Could we take the idea a step further and use launch catapults as used by aircraft carriers?

A steam catapult launching 747 sized jets over a cliff edge - I'm glad that in 40 years I will likely be too old to fly:-))

I believe the most logical place that talk of hydrogen and flight leads is air ships which overcomes the need for a launch velocity.

He didn't say steam, he didn't say over a cliff. Maybe his idea wasn't good, but you filled in details that he did not provide as if you had to reach this conclusion. What if you took the opposite approach?

--- G. R. L. Cowan, former hydrogen-energy fan
http://www.eagle.ca/~gcowan/Paper_for_11th_CHC.html :
oxygen expands around boron fire, car goes