I'm posting this link to another site.  The specifics in this link are about hypersonic vehicles so I posted it here although there is some discussion of nuclear issues as well.  Anyway it is an interview with Paul Czsyz who was for years McDonnell Douglas's top hypersonic engineer specialist and chief engineer on the NASP prior to his retirement.  He then was professor of aerospace engineering at St. Louis university.  Although I never met him within I work at McDonnell Douglas (before the Boeing merger/buyout) but by reputation he is one bright guy.  One other point: I was a bit surprised at seeing his stuff listed on a site called "American Antigravity" but Lisa Randall of the Harvard Physicist has been interviewed there too but if get past Czxyz's stuff you will enter the area of concepts beyond known physical principles. 

http://www.americanantigravity.com/articles/432/1/Paul-Czsyz-Interview-for-Broadband/Page1.html

http://video.google.com/videoplay?docid=-8822205208616104905&pr=goog-sl