HOW PLANES ARE CATAPULTED

Dominion, Volume 30, Issue 249, 17 July 1937, Page 6 (Supplement)

HOW PLANES ARE CATAPULTED

A Simple Invention

When considering the results achieved in the preparations for the opening of a regular trans-Atlantic air service, the part played by the catapult in launching aircraft should not be forgotten. The introduction of the catapult has alone made it possible for heavily-loaded aircraft to bo independent of the state of the sea at the point of departure. The possibility of launching an aircraft from the ground or from a ship and avoiding a long take-off rim was first considered during the Great War. and the first experiments were then made. To-day the launching of aircraft from ships by means of catapults is an established practice with almost every navy in the world.

The credit for having made the aeroplane catapult suitable for commercial use belongs to the Deutsche Lufthansa, who have adopted the catapult constructed by Dr. Ernst Heinkel and assisted in its developments.

The problem of launching an aeroplane from a ship was first attacked in the year 1925, when Dr. Heinkel was given an order to construct a slipway for use on a Japanese cruiser.- He designed this slipway as a simple steel runway and also at the same time designed for use with it two types of aircraft, which had a particularly good take-off: these were mounted on a trolly and took-off under their own power. The success of this first experiment encouraged investigation of the possibility of using a mechanical starting device on the principle of a catapult. Dr. Heinkel favoured the use of compressed air as propelling power in preference to an explosive or electrical force, with which others had experimented, for he was of the opinion that this was likely to be more suitable both from the constructional point of view

as well as in use. Compressed air would allow better and more accurate regulation of the speed of the trolly and consequently of the take-off.

The construction and the operation of the Heinkel catnpuP are extremely simple. Running on two parallel rails is a trolly to which the aircraft to be launched is made fast. Compressed air at pressure of 160 atmospheres is stored in a chamber, and upon the operation of a starting lever, which is secured by several safety devices, a valve in the chamber is opened ami the compressed air gushes into a strongly constructed cylinder where pressure is exerted on a working piston. Leading from the head of the cylinder is a wire rope connecting up with the .starting trolly via a pulley block at the head of the catapult, the pulley block having a ratio of 6to 1. The movement of the piston is therefore transferred at six times its original power to the starting trolly, with the result that corresponding acceleration is imparted to rhe trolly and the aircraft rises from the catapult. As the take-off is made with rhe throttle fully open, the aircraft is able to continue its flight by virtue of the initial speed given to it. The principle embodied in this catapult, built for experimental purposes, proved so satis- ! factory that it was retained in all subsequent types. The improvements since introduced have been confined to increasing the safety and performance of the apparatus. These catapults have been used on board the Bremen and Europa for a number of years, and the catapulting of mail-carrying aircraft from them has accelerated the mail service between Europe and North America by -IS hours. Their use on the depot ships. Westfalen and Schwabenland, has also contributed to the successful operation of the South Atlantic service.