Pallabazzer 



a} 



\.mv .ivi^ii 



b) 



"'■ nf?.'-."""'.T- 



'S) 



*- c; 



Fig. 4 - Pumpjector devices: 

 (a) cryptosteady system; (b) 

 underwater hybrid system; 

 (c) hydrofoil hybrid system 



(i) The gas expansion is adiabatic. This hypothesis is the most 

 critical one, because it is surely not true. As a matter of fact, in one- 

 dimensional homogeneous analysis one must assign the gas-expansion law, 

 and the only other hypothesis which has also often been made (Ref. [8j), that is, 

 an isothermal (at the water temperature) expansion, seems to be less valid 

 than an adiabatic expansion, when the gas is at high temperature. It is obvi- 

 ous that the actual law will depend on the gas permanence time and contact 



1112 



