resulting from them and therefore invited MR YATES of the composite whole that is an aeroplane. In view of this, one cannot COLLEGE OF AERONAUTICS to look into the matter; with the results help being struck by the quite astonishing amount of time and effort that are to be found in the article which appears on later pages. that had to be put into the development of this comparatively minor It appears that the reason is in reality very simple. It is due to the piece of equipment. now familiar fact that with altitude there is a decrease in lift and a One point that did not tend to make the work easier was the diffi­ consequent increase in stalling speed. Indeed, at 62,000 feet, in the culty, amounting in fact almost to impossibility, of reproducing example taken, the stalling speed has reached 134 knots while, further­ flight conditions in a ground test rig—in, for instance, the supply of more, a state of affairs has arrived when either a decrease or an air in such conditions as to make a combustion heater operate satis­ increase in speed results in a stall—terrifying thought. factorily. 'It was only,' writes M R NEWBIGIN, 'after ten months of testing on the ground and in the air, involving many unsuccessful Closing the Gap experiments, innumerable shattered theories, and a good deal of While the stalling speed is creeping up, the limiting speed, or maxi­ political activity (whatever this may imply) that the end of this road mum available speed, is at the same time coming down. Whether was reached.' We have never read a sentence that more forcibly emphasizes the patience and pertinacity that is called for in the or not the Gilbertian situation can arise where the stalling speed has development engineer. so increased as to exceed the limiting speed—a pleasant reflexion on which it is tempting to dwell—we would not like to say. Fortunately— Another indication of the amount of detail that went to the evolu­ or unfortunately according to the point of view—before that position tion of this quite minor aspect of the design of the aeroplane is given is reached, or not as the case may be, buffeting will develop owing to by the description of the instrumentation that had to be used merely the aeroplane attaining its maximum permissible Mach number; to measure wing-surface temperatures. No less than six operations, which will be enough to prevent the pilot seeking a precise answer to for example, were found necessary for the satisfactory cementing of the conundrum we have propounded. As the author well puts it, by the thermocouples to the wing, which took four days to effect and this time 'an intriguing situation can be envisaged'. even then might be rendered nugatory by twenty minutes' flight in We have only dealt with the simpler and more obvious combined hail or heavy rain. effects of speed and height on the aeroplane's performance. M R First Catch Your Ice YATES also deals with the extreme case where the pilot may to all Another source of irritation and frustration irresistibly reminds intents and purposes be unable to effect a turn, which would de­ one of the initial piece of advice popularly attributed to the authoress generate into something more accurately described as a wide sweep of a famous cookery book when giving instruction on the art of pre­ of scores of miles in diameter, and such things as maximum diving paring a hare for the table. As every commercial pilot knows there speed and what he perhaps euphemistically describes as 'the maxi­ is no meteorological phenomenon so unexpectedly and undesirably mum speed for comfortable cruising'. encountered as icing conditions when he has a full load of passengers Altogether, we feel that M R YATES is to be thanked for explaining aboard in circumstances that force upon him flying at some height. so clearly some rather puzzling phenomena and the causes of them. S.B.A.C. DISPLAY • FARNBOROUGH • SEPTEMBER 1—7 • STAND NO. 30

Journal

Aircraft Engineering and Aerospace TechnologyEmerald Publishing

Published: Aug 1, 1952

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