In message , Andrew Chaplin
writes
"Yeff" wrote in message
...
On Mon, 27 Mar 2006 18:49:43 -0500, Andrew Chaplin wrote:
Why the loss of performance?

It doesn't start off with the speed of a launching aircraft.

That's what I thought it would be. So one needs something like a boost
stage if one is to have anything like the same envelope?

Very much so - you get a big difference in energy between lighting the
motor off at co-altitude and 450kt initial airspeed, compared to stopped
and on the ground. Also, with ground launch you're doing all your
accelerating in dense air, which means more drag and so you get less
velocity for your efforts, compared to launching from 20kft (and you
certainly have a better chance of having an altitude advantage, at least
since the Buccaneers retired )

As an example, in open source figures for a good-case target (fast
inbound head-on) you tend to see twenty-odd miles listed as AIM-7
Sparrow range, but maybe eight for RIM-7 Sea Sparrow.


--
He thinks too much: such men are dangerous.
Julius Caesar I:2

Paul J. Adam MainBoxatjrwlynch[dot]demon{dot}co(.)uk