Behaviour of a Ground Effect Machine 



Figure 13 learns that the resistance, the pitch and heave amplitudes de- 

 creased when the rise height was increased by means of higher fan revolutions. 

 The accelerations were therefore expected to be lower at larger flying heights. 

 This appeared to be true except for the accelerations forward in bow seas. 



When the cushion fans were adjusted in such a way that at zero speed the 

 vehicle was trimmed by head or by stern, the character of the behaviour did not 

 change very much. 



Comparison of Fig. 14 with Fig. 10 shows that heave and pitch amplitudes 

 are lower in both trimmed conditions than at even keel. At speeds over 30 knots 

 the resistance increased with trim by the head and decreased when the vehicle 

 was trimmed by the stern. At lower speeds this was reversed. 



HEAVE 



DOUBLE AMPLITUDE 



WAVE LENGTH 105rt 



MOMENT OF YAW 



DOUBLE AMPLITUDE 



HEAVE 



MEAN RISE HEIGHT 



70 -105 ft 



-2580 FAN REVOLUTIONS PER MINUTE 

 -3210 . 



ACCELERATION FORWARD 



" I 



O 20 



S 



a 



ROLL ANGLES 



DOUBLE AMPLITUDE 



LATERAL FORCE 



DOUBLE AMPLITUDE 



— 70tt. 



__ — ■-' MEAN. 



~70-105n 



ACCELERATION AFT 



— SPEED IN KNOTS 



— SPEED IN KNOTS 



SPEED IN KNOTS 



Fig. 13 - Effect of rise height. Wave direction 135° (bow sea), 

 wave height 2 feet. 



709 



