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Aviation History
1941
1941 - 1368.PDF
FLIGHT JUNE IO,TH, 1941. FIGHTER O.T.U. to be of the utmost value in synthetic flying training. In a life which appears to hold constant novelty the pupil pilots at an O.T.U. enjoy the experience for the first time of pressing the button to set eight Browning machine guns going in the wings. Air firing is a most important feature of the training, for it is not until a man is accustomed to the racket produced by multiple armament that he can make proper use of it. Air to ground firing—otherwise known as ground strafing—is CO. AND INSTRUCTOR : The Group Captain commanding the O.T.U. with one of his instructors. The Hurricane in the background doesn't belong to the unit. carried out, paradoxically, over the sea, and while this; practice is in progress protection patrols of fighters keep watch in case Fritz tries to spoil the lesson. Drogue targets are used for other firing exercises employing different methods of attack. The ordinary full-sized drogue is used for quarter and beam attacks, and the special drogue which flies offset to the towing machine*^ for stern attacks. While we were at the station the com- manding officer carried out a dummy alarm and take-off. A red Verey's light gave the signal and within two and a half minutes a neat formation was patrolling the sky under nearly impossible flying conditions. We suggested that perhaps instructors were flying the Spitfires but were most emphatically informed that we were wrong. Proof of the quality of the pilots that are turned out is found by looking at photographs of courses which have left the Unit. In a casual manner instructors will point out those pupils who have brought down Huns on their first encounter, and there are a few who have got more than one on their first operational flight. Correspondence The Editor does not hold himselj responsible Jot the views expressed by correspondents. The names and addresses of the writers, not necessarily for publication, must in all cases accompany letters. THE CASE FOR THE CARBURETTOR Was the Author Biased?W E read with considerable interest your article, '' The Case for the Carburettor," in Flight, and it has aroused much discussion in our immediate circle. The general opinion here is that the author is somewhat biased in favour of the carburet- tor and that he has not given the petrol injection system, as applied to the Junkers Jumo, as much credit as seems really due. This attitude tends to mislead the less technically minded readers such as ourselves. While not daring to hold the author to ridicule we, in all humbleness, put forward the points which have caused the greatest controversy and criticism in our particular sphere. (1.) The graph Fig. 3%to give the Merlin the advantage, is based on the hypothetical assumption that the Merlin has a compression ratio of 6.5 to 1. (2.) In Fig. 4, the auto setting for the J umo is taken at normal, while that of the Merlin is taken at weak. Surely it would be fairer if the curves were formed by values given by a normal setting on both engines. (3.) With regard to maintenance of fuel injection equipment, Diesel-engined lorries, the fuel equipment of which need almost the same high degree of skilled attention, are habitually ser- viced and maintained under conditions which we may describe, from our own experience, as "in the field," (4.) With regard to good distribution of the air to the indi- vidual cylinders, surely this is more dependent on good design of the manifold and ports than on the particular fuel system employed. (5.) It is claimed that the petrol injection system isimmune from freezing and that it ensures continuity of fuel supply during aerobatics. Is it to be assumed that the Merlincarburettor could be similarly safeguarded? If not, the addi- tional weight resulting in the embodiment of these desirableadvantages would probably put a different aspect on the claim that the carburation system is much lighter than that of.petrol injection. We would like to point out again that we are not attemptingto criticise the author from a technical standpoint, but merely inviting an extension of the scope of this particular articlewhich has undoubtedly thrown much appreciated light on a subject which is a pre-eminent topic of present semi-technical discussion. We think, perhaps, that a similar article on "The Case for Petrol Injection" would do much to even up the question, which seems, at present, to be rather one-sided "OPERATIVE ARTIFICERS," R.A.S.C. [Note:—We hope to publish such an article shortly.—ED.] WHEN "GEORGE" JAMS Three Things the Pilot May DoA CONSIDERABLE amount of publicity has recently been given to the Catalina PBY flying boat which lost both ailerons during a flight to this country. Like everyone else, we are filled with admiration for the skill and resource of the pilot who, despite this seemingly devastating occurrence managed to save the aircraft and actually fly it on to its destination. The cause of the mishap was universally given, by the Press and radio, as the jamming of the automatic pilot, and since it is well known that on all American aircraft so fitted this equip- ment is of Sperry manufacture, we think that in fairness to our American friends we should shed a little more light on the subject. We ourselves had an opportunity of examining the automatic pilot, and it is quite true that the aileron hydraulic control valve showed signs of having jammed, due to causes which are not connected 111 any way with the actual apparatus. Any mechanical contrivance may, on occasion, give trouble, and for this reason the Sperry automatic pilot is provided with safeguards for just such occasions as that recorded of the Catalina. When the aileron control jammed, the pilot of the aircraft could have : (1) Over-controlled the automatic pilot by simply exerting pressure on the ordinary manual control of the aircraft. (2) Turned off the aileron by-pass valve in the cockpit, thus cutting his ailerons only out of automatic control. (3) Moved the main automatic pilot lever to the "OFF" position, thus leaving all his controls free. Unfortunately, the pilot returned to America before anyone could ask him why he did not do one of these three things, but we can think of no reason why anyone in the cockpit should not have done so. For The Sperry Gyroscope Co. Ltd j. S. POLE, Assistant Manager, Aeronautical Department.
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