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#740
by
Jorge
on 06 Mar, 2008 03:48
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Spad - 5/3/2008 7:21 PM
From an orbital dynamics perspective; How much difference is there between the lateral RPM maneuvers and the manuever that takes the orbitor entirely around the ISS.
The difference is considerable. For the RPM, the orbiter is offset from ISS 600 ft (180 m) on the +Rbar with zero tangential velocity, and a radial velocity that is a function of range but still closing no faster than 0.4 fps (0.12 mps). The result, as seen from the ISS-centered coordinate frame, is a strong tidal effect ("Rbar effect") that pulls the orbiter radially away from ISS. This is (intentionally) offset by having the orbiter start and stop the RPM using down-firing primary RCS thrusters, which provide a small impulse toward ISS. This minimizes the amount of opening rate that the commander must null after RPM completion, while maintaining a high factor of safety should the approach need to be aborted during the RPM.
For the flyaround, the orbiter is at a range of 600-700 ft (180-210 m), similar to the RPM, but is rotating around ISS at a rate of 0.065 deg/s relative to inertial space (0.13 deg/s relative to ISS), and maintaining a tangential velocity sufficient to keep ISS centered over the orbiter payload bay. The orbital mechanics effects of this tangential velocity vary depending on the orbiter's position relative to ISS, but tend to cancel the Rbar effect when the orbiter is near the +/-Rbar. The net effect is a tendency for the orbiter to pull away from ISS, requiring the pilot to translate toward ISS in order to keep the orbiter within 700 ft. This is the preferable situation because translation away from ISS either involves firing thrusters toward ISS, producing plume impingement effects on ISS, or involves firing forward/aft thrusters to avoid plume impingement but at considerable propellant cost.
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#741
by
Spad
on 06 Mar, 2008 12:59
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Jorge,
Thanx so much for your time.
So both maneuvers are under complete control of the commander? I had assumed that the operation was more automated than that. I can understand why it wouldn't be.
Thanks again.
Bill Spadafora
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#742
by
psloss
on 06 Mar, 2008 12:59
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Gary - 6/3/2008 8:38 AM
First of all I thought that the shuttle had landed in such conditions before and secondly doesn't this add a level of risk for the landing? With only a few shuttle flights left is this just an opportunity to gain additional data on shuttle performance?
I believe the latter; not a bad idea to have a larger data sample, rather than one or two data points.
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#743
by
Jim
on 06 Mar, 2008 13:20
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Spad - 6/3/2008 8:59 AM
Jorge,
Thanx so much for your time.
So both maneuvers are under complete control of the commander? I had assumed that the operation was more automated than that. I can understand why it wouldn't be.
Thanks again.
Bill Spadafora
The fly around is usually done by the pilot.
The orbiter doesn't have the radar and laser range finderd sensors integrated into the control system. The crew does the "integration"
The fly around has some 'automation" The DAP puts the orbiter into a constant pitch rate and the pilot keeps the ISS centered in his view (using the COAS) by using the translation controls. This produces the flyaround.
Jorge or Mark can and will correct any errors
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#744
by
mkirk
on 06 Mar, 2008 13:44
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psloss - 6/3/2008 7:59 AM
Gary - 6/3/2008 8:38 AM
First of all I thought that the shuttle had landed in such conditions before and secondly doesn't this add a level of risk for the landing? With only a few shuttle flights left is this just an opportunity to gain additional data on shuttle performance?
I believe the latter; not a bad idea to have a larger data sample, rather than one or two data points.
The Crosswind DTO (detailed test objective) has been on the wish list for a long time and is intended to help quantify ACTUAL orbiter landing performance in high crosswind conditions. This data could help refine, and increase the confidence in, the existing flight rules.
For DTO 805 the requirement is for the orbiter to touchdown with a steady state crosswind component of 10 knots or greater up to the daytime limit of 15 knots. To my knowledge – and I will have to look at the most recent flights where the go was given for the DTO – the test conditions have not actually been achieved at the actual time of touchdown.
Part of the problem is that IF the forecast conditions at touchdown are at the crosswind limit (15 knots for daytime and 12 for nighttime) then it is likely the landing itself will be waved off – this is certainly the case if the wind spikes are above the limits. Another problem is the forecasts conditions (which include steady state and gust conditions) may not be the same at the precise time of touchdown.
As far as I know, and someone please correct me if I am wrong, the parameters for the test at the time of touchdown have not been met, although the flight control team has given the go to the crew to perform the test numerous times.
Mark Kirkman
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#745
by
mkirk
on 06 Mar, 2008 14:02
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psloss - 1/3/2008 3:47 PM
Trekkie07 - 1/3/2008 4:12 PM
During the FRFs of the shuttle program, am I correct in assuming that the orbiter's were completely unmanned during these test firings?
If so, how were the APUs started if their start-up sequence is accomplished through the manual throwing of switches in the cockpit?
The final inspection team probably went out to the pad after stable replenish, but the pad was clear during the firing. I believe APU start was done remotely from the firing room for FRFs.
Jim - 1/3/2008 4:07 PM
I think ground hydraulic pressure was used, negating the need for the APU's
In case there was still any doubt, the answer is yes, the APUs were used for the FRFs. Hydraulic power is/was required for nozzle gimballing and propulsion system valve operations.
I should also add that the Solid Rocket Booster HPUs (hydraulic power units) were also operated.
As for how the APUs were actually operated with nobody in the crew module, I am ashamed to say that my systems knowledge is a little lacking. Until just now when I read the initial question I had never really given it any thought.
I will check on this and get back to you when I find out.
What I do know is that the crew module hatch was closed during the hold at T-3 hours. So I presume that the APU switches were pre-configured prior to this time.
According to the S0014 Hot Fire Bar Charts, the APU prestart and APU start occurred at the usual times. Immediately following the SSME shutdown sequence, the SRB HPUs were shutdown and the APUs went to High Speed. APU shutdown and cool down occurred shortly after the switchover to High Speed.
Mark Kirkman
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#746
by
Jorge
on 06 Mar, 2008 14:43
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Jim - 6/3/2008 8:20 AM
Spad - 6/3/2008 8:59 AM
Jorge,
Thanx so much for your time.
So both maneuvers are under complete control of the commander? I had assumed that the operation was more automated than that. I can understand why it wouldn't be.
Thanks again.
Bill Spadafora
The fly around is usually done by the pilot.
The orbiter doesn't have the radar and laser range finderd sensors integrated into the control system. The crew does the "integration"
The fly around has some 'automation" The DAP puts the orbiter into a constant pitch rate and the pilot keeps the ISS centered in his view (using the COAS) by using the translation controls. This produces the flyaround.
Jorge or Mark can and will correct any errors
No errors, just some things to expand.
During prox ops, the crew controls translation manually (and in fact, the orbiter provides no capability to automate it). Rotation is controlled automatically using the digital autopilot (DAP). There is capability for manual rotation but it is rarely used during prox ops (the only part of the orbital flight phase that is routinely manually controlled, to my knowledge, is the pitch maneuver post ET sep). The only portion of prox ops where rotation is not controlled automatically is a short period during the RPM when the orbiter is upside-down relative to ISS. During that period the DAP is in free drift and the hand controllers powered off to prevent down-firing thrusters from firing toward the station.
Although rotation is controlled automatically, I wouldn't call it automated. Rotational maneuvers are initiated by the crew using commands on the Universal Pointing display.
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#747
by
Lee Jay
on 06 Mar, 2008 14:53
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I'm looking at KSC via Google Earth, and I'm wondering where all the various viewing locations are. I'm thinking of the press site, the VIP site (same thing?), and the "Banana River" viewing location. I've been to KSC a few times, but only to the visitor locations like the Saturn 5 center, the gantry, rocket garden and so on. It looks to me like there is a location practically in the Saturn V center parking lot that might be the VIP viewing area?
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#748
by
Jorge
on 06 Mar, 2008 15:53
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Lee Jay - 6/3/2008 9:53 AM
I'm looking at KSC via Google Earth, and I'm wondering where all the various viewing locations are. I'm thinking of the press site, the VIP site (same thing?), and the "Banana River" viewing location. I've been to KSC a few times, but only to the visitor locations like the Saturn 5 center, the gantry, rocket garden and so on. It looks to me like there is a location practically in the Saturn V center parking lot that might be the VIP viewing area?
The Banana Creek VIP site is at the Saturn V center.
The press site is just south of the Turn Basin next to the crawlerway.
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#749
by
Lee Jay
on 06 Mar, 2008 17:22
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Thanks, Jorge.
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#750
by
Gary
on 06 Mar, 2008 18:56
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Thank you Mark. Is there a list anywhere of all the DTO's for the Shuttle and there current status?
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#751
by
Gary
on 06 Mar, 2008 18:57
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Just another idle question that occured to me on my way home :-) When the shuttle lands you often hear (or see) the weather airplane fly over the runway. Does this aircraft continue to circle until the Shuttle is moved off the SLF or does it land somewhere else? (Ellington?) thanks.
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#752
by
Jim
on 06 Mar, 2008 19:00
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Gary - 6/3/2008 2:57 PM
Just another idle question that occured to me on my way home :-) When the shuttle lands you often hear (or see) the weather airplane fly over the runway. Does this aircraft continue to circle until the Shuttle is moved off the SLF or does it land somewhere else? (Ellington?) thanks.
CCAFS
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#753
by
Gary
on 06 Mar, 2008 20:04
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Jim - 6/3/2008 8:00 PM
Gary - 6/3/2008 2:57 PM
Just another idle question that occured to me on my way home :-) When the shuttle lands you often hear (or see) the weather airplane fly over the runway. Does this aircraft continue to circle until the Shuttle is moved off the SLF or does it land somewhere else? (Ellington?) thanks.
CCAFS
Ahh of course. I forgot about CCAFS. Thank you, Jim.
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#754
by
psloss
on 08 Mar, 2008 15:42
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Trivia question (probably for Jorge), but I'm trying to remember a fairly short OMS-2 burn. I remember STS-110 as inserting into an orbit with the minimum Hp of 85 n.mi (large phase angle) and there's a nice reference on this here:
http://fdab.gsfc.nasa.gov/live/Home/Symposium/Session1_No3.pdfWas that the smallest delta-V for a direct-insertion OMS-2 (so far)?
Thanks.
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#755
by
Jorge
on 08 Mar, 2008 16:18
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psloss - 8/3/2008 10:42 AM
Trivia question (probably for Jorge), but I'm trying to remember a fairly short OMS-2 burn. I remember STS-110 as inserting into an orbit with the minimum Hp of 85 n.mi (large phase angle) and there's a nice reference on this here:
http://fdab.gsfc.nasa.gov/live/Home/Symposium/Session1_No3.pdf
Was that the smallest delta-V for a direct-insertion OMS-2 (so far)?
Thanks.
I'll have to check on Monday but my first impression is that 110 wasn't the only flight with an 85 nmi post-OMS-2 perigee, so it would likely be in a near-tie with several other flights.
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#756
by
kneecaps
on 08 Mar, 2008 16:23
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Anybody know how the Orbiter wiring harnesses are numbered? I've seen the numbering in the past and seeing it again in a recent doc has prompted me to find out?
What does 83P331 and 83P332 mean? 83 some kind of location code? P some kind of type ID and the last digits a serial number?
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#757
by
Jim
on 08 Mar, 2008 16:53
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kneecaps - 8/3/2008 12:23 PM
Anybody know how the Orbiter wiring harnesses are numbered? I've seen the numbering in the past and seeing it again in a recent doc has prompted me to find out?
They have Rockwell wiring codes, JSC codes, etc
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#758
by
kneecaps
on 08 Mar, 2008 19:48
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Jim - 8/3/2008 5:53 PM
kneecaps - 8/3/2008 12:23 PM
Anybody know how the Orbiter wiring harnesses are numbered? I've seen the numbering in the past and seeing it again in a recent doc has prompted me to find out?
They have Rockwell wiring codes, JSC codes, etc
Understood, so each harness could have more than one code. Do you know what the typical harness wrap material is? Kapton? (but I imagine it varies?)
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#759
by
10W29
on 08 Mar, 2008 21:11
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kneecaps - 8/3/2008 12:23 PM
Anybody know how the Orbiter wiring harnesses are numbered? I've seen the numbering in the past and seeing it again in a recent doc has prompted me to find out?
What does 83P331 and 83P332 mean? 83 some kind of location code? P some kind of type ID and the last digits a serial number?
These refer to connectors, not harnesses. P stands for plug as opposed to J for jack and 83 is for location (Av Bay 3). 80 series are middeck, 30 series are flight deck etc.