ProkhoroVj Treshchevsky,and Volkov 



action between the ACV hull, the air cushion and water surface. I 

 may add that this is stable experimental data and I have seen the cor- 

 relating results in a German paper. 



I can add that frequency characteristic shown on Figure 11 

 being derived experimentally includes the influence of all the factors 

 mentioned by Mr Kaplan (variable pressure, ACV's geometry). The 

 possibility of exact theoretical calculation of this characteristic 

 seems to be doubtful. 



The use of model data in ACV dynamics isn't the subject of 

 the paper. Nevertheless the assumption of the linear character of 

 the natural frequency versus scale dimension is not obvious. As for 

 similarity criterion, the Froude number and dimensionless frequency 

 were used among others. The natural frequency and damping are 

 ACV's characteristics, determined by flight conditions. 



290 



