For a plane shockwave with a fixed small amplitude 
( Wo< 500 at) and smaller angles of incidence it therefore 
can be derived that @ sa 7 and, @'& © as long as 
@ is much larger than @),, , that is, as long as @ is far 
off from the critical Mach angle. The more @ approaches 
@, » the more a falls off comparied with @ and the more 
WF increases. For @ = & @,, the difference is still 
only 10%. But for the critical case @ = ®,, it is found 
@‘= =F and #7 +27. The derived theory no more holds 
for @© >@,, that is for the range when a Mach wave (Bridge 
wave) occurs. 
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