Page:Popular Science Monthly Volume 88.djvu/698

 Taking Photographs From a Skyrocket

��AMONG the aids to the conduct of /-\ the war that have been proposed in Germany is the photography of the enemy's positions by the flight of rockets carrying cameras. The invention is less expensive and can be sent up closer to the enemy without provoking attack than a captive balloon, dirigible or aero- plane. Besides, it is not so dependent upon the wind a§ a kite.

When the inventor, Alfred Maul, be- gan his experiments fifteen years ago, he found, as he tells us in an article ap- pearing in Umschau, that the ordinary rocket can hardly carry a considerable weight, and so he

��View of a German town taken with rocket from a height of 1,550 feet

��was obliged to de vise one of greater strength.

His first inven- tion was a shell closed above and open below con- taining a firmly compressed pow- der composition in which was a deep opening. Ignition dev^eloped a con- siderable volume of gas, w^hich gas pressed down upon the atmospheric air, thus causing

the rocket to rise. In a shot the initial velocity is the highest, whereas in the rocket the initial velocity is low but in- creases until the charge is burnt out. This occurs in about one and one-half to two and one-half seconds, but the rocket continues to rise, through the force generated, from six to nine seconds.

In his first camera experiments Mr. Maul used two small rockets com- bined. Here the rotary camera, which could take a picture about one and one- half inches square and had an oblique downward inclination, was in a hood above the rockets. At the sides of the rockets were two chambers containing parachutes of unequal size. The guide-

��staff had two vanes at its lower end, like an arrow, to prevent rotation and change of direction of the lens. At the highest point of the flight a time-fuse raised the shutter and threw out the smaller para- chute. Just before landing, the larger parachute was opened. The double rocket could carry a load of over half a pound and rose about one thousand feet. Failures accompanied successes in the tests. Rockets exploded, parachutes dropped at the wrong moment and much costly apparatus was destroyed, before the inventor saw the cause of his mis- fortunes, which was that the time taken for ascent depend-

���ed on the density and moisture of the air. The exposure and release of the parachutes were, therefore, arranged independently of the period of ascent, by making the up- per part of the hood resilient and equip- ping it with an electric contact de- vice. When the rocket paused for a moment at its high- est point of ascent, the contact opened the shutter and directly afterward threw out the first parachute. This proving successful, the photographic apparatus was enlarged to a diameter of eight and one-half inches; the plates were made four and three-quarters by four and three-quarters inches, the focal distance was also four and three-quarters inches. The length of the equipment was now over thirteen feet and the weight thirteen pounds. As the apparatus was still in- clined to rotate on its axis corrective experiments were made, but the rocket proved unable to carry the weight of a special governing apparatus. Finally, a gyroscopic device was arranged which works automatically when the rocket

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