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Aviation History
1943
1943 - 1946.PDF
I4O F LIGHT AUGUST 5TH, 1943 THE HORTEN IV angles the drag of the rudder would cause the machine to turn in the desired direction. It may be recollected that,in the Focke-Wulf " Ente " tail-first machine there were fins on the wings, towards the tips, and a large central rudder on the stern of the fuselage. (The machine was twin-engined.) The fins were slightly "toed-in" and were intended to improve directional stability. In the Horten IV the designers have avoided the need for vertical surfaces by a clever arrangement of their trail- ing-edge flaps. Evidently, however, they found from experience that this arrangement was not entirely satisfac- tory in all circumstances, for they fitted in addition drag rudders of an unusual type. Towards the wing tips they placed on the leading edge hinged surfaces which normally fitted the curvature of the wing nose closely. For steering, these surfaces opened out, book fashion, when operated by the pilot via a foot bar. The "praying mantis" position of the pilot presented something of a problem when it came to choosing the type of control column used. Finally, the "spade grip" type of control was chosen, rocking of the grip working the flaps as ailerons, and to and fro movement operating them as elevators. Reference has been made to the fact that controllability is always something of a problem in a tailless aircraft. In the Horten IV a very interesting, if somewhat complicated, system is used. On each side there are three trailing-edge flaps, all capable of differential action as well as of working in unison. This complicated system has been rendered desirable, if not indeed absolutely essential, by the com- bination of the tailless feature with a high aspect ratio. Designers of future tailless types will do well to bear this fact in mind. In orthodox aircraft the adverse yawing moment set up by the ailerons is fairly easily counteracted by giving "opposite rudder." In the Horteu IV it was evidently desired to use the" leading-edge drag rudders as little as pos- sible, and so the yawing moments of the ailerons had to be kept down to the lowest possible value. To. this end the outer flaps (i.e , those nearest the wing tips) have horn balances which come into action for a small upward deflec- tion of the flap. These flaps, for small angles, act as, eleva- tors ; at greater angles, when used differentially, they act as ailerons. The inner flaps (those nearest the wing roots) are used partly as ailerons and partly as elevators, while the middle flaps serve mainly as elevators. The arrangement is, how- ever, complicated by the fact that the inner flaps are used chiefly as negative elevators, while the middle flaps are mainly positive elevators. It has been found that this arrangement ensures the most effective elevator control and preservation of the dihedral with negative elevator. With "starboard elevator up " and "port elevator down,"- the wing-root flaps also have an -aileron effect, in which the tip flaps take part at varying angles of deflection, i.e., with positive elevator the flap angle increases towards the tip and vice versa. This differential action reduces yaw and is assisted by the horn balances of the wing-tip flaps. Great care has been taken to eliminate backlash in the control system. "In addition to rudders and flaps, the Horten IV has air brakes of the slatted type, except that the openings are circular holes and not actual slits. They move out at right angles to the wing surface. When fully extended the air brakes give a sinking speed of 8 metres (26ft.) per seccjxM within the speed range of 50-90 km./h. (31-56 m.p.h.)/ This enables a very steep approach to be made. The maxi- mum diving speed with air brakes extended is 180 km./h. (112 m.p.h.).' The undercarriage of the Horten IV comprises two skids in tandem for taking off, the front skid is placed on two wheels which, however, drop away as soon as the glider is airborne and the skid is retracted. Main data relating to the Horten IV tailless all-wing glider are as follows: — Wing span; 65 6ft. . Wing area: 206 sq ft. * Aspect ratio: 21. Empty weight (equipped): 528 lb. Loaded weight: 770 lb. Wing loading: 3.75 lb./sq. ft. Best gliding angle: 1 in 37. -1 Sinking speed: 1.64ft./sec. j^" The information on which the notion the Horten j are based is an R..T.P. translation Applied by M.A.P.' CEYLON AIRFIELD : When war broke out in the Far East, Ceylon quickly became part of the front line of air defence. The build:ng of new airfields from the jungle became imperative. The latest machinery was employed side by side with elephant labour to clear the sites. Thou- sands of native labourers followed, clearing and levelling the airfields until these sites were ready for final con- solidation by heavy steam-rollers. Work was of such urgent character that-one airfield was ready for use within a fortnight of work beginning.
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