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#41
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Maximum Rate Shuttle Launches
On Jun 12, 4:57 pm, Len wrote:
On Jun 12, 1:21 pm, Oren T wrote: On Jun 12, 12:58 pm, "Ed Ruf (REPLY to E-MAIL IN SIG!)" wrote: On Mon, 11 Jun 2007 12:03:33 -0700, in sci.space.policy Len wrote: technology. As I understand it, even a complicated beast like the SR-71--with hydraulic "fluid" that was solid at room temperature--was flown twice in the same day. IIRC, they only did it once, because of cost considerations--not techinical difficulties. I thought the SR-71 used its JP-7 fuel for hydraulic fluid? JP-7 isn't anywhere near a solid even at winter temps in Hampton, VA where we have several drums of if out back behind our facilities. -- Ed Ruf ) A quick web search shows it had two hydraulic systems: one for the engines which used the fuel as working fluid and another using something solid at room temperature. Len suggests it may have been NaK but a eutectic is liquid at STP (mp -12.6 C). Perhaps it was straight sodium? NaK would be solid on a cool day, but otherwise liquid and more practical. Solid sounds more interesting--and perhaps worth stretching a point when people want to talk about an unusual plane? :-) Len I should have added that Kelly Johnson was not averse to turning a clever phrase such as: "We get all of our thrust out of the inlet; the engine is just a flow inducer." If you keep your books the right way, this is actually true. The forces on the B-70 engine mounts actually reversed at mach 3. Len Oren |
#42
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Maximum Rate Shuttle Launches
On Jun 12, 1:21 pm, Oren T wrote:
On Jun 12, 12:58 pm, "Ed Ruf (REPLY to E-MAIL IN SIG!)" wrote: On Mon, 11 Jun 2007 12:03:33 -0700, in sci.space.policy Len wrote: technology. As I understand it, even a complicated beast like the SR-71--with hydraulic "fluid" that was solid at room temperature--was flown twice in the same day. IIRC, they only did it once, because of cost considerations--not techinical difficulties. I thought the SR-71 used its JP-7 fuel for hydraulic fluid? JP-7 isn't anywhere near a solid even at winter temps in Hampton, VA where we have several drums of if out back behind our facilities. -- Ed Ruf ) A quick web search shows it had two hydraulic systems: one for the engines which used the fuel as working fluid and another using something solid at room temperature. Len suggests it may have been NaK but a eutectic is liquid at STP (mp -12.6 C). Perhaps it was straight sodium? Do you have an actual cite? (sight /pun) The one source I could locate: http://www.blackbirds.net/u2/c_bennett/bbird-03.html " Another problem occurred when trying to pin-point leaks. With oil, fuel, and hydraulic fluids being the same color, it was difficult to actually see what was leaking. " The same source, despite noting that the engines had to be heated in order to thin the lubricating oil significantly fails to make any such notation about the hydraulic system. The online version of the SR-71 flight manual (http://www.sr-71.org/blackbird/manual/) fails to mention solid or unusually thick hydraulic fluid as well. In fact, I could not find _any_ source that specified the hydraulic fluid was a solid at room temperature. (Though I did find one that claimed it was a powder.) D. -- Touch-twice life. Eat. Drink. Laugh. -Resolved: To be more temperate in my postings. Oct 5th, 2004 JDL |
#43
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Maximum Rate Shuttle Launches
"Derek Lyons" wrote in message
... "Greg D. Moore \(Strider\)" wrote: After a year or so though, you start to hit into things like scheduled maintenance (OMDP,) That's not a problem for a sustained rate - because it's merely a scheduling issue. It sounds like your write up was more based on 'how long could a surge be maintained and how high would the surge rate be'. Partly yes. I didn't get to deep into how long a surge you could really maintain etc. I partly see the whole thing as a chicken and an egg problem. Flights cost a lot, so you want to make sure you have as "full" a mission as possible. Which reduces the number of missions you might fly in a year. But of course since fixed costs are just that and incremental costs are more variable, you drive up the costs of individual flights, making them cost more, etc. :-) In general though from my idle musing, 12-16 was definitely doable with some investment (say a few billion) but did not require 10s of billions or anything. D. -- Touch-twice life. Eat. Drink. Laugh. -Resolved: To be more temperate in my postings. Oct 5th, 2004 JDL -- Greg Moore SQL Server DBA Consulting Remote and Onsite available! Email: sql (at) greenms.com http://www.greenms.com/sqlserver.html |
#44
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Unmanned Shuttle
Derek Lyons wrote:
John Doe wrote: Would getting Kurs solve more than 70% of the problem with just the integration with shuttle computers having to be done, or would integrating Kurs with Shuttle end up costing more work than develooping a new system from scratch for the shuttle ? I suspect the latter. I suspect so also. "Integration with the shuttle computers" is 90% of the pain. Also, it's not just the shuttle that would have to be upgraded; none of the APAS ports on ISS have the required passive Kurs system installed. |
#45
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Unmanned Shuttle
Mike Combs wrote:
wrote in message ups.com... On Jun 11, 9:53?pm, "Jorge R. Frank" wrote: Rand Simberg wrote: Charles Talleyrand: Can the shuttle fly with no one on board? Takeoff, dock, land, the whole shebang? No, but the ability to allow it to do so is trivial, Perhaps for launch and landing. Not so for docking. That would be a distinctly non-trivial upgrade. soyuz could ferry trained pilots to handle final docking Maybe Progress could be up-rated to take up a single pilot. It could automatically dock with Station, then the pilot could hop over to the unmanned Shuttle to dock it since automated docking is too complicated. Hmmm..... Hmmm... Progress has no heat shield. So what happens to the pilot in the event of a launch abort? Or a failure to dock? If you're suggesting up-rating the Progress to include a heat shield, don't bother. That already exists. It's called Soyuz, silly. And if the Progress docks to the station, just how does the pilot "hop over" to the unmanned shuttle, since it hasn't docked yet? If your intention was for him to hop back into the Progress, undock from the station, then rendezvous and dock with the shuttle, then why would you bother docking to the station first? That just wastes propellant and time. Besides, you would have to equip the Progress/Soyuz with an APAS in order to dock it with the shuttle. The Russian docking ports on ISS aren't APAS. And the APAS ports on ISS don't support Kurs. So a Soyuz/Progress modified to dock with a shuttle cannot dock with ISS. It would have to be a "throwaway", and therefore would carry a higher price than a Soyuz/Progress that was going to go to ISS anyway. I know bbo hallreb isn't capable of thinking things through before he posts, but I didn't think you'd fall into the same trap. |
#46
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Unmanned Shuttle
I know bbo hallreb isn't capable of thinking things through before he posts, but I didn't think you'd fall into the same trap.- Hide quoted text - talk about not thinking it thru, you add a adapter to one port that allows a soyuz to dock with both ISS and shuttle. or modify a shuttle permanetely to dock with soyuz. shuttle remote control gets within a mile or two of ISS, soyuz already at station flies over and pilots its docking. I would hope that in the future, if nasa has a future things get a standard for emergencies. Remember the apollo 13 hassles where CO2 filters were different in CM & LM? ducttape special |
#47
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Maximum Rate Shuttle Launches
Jeff Findley wrote:
"Charles Buckley" wrote in message ... Henry Spencer wrote: In article .com, This has two big problems. First, it would greatly reduce the power of Astronaut Office management, by taking a lot of the suspense and mystery out of crew selection. And second, the astronauts hate having to let non-astronauts into their flying clubhouses. And even beyond those horrors would be a non-degreed warrant officer from the US army flying as a payload specialist. What's the point in 4 BS degrees, 3 MS degrees, and 2 PhD's on the resume then? Obviously there's not any point in this. The current batch of astronauts are, in general, vastly over qualified. For example, you don't need all those degress to "fly" the RMS. Commercial crane operators arguably have much the same job requirements, and often lift extremely expensive pieces of hardware, but you'd be hard pressed to find people doing those jobs who have multiple MS degrees and/or PhD's. I know. I just used an actual specific example of Thomas J. Hennen. http://www.jsc.nasa.gov/Bios/PS/hennen.html As near as I can tell, this was about the smartest personel decision ever to fly on Shuttle. They took someone from the end customer support who was familiar with the technology. Fed him into the payload development side of things so he was very familiar with the payload. Then, about a year before he flew, he reported to NASA for flight and shuttle training. I don't think NASA had any choice on this guy, at all. He was specified by the DoD. |
#48
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Unmanned Shuttle
"Jorge R. Frank" wrote in message
... I know bbo hallreb isn't capable of thinking things through before he posts, but I didn't think you'd fall into the same trap. Thanks. Actually, I was trying to use humor to question the assertion that automated docking is exceedingly difficult by reminding everybody that Progress does it routinely. -- Regards, Mike Combs ---------------------------------------------------------------------- By all that you hold dear on this good Earth I bid you stand, Men of the West! Aragorn |
#49
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Unmanned Shuttle
"Mike Combs" wrote in message ... "Jorge R. Frank" wrote in message ... I know bbo hallreb isn't capable of thinking things through before he posts, but I didn't think you'd fall into the same trap. Thanks. Actually, I was trying to use humor to question the assertion that automated docking is exceedingly difficult by reminding everybody that Progress does it routinely. Don't you know automated rendezvous and docking is hard because *NASA* has never done it? ;-) Seriously though, it's not a trivial problem to solve, especially when you consider that you need to integrate it into a vehicle that was never designed to be completely automated in this way and you need to put in abort modes that can handle ever conceivable contingency without damaging the shuttle or the station (i.e. no RCS firings in the right magnitude/direction to cause something like solar array damage). Also, why bother to automate it on a vehicle that will always be manned? It's kind of like expecting a fighter aircraft to be able to do mid-air refueling while the autopilot is on and the pilot is sleeping. Jeff -- "They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety" - B. Franklin, Bartlett's Familiar Quotations (1919) |
#50
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Unmanned Shuttle
Also, why bother to automate it on a vehicle that will always be
manned? It's kind of like expecting a fighter aircraft to be able to do mid-air refueling while the autopilot is on and the pilot is sleeping. I wonder if perhaps fighter pilots might like to have that feature It wouldn't surprise me at all to learn that someone is working on something like that for UCAV's...at which point it is a small matter of porting right?-) rick jones -- The glass is neither half-empty nor half-full. The glass has a leak. The real question is "Can it be patched?" these opinions are mine, all mine; HP might not want them anyway... feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH... |
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