Determination of Aero hydro dynamic Performance of ACVs 



is seen that with the increase in Froude number the response of the 



model increases up to the values Fr = 1. 10. The same figure shows 



the variation of the relative amplitude of the model yawing angle at 



fixed frequency and speed as dependent on the pressure factor of the 



air cushion K . 

 P 



Some damage situations with the same model were studied, 

 particularly, the transition process at first instants after suddenly 

 applying the yawing moment, which may be the consequence of a spon- 

 taneous reverse or failure of propellers at one side of the model. It 

 is seen from figure 14 how kinematic parameters of motion are chan- 

 ging after the instantaneous application of the rolling moment (induced 

 for example, by the breaking of the flexible skirt along the side) until 

 the steps are taken to keep the ship in the upright position. This expe- 

 rimental plant makes it possible to simulate the maneuver of course- 

 keeping in this condition by applying the counter yawing moment imi- 

 tating the action of controls. It is typical for this case to set the mo- 

 del in a steady motion with a drift to the inclined side. 



The condition that the towing carriage speed should always 

 be constant makes it impossible to simulate to the full extent the full 

 scale performance of the vehicle. However, this restriction is no bar- 

 rier to solving a wide variety of practical problems; in this case the 

 error is directed to the safe side. 



271 



