Comments on: Orbital Access Methodologies Part IV: Glideback TSTO

By: Jon Goff

Jon Goff — Fri, 25 Jul 2008 07:53:00 +0000

Iain,
You could probably consider that a form of glideback. But you always have to think about off-nominal landings and abort modes.

~Jon

By: Iain McClatchie

Iain McClatchie — Fri, 25 Jul 2008 07:24:00 +0000

Jon,

Does glideback TSTO include a vertical takeoff, paraglider return to launch site? The paraglider should be about 10% of the empty mass of the first stage. A decent RC pilot could do the final landing, and drop the thing right into a big net. With a suitable frame around the engines to keep them from getting badly torqued, that seems like a pretty clean return.

By: ザイツェヴ

ザイツェヴ — Fri, 20 Jun 2008 01:00:00 +0000

Yes, it’s me. Sorry for the katakana. It’s a historical artefact from before Blogger allowed varying IDs, due to, you know, anime — especially the one with a LOX-oxidized hybrid. I primarily blog anime these days:
http://ani-nouto.animeblogger.net/2007/06/23/rocket-girls-capsule-design/
http://ani-nouto.animeblogger.net/2007/12/10/rocket-girls-and-the-reality/

– Pete

By: Jon Goff

Jon Goff — Thu, 19 Jun 2008 23:28:00 +0000

Peter,
One thing about rocket powered HTHL vehicles is that they typically reach takeoff speed very quickly (high T/W compared to an airplane), which means they may have enough runway left to do an immediate emergency landing if their engines fail right at takeoff. XCOR's put a bit of thought into this sort of thing, but so far they've only tested some of their aborts using subsonic-optimized airframes (EZ-Rocket and XRacer). But I imagine if intact abort is a key design parameter, you can probably find a safe way to do it without having to give up too much performance. They'd be the ones to ask (though good luck getting an answer--they like to play their cards close to their chest over there).

~Jon

BTW, Are you the Peter Z. who has a livejournal talking about Linux and Opensource stuff? Just curious because I translated your nickname, and that's my best guess.

By: ザイツェヴ

ザイツェヴ — Thu, 19 Jun 2008 22:01:00 +0000

I figured that seawater was a major issue, considering the infamous cracked nut in F1. But just looking at those stubby high-mach wings makes me wonder how a HTHL would abort, not to mention how much a runway would cost. In the airplane world, early aborts are done forward, because people keep killing themselves trying to turn back to airport after a power loss. But yes, it looks like a dumb idea and I’m bringing a set of unsuitable prejustice into the discussion. Your blog series looked so comprehensive that I thought I’d ask anyway.

By: Jon Goff

Jon Goff — Wed, 18 Jun 2008 07:52:00 +0000

Mr X.,
Sure adding landing gear and proper takeoff wings to that first stage are going to cost something, but that first stage needs such a low mass ratio that it really doesn’t matter unless you’re trying to scale this up to really big payloads.

~Jon

By: Jon Goff

Jon Goff — Wed, 18 Jun 2008 07:51:00 +0000

Adam,
TPS == Thermal Protection System

HTH

~Jon

By: Anonymous

Anonymous — Wed, 18 Jun 2008 06:11:00 +0000

Don’t worry about the jargon, I’d rather you spent your blog time blogging rather than typing out the hideous, clunky phrases instead of the hideous, clunky, but shorter acronyms. Anyway, I got most of them figured out either be reading back posts, by deduction, or by context (I still don’t know what ‘TPS’ means, but I now know what it means–your vehicle’s method for dealing with re-entry heat).

-Adam Greenwood (www.timesandseasons.org)

By: Mr. X

Mr. X — Wed, 18 Jun 2008 05:42:00 +0000

I think NASA’s fetish for VTOHL comes from a desire to skimp on the landing gear, wings, and other essentials for horizontal flight. Keep everything sized for the spacecraft when it’s empty. I’d be interested in seeing how much mass would be added from the wings and gear from going HTOL, but I’m sure the results wouldn’t be pretty.

By: Jon Goff

Jon Goff — Wed, 18 Jun 2008 02:56:00 +0000

Selenite,
Yeah, but as I said, it isn’t as big of a deal for TSTO design. For an SSTO it’s a lot more important–but you can get many of those same benefits from air-launching.

~Jon