On Tue, Sep 20, 2016 at 10:08 PM, Evan Daniel <evanbd@xxxxxxxxx> wrote:
On Tue, Sep 20, 2016 at 9:56 PM, Keith Henson <hkeithhenson@xxxxxxxxx> wrote:
If anyone has another proposal that will get the cost down below
$100/kg to LEO, I would sure like the read the proposal.
At what capital cost and launch rate?
If you're seriously considering
space elevators, then you probably give launch loops some serious
consideration as well. Fewer materials science headaches, fewer power
transmission headaches, but they pay for it with other difficulties
surrounding a high speed cable and a lightweight cable management
system.
The wiki article covers the basics and references the major works, I think:
https://en.wikipedia.org/wiki/Launch_loop
VTVLs can be flown places where a WWJ can't land or take off. Whether
they would be allowed to is a different question... but then, the WWJ is
quite likely to be constrained by things like noise regulations too.
(It's going to be a lot louder than a 747, and horizontal takeoff means
flying low over surrounding areas.)
"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). It's not just possible
that there are big new problems lurking and much of the existing
experience is inapplicable -- it's almost inevitable.