Manual re-entry?
Mary Pegg
a reference on the web the other day to somebody once flying a manual
re-entry, i.e from orbit to ground.
Did this happen? I've done a lot of googling since and I've
not found anything on this.
Also, how much of the landing can be done automatically?
Again, I recall a website / posting / something saying that
the only thing that *must* be done manually is lowering the
landing gear.
I've read as many FAQs as I can, but...
Jorge R. Frank
news:Xns92D33EB6E...@80.1.224.4:
> Hope this doesn't sound like too stupid a question, but I came across
> a reference on the web the other day to somebody once flying a manual
> re-entry, i.e from orbit to ground.
>
> Did this happen? I've done a lot of googling since and I've
> not found anything on this.
Hasn't happened in the shuttle program, to my recollection. The only
scenario that would require an *entire* entry to be flown manually would be
if the crew had to shut down the four primary computers and engage the
backup, which has no auto re-entry capability.
> Also, how much of the landing can be done automatically?
> Again, I recall a website / posting / something saying that
> the only thing that *must* be done manually is lowering the
> landing gear.
For landing, yes, the only thing that *must* be done manually is to lower
the gear. For entry, there are a number of other manual-only tasks like
deploying the air data probes.
--
JRF
Reply-to address spam-proofed - to reply by E-mail,
check "Organization" (I am not assimilated) and
think one step ahead of IBM.
Stuf4
> Hope this doesn't sound like too stupid a question, but I came across
> a reference on the web the other day to somebody once flying a manual
> re-entry, i.e from orbit to ground.
>
> Did this happen? I've done a lot of googling since and I've
> not found anything on this.
Although this can be done and is practiced in the simulator, no one
has ever done it. I've been told by a person who has worked shuttle
entry at JSC throughout the entire program that there have only been
two astronauts who have flown manually while the shuttle was
supersonic, and this was only for a short duration. While human
memory can be faulty, I am certain that if someone had flown a manual
entry, he would have known about it and it would stand out in his mind
(along with many others).
My conversation with this person happened a long time ago. What I
recall him telling me is that Young and Engle flew S-turns during OFT.
> Also, how much of the landing can be done automatically?
> Again, I recall a website / posting / something saying that
> the only thing that *must* be done manually is lowering the
> landing gear.
As you've probably guessed, it is simple to rig the gear to deploy
automatically. If you want details on how easy it is to fly the
shuttle with no one on board, you can search the archives for [shuttle
autoland].
I have heard a story that the shuttle was once flown to near touchdown
with the autopilot engaged. This happened inadvertantly because the
commander *thought* he was flying it (something to do with a double
push of the CSS -control stick steering- button).
> I've read as many FAQs as I can, but...
Another interesting story is the shuttle's "manual direct" mode. From
the archives:
"In the early days of Shuttle there was a "manual direct" mode which
translated hand controller position directly into surface motion. It
was insurance against the control system becoming unstable if the
actual aerodynamics were different from the predictions. It quickly
demonstrated the native handling qualities (instant transition to
inverted flight) of the Orbiter were really near non-existant, and
gave me real respect for the astronaut's piloting skills that could
keep the Manual Direct beast under control in both the ground
simulators and in the shuttle training aircraft. Fortunately the aero
and control systems did quite nicely and Manual Direct was the first
function removed from the cockpit."
(From news:<01bbb562$73c603c0$a179...@dialin.phoenix.net>)
As with the story of how the YF-12C(SR-71) was used in the shuttle
program, I'm sure that there are other members of the forum who have
lots more info on this topic, but for some reason a sci.space search
on [manual direct] turns up empty.
Here's a photo of the old shuttle simulator:
http://www.dfrc.nasa.gov/gallery/photo/Simulator/HTML/ECN-13409.html
If you click on the large image format, you can actually read the
buttons on the "dash board" (to the right of the "body flap" and
"speed brake / throttle" buttons) that say:
_______ _______ ________
| | | | | |
| GAIN | | CSS | | AUTO |
| ENA | | | | |
|_______| |_______| |________|
...in both Pitch and Roll/Yaw channels. I figure that "GAIN ENABLE"
is the term that was used for the "manual direct" mode.
The button to the left of the "body flap" AUTO/MAN is labeled "BFC".
I figure that Backup Flight Control was engaged by pushing this
button. The BFS (Backup Flight System) software took more deliberate
action to engage when Columbia took to flight.
~ CT
Mary Pegg
news:Xns92D3676E...@204.52.135.10:
> For landing, yes, the only thing that *must* be done manually is to
> lower the gear.
Next dumb question - why fly it manually for the touchdown?
Mary Pegg
Mary Shafer Iliff
>
> Mary Pegg <m...@widetrouser.freeserve.co.uk> wrote in
> news:Xns92D33EB6E...@80.1.224.4:
>
> > Hope this doesn't sound like too stupid a question, but I came across
> > a reference on the web the other day to somebody once flying a manual
> > re-entry, i.e from orbit to ground.
> >
> > Did this happen? I've done a lot of googling since and I've
> > not found anything on this.
>
> Hasn't happened in the shuttle program, to my recollection. The only
> scenario that would require an *entire* entry to be flown manually would be
> if the crew had to shut down the four primary computers and engage the
> backup, which has no auto re-entry capability.
Actually, STS-2 had a hand-flown reentry, because of the
problem with the energy management maneuvers on STS-1 (L_YJ
was the wrong sign and twice the magnitude of the estimate,
so sideslip exceeded the limit briefly). It wasn't from
orbit to runway, because the OMS burn was done automatically.
It was just from entry interface (enough molecules of air
to count as atmosphere) to runway.
I don't know what they used for guidance but I'm sure they
had it and used it to fly the trajectory.
I think you can read about it at dfrc.nasa.gov, in the
research paper archive. Look for Iliff and Shafer, in
about 1993 or so.
Mary
Jorge R. Frank
news:3DE52F4E...@qnet.com:
> Actually, STS-2 had a hand-flown reentry, because of the
> problem with the energy management maneuvers on STS-1 (L_YJ
> was the wrong sign and twice the magnitude of the estimate,
> so sideslip exceeded the limit briefly). It wasn't from
> orbit to runway, because the OMS burn was done automatically.
> It was just from entry interface (enough molecules of air
> to count as atmosphere) to runway.
Major modes 304 and 305, then?
> I think you can read about it at dfrc.nasa.gov, in the
> research paper archive. Look for Iliff and Shafer, in
> about 1993 or so.
Thanks for the heads-up. There are actually three reports in 1993 by Iliff
and you about the shuttle, Do you remember which one? None of the abstracts
mention manual entry, and the reports themselves aren't online.
A COMPARISON OF HYPERSONIC VEHICLE FLIGHT AND PREDICTION RESULTS
SPACE SHUTTLE HYPERSONIC AERODYNAMIC AND AEROTHERMODYNAMIC FLIGHT RESEARCH
AND THE COMPARISON TO GROUND TEST RESULTS
EXTRACTION OF STABILITY AND CONTROL DERIVATIVES FROM ORBITER FLIGHT DATA
Jorge R. Frank
The astronauts don't trust autoland.
Greg D. Moore (Strider)
"Jorge R. Frank" <jrf...@ibm-pc.borg> wrote in message
news:Xns92D3AD8C...@204.52.135.10...
> Mary Pegg <m...@widetrouser.freeserve.co.uk> wrote in
> news:Xns92D3C4166...@80.1.224.4:
>
> > "Jorge R. Frank" <jrf...@ibm-pc.borg> wrote in
> > news:Xns92D3676E...@204.52.135.10:
> >
> >> For landing, yes, the only thing that *must* be done manually is to
> >> lower the gear.
> >
> > Next dumb question - why fly it manually for the touchdown?
>
> The astronauts don't trust autoland.
Don't trust? Or don't want to feel redundant?
Seriously, considering that take-off is flown automatically.
Mary Shafer Iliff
>
> Mary Shafer Iliff <mil...@qnet.com> wrote in
> news:3DE52F4E...@qnet.com:
>
> > Actually, STS-2 had a hand-flown reentry, because of the
> > problem with the energy management maneuvers on STS-1 (L_YJ
> > was the wrong sign and twice the magnitude of the estimate,
> > so sideslip exceeded the limit briefly). It wasn't from
> > orbit to runway, because the OMS burn was done automatically.
> > It was just from entry interface (enough molecules of air
> > to count as atmosphere) to runway.
>
> Major modes 304 and 305, then?
>
> > I think you can read about it at dfrc.nasa.gov, in the
> > research paper archive. Look for Iliff and Shafer, in
> > about 1993 or so.
>
> Thanks for the heads-up. There are actually three reports in 1993 by Iliff
> and you about the shuttle, Do you remember which one? None of the abstracts
> mention manual entry, and the reports themselves aren't online.
>
> A COMPARISON OF HYPERSONIC VEHICLE FLIGHT AND PREDICTION RESULTS
>
> SPACE SHUTTLE HYPERSONIC AERODYNAMIC AND AEROTHERMODYNAMIC FLIGHT RESEARCH
> AND THE COMPARISON TO GROUND TEST RESULTS
>
> EXTRACTION OF STABILITY AND CONTROL DERIVATIVES FROM ORBITER FLIGHT DATA
The S&C one, because L_YJ is a control derivative (it's
yawing moment due to yaw jet).
Actually, they're all three excellent, although most of
the second one is included in the first one. I did the
actual writing on all three and Iliff says I did a better
job of it than he could have, but that just means that
there weren't any sentences half a page long and all the
sentences had subjects and predicates. He's not that fond
of the actual writing and I am, so he likes to encourage
me. (I didn't marry Ken 32 years ago because he was dumb).
Might someone like to scan them in and put them online?
I've got a very few of the first, a few of the second,
and a good few of the third. I could probably spare
one of each for such a project.
Mary
Jon Berndt
> Might someone like to scan them in and put them online?
> I've got a very few of the first, a few of the second,
> and a good few of the third. I could probably spare
> one of each for such a project.
These look very interesting - offhand I'd be inclined to think (given the
titles) they'd be good for modeling and simulation purposes. Are they pretty
hefty documents?
Jon
Mary Pegg
news:FwcF9.110829$Em.34...@twister.nyroc.rr.com:
> "Jorge R. Frank" <jrf...@ibm-pc.borg> wrote in message
> news:Xns92D3AD8C...@204.52.135.10...
>
>> The astronauts don't trust autoland.
>
> Don't trust? Or don't want to feel redundant?
"Pilots love to fly", as they say?
> Seriously, considering that take-off is flown automatically.
Hypothesis 1: it's a cultural issue, not a technical one.
Shuttle pilots train intensively on the STA (as they need
to, in case the computers "blue-screened") and to prevent
that looking like a waste of money, they put the practice
into practice.
And pilots love to fly.
Hypothesis 2: *all else being equal*, make the manual
approach the default one. That way your backup system
is not going to be flustered by the fact that it's been
called into play because something has gone wrong.
Hypothesis 3: <troll>humans make better pilots.</troll>
>> Reply-to address spam-proofed - to reply by E-mail,
>> check "Organization" (I am not assimilated) and
>> think one step ahead of IBM.
Spam-proofed *and* low-IQ-proofed. I like it.
Further questions - you lot seem to have a *lot* of patience
with a newcomer. (I'll confess to not lurking for two months
before posting.)
1. <another_troll> "Blue-screened" reminds me: In Peggy Whitson's
letter home #13 she talks of "routine things like rebooting laptops"...
sorry, I've forgotten what the question was <g>. </another_troll>
2. On STS-1's landing, the Orbiter looked at one moment like
it was about to flip, and I've since read other comments about
this. What was the final verdict?
I expect these two have been done to death here - but still,
any answers are, as ever, appreciated.
Mary Pegg
> Actually, STS-2 had a hand-flown reentry, because of the
> [snip]
> It was just from entry interface (enough molecules of air
> to count as atmosphere) to runway.
"just"...? Engle and Truly probably had to put their balls
in the payload bay for lack of space on the flight deck...
David Higgins
Mary Pegg wrote:
>
> 2. On STS-1's landing, the Orbiter looked at one moment like
> it was about to flip, and I've since read other comments about
> this. What was the final verdict?
??? Are you thinking of STS-2/3/4 (can't remember which
one) where the nose was coming down a little too fast
and the pilot appeared to over control, driving the nose
*way* up? I don't remember STS-1's landing being abnormal.
Or perhaps one of the Enterprise drop tests, where (if my
failing memory works for once) a bad case of PIO developed.
Al Jackson
> "Jorge R. Frank" wrote:
> >
> > Mary Pegg <m...@widetrouser.freeserve.co.uk> wrote in
> > news:Xns92D33EB6E...@80.1.224.4:
> >
> > > Hope this doesn't sound like too stupid a question, but I came across
> > > a reference on the web the other day to somebody once flying a manual
> > > re-entry, i.e from orbit to ground.
>
> Actually, STS-2 had a hand-flown reentry, because of the
> problem with the energy management maneuvers on STS-1 (L_YJ
> was the wrong sign and twice the magnitude of the estimate,
> so sideslip exceeded the limit briefly). It wasn't from
> orbit to runway, because the OMS burn was done automatically.
> It was just from entry interface (enough molecules of air
> to count as atmosphere) to runway.
>
That is interesting! I don't remember 'entry interface' ever being
flown
manually. This is because I have heard that the 'dutch roll' maneuver
at entry interface has proved very difficult to fly , manually, in the
simulators.
I guess they still do this slow roll maneuver to distribute the 'hot'
re-entry heating on the tiles? [At least on that part of the re-entry
trajectory.]
Greg D. Moore (Strider)
"Mary Pegg" <m...@widetrouser.freeserve.co.uk> wrote in message
news:Xns92D41ABAA...@80.1.224.4...
>
> 2. On STS-1's landing, the Orbiter looked at one moment like
> it was about to flip, and I've since read other comments about
> this. What was the final verdict?
>
I believe you're probably referring to the incident that Mary mentioned that
during an S-turn the shuttle banked more than planned?
Mary can go into detail on that.
Stuf4
> [snip]
>
> Thanks.
You're welcome. And welcome to the forum, by the way.
I would like to learn more about Mary's (the Dryden Mary) paper where
she says that Engle hand flew from 400k (EI) to touchdown. I've never
heard this in any of the discussions that I've had with people who
would have known (Jorge is another person who I expect would clearly
know about something as major as this). Nor have I read about it
anywhere before. Curious.
Last I checked, Joe Engle still has an office in Building 1 at JSC.
It would be great to get the story straight from the man himself.
Hand flying a full entry isn't a difficult task in terms of hand-eye
coordination, but it does get tedious (as related by someone who has
done it many times in the sim).
~ CT
Roger Balettie
> Hand flying a full entry isn't a difficult task in terms of hand-eye
> coordination, but it does get tedious (as related by someone who has
> done it many times in the sim).
I've done several "manual" entries in the simulators... it's not tough, if
you have guidance to follow. But... if you have Entry Guidance active, why
fly manual? That's what it's there for.
Roger
--
Roger Balettie
former Flight Dynamics Officer
Space Shuttle Mission Control
http://www.balettie.com/
Jorge R. Frank
news:eovF9.82059$8D.19...@twister.austin.rr.com:
> "Stuf4" <tdadamemd-...@excite.com> wrote:
>> Hand flying a full entry isn't a difficult task in terms of hand-eye
>> coordination, but it does get tedious (as related by someone who has
>> done it many times in the sim).
>
> I've done several "manual" entries in the simulators... it's not
> tough, if you have guidance to follow. But... if you have Entry
> Guidance active, why fly manual? That's what it's there for.
The two examples given previously in the thread were bad control derivative
I-loads (so PASS guidance is GO, but auto flight control is NO-GO), or BFS
engage (BFS has guidance down to 1500 ft, but no auto flight control).
A third I can think of is lack of air data to G&C by Mach 2.5, but that
only requires the crew to fly theta limits, not full manual control in all
axes. There are several other circumstances where the crew would have to
fly theta limits, but I can't remember them offhand.
Mary, Andy... any others?
--
JRF
Stuf4
> has ever done it. I've been told by a person who has worked shuttle
> entry at JSC throughout the entire program that there have only been
> two astronauts who have flown manually while the shuttle was
> supersonic, and this was only for a short duration. While human
> memory can be faulty, I am certain that if someone had flown a manual
> entry, he would have known about it and it would stand out in his mind
> (along with many others).
>
> My conversation with this person happened a long time ago. What I
> recall him telling me is that Young and Engle flew S-turns during OFT.
Here are a couple of references I just found in support of what Mary
Shafer Iliff posted:
"...in November 1981, commanded STS-2, a flight in which he manually
flew re-entry – the only time a winged aerospace vehicle has
been manually flown from orbit through landing."
(From http://www.edwards.af.mil/archive/2001/2001-archive-astronaut_hall_of_fame.html)
"On 12 November 1981, he commanded Space Transportation System (STS)-2
and manually flew the Shuttle Columbia from space at Mach 25 to
landing, a feat never repeated, while performing flight test maneuvers
to explore the shuttle's aero-thermodynamic characteristics."
(From http://www.au.af.mil/au/goe/eaglebios/01bios/engle01.htm)
Again, this leaves open the question as to why such a major
accomplishment is not more widely known. It would be great to hear
Joe's first hand account of flying this entry.
~ CT
Stuf4
I didn't check for the others, but the S&C paper *was* online:
http://www.dfrc.nasa.gov/DTRS/1993/PDF/H-1912.pdf
Scanning through it, I didn't see where the paper stated how much of
the entry that Engle flew, although I found other sources (posted
elsewhere in this thread) stating that Engle flew the full entry.
Here are some excerpts from this Shafer Iliff Shuttle S&C paper:
(From p8of48)
The Space Shuttle Orbiter trajectory during reentry and,
therefore, its heating profile are controlled through a
series of energy-management bank reversals. The vehicle
is controlled by conventional aerodynamic surfaces and by
the RCS jets. The first bank reversal on the first Space
Shuttle flight, STS-1, resulted in a significantly larger
response than had been predicted.
...
It is fortunate that a conservative control system design
philosophy had been used for the Space Shuttle. Although
the flight maneuver resulted in excursions greater than
planned, the control system did manage to damp out the
oscillation in less that 1 min.
(From p9of48)
The primary problem with the initial bank maneuver was the
poor prediction of L[subscript]YJ. The Space Shuttle control
system software is very complex and cannot be changed and
verified between missions. As a result, an interim approach
was taken to keep this large excursion from occurring on future
flights. First, the flight-determined derivatives were put into
the simulation database. Next, Space Shuttle pilots practiced
performing the maneuver manually, trying to attain a smaller
response within more desirable limits. Then, the maneuver was
performed manually on STS-2 through STS-4.
...
The software was updated for STS-5, ...
~ CT
Mary Shafer Iliff
>
> "Stuf4" <tdadamemd-...@excite.com> wrote:
> > Hand flying a full entry isn't a difficult task in terms of hand-eye
> > coordination, but it does get tedious (as related by someone who has
> > done it many times in the sim).
>
> I've done several "manual" entries in the simulators... it's not tough, if
> you have guidance to follow. But... if you have Entry Guidance active, why
> fly manual? That's what it's there for.
Because the FCS had proven, on STS-1, that it had a glitch
in it that could cause the loss of the vehicle. A beta of
over 2 deg means that the stagnation point has moved off the
carbon-carbon nose cap that's designed for that much heat
and onto the tiles that aren't. Pilots are highly averse
to burning holes in the vehicle, so this generated a
certain amount of concern.
However, we were still working on what was wrong and how to
fix it. Since hand-flying a manual reentry was possible with
guidance and hand-flying meant that the energy management turns
could be flown to keep the stagnation point on the nose cap,
the powers that be decided to go with it.
Meanwhile, the S&C guys were pinning down the problem to L_YJ
and coming up with a new automatic energy management turn
technique. I don't remember when they did the FCS upgrade,
but the more I think about it, the more I think that STS-2
was just the first to be hand-flown. I'm pretty sure 3 & 4
were, too, and it might have continued until about STS-12,
when Columbia went down for an FCS upgrade.
It's been a while and the answer's in the paper, which is at
work, where I'm not.
Everyone does understand that this is aerodynamics, pure and
simple, right? And the fix was in the S&C terms used in the
FCS? It wasn't imaginary or political or anything. All the
information has been published repeatedly in public documents
in the '80s. If you don't know about it, it's because you
skipped all those AIAA papers, not because it was concealed.
Mary
Mary Shafer Iliff
>
> "Mary Pegg" <m...@widetrouser.freeserve.co.uk> wrote in message
> news:Xns92D41ABAA...@80.1.224.4...
> >
> > 2. On STS-1's landing, the Orbiter looked at one moment like
> > it was about to flip, and I've since read other comments about
> > this. What was the final verdict?
I didn't see anything like that. He greased it on,
in as slick a landing as you'd ever want to see.
Might you be thinking of STS-3, at White Sands? There
was a bobble on that landing, but it never looked as if
it were in any danger of flipping or anything.
The ALT-5 PIO problem had been fixed long before STS-1,
with a PIO suppressor dropped into the FCS.
> I believe you're probably referring to the incident that Mary mentioned that
> during an S-turn the shuttle banked more than planned?
No one saw it, because it was just after entry interface. We
didn't even know about it because of the usual pre-TDRSS lack
of comm. Believe me, however, John Young didn't let us remain
ignorant for long.
Mary
john_thomas_maxson
news:d3af8584.02112...@posting.google.com...
>
> Again, this leaves open the question as to why such a major
> accomplishment is not more widely known. It would be great
> to hear Joe's first hand account of flying this entry.
I thought everybody knew it was mixed -- manual and automatic.
Although my book covers launch and it's references have been
ridiculed by some JSC folks in this group, one of those references
has a couple of fine pages on the STS-2 entry.
Here are just a few teasers fom 'An Illustrated History of Space
Shuttle,' by Melvyn Smith (1985) pp. 182-183:
"The day of re-entry began for Joe Engle and Dick Truly with a
call up from Houston. A quick chorus of patriotic naval music
was followed in lighter vein by a prerecorded message from
characters in the popular TV series The Muppets. Two astronaut
muppets spoke to the crew: 'We wish the Columbia happy
landings. We will be staying here in the outer reaches of space
--- because we don't know how to get down!! Oh! Joe --- Dick
--- which button do you press? Help --- give us a break!'
... ... ...
... As Columbia streaked across the Pacific sky at Mach 25, Joe
Engle manually performed a series of manoeuvres using Columbia's
reaction controls to gather data on her hypersonic handling.
... ... ...
... Joe Engle was switching control to automatic and then back to
manual performing a series of tests before flying around the
approach circle manually and then onto automatic control for the
first part of the approach and landing phase.
... ... ...
... Tenuous contrails streamed back from Columbia's wing tips.
'Columbia, this is Houston. 3,000 ft low now out of 24,000 ft.'
--- 'Roger that.' --- 'We're showing 290 at 20,000 ft.' --- 'Check
body flaps to manual.' --- 'Roger, body flaps on manual.' "
(Fair use intended here. The entire two pages are excellent.)
JTM
Jorge R. Frank
They're 45, 31, and 50 pages, respectively. To see the full abstracts, go
to <http://www.dfrc.nasa.gov/DTRS/index.html> and enter the keywords "iliff
AND shafer AND shuttle".
If I had a better scanner, I'd take her up on the offer myself.
Jorge R. Frank
> "Jorge R. Frank" wrote:
>
>> EXTRACTION OF STABILITY AND CONTROL DERIVATIVES FROM ORBITER FLIGHT
>> DATA
>
> The S&C one, because L_YJ is a control derivative (it's
> yawing moment due to yaw jet).
Dumb question: is that really rolling moment, or did NASA change the
standard nomenclature (I usually associate L-M-N with roll-pitch-yaw). The
latter wouldn't surprise me one bit. It also wouldn't surprise me if I
misremembered the L-M-N roll-pitch-yaw thing.
Jon Berndt
> A beta of over 2 deg means that the stagnation point has moved off the
> carbon-carbon nose cap ...
!?
That seems odd. 2 degrees beta does that? Off the nose cap? I'm trying to
picture that one ...
Jon
Stuf4
> "Roger Balettie" <rbal...@austin.rr.com> wrote
> > "Stuf4" <tdadamemd-...@excite.com> wrote:
> >> Hand flying a full entry isn't a difficult task in terms of hand-eye
> >> coordination, but it does get tedious (as related by someone who has
> >> done it many times in the sim).
> >
> > I've done several "manual" entries in the simulators... it's not
> > tough, if you have guidance to follow. But... if you have Entry
> > Guidance active, why fly manual? That's what it's there for.
>
> The two examples given previously in the thread were bad control derivative
> I-loads (so PASS guidance is GO, but auto flight control is NO-GO), or BFS
> engage (BFS has guidance down to 1500 ft, but no auto flight control).
>
> A third I can think of is lack of air data to G&C by Mach 2.5, but that
> only requires the crew to fly theta limits, not full manual control in all
> axes. There are several other circumstances where the crew would have to
> fly theta limits, but I can't remember them offhand.
>
> Mary, Andy... any others?
- Just for the fun of it.
Along with the full entry, we can ask why *anything* is flown manually.
~ CT
John
was flying w/Chuck Yeager (quite a day that was!)
I heard it confirmed that he indeed flew Columbia manually from entry
interface down to runway what-ever-it-was on the dry lakebed of
Edwards.
John
Mary Shafer Iliff
>
> Mary Shafer Iliff <mil...@qnet.com> wrote in
> news:3DE583D0...@qnet.com:
>
> > "Jorge R. Frank" wrote:
> >
> >> EXTRACTION OF STABILITY AND CONTROL DERIVATIVES FROM ORBITER FLIGHT
> >> DATA
> >
> > The S&C one, because L_YJ is a control derivative (it's
> > yawing moment due to yaw jet).
>
> Dumb question: is that really rolling moment, or did NASA change the
> standard nomenclature (I usually associate L-M-N with roll-pitch-yaw). The
> latter wouldn't surprise me one bit. It also wouldn't surprise me if I
> misremembered the L-M-N roll-pitch-yaw thing.
Rolling moment, not yawing moment. I always mix those two up.
I don't have any problem with the others but I've spent my entire
career having to check whether it's L or N I really mean. The
funny thing is, I can write out the matrices for the state eq'ns
without a second thought.
I can't look anything up because I don't keep my technical papers
around the house. Thanks for the quick catch. You're good.
Mary
Mary Pegg
>> > 2. On STS-1's landing, the Orbiter looked at one moment like
>> > it was about to flip, and I've since read other comments about
>> > this. What was the final verdict?
>
> I didn't see anything like that. He greased it on,
> in as slick a landing as you'd ever want to see.
I've just loooked at some vid, and yes, it was a greaser.
> Might you be thinking of STS-3, at White Sands? There
> was a bobble on that landing, but it never looked as if
> it were in any danger of flipping or anything.
I just remember one early landing where after the main
wheels touched down the nose rose, and rose, and rose...
David Corsi
feet, the lowest ever. It looked *ugly*. Look folks I fly for the 'lines and
yep many planes have autoland it does a good job, but no doubt in my mind
the whole final flare, roundout, and touchdown is ALWAYS much smoother when
a human flys it... and safer!
"David Higgins" <david....@worldnet.att.net> wrote in message
news:3DE5BE77...@worldnet.att.net...
David Corsi
"Mary Pegg" <m...@widetrouser.freeserve.co.uk> wrote in message
news:Xns92D529B3D...@62.253.162.109...
Jorge R. Frank
> Rolling moment, not yawing moment. I always mix those two up.
> I don't have any problem with the others but I've spent my entire
> career having to check whether it's L or N I really mean. The
> funny thing is, I can write out the matrices for the state eq'ns
> without a second thought.
The ones that trip me up are the body rates (p, q, r). I really wish they
hadn't chosen the same letter for both pitch rate and dynamic pressure.
> I can't look anything up because I don't keep my technical papers
> around the house. Thanks for the quick catch. You're good.
Thanks! That particular moment (roll from the yaw jets) bites us during
prox ops, as well. When the crew performs a Y translation (which fires both
forward and aft yaw jets), the roll moment causes the target to "bounce
back" as seen through the -Z COAS. This can lead to overcontrol of Y. We
therefore train crews to wait for the DAP to take out the roll motion
before they can believe what they see in the COAS again.
In addition, since we're using the vernier jets for attitude control, the
subsequent roll firing is heavily cross-coupled into -Z translation (toward
the target vehicle). Sudden increases in closure rate are unwelcome at
close range, for obvious reasons. So we also train crews to get Y and Ydot
under control as soon as possible during the approach.
Stuf4
> Stuf4 <tdadamemd-...@excite.com> wrote
> >
> > Again, this leaves open the question as to why such a major
> > accomplishment is not more widely known. It would be great
> > to hear Joe's first hand account of flying this entry.
>
> I thought everybody knew it was mixed -- manual and automatic.
Thank you, John! That explanation is consistent with my previous understanding.
Perhaps Mary would like to reevaluate the validity of her statement.
~ CT
Stuf4
> > > was a bobble on that landing, but it never looked as if
> > > it were in any danger of flipping or anything.
> >
> > I just remember one early landing where after the main
> > wheels touched down the nose rose, and rose, and rose...
From David Corsi:
> That was STS-3.
Definitely one of the heart-stopping moments of the shuttle program.
And up there with ALT-5 as one of the worst landing/rollouts of the
program.
Here's the kicker...
The right seater for both landings was Gordon Fullerton.
Notice that neither left seater got another flight. On top of that, I
would venture a guess that STS-3 closed the door to all non-TPS grads
who dreamed of piloting the shuttle.
~ CT
Al Jackson
> "Stuf4" <tdadamemd-...@excite.com> wrote:
> > Hand flying a full entry isn't a difficult task in terms of hand-eye
> > coordination, but it does get tedious (as related by someone who has
> > done it many times in the sim).
>
> I've done several "manual" entries in the simulators... it's not tough, if
> you have guidance to follow. But... if you have Entry Guidance active, why
> fly manual? That's what it's there for.
>
> Roger
Ah ha!
What about a manual re-entry if all the GPC's are down, and Backup GPC
is down? Rest of the avionics active?
Has this ever been done? Even SIM-wise?
Jorge R. Frank
news:fa9de496.02112...@posting.google.com:
I'm sure it's been done in sims (usually unintentionally), but it has
always resulted in (simulated) death.
The hand controller inputs go through the GPCs. If all the GPCs go down,
the vehicle loses control, and is destroyed. The crew dies. End of story.
Roger Balettie
> What about a manual re-entry if all the GPC's are down, and Backup GPC
> is down? Rest of the avionics active?
> Has this ever been done? Even SIM-wise?
As Jorge said, if the GPCs are down... it's a "Bad Day (tm)".
If *guidance* is hosed somehow (bad state, bad inputs from sensors, etc.)
but the GPCs are still online and providing attitude information and flight
control, there are cue card-based procedures for flying the alpha profile
(wings level) until the time for roll reversals occur. Hopefully guidance
is back online by then, or you have adequate comm so that the FDO can
execute the GCA (Ground Controlled Approach) -- which are calls for bank
angle, etc. to maintain a proper energy profile until the HAC and final
approach.
Mary Shafer Iliff
>
> Mary Shafer Iliff <mil...@qnet.com> wrote in
> news:3DE52F4E...@qnet.com:
>
> > Actually, STS-2 had a hand-flown reentry, because of the
> > It was just from entry interface (enough molecules of air
> > to count as atmosphere) to runway.
>
> in the payload bay for lack of space on the flight deck...
It wasn't a surprise, they'd practised it a million times,
and the guidance was working. Any good test pilot, which
both Engle and Truly are, would call that a normal day's
work. It was a test flight, after all.
Actually, we were all comforted knowing that Joe Henry was
going to be flying it. We knew he could do it because he'd
shown he could in the X-15. Not exactly an amateur, either
in the thin wispy parts of the atmosphere, on approach, going
around the HAC, or doing the low-L/D landing with the late
flare.
What about the crews of STS-3 and -4? They did the same
thing. STS-3 even ended up having to land at the least
familiar aerodrome.
Mary
Mary Shafer Iliff
>
> "Mary Shafer Iliff" <mil...@qnet.com> wrote in message
>
> > Might someone like to scan them in and put them online?
> > I've got a very few of the first, a few of the second,
> > and a good few of the third. I could probably spare
> > one of each for such a project.
>
> These look very interesting - offhand I'd be inclined to think (given the
> titles) they'd be good for modeling and simulation purposes. Are they pretty
> hefty documents?
Not really. The S&C report tells how to use the data to
update the aero model, which is then used to update the
FCS and the math model.
Mary
Mary Shafer Iliff
> This is because I have heard that the 'dutch roll' maneuver
> at entry interface has proved very difficult to fly , manually, in the
> simulators.
"Dutch roll" isn't a maneuver. It's a dynamic mode.
That means that the pilot doesn't try to fly the
Dutch roll manually or automatically. It's like the
phugoid.
Dutch roll is a coupling of roll and yaw. Roll causes
yaw which causes roll which causes yaw.... We assess
Dutch roll using phi/beta (yes, beta should be psi, but
it's kind of delta psi, with the steady-state subtracted
out, so beta works just fine except it has the wrong sign,
bet we ignore the sign). The more phi, the more roll and
the higher the oval the wingtip traces. The more beta,
the more yaw and the flatter the oval the wingtip traces.
It's called Dutch roll because it reminded someone of the
motion of the bottom of a Dutchman skating on a frozen
canal.
Usually, a feedback loop in the FCS will render Dutch roll
bearable.
Mary
Mary Shafer Iliff
> Meanwhile, the S&C guys were pinning down the problem to L_YJ
> and coming up with a new automatic energy management turn
> technique.
Someone asked by L_YJ was actually so different from the model
value, but I can't find the message so I'm just posting.
The maneuvers at high altitude were performed at 40 deg alpha,
so there was separated flow on the upper surface of the wing.
When the RCS side jets are fired, the exhaust enters this
separated flow region and pressurizes the volume defined by
the wing upper surfaces and the flow separation wake boundaries.
The aerodynamic flow field for this high-altitude flight
environment cannot be properly simulated in the wind tunnel.
For example, at the first bank maneuver at Mach 24, the flight
dynamic pressure is 14 lb/ft**2. In these conditions. the wake
boundary is much more easily deflected on the flight vehicle
than on the wind tunnel model.
> Everyone does understand that this is aerodynamics, pure and
> simple, right? And the fix was in the S&C terms used in the
> FCS? It wasn't imaginary or political or anything. All the
> information has been published repeatedly in public documents
> in the '80s. If you don't know about it, it's because you
> skipped all those AIAA papers, not because it was concealed.
Two of those three papers were given at AIAA conference and all
three were published as TMs.
By the way, the TM version of "A Comparison of Hypersonic
Vehicle Flight and Prediction Results" was published in
Oct 1995. If you look there you may find the online version.
This is probably one of the most significant papers, along
with the Shuttle S&C paper, that Ken and I ever wrote.
Mary
john_thomas_maxson
>
> The aerodynamic flow field for this high-altitude flight
> environment cannot be properly simulated in the wind tunnel.
Mary, I'm just wondering what your understanding is of your
wind tunnel limitation here, in terms of both altitude and Mach
number. (I've studied the problem more from the launch end,
rather than the landing end.)
In looking into yaw-jet effects relative to Mission 51-L, I came
at the problem from the supersonic studies. For 51-L I had no
wind-tunnel-related Mach # or altitude limitations. One study I
liked had modeled only the orbiter though, not the entire stack:
NASA Technical Memorandum 84645
Interference Effects of Aft Reaction-Control Yaw Jets on
the Aerodynamic Characteristics of a Space Shuttle Orbiter
Model at Supersonic Speeds
Peter F. Covell, June 1983 (Langley Research Center)
I assume that you are quite familiar with it and its implications,
but I have not found anyone else here in the groups who are.
John Thomas Maxson - www.mission51l.com
Stuf4
> The ones that trip me up are the body rates (p, q, r). I really wish they
> hadn't chosen the same letter for both pitch rate and dynamic pressure.
I think even Euler himself would have wanted "p" to be "pitch".
...that way when the later decision was made to confuse aero types by
using the same symbol for dynamic pressure, we would today have an
astro-rock band called Max-P!
~ CT
Stuf4
> The hand controller inputs go through the GPCs. If all the GPCs go down,
> the vehicle loses control, and is destroyed. The crew dies. End of story.
You may have seen the recent post about the old "manual direct" mode
that never got implemented for flight. I wonder if that was dependent
upon the GPCs (I've heard one person say that it was). If not, then
that would give the crew something to do before they died. Who knows?
They might even make it to a bailout condition.
Perhaps someone should take a look at reimplementing "manual direct"
for orbiter upgrades (retrogrades?!) as a means of increasing
survivability.
~ CT
Al Jackson
> "Al Jackson" <aa...@flash.net> wrote:
> > What about a manual re-entry if all the GPC's are down, and Backup GPC
> > is down? Rest of the avionics active?
> > Has this ever been done? Even SIM-wise?
>
> As Jorge said, if the GPCs are down... it's a "Bad Day (tm)".
>
> If *guidance* is hosed somehow (bad state, bad inputs from sensors, etc.)
> but the GPCs are still online and providing attitude information and flight
> control, there are cue card-based procedures for flying the alpha profile
> (wings level) until the time for roll reversals occur. Hopefully guidance
> is back online by then, or you have adequate comm so that the FDO can
> execute the GCA (Ground Controlled Approach) -- which are calls for bank
> angle, etc. to maintain a proper energy profile until the HAC and final
> approach.
>
> Roger
Been so long since I worked non-On-Orbit Flight Software I have
forgotten all the details of how the GPC's hook into entry GN&C.
As I said before, friends over there in Bldg. 4 , O, 15 or 16 years
ago, I thought? , told me that with the main GPC's down and only the
Back UP Flight Control System active that it was very very difficult
to manually fly entry interface. (Don't know if this was on the SMS or
the motion-base-simulator over in Bldg 5.)
Tom of Bunyon
"Al Jackson" <aa...@flash.net> wrote in message
news:fa9de496.02112...@posting.google.com...
No computers ::= no control at all. There's no mechanical linkage between
pilot and surfaces - the computer must "interpret" all inputs.
Stuf4
> "Al Jackson" <aa...@flash.net> wrote in message
> > What about a manual re-entry if all the GPC's are down, and Backup GPC
> > is down? Rest of the avionics active?
> > Has this ever been done? Even SIM-wise?
>
> No computers ::= no control at all. There's no mechanical linkage between
> pilot and surfaces - the computer must "interpret" all inputs.
It's possible to have a fly-by-wire control system that uses no
computers at all. Here's a link to a discussion about the old "manual
direct" mode of flying the shuttle:
news:<d3af8584.02112...@posting.google.com>
(I don't know whether or not this mode used the GPCs.)
~ CT