SKI@RICEVM1.BITNET (David Palkowski) (10/31/89)
Perhaps this topic has been addressed before in this group, but alas, I missed it and remain curious. I understand the reason for the roll maneuver after liftoff based on the shuttle's relative postion at launch to that reqired for orbital penetration. Question that nags me though, is why not position the shuttle and launch assembly so the maneuver can be eliminated all togeather ? I'm missing something here, and would appreciate being educated about it. Thanks in advance... David Palkowski NCS / Rice University
henry@utzoo.uucp (Henry Spencer) (10/31/89)
In article <1596SKI@RICEVM1> SKI@RICEVM1.BITNET (David Palkowski) writes: >... Question that nags me though, is why not >position the shuttle and launch assembly so the maneuver can be >eliminated all togeather ? ... Because the launch facilities were not built from scratch for the shuttle; they were converted from Saturn V facilities. This involved some compromises. -- A bit of tolerance is worth a | Henry Spencer at U of Toronto Zoology megabyte of flaming. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
smb@ulysses.homer.nj.att.com (Steven M. Bellovin) (10/31/89)
In article <1596SKI@RICEVM1>, SKI@RICEVM1.BITNET (David Palkowski) writes: > Question that nags me though, is why not > position the shuttle and launch assembly so the maneuver can be > eliminated all togeather ? I've always wondered, too. My tentative answer is that different missions require a different orbital inclination, and hence a different amount of roll; hence, the capability is needed no matter what. Therefore, you may as well use it on every flight, and optimize the launch assembly for other criteria, i.e., ease of travel from the VAB.
mcdowell@cfa250.harvard.edu (Jonathan McDowell) (10/31/89)
From article <1989Oct31.002441.7817@utzoo.uucp>, by henry@utzoo.uucp (Henry Spencer): [discussion of STS launch roll..] > Because the launch facilities were not built from scratch for the > shuttle; they were converted from Saturn V facilities. This involved > some compromises. So my next question is ... why did the Saturn V roll after launch? -Jonathan McDowell
sw@cbnewsl.ATT.COM (Stuart Warmink) (11/01/89)
David Palkowski writes: > I understand the reason for the roll maneuver after liftoff based > on the shuttle's relative postion at launch to that reqired for > orbital penetration. Question that nags me though, is why not > position the shuttle and launch assembly so the maneuver can be > eliminated all togeather ? There are (at least) two reasons: 1) The pads are modified Apollo pads, and hence the flame trenches and tower etc. were in fixed positions. They could hardly be moved! 2) The Shuttle's launch direction+ can be up to about 57 degrees North East down to about 34 South East, depending on the type of mission flown. These numbers may not be quite correct, but the end result is that some kind of roll manouever is required *anyway*. + From the Cape -- ------------------------------------------------------------------------------ Stuart Warmink, Whippany, NJ, USA | sw@cbnewsl.ATT.COM | Pretentious? Moi? -------------------------> My opinions are just that <------------------------
gwh@typhoon.Berkeley.EDU (George William Herbert) (11/01/89)
In article <1758@cfa237.cfa250.harvard.edu> mcdowell@cfa250.harvard.edu (Jonathan McDowell) writes: >From article <1989Oct31.002441.7817@utzoo.uucp>, by henry@utzoo.uucp (Henry Spencer): >[discussion of STS launch roll..] >> Because the launch facilities were not built from scratch for the >> shuttle; they were converted from Saturn V facilities. This involved >> some compromises. > >So my next question is ... >why did the Saturn V roll after launch? If i remember correctly, it didn't. It just pitched, being symmetric. The shuttle does because the pad is oriented such that it needs to roll to be headed the right way. Thetower was set up for engineering convenience and the apollo just pitched after it cleared it. The shuttle needs to do more, 'cause the tower is in the way for it. **************************************** George William Herbert UCB Naval Architecture Dpt. (my god, even on schedule!) maniac@garnet.berkeley.edu gwh@ocf.berkeley.edu ----------------------------------------
gaudiot@priam.usc.edu (Jean-Luc Gaudiot) (11/01/89)
My $0.02 worth: could it be that the shuttle is aligned on the launch pad so as to present the smallest possible cross section to the dominant winds (presumably from the ocean)? Jean-Luc Gaudiot Flying will never be safe as long as one must drive to the airport.
kclenden@silver.bacs.indiana.edu (Kevin Clendenien) (11/01/89)
>David Palkowski writes: [stuff deleted] >> orbital penetration. Question that nags me though, is why not >> position the shuttle and launch assembly so the maneuver can be >> eliminated all togeather ? Just out of curiosity, if the pad were designed to change orientation, what is the latest, relative to launch time, that the pad's orientation could be changed? I ask only because the DOD seems to be very paranoid about people knowing what they're doing, and the pad's orientation, with no shuttle roll, would give a big hint as to where the shuttle was going. -------------------------------------------------------------------------- kclenden@silver.bacs.indiana.edu Kevin Clendenien BLoomington Atari ST users group BLAST, President BLAST BBS - (812) 332-0573 FNET node #141 "Of course any opinions or views stated above do not necessarily represent the official position of any person, or organization other that of Kevin Clendenien." --------------------------------------------------------------------------
lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall) (11/02/89)
So why don't they put airport runways on a big turntable so they can always point the airplane the direction it wants to go? If you've already gotta have a control system on the craft, good enough that it doesn't (hopefully) have to do anything heroic to control the orientation of the craft, why build a ground system to do the same thing, just to make it a teensy weensy bit easier on the craft? Larry Wall lwall@jpl-devvax.jpl.nasa.gov
SKI@RICEVM1.BITNET (David Palkowski) (11/02/89)
Ah ! But they *do* make runways that can turn into the wind on command...problem is, you have to be a naval aviator to use them ! ;-)
fiddler%concertina@Sun.COM (Steve Hix) (11/03/89)
In article <6371@jpl-devvax.JPL.NASA.GOV>, lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall) writes: > So why don't they put airport runways on a big turntable so they can > always point the airplane the direction it wants to go? First, let's ignore cost...of real estate, if nothing else. Imagine the feelings of pssengers in the terminal when the runway is turned into the current wind...aimed directly at the terminal in which they are currently residing. Adds a new dimension to the term "pre-flight jitters". ------------ "...I was to learn later in life that we tend to meet any new situation by reorganizing: and a wonderful method it can be for creating the illusion of progress, while producing confusion, inefficiency and demoralization." - Petronius Arbiter, 210 B.C.
Mike.Pompura@f49.n363.z1.FIDONET.ORG (Mike Pompura) (11/04/89)
Perhaps I may be of assistance in this discussion over the Saturn V.
Reprint taken from: SATURN V FLIGHT MANUAL SA-508
Section II - Performance
Launch And Boost To Earth Parking Orbit
---------------------------------------
The vehicle rises nearly vertically from the pad, for approx 450 feet,
to clear the tower. During this period, a yaw maneuver is executed to
provide tower clearance in the event of adverse wind conditions,
deviation from nominal flight and/or engine failure. After clearing
the tower, a tilt and roll maneuver is initiated to achieve the flight
attitude and proper orientation for the selected flight azimuth.
Launch azimuth is 90 degrees; flight azimuth may vary between 72 and 96
degrees. The actual flight azimuth within this range is computed is
computed just prior to launch from a launch-day-dependent polynomial of
launch azimuth as a function of launch time. From the end of the tilt
maneuver to tilt-arrest, the pitch program provides a near-zero-lift
trajectory that satisifies vehicle performance, heating, and loads
requirements. Tilt-arrest freezes the pitch attitude to dampen out
pitch rates prior to S-IC/S-II seperation. The pitch attitude remains
constant until initiation of the Iterative Guidance Mode <IGM> which
occurs during the S-II stage flight. Mach 1 is achieved approx 1
minute 8 seconds after first motion. Max dynamic pressure is
encountered at approx 1 minute 25 seconds after first motion. S-IC
center engine cutoff is commanded at 2 minutes 15 seconds after first
motion, to limit the vehicle acceleration to a nominal 3.98g. The S-IC
outboard engines are cut off by propellant-depletion sensors.
A time interval of 4.4 seconds elapses between S-IC cutoff and the
time the J-2 engines of the S-II stage reach mainstage <approx 90% of
the operating thrust level>. During this period, ullage rockets are
fired to seat the S-II propellant, the S-IC/S-II seperation occurs and
the retrorockets back the S-IC stage away from the flight vehicle.
Threshold for engine status light OFF is 65% thrust. The S-II aft
interstage is jettisoned 30.7 seconds after S-IC cutoff, and the LET is
jettisoned by crew action approx 6 seconds later, after assurnace that
S-II ignition and thrust buildup have occured. IGM is initiated about
39 seconds after S-II ignition.
An early S-II center engine cutoff is programmed for Time Base 3 +
299 seconds. This early cutoff is designed to preclude the vehicle
longitudinal oscillations <POGO effect> which have occurred late in the
S-II burn in previous missions. The outboard engines are cut off
simultaneously when any 2 of 5 cutoff sensors in either tank are
activated. An interval of 6.5 seconds elapses between S-II cutoff and
the time the S-IVB J-2 engine attains mainstage. During this coast
period, the S-IVB ullage rockets are fired to seat the stage
propellant, the S-II/S-IVB seperation occurs, and the retrorockets back
the S-II stage away from the flight vehicle. Threshold for engine
status light OFF is 65% thrust. The S-IVB first burn inserts the
vehicle into a 100 nautical mile altitude circular parking orbit.
If there is anything else that anyone wishes to know about the SATURN V
launch vehicle <including the Apollo capsule>, post your questions
here, and I will attempt to find the answers.
--
Fidonet: Mike Pompura via 1:363/9
Internet: Mike.Pompura@f49.n363.z1.FIDONET.ORG
UUCP: uunet!sceard!tarpit!libcmp!mamab!49!Mike.Pompurahovanes@ingr.com (Kenneth Hovanes 7938) (11/04/89)
In article <1758@cfa237.cfa250.harvard.edu>, mcdowell@cfa250.harvard.edu (Jonathan McDowell) writes: > From article <1989Oct31.002441.7817@utzoo.uucp>, by henry@utzoo.uucp (Henry Spencer): > [discussion of STS launch roll..] > > Because the launch facilities were not built from scratch for the > > shuttle; they were converted from Saturn V facilities. This involved > > some compromises. > From what I understand the roll manuver is not because of the design of the launch pad. The roll manuver is designed to allow th pilot of the shuttle to watch the ocean, thereby seeing where he is during launch. Apparently the roll is used as a precaution to allow the astronaut to know where he is located in relation to emergency landing areas. By looking backward over his head he can immediatly see where he is. Ken "I asked a NASA dude" Hovanes
henry@utzoo.uucp (Henry Spencer) (11/04/89)
In article <7255@ingr.com> hovanes@ingr.com (Kenneth Hovanes 7938) writes: >From what I understand the roll manuver is not because of the design of >the launch pad. The roll manuver is designed to allow th pilot of the >shuttle to watch the ocean, thereby seeing where he is during launch. You've missed the point: why not just rotate the pad so the roll is unnecessary? I.e., start the launch with the orbiter's back facing the ocean? The answer is, because use of existing pad facilities imposed constraints that made this difficult. Also, I doubt the explanation. The pilots have displays that tell them much more of what they need to know than they would get by looking out the window. I went and [gasp!] looked it up, just to confirm my recollection: the main reason for the roll is simply that most of the communications antennas are on the orbiter, and keeping them in line of sight of ground stations requires that the orbiter be on the underside of the shuttle assembly during ascent. -- A bit of tolerance is worth a | Henry Spencer at U of Toronto Zoology megabyte of flaming. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
BARRY@RICEVM1.BITNET (11/05/89)
As a Space Shuttle Flight Controller, I feel compelled to respond to the roll maneuver controversy. The launch pads are indeed retrofitted for the Shuttle program, and as noted in previous messages, some sort of maneuver would have to be performed from any *fixed* platform for a given orbital inclination. The launch pads are so big that I can't imagine rotating them, along with the flame trench, cryogenic recirculation lines, etc. There are only three DOD missions remaining (on the current manifest), so secrecy is not a concern. Besides, the inclination is obvious just after liftoff. The folks in the Launch Control Center at KSC like to be able to see the orbiter, too. The orbiter is carried underneath the stack for several reasons. The heads-down configuration is more stable for roll and pitch than the heads-up configuration; thus it's more efficient with propellant. The crew, regardless of displays, like to have a horizon reference. The antennae for communications with Merritt Island Launch Area (MILA) and Bermuda during ascent must point to the ground, and the external tank must not block the transmission path. [You say, "What about TDRSS?"...] One note for interested parties: for intact launch aborts (the Return To Launch Site (RTLS) and Trans-Atlantic Landing (TAL) modes), the orbiter actually winds up in the heads-up configuration prior to main engine cutoff in order to separate from the external tank by simply dropping it. In nominal separation modes, the orbiter remains in the heads-down configuration and translates away from the external tank from underneath it. Most of the time spent on-orbit is in the heads-down attitude. Don't think that the ascent design folks haven't thought about the alternatives! Matt Barry (barry@ricevm1.rice.edu, mbarry@nasamail.nasa.gov).
dvadura@watdragon.waterloo.edu (Dennis Vadura) (11/05/89)
In article <1989Nov4.073508.10143@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes: >In article <7255@ingr.com> hovanes@ingr.com (Kenneth Hovanes 7938) writes: >looking out the window. I went and [gasp!] looked it up, just to >confirm my recollection: the main reason for the roll is simply >that most of the communications antennas are on the orbiter, and >keeping them in line of sight of ground stations requires that the >orbiter be on the underside of the shuttle assembly during ascent. Not to mention the fact that if they turned the whole assembly around on the pad, all those news people's cameras would have a wonderful view of the back of the ET. Not nearly as impressive as the view of the the orbiter along with the roll maneuver. I'm not suggesting this was a factor in the decision of orbiter placement on the pad, but PR is important and it wouldn't suprise me if someone hadn't pointed out the PR benefit of the current orientation. -dennis -- -------------------------------------------------------------------------------- The only happy people are Single MEN |Dennis UUCP,BITNET: dvadura@water and Married WOMEN. |Vadura EDU,CDN,CSNET: dvadura@waterloo ================================================================================
smb@ulysses.homer.nj.att.com (Steven M. Bellovin) (11/06/89)
In article <17825@watdragon.waterloo.edu>, dvadura@watdragon.waterloo.edu (Dennis Vadura) writes: > Not to mention the fact that if they turned the whole assembly around on > the pad, all those news people's cameras would have a wonderful view of > the back of the ET. Not nearly as impressive as the view of the the > orbiter along with the roll maneuver. I'm not suggesting this was a > factor in the decision of orbiter placement on the pad Nah -- did you watch the first shuttle launch? Poor Dan Rather was so confused about the orbiter attitude, including when it's in orbit. ``You mean it's flying upside down? The whole time?'' He kept finding different ways to repeat the same question; he couldn't seem to grasp that in orbit, the crew didn't really notice being ``upside down''...
clyde@ut-emx.UUCP (Clyde W. Hoover) (11/07/89)
I've seen a picture of one of the Soyuz pads which DOES use a turntable to adjust the launch azimuth to obviate the need for a roll manuever. The ground support for the Proton booster is quite different from anything the US has built, so they can be popped up from a large Lazy Susan :-) Shouter-To-Dead-Parrots @ Univ. of Texas Computation Center; Austin, Texas clyde@emx.utexas.edu; ...!cs.utexas.edu!ut-emx!clyde Tip #268: Don't feel insecure or inferior! Remember, you're ORGANIC!! You could win an argument with almost any rock!
henry@utzoo.uucp (Henry Spencer) (11/08/89)
In article <20539@ut-emx.UUCP> clyde@ut-emx.UUCP (Clyde W. Hoover) writes: >I've seen a picture of one of the Soyuz pads which DOES use a turntable to >adjust the launch azimuth to obviate the need for a roll manuever... Long March does the same, with sophisticated high technology :-) to do the adjustment: an engineer reading a laser measuring gadget and giving orders to a few husky soldiers turning big handcranks. -- A bit of tolerance is worth a | Henry Spencer at U of Toronto Zoology megabyte of flaming. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
shafer@elxsi.dfrf.nasa.gov (Mary Shafer) (11/09/89)
Just a little historical note about the Shuttle roll maneuver.
Before the Shuttle was launched there was a lot of concern about the
roll maneuver--getting the flight control system to do it right, etc.
The Australians were quite amused by this, because they'd solved the
problem quite handily for Jindivik.
Turned out that the Shuttle was just as simple, in the event.
--
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 NASAnickw@syma.sussex.ac.uk (Nick Watkins) (11/12/89)
In article <SHAFER.89Nov8082121@drynix.dfrf.nasa.gov> shafer@elxsi.dfrf.nasa.gov (Mary Shafer) writes: >The Australians were quite amused by this, because they'd solved the >problem quite handily for Jindivik. Once upon a time I knew what Jindivik was. I seem to have forgotten. Could you please remind me? Nick -- Nick Watkins, Space & Plasma Physics Group, School of Mathematical & Physical Sciences, Univ. of Sussex, Brighton, E.Sussex, BN1 9QH, ENGLAND JANET: nickw@syma.sussex.ac.uk BITNET: nickw%syma.sussex.ac.uk@uk.ac
shafer@elxsi.dfrf.nasa.gov (Mary Shafer) (11/18/89)
In article <1753@syma.sussex.ac.uk> nickw@syma.sussex.ac.uk (Nick Watkins) writes: >In article <SHAFER.89Nov8082121@drynix.dfrf.nasa.gov> shafer@elxsi.dfrf.nasa.gov (Mary Shafer) writes: >>The Australians were quite amused by this, because they'd solved the >>problem quite handily for Jindivik. >Once upon a time I knew what Jindivik was. I seem to have forgotten. >Could you please remind me? Part of the reason you're confused is because I should have said Ikara, not Jindivik. Jindivik is a trolley-mounted drone used as a weapons target. Ikara is a ship-borne guided missle that delivers an anti-submarine homing torpedo to the target submarine. The missile is launched from a surface ship which uses a computer to calculate the torpedo dropping position. After release from the Ikara vehicle, a lightweight anti-submarine torpedo such as the Mk 44 descends by parachute. When the torpedo reaches the sea the parachute is discarded and the torpedo carries out a homing attack on the target submarine. [Excerpted and/or paraphrased from Jane's Weapons Systems 87-88] Rather than maneuver the ship, the Ikara executes a roll maneuver shortly after launch. -- 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