How hard would it be to build a hot-air blimp or dirigible?

Factual Questions
1

I was going to hijack this thread with this question, but I think it probably deserves its own thread.

How feasible would it be to build an airship similar in general design to blimp/dirigibles of the goodyear/zeppeling type - that is, one that can be moved around under power, as opposed to just going where the wind takes it… but using hot air for buoyancy instead of helium (or hydrogen)?

2

There are already hot air powered blimps. They’re not as big or have the same range as the Goodyear type blimps though.

3

D’oh! Oh, and here’s a link:

http://www.myairship.com/hotship/index.html