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Aviation History
1928
1928 - 0955.PDF
17 OCTOBER 11, 1928 not perhaps occupying as much space as would a Handley Page multi-engined air liner, is none the less interesting. In fact, we venture to say that it will form one of the attractions of the show. Their exhibit deals entirely with the Handley Page " slot " device, which is shown, first by a complete (full-size) D.H. "Moth" wing fitted with the slots ; secondly, by a working model ; and, finally, by a selection of large photographs of aircraft fitted with this device. The Handley Page " slot " is undoubtedly the most important invention that has so far been contributed to the modern development of aeronautics, and even though it has now reached the practical stage, its application and further development will most certainly make still more progress in the future. We assume the nature of this device is sufficiently well known to our readers to render unnecessary any technical description of it here. To those— should there be any—who are ignorant as to what the Handley Page slot is, we may briefly sum up its action as follows. It consists of a small auxiliary surface, disposed along and parallel to the leading edge of the wing, or control surface, somewhat after the fashion of a slat of a Venetian blind. This slat can be opened or closed, so that, in the former case, a slot or gap is formed between it and the aersfoil proper, or, when closed, lies flush against it. The employment of the slot has been found to give not only increased lift, but to render the aerofoil stable at high angles of incidence—above its normal stalling angle. As a result, a machine so fitted maintains its stability, and is under full control when flying below its normal stalling speed. The value of this, as regards safety in flying, is, of course, obvious, for it not only safeguards the pilot against the serious consequences of getting the machine beyond the stalling angle or speed, but it enables a machine to take off from, or alight in, extremely restricted areas. At the Berlin show the action of the automatic slot gear is effectively demonstrated by a model of an aeroplane, fitted with slatted wings, which is placed in front of an electric fan supplying a flow of air past the model. By increasing the angle of the machine until the stalling angle is reached, the slots may be observed to open automatically, and close again when the model is brought back to normal flying trim. The practical application and construction, etc., of the slots can be examined by means of the slotted " Moth " wing. The Handley Page slot is now being fitted to a number of aircraft, with complete success, and a few examples of these are shown by a collection of large photographs. HENRY HUGHES & SON, LTD. WE feel somewhat at a loss to know where to begin in describing the exhibit of the old-established instrument firm of Henry Hughes and Son, Ltd., of 59, Fenchurch Street, London, E.C.3. On their stand, No. 56 in Hall II, is a very comprehensive range of aeronautical instruments. It is, of course, impossible on this occasion for us to describe each instrument in detail, and we are afraid we must content our- selves with just a list of these with brief remarks on the main features concerning some—even this consumes much of the limited space available in this present issue. Perhaps the most important instruments comprise the Aperiodic compasses for use on aircraft. These include the following models, suitable for every type of aircraft :— 6/18 Mk. ///.—The latest pattern of the original type of Aperiodic compass. Mk. Ill A.—Smaller model of the above with latest type of suspension ; particularly adapted for use in modern light aeroplanes. P. 2.—Pilot's compass, without radium ; this type has been used by Sir Alan Cobham on his flights to South Africa and Australia. (For large machines.) P. 4.—Pilot's compass with black interior and radium illumination ; designed on the same principles as the P.2. (For large machines.) 0.2.—Observer's compass fitted with sight for taking bearings, but without radium. 0.3.—Observer's compass fitted with sight for taking bearings, with black interior and radium illumination. (Fig. 1, p. 886). P.3.—Pilot's compass for small fighting aircraft. (Fig. 2.) 5.0.2.—Special type of Aperiodic compass with sight, preferred by Marquis de Pinedo, and used by him and other Italian world flyers. (Fig. 5.) 253 A.C.—A special type of pilot's compass, using a scale covering 100° in conjunction with a special system of filament pointers enabling the pilot to read the compass to 1° from 0° to 360°. (Fig. 4.) Among the " Dead Beat " compasses may be mentioned the following :— 259^4.—Large and small patterns with circular vertical strip card and damping filaments. 5/27 A.—A small compass for light aeroplanes ; fitted with dome glass giving a magnified image of the compass card when placed at eye-level. 253 D.B. Dome.—A special compass of normal size having a very narrow horizontal strip card and fitted with dome glass giving eye-level readings. Airship Compass.—This compass has been specially designed for the navigation of large airships. It has a special azimuth sight designed to facilitate the accurate determination of bearings even when the airship is unsteadv in its movements. (Fig. 3.) Other special compasses for aerial purposes are the 254, suitable for the determination of bearings when held in the hand, and the Medium Landing Compass, a dead-beat compass with prismatic sight, suitable for rough survey work and also for use on temporary aerodromes in laying out bearings for the correction of compasses mounted in aeroplanes. Then we have a variety of other aero navigating instruments, such as wind gauge bearing plates. When any aircraft is in flight, three vectors are always present ; these are the direction and speed of the aircraft through the air, the direction and speed of the wind and the resultant vector, the direction and speed of the aircraft relative to the earth. By the use of these instruments the unknown vectors are readily deduced from those that are HUGHES AERO NAVIGATING INSTRUMENTS AT BERLIN: On the left the Mark II and Mark IIA Wind-gauge Bearing Plates, and on the right the Course and Distance Calculator 885 ^?
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