THROWN INTO THE AIR

Evening Star, Issue 22952, 9 May 1938, Page 2

THROWN INTO THE AIR

CATAPULTING AEROPLANES Though the plane launched in midair from a parent craft has attracted notice lately, the catapult is the usual device for applying a “flying start plane whichlias no runway space (writes 11. J. C. Harper). So long ago as 1903 the Wright brothers were using a primitive sort er catapult, operated by falling weights, to get their craft into the air. Since that time a number of alternative devices have been used and discarded. It was in 1917 that designs were put' in hand for two different types of poweroperated catapults, and they were completed towards-the end of that year. One was mounted in a pit at Hendon-, and the other was installed in a hopper barge, nicknamed H.M.S. -Slinger. Although a number of successful launches were made with both types, neither specified load of 5,0001 b, nor the speed of 60 miles an hour was attained id either case. The armistice brought an I end to the experiments for some years Now the Navy has catapults whicli can launch aircraft up to a weight ot 8 0001 b at 60 miles an hour; in fact, majority of our cruisers and severai battleships have been, fitted with catapults. - The catapult consists of a pair of steel lattice girders, similar to those ot a bridge, placed about 3ft apart and connected by cross-members.' A.cylinder is rigidly fixed between the girders, from which a piston or ram is forced out by pressure from slow-burning powder, such as melinite or cordite, or compressed air, though this is..seldom employed in the latest types. ■ The launching cradle is connected to the ram through a system of wire ropes and pulleys, by which the motion of the ram is increased three or four times.

Just before the launch the catapult is trained into wind and the engine is started and' warmed up. The aeroplane crew take their seats. If there is a passenger the pilot makes sure that hia safe'tv belt is secured, and he is instructed to grip the cockpit fairing on either side and to lean forward, head between his arms, so as to minimise the effects of the jerk.

The pilot fastens his belt. _ Having tested his engine, he holds up his thumb as a signal to the catapult directing officer, who signals by flag for the gunner to place the cordite charge in the breech. Then the officer waves his flag, the pilot places his head against the head rest to prevent the risk of a dislocated neck, ooens his engine full out, and when satisfied that it is giving the required revolutions signals that ah. 1 * ready. The catapult officer gives him two seconds to get set and drops th# flag. : The charge is fired; the seaplane on its trolley moves forward with everincreasing speed, until at the end of the 50ft run it leaves the carriage and is in the air in full flight. From personal experience I can say that the sensation of being catapulted, is not so terrifying as it would at first appear,' As the seaplane moves along the runway the occupants feel as if a mighty hand jyere pushing them with an irresistible force. The sensation last# about a second and There i# not much difference in the smoothness of working whether cordite .or compressed air is used, but with compressed air, if the valves are not properly adjusted, there is the sensation not so much of a mighty hand as of a mighty foot behind the plane.