"Hobo" wrote in message

Many low-cost space launch concepts have been proposed over
the years.
How practical is this one?

During one of the threads concerning whether or not the F-22 could go
past mach 2 without variable inlets someone mentioned the possibility
of injecting water into the airflow and said that this had been
previously tested on a F-4 which got past mach 2.5 using the system.
If I
understood the article correctly they are going to try and use a
similar system.

As to the space-launch issue, I think you have to get up to around
mach 25 to enter into a stable orbit and I don't see how this system
is going to get you going that fast.

The air-breathing vehicle doesn't get anywhere close to that fast. The
expendable rocket upper stage adds the oomph to get the (very small) payload
rom 200,000 ft into orbit. Note that the reusable air vehicle carries
16,000 lbs of rocket aloft to put a total of 110 pounds into orbit. One
might profitably ask whether you gain a whole lot by not simply putting the
expendable upper stage on an expendable lower stage and launching the stack
from a pad somewhere. The savings sources offered seem questionable to me
and some could be used by a conventional expendable anyway.

The other real problem here is that the whole concept is premised on being
able to get a useful reconaissance payload (what else needs to be
sun-synchronous?) into a 110-lb package. I'm not holding my breath.

--�
Tom Schoene Replace "invalid" with "net" to e-mail
"If brave men and women never died, there would be nothing
special about bravery." -- Andy Rooney (attributed)