Helicopters

Sixteen entries have been received by the British Air Ministry for its Helicopter prize of $25,000. Not all the contestants are British. The U.S. is represented by Emil Berliner and his son Henry who have already achieved considerable success with a vertical lift machine in various tests in Washington. Pescara represents France, and there is at least one Spaniard in the running.

The conditions of success are severe. The machine must be able to rise vertically to 2,000 feet, remain at that height for half an hour hovering over a small area, make complete circles, fly horizontally at not less than 60 miles an hour, and finally descend vertically from a height of not less than 500 feet with the engines stopped.

It is easy to build a machine which will rise vertically. With skilled design, one horsepower can be made to lift 100 pounds; 35 horsepower will lift a weight for which an airplane like the De Havilland requires a 400 horsepower Liberty. Nor is a high degree of forward speed really hard to achieve. It is in coming down with engines stopped that the main difficulty lies. The airscrew must then act as a giant parachute. When one man sails down gently in a parachute its supporting area must be over 100 square feet. It is enormously difficult to provide a supporting area enough to prevent a 2,000 pound machine from crashing violently to the ground. The airscrew blades revolving like a windmill must have gigantic proportions which will militate against achievement in other directions.

But nothing is impossible, and with this high reward and world wide fame to be gained, inventors may yet find an ingenious solution.

While considerable secrecy at present attaches to all helicopter experiments, there is no doubt that the American Berliners are at least as far advanced in the art as any of their competitors. Mr. Berliner has previously won wide recognition by his inventions on the telephone transmitter and the gramophone and his great ingenuity is balanced by the mathematical ability of his son.