Xref: utzoo sci.aeronautics:97 sci.space:14417 sci.space.shuttle:3722
Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!uw-beaver!sumax!quick!srg
From: srg@quick.COM (Spencer Garrett)
Newsgroups: sci.aeronautics,sci.space,sci.space.shuttle
Subject: Re: X-30, Space Station Strangles NASP
Message-ID: <6430@quick.COM>
Date: 5 Oct 89 22:23:37 GMT
References: <5292@eos.UUCP> <4983@omepd.UUCP> <SHAFER.89Oct4080229@drynix.dfrf.nasa.gov>
Organization: Quicksilver Engineering, Seattle
Lines: 37

In article <SHAFER.89Oct4080229@drynix.dfrf.nasa.gov>, shafer@elxsi.dfrf.nasa.gov (Mary Shafer) writes:
-> 
-> The shuttle comes in from the north to north east.  It comes "feet
-> dry" at about Mach 7 and 145K ft, it's overhead at Edwards at Mach 1
-> at about 40K ft.  It does a HAC (Heading Alignment Circle) to put it
-> on the runway heading (usually 17 or 22), so essentially the pattern
-> is about a 270 teardrop with a longish final.  I think it's a 20 deg
-> glidepath, with a fairly short flair.  Final is flown at 285 KEAS,
-> gear deployed at 275 KEAS, touchdown at 185 KEAS.  (I'm taking these
-> figures from Young and Crippen's 1981 SETP paper on STS-1, so the
-> speeds may not be exact for any given mission, but they're about
-> right.)

Um, I believe that should be *towards* N-NE.  Equatorial orbits are
done in the same direction as the Earth's rotation, so they come in
from the W-SW.  (It costs an extra 2000 mph in acceleration to go
the other way.)  Flights employing polar orbits could come in from
either N or S, but I don't think any have yet been made in a Shuttle.
(And may never - I think they need the pad at Vandenburg for polar
launches, and I think that's been officially abandoned.)  Of course,
after that 270 teardrop I believe they do land towards the S-SW,
(ie - from N-NE) so maybe that's what you were talking about.

The Shuttle uses *two* glidepaths on final.  They fly most of the
approach on a 17 degree (as I recall) glideslope, then make an
abrupt pitch up to the normal 3 degree glideslope.  It looks
like the two intersect right off the end of the runway (where
"right off" may be a mile or two at these speeds) and they only
spend a few seconds (10 or 15?) on the 3 degree slope before
starting the flare.

Now for the questions!  Is "coming feet dry" the same as extending
the landing gear?  I'm pretty sure I remember seeing the gear pop
out *after* the flare, and I can't imagine having to design gear
(much less gear doors) that could handle Mach 7!
And what's the "E" in KEAS?  Surely Edwards doesn't have its own
standard of measurement! :-}