A powerful but short-legged point defense interceptor powered by a mix of jets and a rocket booster. I came up with this messing around with an idea for an aircraft that was more engine than wing, and incorporated bits and pieces of the Arado Ar 234, Horton flying wings, and some of the Bell lifting bodies. The pilot lies prone to minimize the effect of G-forces and to have a craft which can present the smallest possible frontal profile.
I figure... what if it was war? What if for whatever reason there was a need to shoot down ongoing incursions of flying saucers with the technology of the pseudo-1940s. Get to altitude as quickly as possible, launch your nuke, get out and try not to get shot down.