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Aviation History
1923
1923 - 0581.PDF
SEPTEMBER 27, there are six pins (with quick-release locking wires) to undo,when the wing can be unshipped, the aileron control cables having, of course, first been cast off. The whole operationshould not occupy more than a few minutes. The ailerons, it will be seen, are of large area, and the de Havilland patenteddifferential aileron control is used. The bracket supporting the sprocket of this control is shown in a sketch. Thealuminium plate on the lower surface fits flush into the wing, Ihe only projection being the bolt to which the aileron tubefrom the king-post is attached. The whole makes an ex- ceptionally clean job, and seems to be worth the extra troublethat has been taken over it. The action of the de Havilland type of differential control is, of course, to cause the upward-moving aileron to travel through a greater angle than that of the downward-moving aileron on the opposite side. Thusthe yawing moment set up is smaller than where the lower flap moves through a large angle and offers a great amount ofresistance. In the D.H. 53 the angles chosen for the point of attachment of the crank lever control tube is such thatQ.S _ with a certain amount of stick movement the downward- .*" moving flap reaches a maximum, and then, as the upward- U moving flap rises further, begins to rise again. Thus, at no ' ' time during the full movement of the stick does the lower flap exceed a certain angle, pre-determined by the setting ofthe tube on the sprocket. During preliminary flying tests the D.H. 53 has been found to be very controllable, and itappears that lateral control is effective right up to, or even past, the stalling angle. The longitudinal controls are alsovery effective, while directional control is quite exceptionally good, the machine handling well even when taxying at lowspeed on the ground. The 750 c.c. Douglas engine is very simply and neatlymounted on a flat horizontal engine plate, the " feet " of which rest on the longerons, as shown in a sketch. The lowerportion of the crank-case, which is bolted to the upper and has semi-circular grooves for mounting in a bicycle frame,has been omitted, and the engine rests with the flat bottom of its crank-case on the engine plate. A small cowl fits overthe top of the engine, and makes a very neat nose. As direct drive is used a special propeller boss has been made, which is secured to the tapering end of the crank-shaft. Thediameter of the propeller varies from 4 ft. to 4 ft. 9 ins., according to whether the machine is to be used for speedwork or for mileage-per-gallon competition. A small petrol and oil tank is mounted aft of the enginebulkhead, and although it is not placed particularly high, there is sufficient head to give direct gravity feed to thecarburettor, the fuel being led to the engine through a length of " Petroflex " tubing. A feature of the D.H. 53 which shouldparticularly appeal to the owner-pilot of the future is the effective silencing of the engine. From the illustrations itwill be seen that short exhaust pipes are taken from each cylinder and join a long collector pipe curving underneath thebottom of the fuselage. When the engine is running only a pleasant purr is heard, while a two-cylinder engine with openexhaust makes quite an unpleasant noise, owing to the fact that with but two cylinders there is no overlapping of theexhausts, which are consequently heard as distinct and separate cracks. The undercarriage of the D.H. 53 is of the usual de Havillandtype with the exception that no oleo gear is fitted. On the larger machines this type of chassis works extremely well, andthere is no reason to doubt that it will be equally suitable for the small machine. The tail is very similar to that of last year's D.H. gliders ingeneral shape and construction, and rudder and elevator are operated by cables placed externally on the fuselage wherethey can be readily inspected. All the main dimensions of the D.H. 53 light 'plane areshown on the accompanying general arrangement drawings. The empty weight of the machine is 310 lbs., " dry." Witha 168-lb. pilot, one gallon of petrol and half a gallon of oil the total loaded weight is 490 lbs. As the wing area is120 sq. ft. the wing loading is just over 4 lbs. per sq. ft. The maximum speed is probably in the neighbourhood of70 m.p.h., while the landing speed appears to be about 30 m.p.h As already stated, the machine is very man-oeuvrable, and should appeal to the private owner-pilot. Two are being built for the competitions, one of which willbe piloted by Captain de Havilland himself ROYAL AIR FORCE CADETS THE Air Ministry announces that an examination forthe entry into the Royal Air Force of cadets with a view to their becoming permanent commissioned officers after atwo years' course at the Royal Air Force Cadet College, Cranwell, Lincolnshire, will be held on November 20 andfollowing days. The closing date for entry for this examination is October 4, and no form of entry will be accepted under any circum- stances after October 18. Applications should be made to the Secretary, Civil Service Commissioners, Burlington Gardens, W. 1. The number of cadetsbips open to competition on this occasion owing to the authorised expansion of the Air F"orce will not be less than 45. This number will include any candidates who may be awarded King's Cadetships or Honorary King's Cadetships. There will also be a grant of not less than one prize cadet-ship, and in addition two Wakefield scholarships of the value of /75 each are offered for competition among candidateswhose parents or guardians are in reduced circumstances, with preference to cases due to the late War. * Candidates must be physically fit, and have attained the age of 17£ and not exceeded the age of 19 on January 1,1924. The official medical examination will take place in Londonabout the same date as candidates attend for the educational examination. It has been found that certain candidates inprevious examinations have failed to attain the standard of physical fitness required owing, it is thought, to their havingneglected to take outdoor exercise while preparing for the educational examination, and it is, therefore, desired todirect the attention of candidates to the desirability of taking proper care of their health in this respect. The entrance examination is the same as that for the entryof cadets to the Royal Military Academy, Woolwich, and the Royal Military College, Sandhurst, the examination forentry to the three colleges taking place simultaneously. Candidates entering their names for the examination foreither of the two Army colleges can also submit their names at the time of application for entn into the Royal Air ForceCadet College as a second preference. The competition will be conducted in accordance with the1regulations for the Royal Air Force (Cadet) College, Air Publication 121, which maybe obtained from H.M. StationeryOffice, Imperial House, Kingsway, W.C. 2, r>ri£e 9d. RADIO RESEARCH BOARD REPORT THE first Special Report of the Radio Research Board (De-partment of Scientific and Industrial Research) has just been issued, and is entitled " A Discussion of the Practical Systemsof Direction-Finding by Reception," by R. L. Smith-Rose, Ph.D., M.Sc, and R. H. Barfield, M.Sc. This paper, whichis the first of a series of special reports dealing with the work of the Radio Research Board, describes investigations whichhave been carried out on behalf of the Directional Wireless Committee of the Board, chiefly at the Board's Station at theAdmiralty Compass Observatory, Ditton Park. The subject-matter of the report is arranged under thefollowing headings :— Part I.—Simple Theory of Direction-Finding.—1. Generaltheory of a closed loop in an electro-magnetic field. 2. The single coil direction-finding system. 3. The Bellini-Tosi direction-finding system. 4. The Robinson direction-findingsystem. 5. Effect of inclination and polarisation of wave front on direction-finders of the above system. Part II.—Experimental Comparison of the above Direction-Finding Systems.—6. Introductory. 7. Comparison of Bellini- Tosi and Robinson systems on damped waves of length2 to 5 kms. 8. Comparison of single frame, Bellini-Tosi and Robinson systems on damped and undamped waves of lengths1.8 to 9 kms. 9. Comparison of Bellini-Tosi and Robinson systems on damped and undamped waves of lengths 2 to9 kms. Part III.—General Discussion on the Operation of the ThreeSystems.—General conclusions. Copies of the Report may be obtained from H.M. StationeryOffice, Kingsway, etc., price 9d. 580
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