Johnson, Jr. 



Fig. 10 - The planing craft Thunderbird pro- 

 pelled by the Pratt and Whitney Sea Jet-6 

 waterjet system 



of the Pratt and Whitney planing craft "Thunderbird," propelled with a waterjet 

 system using the high solidity -rotor. 



TEST APPARATUS FOR WATERJET SYSTEMS 



The "physics" of waterjet propulsion are well understood. No new theoreti- 

 cal analyses other than those of an engineering nature are required. Further 

 development of optimum systems must be made through model and full-scale 

 experimentation. An example of such a model test and the experimental appa- 

 ratus used is given in Ref. (6). The tests described in Ref. (6) were carried out 

 in the Hydronautics, Inc. High-Speed Channel. The test rig is shown schemati- 

 cally in Fig. 11. The entire inlet-diffuser -pump-nozzle combination was sup- 

 ported as an isolated section of the tunnel roof. This section was supported on 

 linear bearings, so as to be free in the direction of flow. Power was supplied to 

 the pump through a thrust-torque dynamometer so that thrust on the entire sys- 

 tem could be measured along with the power supplied. The characteristics of 

 the waterjet system were obtained for a variety of forward speeds, pump rpm, 

 jet velocities, and discharges. Since the facility has a variable pressure capa- 

 bility, the effect of cavitation number may also be readily studied. Experiments 

 with the inlet closed provided tares for the thrust produced and velocity surveys 

 forward of the inlet and within the jet, provided deduced measurements of the 

 thrust breakdown; that is, drag added by the inlet. Complete details of the stud- 

 ies carried out are presented in Ref. (5). 



1052 



