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Aviation History
1928
1928 - 0472.PDF
W * fisslkgy JUNE 7, 1928 [" FLIGHT " Photograph SLOTS AND THE SERVICE : A Handley Page *' Hyderabad " in Flight. Note the automatic slots open at the upper wing tips. 2, chord of forward aerofoil one-eighth of main chord, and span two-ninths of main plane span ; 3, chord of forward aerofoil one-sixth of main chord, and span two-ninths of main plane span. Measurements of lift coefficient gave little indication of the relative value of the different arrangements, but there were great differences in the values of rolling and yawing moments with the different aileron settings. With the first two arrangements, rolling and yawing moments were measured with the ailerons set at ±10° and ±20°, and these moments measured for three positions of the forward aerofoil ; (a) at the wing tips, b) with the outer edge 2-5 ins. from the wing tip, and (r) with the outer edge 5 ins. from the wing tip. In the case of the large-span, large-chord auxiliary aerofoil, the rolling and yawing moments were measured only at the midway position, i.e., with the outer edge 2-5 ins. from the wing tip. In each case measurements were taken (1) with slots closed, (2) with both slots open, and (3) with one slot open and one slot closed, the last case being that in which a controlled type of forward aerofoil is used. It was found that as the forward aerofoil was moved inward from the tip so did the rolling and yawing moments improve from a control point of view, and almost as good results were obtained as from the mechanically-operated auto-slot, where one slot was closed by the upward movement of the aileron. This was particularly the case with the flaps up and down 20°, and with the auxiliary aerofoil in the farthest inboard position. The main feature of the tests with both slots open was the improvement which resulted from fitting the forward slot inboard from the main wing tip. In this position there was a remarkable increase in rolling moment as compared with the unslotted section. Obviously, Mr. Handley Page said, the best improvement in control would in all cases be obtained with the arrangement in which the slot was closed, or its effect neutralised, on one side of the wings by the upward movement of the aileron. Such an arrangement gave at large angles of incidence a yawing moment of the right sign. An arrangement for inter-linking the slot and aileron was shown, but the lecturer pointed out that many variations were possible, notably by the movement of the link hinge point so that a closing torque was brought into action on the forward aerofoil. Admitting that objection might be raised to the extra complication of interconnecting slot and aileron, Mr. Handley Page described and illustrated a method of effecting the same purpose by the use of an " interceptor " or " spoiler," which is a small strip placed on the upper surface of the aerofoil, and so hinged that it can lie flat against the wing or be raised at right angles to it. The action of this " interceptor " is to cause burbling, in the same manner as if the slot was closed. One of the slides illustrated the rolling and yawing moments on R.A.F. 28 section for : (a) both wing-tip slots open without interceptor; (b) both wing-tip slots open, with an " interceptor " fitted on one side ; and (c) one wing- tip slot closed and no " interceptor " fitted. The moments were measured for the ailerons at 10° and 20°. With the " interceptor " there was a great improvement in control over the case of both slots open, and at the smaller angles (up to 20° incidence) over the case of one slot closed. Beyond this angle the rolling moments were not quite as large as with one slot closed. A similar arrangement was tested for a complete model biplane, and tested in full-scale free flight the model results were fully borne out. The control was no different in " feel " from the ordinary aileron, and no heavier to operate. In all the tests described by Mr. Handley Page a forward or auxiliary aerofoil forming part of the original wing section was used. It was somewhat easier in construction to fit an additional forward aerofoil on top of the normal section, much in the way in which a plaster is fitted. Such a varia- tion had been developed by Mr. Bruce, of the Westland Company, and had shown itself as effective as the type illus- trated and tested by Handley Page. Summarising the main points of his lecture on the slot, Mr. Handley Page said : (1) With thick wing sections an increase in lift coefficient can be obtained by the use of the slot, equal in magnitude to that obtained with thin wings. (2) As the use of the slot for control purposes is dependent on the lift increase obtained, a similar result in stalled flight can be obtained with both thick and thin sections. (3) Where the aerofoil is used for a portion of the span only, the best result for control is obtained when the auxiliary aerofoil is fitted in an intermediate position between the tip and the centre of the wing. (4) With a correctly-designed and positioned auxiliary aerofoil opening and closing automatically, a very good control at and beyond the stall can be obtained without the added complication of control by the forward aerofoil. (5) If increased control is required at and beyond the stall, particularly at very high angles of incidence, the controlled slot or the " interceptor " should be used. It is the custom of the Royal Aeronautical Society, with which is incorporated the Institution of Aeronautical Engineers, that after a Wilbur Wright Memorial Lecture there is no discussion. Major Wimperis proposed a vote of thanks to the lecturer, and was seconded by Lieut.-Col. Moore Brabazon. The S.M.A.E. Journal THE May issue of the S.M.A.E. Journal, the official organ of the Society of Model Aeronautical Engineers, is to hand, and it is quite an interesting number. Besides containing a diary of events, sundry Society notices, rules for the various forthcoming competitions, etc., it also gives the lecture on " Airscrews " which was read before the Society on March 23 last. This lecture is very instructive and should provide some useful data for model constructors. We are not certain whether the S.M.A.E. Journal is available to non-members, but no doubt a copy (price 6d.) would willingly be sent to any of our readers interested on application to the Hon. Secretary, S.M.A.E., 23, Mayfair Avenue, Ilford. An Air Novel As flying is rapidly becoming a fashion, there should be a wide interest in novels with an aviation appeal. Sampson Low, Marston & Co., Ltd., have published a novel by Faith Bald-win entitled " Departing Wings." (7s. 6d.) The flying interest is slight, being practically confined to the fact that the hero is an American service pilot; and he does not remain that very long. There is very little flying actually described, and although the authoress is not intentionally funny, we think that airmen readers will find her amusing when she treads the air. But as a novel it is very readable, if conventional. The scenes are laid in America, and the characters are Americans. Broadly outlined the story tells you that the flying hero fell in love, married, met trouble that never matured, and then lived happy ever after. After all, if that is what happened to everyone life would not be intolerable. Australian Aerial Derby Mishap DURING a race in the Victorian Aerial Derby at Essendon on May 27, Flight-Lieut. A. G. Wells, piloting a D.H.9, collided with a high-tension electric cable. The wings were torn off and the machine crashed to the ground, fortu- nately clear of the cables. The pilot was seriously injured. 428
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