New Developments in Science 



581 



3' Photo Service. 



AN AUTOGIRO IN FLIGHT 



This machine has small wings which act as balancers. Other types have much smaller 



balancers, and some have none at all. Note the large size of the "windmill," which 



holds up the machine. 



The autogiro is driven forward by a vertical motor-driven pro- 

 peller mounted in front, in the same way as the airplane is pro- 

 pelled. The windmill which holds up the autogiro is not driven 

 by a motor but is turned by the force of the wind as the machine 

 moves through the air. In some types the turning of the windmill 

 is started by power from the motor, but as soon as the autogiro 

 begins to move forward the motor is disconnected from the wind- 

 mill and the force of the air turns it. The autogiro can take off 

 and land at very slow speed and can rise and descend at a steep 

 angle. It therefore does not require a large landing field. Besides 

 being able to start and land within a small area, the autogiro is 

 not dependent upon rapid forward motion to keep it up, as the 

 airplane is, for the windmill exerts great lifting power even at 

 slow speed. Another advantage of the autogiro is that it can 

 usually land safely if the engine stops in mid-air, because the 

 windmill continues to turn and thus supports the machine as it 

 settles to the earth. As the autogiro comes into wider use, it 

 should give us more safety in air-travel and should enable avia- 



