Hi,

The answer to the origional question is quite simple.
The thrust to weight ratio of jet engines is BAD, really bad. The best jet
engines are around 10 or 12:1 and most are 5:1 or less. Bottom line: they
are just too friggin heavy... lol

As Always,

Jay Troetschel

"Sander Vesik" wrote in message
...
In sci.space.policy Axel Walthelm wrote:
wlhaught wrote:
Alright, back to powered flybacks for first stages. Are jet engines
worth the trouble of extra systems?

As I recall, I read somewhere that the shuttle uses half its fuel to
reach 1,000 mph.


You sure?

I have a copy of a speed/height/time diagram of the shuttles ascend.
1000 mph would be 1600 km/h. The diagram says that this speed is
reached within the first minute of launch at a height of about 8-10
km.

Launch takes 8.5 minutes, boosters burn 2 minutes. If you would say
half of the boosters fuel is used up at 1000 mph that would fit. But
total fuel including the fuel of the big external tank?

Ok, solid booster rocket fuel is quite heavy, and the booster burns
faster in the beginning than at the end. So maybe overall this could
be true.

But what does it mean? Solid rocket boosters are not economic?

"You should use a different flight profile that didn't try to
get to high speed while in teh densest parts of teh atmosphere"?


--
Sander

+++ Out of cheese error +++