Re: RLV physicaly impossible ?

Virtually all managers and most all engineers that have grown up in the 
current space hardware design bureaus have been steeped in the "rockets 
as artillery" school.  Design constraints are fire the engine once for 
testing, put it on the stand for its first flight, then through it away 
after four or five minutes operation.  Any effort or materials to give 
it a longer life are considered a waste.  This does not mean that large 
rocket engines can't be built for longer service, only that the 
engineers don't need it for "artillery" use.  A good example of a flight 
weight engine with long life is the RL-10.  This engine used on several 
upper stages was used (in the short bell version) for the DC-X, and has 
had dozens of starts and hours of total time.  
Another area that is not considered by most engineers developing RLVs is 
that propellents used by most designs are about three orders of 
magnitude lower in cost than flight hardware, and that adding propellent 
to reduce the quantity of flight hardware will eliminate any failure 
modes that were possible in the eliminated hardware.  An example would 
be if the Shuttle had no wings there would have been no wing leading 
edge failure.
RLVs require companies and engineers willing to try new paradigm, not 
just incremental improvements.  The Space Shuttle was a try, however 
many of its design requirements were made for political reasons not 
economic or technical. 

Mike

In article <[EMAIL PROTECTED]>,
 [EMAIL PROTECTED] (Henry Spencer) wrote:

> In article <[EMAIL PROTECTED]>,
> Paul Spielmann <[EMAIL PROTECTED]> wrote:
> >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.

> >...I still wonder though how long
> >life spans sub/orbital rlv vehicles will have though..