Although this talk, to conform to the general pattern of the Symposium has the word “Economics” in its title, the plain fact is that nobody at the present time is able to make a reliable assessment of the economics, in the usual financial sense, of ramjet launchers.

Rockets have already demonstrated their ability to fill this role and assessments of the cost can be based upon real experience, as Mr. Rothrock's paper clearly shows. The use of ramjets for this duty, or more strictly for part of the duty, since we cannot hope to provide ramjet power all the way from take-off to orbit, remains problematical. The first step must be to prove the feasibility of using ramjets and only when some of the major problems on which feasibility hinges have been solved, can any really rational assessment of the probable cost be made.