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Aviation History
1945
1945 - 1186.PDF
648 FLIGHT JUNE 14TH, 1945 CORRESPONDENCE test pilots, the definite information m cine form available from an automatic observer is of great help to the designer in-supple- mtviting and checking the pilot's impressions. The lying-designer suggestion brings up a fundamental weak- ntVs in our design organisation which calls, I think, for bold action on a long-term policy basis. The weakness consists of ignorance of—and to some extent, indifference to—the practical aspects of design from both production and flying points of view, and is due in large measure to the increasing hiatus between the slide rule and drawing board on the one hand and the workbench and cockpit on the other. The result is a lack of incentive, imagination and practical gumption On the part of the majority of the design stuff, both high and low. There is a general tendency to-day towards over-specialisa- tion ; personnel are divided up into watertight compartments and are not encouraged to co-operate fully with individuals in <fther departments. A greater degree of interlocking of func- tions and better all-jound knowledge and experience are required if serious design mistakes and weaknesses due to lack of co-operation are to be avoided. The cure, which should have excellent results in the long run, would appear to consist of organising for a minimum of so many weeks in shops and ground crew, and so many hours oi flying per year for each individual playing any direct part in design, either basic or detail. A certain nucleus of design staff, including project engineers, aerodynamics, engine and airframe technicians and senior draughtsmen should cer- tainly be assisted to qualify for " A " licences, and later this should become a necessary qualification for major design posts throughout our industry During the war we have had to adopt a short-sighted policy of rushing out designs—on the principle that anything is better than nothing—and design refinements and efficiency have to a considerable extent gone by the board under the pressure of extreme urgency and Shortage of technicians. The same can also be said of the organisation of design work. We must drop our bad habits now, however, as performance and imme- diate production are no longer the sole criteria. An overall reduction in man-hours for design, production and main- tenance, and concentration on development of excellent flying properties, are now called for if we are going to hold our own against hot competition from abroad. We are in for the fight of our life in aircraft design, and wecannot afford any inefficiencies. Thank heavens ior the new competition—let's roll up our sleeves and best it! " STRAINING STRESSMAN." DANGERS IN TURNING Only Elevators Affect Wing-loading IN his letter to the Editor (May 24th issue), Mr. H. W. Jonessounds plausible enough, but I feel he is not completelylogical. He agrees that in a steep turn the increase in wing- loading is governed by acceleration in the pitching plane. He then says that force must be applied to cause such accelera- tion, and that "such force could only be supplied by the lift of the wings in a ... degree proportional to the bank," thus proving (he says) that acceleration in the pitching plane is governed by the angle of bank. .How easy it is to disprove this statement! A loop, a zoom or a pull-out from a dive all entail an acceleration in thepitching plane, and the force which causes the acceleration is applied by the pilot via the elevator control, causing a changein the aircraft's angle of attack. By strong enough back- pressure on the stick, the wing-loading can be increased to sucha value that either the pilot blacks out, a high-speed stall occurs, or the aircraft bursts apart in the man's face. Takeyour choice, but notice thai no bank need be used whatsoever. Perhaps Mr. Jones is still unconvinced, as the above exampleis divorced from banking? If so we can bank during any of these manoeuvres through 70 or 80 or go or 120 or 170 degrees,without affecting the issue in the slightest. The acceleration in pitch is still caused by pulling back on the stick, and canbe stopped in any attitude of bank by easing the stick back to neutral again. To give another example, an axial roll is made by banking only, preventing any tendency to turn by appropriate" use of elevator and rudder. There is no acceleration in the pitching plane (or not much—depending on how ham-fisted we are). The wing-loading only varies to the extent of acting in an unusual direction during the inverted part of the roll, wheni the dried mud on the cockpit floor falls up into our face, 7 making us glad we are wearing our goggles. For a third example let us try a steep turn using bank only. We are flying, say, at 200 m.p.h., at 10,000 feet. Holding the rudder quite still,, we gently apply 70 degrees of bank, taking care not to allow the stick to move either back or for- ward. Almost at once the nose begins to drop, owing largely to weather-cock effect. Then begins a slpwish turn, the weather-cock effect yawing the nose until it is finally pointing vertically downwards. At about this time we take a glance at the artificial horizon, the little aircraft on which is probably standing shyly on its head in the corner. The '' angle of bank" can still, of course, be judged (if w« are interested) by a convenient road straight ahead, as we dive vertically toward it. As from now on no further sideslip occurs, yawing ceases and the aircraft goes straight down. The wing-loading is quite normal, there being no acceleration in pitch. The pointer on the A.S.I, is very likely starting on its second trip Tound the clock, so we ease back the stick and pull out. This action, of course, introduces acceleration in the pitching plane for the first time since beginning the turn, and has nothing to do with angle of bank. Normally, of course, the stick is eased back as the turn begins, first to prevent the nose from dropping, and secondly to -make the aircraft- turn. - If the stick be eased forward to neutral again, the turn stops immediately and becomes a side- slip instead. Mr. Jones remarks that 70 degrees bank is nearly the useful limit for a level turn, and I agree. Nevertheless, the tightness of a turn at 70 degrees bank can be varied con- siderably, up to the pilot's black-out point, so why bank any steeper for a tight turn? And as the tightness affects the increase in wing-loading, and is controlled by the elevator, how- can the angle of bank be said to govern the wing-loading? In high-speed diving or climbing turns, of course, it is quite usual to bank past the vertical, but no matter what the angle of bank, the wing-loading does not increase appreciably unless the stick is pulled back. -^ Mr. Jones misrepresents my contentions twice in Iris final paragraph, so I would merely suggest that he re-reads my first letter. " R. H. HENDERSON. BOOK REVIEWS The Modern Gas Turbine, By R. Tom Sawyer. Prentice- Hall Inc., 70, Fifth Avenue. New York, U.S.A. •HPHE enormous amount of publicity accorded in recent years JL to the jet-propelled aircraft has tended to overshadow the actual and potential development of the gas turbine for other applications. This book will serve as a useful corrective. It shows the importance attached in the U.S.A. to the gas turbine as a sonrce of power for various industries and a propulsion unif for locomotives and ships as well as aircraft. Special sections are devoted to all these aspects. The author, who is the chairman of the America^ Society of Mechanical Engineers' Co-ordinating Committee on Gas Tur- bines, gives a comprehensive history of gas turbines from the earliest attempt to current productions and projects. Consider- able space is devoted to exhaust gas-driven turbo-superchargers for petrol aircraft engines and diesel engines. The possibility of employing a diesel engine, of either conventional or free- piston type, as a gas generator for a turbine is also discussed. The text is supplemented by useful formula;, calculations, graphs and illustrations, and numerous references to other sources of information are quoted. " Red Air Ace." By Guards Colonel Alexander PokrysKkin of. the Red Air Force. Published by Soviet War News, 630, Grand, Buildings, Trafalgar Square, London, W.C.2.is. net. COL, POKRYSIIKIN is the leading air fir.- of the SnvbTUnion. He has written a book about the work of a fighter squadron in the late war with Germany, much on the lines of many books written by Allied fighter pilots abont the war of 1914-18, The impression he gives is that when Russia was first invaded her fighter squadrons were inadequately trained fri their special business. They gradually learnt how to light by fighting; and as the older hands became adepts they trained the new pilots very carefully. The author speaks, with the highest praise of the aircraft turned out by Russian designiS-
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