Applied Science 865 



is gained. Then he slowly pulls the control lever back, when 

 the machine will put up her nose and loop. As the machine 

 descends from the loop the pilot gradually centralises the control 

 lever. On certain types it is necessary to use the rudder control 

 to prevent the machine swinging and slipping off the top of a 

 loop. 



In side-slipping the pilot, to side-slip to the left, pushes the 

 control lever over to left and keeps the rudder central. When 

 the machine commences to slip he puts on a little right (or top) 

 rudder to prevent the machine turning to left. To level up, the 

 pilot pushes the control lever to the right and slightly forward, 

 keeping the rudder central. Almost every "stunt" is a variation 

 or combination of these three manoeuvres. 



To those unused to flying a "spin" is an unpleasant sen- 

 sation, which if unintentionally caused is usually due to "stalling" 

 or losing flying speed. It is, however, not at all dangerous and 

 can easily be counteracted by the pilot. "Bumping" is the slight 

 rocking motion felt when an upward or downward current of 

 air is encountered. It is usually felt most when flying low in 

 hot weather, but small bumps are invariably encountered under 

 all conditions. In extreme cases, in a thunderstorm or when 

 flying over the desert, the machine may descend or ascend a hund- 

 red feet or more in one bump. Needless to say, even such 

 extreme cases as this are not in the least dangerous, though pos- 

 sibly unpleasant. 



War in the Air 



The needs and requirements of military machines and com- 

 mercial aeroplanes differ greatly. The military machine intended 

 for fighting must be very fast, capable of climbing to great 

 heights at tremendous speeds, and capable of being quickly 

 manreuvred in every possible way. On more than one occasion 

 the flying qualities of his machine enabled a pilot to save his life 

 during the Great War. 



