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Aviation History
1963
1963 - 0226.PDF
•site First Flight of the Peak 100 two-seat high-performance sailplane was made at the College of Aeronautics Aerodrome, Cranfield, on February 5. The pilot was Mr Harry Midwood, one of the designers of the aircraft, who is seen (right) in the cockpit. With him is Mr C. Williams of Peak Sailplanes Ltd, the manufacturers 216 FLIGHT International, 14 February''/j WORLD NEWS . . . Shackleton Display Cancelled The 1963 Shackleton International Air craft Display, scheduled to take place from May 17 to 19, has been cancelled. Follow ing the announcement of the Biggin Hill Air Fair (Flight International, November 29, 1962, and January 10, 1963), the Shackleton directors consider that it is better for the whole aircraft industry that two shows featuring an extensive range of private and business aircraft should not take place within three weeks of each other as neither could be expected to be fully supported by exhibitors. They point out that the Shackleton Display has grown in size and scope since it was inaugurated in 1958 and say that they do not wish to con tinue with it in circumstances that could only impair the standard of previous years. "Flight International" Photographs A proportion of the photographs pub lished in Flight International are our own copyright, and where this is the case (as indicated by the words "Flight Inter national" printed in small type beneath the reproduction) prints are obtainable to order. Prices for seven standard sizes are follows (quotations for larger sizes are obtainable on application) and these include postage and packing:— Size (in) Half plate (*i X 4#) Glossy Semi-matt Whole plate 10 X 8 12 X 10 15 X 12 20 x 16 20 X 30 8* x 6i) s d 3 6 4 6 6 6 8 6 12 6 — — i s d i 3 5 i 7 i 9 i 14 1 1 0 1 10 [ THE DAM-BUSTING WEAPON DESCRIBED ALMOST 20 years after the operation in which it was used so successfully by 617 Sqn—the attack on the Moehne, Eder and Sorpe dams of May 16/17, 1943—the secret of the specially designed weapon has been revealed, partly as the result of public ity over recent months in the correspon dence columns of this journal. Last week Vickers-Armstrongs (Aircraft) Ltd issued some descriptive notes—of which the fol lowing is a summary—by the designer, Dr Barnes Wallis, now chief of their aeronautical research and development, and a drawing of the weapon (reproduced below). They also showed a film of trials at Reculver and North Foreland, from which the still reproduced below was taken. A number of experiments on small-scale models of dams had been carried out prior to August 1942, when it was finally shown by means of a larger-scale experiment on the Nant-y-gro dam in Wales—approxim ately one-fifth the size of the Moehne and Eder dams—that a charge of 6,5001b of RDX exploded in contact with the wall on the upstream side and 30ft below the water surface could be expected to breach the dam. The main problem was one of getting the charge into position. Accuracy of the required order was impossible by the usual methods of bombing; moreover, the dams were protected by dual screens of torpedo netting suspended from rows of buoys. It was decided to investigate the possibil ity of using a spherical weapon delivered from a low altitude so that it would bounce on the surface of the water in similar fashion to the ricochet cannon-balls used in Naval gunnery centuries ago. Extensive experiments showed that the number of bounces, and hence the distance travelled over the surface of the water, could be greatly increased by imparting to the weapon a high rate of back-spin about a horizontal axis. Moreover, the great momentum of the weapon ensured that, if it did not jump over the nets it would easily burst through them, and would reach the dam while still spinning at a high rate. After a bounce back (caused by impact with the dam) the spin, acting in conjunction with the vertical velocity of sink (the density of the weapon being greater than that of water) then caused the weapon to continue forward in the water until it reached the face of the dam, down which it rolled in close contact until the critical depth for explosion was reached. The decision to instal the weapon wa not made until February 26, 1943. A. Roe & Co Ltd were immediately called in to modify the Lancaster bomb-bay, whili Vickers proceeded with the detail design ol the weapon and the installation. Twenty aircraft were modified. The original design of weapon wai spherical, but production consideration! dictated the substitution of a cylindrica container. The weapon as fitted was 60ii long by 50in diameter, with three hydro static pistols set to detonate at 30ft and with a 90sec time-fuse (initiated at release intended to destroy the weapon if the pistol! failed to function. Each end of the casini carried a hollow circular track of 20ii diameter into which fitted disc-like wheel! mounted on supporting arms in the bomb- bay. The total weight of the weapon as use was 9,2501b, of which 6,6001b was chargi weight. The aircraft installation consisted of tw< V-shaped calliper arms, so arranged that by means of the disc wheels, the cylindrica case could be rotatably held between them the wheels being mounted on ball bearings [Continued opposil A partly cutaway view of the weapon and, right, a frame from the trials film, showing release from a Lancaster
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