854 The Outline of Science 



control lever, this moving the elevator so that the machine dips 

 downwards and glides towards earth. When a few feet from 

 the ground he gently moves back the control lever, so that the 

 aeroplane assumes a horizontal position, and as it loses speed 

 with the engine throttled right back and the propeller turning 

 very slowly, it sinks gently to earth and runs along the ground 

 to a standstill. 



A glide can be made in any direction, but the landing itself 

 should be made "up wind." The landing speed of aeroplanes 

 varies according to the type, some coming to earth at about 30 

 m.p.h. and others at nearly 100 m.p.h. Probably an average is 

 50-55 m.p.h. 



Stunting 



Aerial manosuvres are all simple to the experienced pilot, 

 and if properly performed involve no strain on the machine 

 which the designer has not taken into consideration. Smooth- 

 ness of movement and absence of jerking of the controls are 

 essential. An aeroplane in a nose dive should be corrected 

 slowly. If the pilot abruptly pulls back the control lever, the 

 machine may be injured in a vital part, owing to the sudden extra 

 strain. 



Aerial "stunts" or "aerobatics," as they are officially called, 

 need slightly different methods in different types of craft. Gen- 

 erally speaking, the principal manoeuvres performed are spin- 

 ning, looping, and side-slipping. 



In spinning the pilot throttles the engine right back, pulls 

 the control lever right back, and pushes the rudder hard over. 

 Ruddering to the left will cause a left spin, and vice versa. To 

 come out of a spin, the pilot centralises all the controls, and when 

 a dive results he -gently pulls back the control lever until the 

 machine once more attains an even keel. 



In looping the pilot pushes the control lever slightly for- 

 ward so that the nose of the machine drops and additional speed 



