Panel Discussion 



In reply to Dr. St. Denis, Dr. Sheets said that his treatment did not include 

 nonsteady- state phenomena such as hydrodynamic impact because of the short 

 time available in the panel discussion. Dr. Sheets also noted that larger ships 

 may require greater flexibility. 



The craft must have variable flexibility with hard structures to carry loads 

 and a soft cushion of air connected by semirigid structures. 



Dr. Wang asked if the data indicated that we could look forward to ships of 

 100 knots from a drag point of view. Dr. Sheets acknowledged that the curves 

 he showed were cut off above hump speed. Above hump speed it is a third- 

 power c\irve. 



Dr. Skolnick then presented a contribution to the effect that bold ventures 

 such as the surface effect ship (SES) were needed to galvanize the marine com- 

 munity into action. If the marine community did not heed the challenge, it would 

 be accepted by the aerospace industry. 



Mr. Weller asked how this related to the traditional marine concept of pro- 

 viding low-cost transport. Dr. Skolnick agreed that the SES case has not yet 

 been adequately made. 



Dr. Wang asked if the systems approach to SES had a clear objective. Dr. 

 Skolnick stated that the SES program has a clear objective. 



Dr. St. Denis lamented the emphasis on studies which can cost large 

 amounts of time and money and hoped we would not suffer from "paralysis of 

 analysis." Mr. Calkins asked if part of the problem could be the kind of train- 

 ing given to naval architects. Dr. Skolnick concurred that this added to the 

 problem. 



Mr. Christopher Hook raised the problem of the "rogue" wave. Dr. Skolnick 

 was sure that such problems should not be overlooked — neither should they be 

 overemphasized. 



Mr. J. B. van den Brug presented some clear exposition of recent model 

 tests including films and outlined a straightforward method for deriving lift fan 

 requirements. He noted that in some cases the model acted as if it had a "neg- 

 ative added mass." That is to say, it has precisely the effect on damping. In 

 reply to a question from Dr. Skolnick, he noted that their open water tests were 

 not yet complete. 



Mr. Everett asked if the behavior was different with upward motion than 

 with downward motion. Mr. van den Brug stated that their tests centered on 

 stability and therefore focused on small deviations from equilibrium. 



Dr. Savitsky asked how the vehicle natural frequencies compared to the 

 natural frequency of encounter with the waves. Mr. van den Brug stated that he 

 would answer the question with data after the session. 



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