On 21/09/16 05:56, Henry Spencer wrote:
On Tue, 20 Sep 2016, Peter Fairbrother wrote:
First of all, weather - it does seem evident that a WWJ can operate in
higher winds than a VTVL.
As per other postings, no, that's not evident, and indeed there is good
evidence that it's the other way 'round.
Has it escaped your attention that SpaceX is *already* landing their
VTVL first stages at the takeoff site? And they're coming back from a
fair way downrange to do that, too. You don't need to backtrack in
advance if you can backtrack after separation instead.
Even if that was not possible, I don't think a VTVL can be refuelled,
recargoed, and take off from the spot where it landed.
It has been done.
"This *isn't* just like an airplane." -- Jeff Greason.
No, but a WWJ is a lot more like an airplane...
Again you're appealing to faith rather than logic. No, it *isn't*
necessarily a lot more like an airplane -- that was precisely Jeff's
point. One WWJ is not just like another. When you start wanting
seriously high performance, you can easily find yourself operating in
areas of the trade space that are actually very poorly populated, with
little real past experience to go on.
(Historical example: the designers of the US SST discovered, to their
dismay, that although it had seemed like there was a lot of experience
with supersonic aircraft, very little of it was relevant! Brief sprints
to Mach 2.5+ had little in common with trying to cruise at such speeds,
and they were spending a lot of extra money and time pioneering new
technology in areas where they'd expected off-the-shelf solutions.)
Indeed, "very poorly populated" is probably an understatement. Mach 6
at 100km is beyond anything ever done with a WWJ. Even the X-15
couldn't do that (either one, but not both simultaneously).
