Morphing/Collapsible airframe, possible?

I was wondering, would a collapsible airframe be possible? Has there been any project to try it?

Also would it be possible to build collapsible internal fuel tanks? The fuel tanks would be along the fueselage, and as they empty the airframe would collapse to reduce drag.

Collapsible fuel tanks exist but not on military aircraft. They could be used for EFTs too.