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Aviation History
1936
1936 - 1490.PDF
JUNE 4, 1936. FLIGHT. 611 MODELS Improving the Glide : The Wakefield Cup Elimina ting Trials : Forthcoming Club Events By M. R. KNIGHT With Retractable Airscrew THE model which we illustrate this month, the work of Mr. W. L. Henery (T.M.A.C.), is of exceptional interest and ingenuity. Distinguished by the neatly filleted wing roots (as opposed to the usual elastic-secured centre section), and elegant tail unit merging into the graceful lines of the multi-sided fuselage, the machine has as its out standing feature the airscrew, which is made to fold its blades when the power ceases. Quite a sharp controversy rages in model aviation circles as to whether a free-wheeling airscrew sets up less resistance dur ing the glide than the fixed variety. Mr. Henery offers an alternative to either, and reports a 30 per cent, increase in duration when his model is hand-launched^ as a glider. A lengthier test period is needed to determine whether his device secures sufficient advantages to justify the additional complica tion, but the experiment is certainly commendable. The retracting mechanism is concealed in the spinner. Centrifugal force holds the pivoted airscrew blades out stretched during power flight, and, in fact, during the glide until the rotation is terminated by a trip, actuated by a rubber-tensioning mechanism. When the power runs out and the rubber skein slackens, the airscrew shaft is drawn forward bv a compression spring in the forward end of the spinner. This brings a trip wire soldered to the shaft in contact with a stop on the rear face of the nose-block, and prevents the shaft turning. The airstream past the now stationary blades there upon folds them back. Wilfred (as the machine is known, owing to its rabbit-like appearance with " ears " folded) has a span of 45m., 6 degrees of dihedral, and a chord tapering from 5|in. to 3jin. The under surface is slightly concave, and the tips are slightly negative. Each half of the wing has two hard balsa projec tions which engage in slots in the fuselage, permitting a cer tain variation in longitudinal positioning, and allowing them to tumble out undamaged in the event of a rough landing. The undercarriage is unusual in having the bamboo struts to the rear, with the wire springs in tension. The overall length of the model is 34m., and the total weight 6 oz. The structural material throughout is balsa wood, with Jap tissue covering, the wings and tail being clear doped, and the fuselage finished in aluminium. Fin and tail plane are separately detachable. An original wing constructional system evolved by I'.Ir. D. W. H. Owen, of Maidenhead, his idea being to secure an even cross-section, particularly at the wing-tips, prevent torsional movements, and stand up to wing-tip blows. The accompanying fuselage is a monocoque structure made from numerous strips of balsa, the thickness of paper, wound around a solid wooden template. The British Wakefield Team THE eliminating trials for the purpose of selecting a team of six to compete in America for the Wakefield International Trophy were held at Fairey's Great West Aerodrome on May 17. Potential soaring conditions were to some extent marred by the presence of a damp area, precursor of heavy rain, which fortunately held off until the conclusion of the trials. At times a stiff wind also hampered the contestants, but some excellent durations were achieved. There was a greater variety of types than is usually to be met with, these including C. A. Rippon's model with airscrew behind the tail unit, a backswept low wing, and a neatly faired mid-wing, flown by the winner of the 1929 Wakefield contest. R. N. Bullock. Diamond section and monocoque fuselages were also to be seen. Though there was a preponderance of the familiar lightweight high-wing type, with one-piece cantilever wing flexibly coupled to a fuselage of rectangular section, one observed a pleasing tendency to use a circular or oval nose, merging into the straight sides. The best result of the day was an average duration on three rise-off-ground flights of 268.3 sec. by J. B. Allman (Leaming ton and Warwick M.A.C.), winner of the Wakefield Cup in 1934. This effort brought him into the Wakefield Team, and . won for him the Premier Shield donated to the S.M.A.E. by Mr. F. R. Barnard. Mr. Allman's high-wing model had the multi-skein motor with geared-up airscrew which he has spon sored for some time, the airscrew being of the variable pitch type. Two juniors, A. Greenhalgh, aged n (Lanes. M.A.S.), and H. A. Jones, aged 13 (N. Kent M.A.S.), earned inclusion in the team with averages of 220.5 ar)d 106.9 sec- respectively. The other successful aspirants were D. Fairlie (Wembley M.F.C.), 215.03 sec; A. A. Judge (T.M.A.C), 156.8; and R. Copland (Northern Heights M.F.C.), 143.6. These six stalwarts will sail from Southampton on June 20, and the writer and Flight join in the volume of good wishes (and fervent hope for the retrieving of the Cup!) which will accompany them to Akron. June Fixtures READERS are reminded that the popular " Northern Heights " Gala Day, details of which were given last month, will take place at Fairey's Great West Aerodrome on June 21, from n a.m. On June 14 a contest for gliders will be flown simultaneously on the grounds of the various clubs affiliated to the S.M.A.E. Gliders will be launched by elastic cord, and the average of three attempts will count. The Seaplane contest for the Lady Shelley Cup has in former years attracted numerous entries. It will take place this year on June 28, at 3 p.m., the lake in Danson Park, near Bexley- heath, again being the venue. Floatplanes and flying-boats are eligible, and the average will bs taken of three rise-off- water attempts. T.M.A.C. will hold a seaplane contest, open to non-members at a small fee, at Wimbledon on June 14. Disdaining ponds, they will make use of a portable canvas tank evolved and con structed by the competition secretary, Mr. H. Fialko.
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