0* 20* 40* 00* 



Pi 



Figure 1 7. Strip theory for flow past yawed 



Figure 1 8. Variation of lift curve slope with 

 cone angle (/? 3 ). 



V. Concluding Remarks 



Having now completed our review of some of the recent advances in theoretical 

 hydroballistics it may be of value to comment briefly on the present position of research 

 in the several sections of the subject and to remark generally on some of the outstand- 

 ing problems which need attention if the science is to continue its advance. 



In this connexion it is clear that research on the steady cavity phase, especially 

 when the body has straight line contours so that the point of separation is known, is 

 much more highly developed than research on other aspects of the subject. Axi- 

 symmetric problems in the steady cavity phase have, at least with abrupt separation, 

 become mainly a question of the labour involved; this should resolve itself once ade- 

 quate programming techniques have been developed on high speed digital computers. 

 Before we can attain this happy state with curved profiles it will be necessary to under- 

 stand better the physical conditions at the point of separation. There is also a need for 

 exact solutions with yawed bodies. 



The entry phase remains a most difficult topic for basic research and calls for 

 further elementary solutions, especially for oblique entry, which may help us to under- 

 stand the flow mechanism during this phase. A direct theoretical attack on this 

 essential practical problem is still a distant objective. The need for carefully controlled 

 experimental data concerning this phase has been evident for several years and it is to 

 be hoped that such information will be available before long from the experimental 

 facilities in the U.S.A. and U.K. 



231 



