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Aviation History
1923
1923 - 0198.PDF
APRIL 12, 1923 feature would be less desirable in the case of the rudder, because it may be necessary to remove the rudder more often. " The landing gear consists of two main skids and a tail skid. The two main skids are placed well forward of the centre of gravity. They are mounted on the ends of a torque tube, which transmits the rotational deflection to a shock absorber located inside the fuselage. This arrangement permits quite a wide track for the landing skids. The skids are hinged to the tube by means of vertical pins. This feature tends to relieve any side thrust, and minimises the possibility of overturning, at the same time greatly reducing the racking stresses. The tail skid follows more or less conventional practice." Without going into detailed criticisms of the structural design, which we hope to deal with when the construction drawings are published, a few comments upon the general design of " Turkey Buzzard " may not be without interest here. The drawings are, almost without exception, very neatly and carefully done, and arranged to proportions of the pages of FLIGHT as called for in the rules governing the competition. In fact, quite apart from the merits of the design, " Turkey Buzzard's " drawings were the cleanest and best sent in. That fact has naturally been taken into account, although if another design had been superior—as a glider— but the drawings poor, this fact would not have caused the better design to be discarded in favour of the other. As it is, however, " Turkey Buzzard " combines good drawing with reasonably good design. One or two points in the design we do not quite like. Reference has already been made to the somewhat small control surfaces, and we think that anyone intending to build from the drawings would be well advised to increase the size of ailerons, elevator and rudder. From the point of view of efficiency, the aspect ratio of the wing is not as high as it might have been, and we are not quite in agreement with the designer when he assumes an equivalent aspect ratio of 10-7. However, that is a point to which we hope to return in a subsequent issue, when the performance calculations are published. The undercarriage we frankly do not like at all. To begin with, the large overhang to give a wide track would be a source of weakness, as the beams are cantilevers with a concentrated load at the end. The shearing force would be considerable, and the beams would need to be fairly heavy. Secondly, the use of skids of the tail skid type was found at Itford to be undesirable. The " Airdisco " monoplane was fitted with two Bristol Fighter tail skids on the main undercarriage, and it was found impossible to drag the machine off the ground until wheels had been substituted for the skids. In other respects the design appears clean and of good lines, and although we doubt if the gliding angle of 1 in 20 estimated by the designer will be realised, the machine should be quite a good glider and have a fairly low rate of descent. KL" BIPLANE GLIDER The following short description accompanied the drawings submitted by " Ki,":— " The design comprises a fuselage biplane with monoplane tail. The pilot is seated on the lower front spar, and has a good view forward and downward, while being very well protected in a bad landing. " The fuselage is constructed of birch 3-ply 1 mm. thick (which is obtainable), stiffened by spruce struts and occasional wire or gusset bracing. This construction has been chosen as being easy to build, especially in quantities ; it is very strong, does not get out of truth, is cheap and light, and is good in torsion. " The planes are not remarkable for their construction, being an ordinary ' one strut out ' job with spruce spars stiffened against lateral failure by a ply nosing. The ailerons are hinged at -35 chord, and act as flaps as described later. " The undercarriage is merely a cross axle carrying a pair of Palmer wheels, 450 x 60 mm. The axle works in a slot in the fuselage, and is sprung by rubber. A light ash tail skid is fitted. Towing and launching hooks are provided at the nose of the body. " The tail plane, elevators, fin and rudder form a self- contained unit, readily removable, since the rudder is not hinged on the fuselage sternpost. The seat and controls in the cockpit also form one easily removed unit. The rudder is controlled by the usual bar. The control is a frank copy of the ' Peyret ' Glider control, but whereas the Peyret was a tandem monoplane of problematic efficiency, it is claimed that the present arrangement has the advantage of quick control laterally and longitudinally upon an aerodynamic assembly which is of known behaviour. The essential of the control is that, as is to be gathered from Diagram No. 1, the elevators act with the ailerons for lateral control, while the ailerons work with the elevators for longitudinal control. It is in order to get as large an aileron effect as is practicable, that the tail plane has been given such a large span. The lower ailerons only are coupled to the joystick, the upper pair being actuated by a strut connecting upper and lower aileron. " An attempt has been made to keep the number of fittings down and to make them simple. Bending has been avoided, as if the machine is to be made by amateur fitters, it seems wise to avoid the necessity for annealing. Eyebolts are freely used, but are kept down to as few different kinds as possible. " The gliding angle is not remarkable, it is true, but it is good enough, and it has been thought better to give attention to a robust structure and aerofoil sections whose habits are known, than to attempt a super-efficient glider on an aerofoil of problematic credentials and possibly requiring expensive methods of construction. " It should be pointed out that the whole machine should be able to be dismantled very quickly, as all attachments are by pins or bolts " The following comments on " KL " by one of the judges should be carefully studied :— " It is pointed out that the use of the Peyret control system on a glider of this type would give unsatisfactory results, for the reason that, if the ailerons operate in conjunction with the elevators as proposed, when the ailerons are brought down a great fall off of lateral control will be experienced. This effect will be all the more marked on the wing section chosen, which is -08 camber with flat undersurface and, therefore, of fairly high lift, as the fall off of lateral control in arrangements of this type is greater with high lift than with low lift wings. " If it is proposed to adopt a very strong fore and aft control it could be accomplished more readily by a slight increase of tail plane and elevator area. Also the effect of warping the elevators with the ailerons could be obtained quite easily by a slight increase of the span of the main planes. " There is a great deal of uncertainty as to whether the proposed arrangement would be correctly proportioned for control in the stalled and landing conditions. In the case of the Peyret glider, the C.G. position and other features of the design lent themselves better to the adoption of that particular type of control, which would not necessarily be successful on another design of glider. From all points of view it would be safer to adopt a more usual type of control. " No general arrangement of details of the control system are shown, and it is pointed out that these are among the most important features of any design. " The general design of the wings is very good. It would be possible, without affecting the cost of production, to increase the rounding of the wing tips, with corresponding improve- ments in the airworthiness of the glider. . " The spar design might be simplified by substituting yiin rectangular sections, taking advantage of the leading edge stiffening and the fact that the spar stresses are low. " The aileron spar design is good but expensive, and might be simplified with advantage. The general layout of the machine is practical, and the constructional methods proposed are commendable." To Golf by Air A LONDON business man who flew to Le Touquet on Good Friday by taxiplane wired to the Lepaerial Bureau to send a special aeroplane to pick him up at the golf course there and bring him to London. Desiring to play in an amateur tournament that morning, and having an important business appointment in the afternoon in London, he found that the only way by which he could keep both fixtures was to make use of the taxiplane. There has been a considerable increase in the demand for these machines ; in fact, during the last few weekends every available taxiplane has been in use for journeys to all parts of England and the Continent. The latest machine to be added to the Lepaerial fleet of taxi- planes is the machine which won the King's Cup Race last year. This aeroplane, piloted by Capt. F. L. Barnard, took a passenger last week from London to Melton Mowbray, back to London, and from London to Paris in a total flying time of less than four hours. 198
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