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#2020
by
butters
on 28 May, 2009 06:13
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Why does operating the Shuttle require so much switch flipping?
It seems like much of the switch flipping is based on following checklists and flowcharts from the flight plan.
There are hundreds of switches, many of which are flipped once or twice per flight in particular sequences. Much of time, the system is waiting for one of two user inputs: the next switch flip in the nominal sequence or an abort. At any given moment, the vast majority of the switches are not appropriate inputs. Even in the most open-ended mission context, most of the switches are inappropriate.
So why not develop the flight plan in a simple wizard language so that the interface can navigate through each phase and contingency step by step with prompted dialogs presenting the most relevant data and inputs at all times. Of course, a command shell would be provided for unplanned contingencies.
A context-sensitive interface would dramatically reduce the number of switches and reduce much of the user interaction to hitting "continue" and monitoring system state as the computer steps through procedures and prompts for confirmation.
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#2021
by
tva
on 28 May, 2009 06:27
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Why does operating the Shuttle require so much switch flipping?
...why not develop the flight plan in a simple wizard language so that the interface can navigate through each phase ...context-sensitive interface would dramatically reduce the number of switches and reduce much of the user interaction to hitting "continue"...
You can easily deduct part of the answer by taking a glance at
Jim's answer to my question.
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#2022
by
usn_skwerl
on 28 May, 2009 06:42
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We have to have L2 to see the video of the damage to 27? FOIA indeed.
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#2023
by
Jim
on 28 May, 2009 11:44
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A context-sensitive interface would dramatically reduce the number of switches and reduce much of the user interaction to hitting "continue" and monitoring system state as the computer steps through procedures and prompts for confirmation.
What computer? The orbiter's 70's vintage avionics architecture which needs a mass memory unit to contain the programs during ascent?
If it is another computer, where will it reside during launch and landing and how would it be accessible to the crew?
And where do you get the idea that most of the switch throws are unnecessary?
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#2024
by
Danny Dot
on 28 May, 2009 14:38
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I love this quote from Hoot talking about aileron trim on entry, "So I knew that that's what I was going to see if it started to go," Gibson said. "And therefore, that told me that I'd have at least 60 seconds to tell mission control what I thought of their analysis."
This is classic Hoot Gibson.
I can't believe the knowledge that foam can kill a shuttle wasn't used to fix foam shedding before Columbia. They could have implemented inspection, repair, and launch on need -- but just like the joint leaks that led up to Challanger, NASA did NOTHING.
Even after Columbia, I was part of the trajectory modification team in mission operations directorate to see if we could reduce the heating problems if damage was detected. We looked at everything but flying 50 degrees angle of attack instead of 40. Nothing we had looked at worked very well. 50 degrees angle of attack was and is an emergency procedure for high energy TALs. It reduces both heat rate (temperature) and total heat load. The trade off is a lower L/D and reduced cross range. I couldn't even get a discussion started in the group.
I asked for and got a private session with the lead of the team. I didn't tell him the topic, because I don't think he would have approved a meeting to discuss an idea that had already been rejected. During the meeting it was obvious didn't understand the physics (he wasn't a heat guy, he was a GNC guy) and blew me off without any analysis. I was considered one the the top guys at NASA on shuttle entry, but could not get a viable idea to be discussed for 30 seconds. This was before LON and we really needed a way to save the crew if we detected damage in the future. I have no doubt people in that group agreed with me but were afraid to support me. Typical NASA culture. I can tell you from first hand experience the NASA culture that killed 14 astronauts is alive and well.
Danny Deger
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#2025
by
Danny Dot
on 28 May, 2009 14:42
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#2026
by
Danny Dot
on 28 May, 2009 14:53
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Why does operating the Shuttle require so much switch flipping?
It seems like much of the switch flipping is based on following checklists and flowcharts from the flight plan.
There are hundreds of switches, many of which are flipped once or twice per flight in particular sequences. Much of time, the system is waiting for one of two user inputs: the next switch flip in the nominal sequence or an abort. At any given moment, the vast majority of the switches are not appropriate inputs. Even in the most open-ended mission context, most of the switches are inappropriate.
So why not develop the flight plan in a simple wizard language so that the interface can navigate through each phase and contingency step by step with prompted dialogs presenting the most relevant data and inputs at all times. Of course, a command shell would be provided for unplanned contingencies.
A context-sensitive interface would dramatically reduce the number of switches and reduce much of the user interaction to hitting "continue" and monitoring system state as the computer steps through procedures and prompts for confirmation.
The shuttle's computers are completely maxed out doing what they do today, but I think a lot of what you are describing is going into Orion. Even then part of it is a maybe misplaced philosophy to keep a person in the loop. For example feeding OMS to RCS could be automated today, but it is not. All of the OMS and RCS valves can be controlled by the computers and in this phase of flight the computers are not maxed out.
Also, in the MCC there is beastly piece of software called the Abort Region Determinator (ARD). It is configured manually in the MCC based on what the controller sees. It would be trivial now to have the ARD input the data the flight controller is looking at, then configure itself. But , the controllers want to stay in the loop. I recommended it be automated, but the controller has to click OK for the reconfig to take place. This would reduce the likely hood of making a typing error. This idea was also rejected. Today it is still 100% manual inputs because NASA chooses to do it this way.
Danny Deger
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#2027
by
mmeijeri
on 29 May, 2009 04:08
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What is the highest altitude 28 deg inclination circular orbit the shuttle can reach without any payload in the payload bay? Is there a simple way to estimate this short of simulating an ascent trajectory?
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#2028
by
Danny Dot
on 29 May, 2009 04:20
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What is the highest altitude 28 deg inclination circular orbit the shuttle can reach without any payload in the payload bay? Is there a simple way to estimate this short of simulating an ascent trajectory?
One way or two way trip?
A couple of rules of thumb I remember are it takes 1.8 feet/sec to change one side of the orbit 1 Nautical Mile. IIRC 20,000 pounds of prop is worth about 1,000/sec. Hubble is about 340 NM high and this is about max for the shuttle carrying a Hubble. There was a plan for an OMS kit to put in the payload bay, but was never fully developed. Some of this info might be useful.
Danny Deger
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#2029
by
mmeijeri
on 29 May, 2009 04:31
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One way or two way trip?
Lol, good question!
A couple of rules of thumb I remember are it takes 1.8 feet/sec to change one side of the orbit 1 Nautical Mile. IIRC 20,000 pounds of prop is worth about 1,000/sec. Hubble is about 340 NM high and this is about max for the shuttle carrying a Hubble. There was a plan for an OMS kit to put in the payload bay, but was never fully developed. Some of this info might be useful.
Thanks. I was wondering about using the main propulsion system to insert into the highest possible orbit. I'm also curious about the same question for Shuttle-C. Suppose you were trying to get a 20 mT payload to L1 or GEO with a Centaur. The combined mass of the Centaur + additional payload would be around 40mT, much less than the >70 mT of Shuttle-C. Could you use the excess payload capacity to insert the Shuttle into a higher orbit, thus making things easier for the upper stage? Would that make a meaningful difference? When the IUS was still operational, did they try to move the Shuttle into the highest possible orbit first? And what where the plans for Centaur G?
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#2030
by
Danny Dot
on 29 May, 2009 05:01
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One way or two way trip?
Lol, good question!
A couple of rules of thumb I remember are it takes 1.8 feet/sec to change one side of the orbit 1 Nautical Mile. IIRC 20,000 pounds of prop is worth about 1,000/sec. Hubble is about 340 NM high and this is about max for the shuttle carrying a Hubble. There was a plan for an OMS kit to put in the payload bay, but was never fully developed. Some of this info might be useful.
Thanks. I was wondering about using the main propulsion system to insert into the highest possible orbit. I'm also curious about the same question for Shuttle-C. Suppose you were trying to get a 20 mT payload to L1 or GEO with a Centaur. The combined mass of the Centaur + additional payload would be around 40mT, much less than the >70 mT of Shuttle-C. Could you use the excess payload capacity to insert the Shuttle into a higher orbit, thus making things easier for the upper stage? Would that make a meaningful difference? When the IUS was still operational, did they try to move the Shuttle into the highest possible orbit first? And what where the plans for Centaur G?
In principle you could take shuttle to a higher initial apogee with the MPS if the shuttle was light. I don't know off the top of my head a good rule for how much higher the apogee would be if you lightened up the shuttle. IIRC 1,200 pounds of performance margin is worth about 125 ft/sec. I think taking off weight from shuttle is within 10% of the same delta to performance margin. Taking 10,000 pounds off shuttle would give you another 1,041 ft/sec at MECO by this rule. But this sound too high and makes me think something is wrong.
If it is correct, this 1041 ft/sec would give you about another 578 NM of apogee. This does seem too high for just off loading 10,000 pounds. Someone out there in Shuttleland help us out. How much delta-v at MECO will you gain by offloading 1,000 pounds of payload?
Danny Deger
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#2031
by
Jim
on 29 May, 2009 14:11
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1. When the IUS was still operational, did they try to move the Shuttle into the highest possible orbit first?
2. And what where the plans for Centaur G?
1. It depended on the payload
2. It was the lowest shuttle orbit, since it maxed out the performance of the shuttle
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#2032
by
mmeijeri
on 29 May, 2009 16:19
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Jim, Danny, thanks for the answers. It's great to have people like you on the forum who are willing to share their knowledge. After Danny mentioned the OMS kit, I did some googling and found a very interesting document on the OMS:
ORBITAL MANEUVERING SYSTEM (OMS)It is very readable and goes into quite a bit of detail. As they say, "A fool can ask more questions than a wise man can answer", so here's another one:
I noticed that OMS has a nitrogen system for purging and a helium system for pressurisation. I wondered why a separate helium system is needed. I read that sometimes nitrogen is also used for pressurising hypergolics. Having two systems is more complicated than having just one and helium is more expensive than nitrogen, so there must be some advantage that made them use helium. Anyone know what that advantage is?
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#2033
by
Jim
on 29 May, 2009 16:27
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Delta II uses helium for pressurizing the hypergolic second stage.
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#2034
by
mmeijeri
on 29 May, 2009 19:12
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According to this page from
Sutton, nitrogen is less useful for pressurising NTO and LOX because it will dissolve in the oxidiser much more readily than helium, requiring 2.5 x more pressurant. The document I linked to above explains that the OMS fuel and oxidiser tanks are pressurised by a single helium system in order to maintain identical pressures and therefore constant mixture ratios.
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#2035
by
spaceshuttle
on 01 Jun, 2009 05:04
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I might be asking this in the wrong thread, but why is there a close-out (the ring around the nose of STS-127's external tank) on the tank? I don't remember it being there originally. What inspections were done?
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#2036
by
ChrisGebhardt
on 01 Jun, 2009 06:40
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I might be asking this in the wrong thread, but why is there a close-out (the ring around the nose of STS-127's external tank) on the tank? I don't remember it being there originally. What inspections were done?
What are you referring to? If you're referring to the rings of different colored foam in the attached picture, these are just discolorations in the foam caused by different application times at MAF (or touch-ups in the VAB checkout cell) and exposure to UV radiation on the pad.
They were there when Endeavour rolled out to LC-39B. The first image was taken yesterday at Pad-A. The Second was taken in April at Pad-B.
Scroll through here:
http://mediaarchive.ksc.nasa.gov/search.cfm The variations in foam coloring are there during stacking. They're just more prominent now because of uneven foam darkening due to UV radiation exposure at the pad.
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#2037
by
spaceshuttle
on 01 Jun, 2009 07:24
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I might be asking this in the wrong thread, but why is there a close-out (the ring around the nose of STS-127's external tank) on the tank? I don't remember it being there originally. What inspections were done?
What are you referring to? If you're referring to the rings of different colored foam in the attached picture, these are just discolorations in the foam caused by different application times at MAF (or touch-ups in the VAB checkout cell) and exposure to UV radiation on the pad.
They were there when Endeavour rolled out to LC-39B. The first image was taken yesterday at Pad-A. The Second was taken in April at Pad-B.
Scroll through here: http://mediaarchive.ksc.nasa.gov/search.cfm
The variations in foam coloring are there during stacking. They're just more prominent now because of uneven foam darkening due to UV radiation exposure at the pad.
Thanks so much!
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#2038
by
The-Hammer
on 02 Jun, 2009 23:16
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I searched the Q&A but couldn't find this question.
Who flies the SCA? Do astronauts get that duty or are there pilots hired specifically for the job?
On the one hand, I imagine the astronauts would consider it part of their duty to bring her home. On the other hand, though, I also imagine handling the SCA+Orbiter would require specific training that wouldn't fit in with everything else the astronauts have to do.
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#2039
by
Jim
on 03 Jun, 2009 01:23
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I searched the Q&A but couldn't find this question.
Who flies the SCA? Do astronauts get that duty or are there pilots hired specifically for the job?
On the one hand, I imagine the astronauts would consider it part of their duty to bring her home. On the other hand, though, I also imagine handling the SCA+Orbiter would require specific training that wouldn't fit in with everything else the astronauts have to do.
NASA test pilots
