eugene@eos.UUCP (Eugene Miya) (09/30/89)
Yeah, I think Henry and I agree on this one. We need more X-30
type programs. And its not clear what kinds of directions are needed.
We sort of got side tracked from the X-15/X-20 lines of doing things.
Some years back I was looking at X-15 flight paths. These weren't trivial
tests, they had to fly all the way to Utah to launch and get to EAFB.
Imagine what troubles would have been.
The X-30 will require immensly area to test in. Saw a proposed test course
for it in a meeting. You have to keep to US airspace. I do not think
its just a matter of having ground facilities, or different vehicles.
There's a lot of research required for sustained hypersonic flight.
We don't have nearly enough knowledge as we would like, and then only
on the low end. So many questions so little time.
Another gross generalization from
--eugene miya, NASA Ames Research Center, eugene@aurora.arc.nasa.gov
resident cynic at the Rock of Ages Home for Retired Hackers:
"You trust the `reply' command with all those different mailers out there?"
"If my mail does not reach you, please accept my apology."
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Live free or die.henry@utzoo.uucp (Henry Spencer) (10/01/89)
In article <5292@eos.UUCP> eugene@eos.UUCP (Eugene Miya) writes: >Yeah, I think Henry and I agree on this one. We need more X-30 >type programs. And its not clear what kinds of directions are needed. >We sort of got side tracked from the X-15/X-20 lines of doing things.... >There's a lot of research required for sustained hypersonic flight. Actually, I was thinking of space launchers in general rather than hypersonic flight in particular -- I'm actually not convinced that hypersonic flight is the way to go for cheap spaceflight -- but the point still holds: too many ideas with potentially large payoffs are languishing on the ground instead of being tested in flight. -- "Where is D.D. Harriman now, | Henry Spencer at U of Toronto Zoology when we really *need* him?" | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
ccsupos@prism.gatech.EDU (SCHREIBER, O. A.) (10/02/89)
In article <1989Sep30.220055.28004@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes: >Actually, I was thinking of space launchers in general rather than >hypersonic flight in particular -- I'm actually not convinced that >hypersonic flight is the way to go for cheap spaceflight -- but the Has anybody ever proven that single stage to orbit is possible? I remember an engineer from Aerospatiale who was saying that it was not with the present structural indices possible (weight of fuel/ weight of structure of fuel tank). Perhaps he was not thinking of airbreathing engine configurations. Also, a hypersonic vehicle has to navigate in a narrow velocity-altitude region, between the sustentation barrier and the thermal barrier: too slow and high and it does not climb, too fast and low and it melts. Any opinion? -- Olivier Schreiber (404)894 6147, Office of Computing Services Georgia Institute of Technology, Atlanta Georgia, 30332 uucp: ...!{allegra,amd,hplabs,seismo,ut-ngp}!gatech!prism!ccsupos ARPA: ccsupos@prism.gatech.edu
raveling@isi.edu (Paul Raveling) (10/04/89)
In article <5292@eos.UUCP>, eugene@eos.UUCP (Eugene Miya) writes: > > Some years back I was looking at X-15 flight paths. These weren't trivial > tests, they had to fly all the way to Utah to launch and get to EAFB. > Imagine what troubles would have been. In the case of the X-15 the high speed part needed lots surface space, but once the speed dropped the vertical space it needed was another attention-getter. In the worst case, inadvertent speed brake deployment, the landing pattern was a 270-overhead, entered from 42,000 feet. A vertical view of the pattern up to final approach looks like a tightening curve with a typical radius of about a mile. It's a 45-degree banked turn @ 300 kt IAS, winding up as TAS decreases with altitude, using about 2 minutes from pattern entry to touchdown. Call it about 20,000 fpm descent rate. Can any of the NASA folks post info on the shuttle's approaches? Isn't the standard pattern a simple 180? What sorts of descent rate or glide slope profile does the shuttle have as a function of altitude & airspeed? ---------------- Paul Raveling Raveling@isi.edu
shafer@elxsi.dfrf.nasa.gov (Mary Shafer) (10/04/89)
In article <9991@venera.isi.edu> raveling@isi.edu (Paul Raveling) writes:
Can any of the NASA folks post info on the shuttle's
approaches? Isn't the standard pattern a simple 180?
What sorts of descent rate or glide slope profile does
the shuttle have as a function of altitude & airspeed?
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.)
--
Mary Shafer shafer@elxsi.dfrf.nasa.gov ames!elxsi.dfrf.nasa.gov!shafer
NASA Ames-Dryden Flight Research Facility, Edwards, CA
Of course I don't speak for NASAsrg@quick.COM (Spencer Garrett) (10/06/89)
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! :-}raveling@isi.edu (Paul Raveling) (10/06/89)
In article <6430@quick.COM>, srg@quick.COM (Spencer Garrett) writes: > > 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. That's about right, but I'm not convinced there's really a 3-degree portion. The approach profile is just about like the X-15's speed-brakes-inadvertently-extended approach, where the flare was a 2G pullup ending essentially on the deck. The end of this approach went like this: Time Altitude Speed Event (sec) (ft MSL) (knots) ----- -------- ------- -------------------------------- 23 5,200 325 Roll out onto runway heading 18 3,900 325 Begin flare (2G pullout) ~10 ..... ... Lower flaps 8 ..... 275 Flare completed: Drop gear, jetisson ventral fin 0 2,200 180 Touchdown BTW, earlier I cited a 300 knot approach speed. That's for a normal approach and for the 1st 2/3 of this emergency approach; procedure for this one calls for accellerating to 325 knots when approaching the 90-degree key point, which in a rectangular pattern would be the middle of the base leg. Note the level flight deceleration -- 95 knots in 8 seconds, about 20 ft/sec**2, or 2/3 G. > Now for the questions! Is "coming feet dry" the same as extending > the landing gear? I think Mary was referring to the point where the shuttle crosses the coastline. ---------------- Paul Raveling Raveling@isi.edu
lhe@sics.se (Lars-Henrik Eriksson) (10/06/89)
In article <6430@quick.COM>, srg@quick (Spencer Garrett) writes: >And what's the "E" in KEAS? Surely Edwards doesn't have its own >standard of measurement! :-} EAS = Equivalent Air Speed. This is the CAS corrected for the compressibility of air at higher speeds (higher dynamic pressure). In light aircraft the compressibility effects are negligible, so it is safe to set EAS=CAS. Indeed, when you convert TAS to CAS (or vice versa) using density altitude, you are usually converting between TAS and EAS instead, assuming EAS=CAS! -- Lars-Henrik Eriksson Internet: lhe@sics.se Swedish Institute of Computer Science Phone (intn'l): +46 8 752 15 09 Box 1263 Telefon (nat'l): 08 - 752 15 09 S-164 28 KISTA, SWEDEN
shafer@elxsi.dfrf.nasa.gov (Mary Shafer) (10/06/89)
In article <6430@quick.COM> srg@quick.COM (Spencer Garrett) writes: 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. I meant from West to North-West. The orbits aren't equatorial. (I think the angle of inclination can be over 40 deg, but I don't have one of the ground-track maps to confirm this.) They usually land on 17 or 22, although they have landed on 15. 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. They come around the HAC (heading alignment circle) and aim at a point on the lakebed about 1 mi before the touchdown point. This point is identified by a big X in black paint and a set of directional lights. (Actually they're narrowish spotlights.) This first portion, known appropriately as "final", is about a 20 deg glide slope. When they get fairly close to the ground they "flare" to a 3 deg glide slope, using the ball and bar beside the runway. 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! Coming "feet dry" means coming over dry land at the coastline. (I've been talking with too many Navy attack pilots. Sorry.) You're right about the gear; they pop it at about 150 ft AGL, maybe lower. It _always_ looks like they've left it until too late. And what's the "E" in KEAS? Surely Edwards doesn't have its own standard of measurement! :-} Equivalent. Ve = Vt * sqrt(rho/rhosl), where Ve is equivalent velocity, Vt true velocity, rho density at altitude, rhosl sea level density. (I need subscripts!) At sea level, Ve = Vt. In fact, at Edwards Ve pretty much equals Vt. However, at 40 K ft .... My Flight Test Engineer's Handbook says that Ve is frequently used for piston-engined aircraft (because it's a direct function of dynamic pressure, or qbar). We don't use it commonly here at Dryden, but we do use qbar itself. Since qbar is a primary measurement it's more sensible to use it, rather than Ve, which is a derived term. We mostly fly fighters and other military aircraft so we use KIAS or KCAS for airspeed. Is anybody interested in how and why we instrument our research aircraft? If so, I'll write something. -- Mary Shafer shafer@elxsi.dfrf.nasa.gov ames!elxsi.dfrf.nasa.gov!shafer NASA Ames-Dryden Flight Research Facility, Edwards, CA Of course I don't speak for NASA
scw@ollie.SEAS.UCLA.EDU (10/06/89)
In article <6430@quick.COM> srg@quick.COM (Spencer Garrett) writes: >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! :-} 'Feet Dry' is (US)Naval Avation (I wanted to say Navyese) talk for crossing the coast from sea to land, 'Feet Wet' is crossing the coast in the other direction. ----- Stephen C. Woods; UCLA SEASNET; 2567 BH;LA CA 90024; (213)-825-8614 UUCP: ...!{ibmsupt,hao!cepu}!ollie}!scw ARPA:scw@{Ollie.,}SEAS.UCLA.EDU