[narby]

The image here is labeled XB-70 and X-15, but I think that it is rather the DynaSoar launching from underneath the XB-70. It must have been an old concept image from before this thing went black.

Note the scramjet looking ramp on the bottom. That's not the X-15. Vertical tail is wrong too.

Remember that one of the last X-15 flights was a test of a scramjet engine, so this stuff has been under development for a long time.

With 20/20 hindsight, was the XB-70 ever supposed to be a "bomber" at all, but instead a first stage of an orbital system.

[orionblamblam]

> Note the scramjet looking ramp on the bottom. That's not the X-15. Vertical tail is wrong too.

Nope, that's the X-15. X-15 A-3, to be exact, which was to have an extended fuselage, a larger expansion-ratio engine and delta wings. The problem you're ahving with the dorsal fin is that the A-3 was also to have wingtip fins; the "scramjet ramp" on the underside is actually the port delta wing.

There *were* airbreathing X-15's studied, such as the SERJ-equipped concepts from Marquardt, see below. However, the B-70/X-15 concept shown was for a regular rocket version, just capable of higher speed. However, as the D-21/M-12 disaster showed, launching off the back of a supersonic aircraft is a recipe for total vehicle loss. Best to drop from underneath.