James Logajan wrote in message 5...
(Paul Spielmann) wrote:
[...] let me remind you about the physical laws of thermodynamics (heat)
that makes it impossible to turn the engines on and off forever or
at least alot of times!

I turn my car engine on and off a lot. Jet engines get turned on and off a
lot. Not sure what physical law you are talking about.

Or am i wrong ?

I don't want to be the one to break the bad news to you....

here is the thing i am really not so sure by my own nolage, its just
that i have asked peoeple that i think are credible people that work
in the field of physics (not space engineering though) and accoarding
to what they have said: the energy and heat stress of going to orbit
and back are much more higher than for example what a car experience
and therefore it cuts back what is possible to do with space crafts.
Either the person i asked is right or wrong because he is no expert in
space crafts and is too "theoretical". I still wonder though how long
life spans sub/orbital rlv vehicles will have though..