Semi-Buoyant Airships
What about the modern reincarnations we keep hearing about? The proposed semi-buoyant heavy lift rigid skin craft the US military is interested in, like this
If a semi-buoyant airship with a 400 ton payload is feasible, (Presumably intended for deploying stuff like the M-1 Abrams and their requisite support infrastructure, or other high value heavy logistics packages) then could that technology be adapted to loft a CXV and it's booster? (Or similar spacecraft)
Are they just too slow and low?
