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Space Forum / Shuttle / May 2006RTLS Abort
In the event of an RTLS abort, are there shut off values on the umbilical lines to prevent remainning fuel to leak out of the tank once the orbiter separates? I could see leaking fuel being a danger at that moment, not to mention pollution in the water. Also, when the tank hits the water, would it remain intact or break apart? Thanks. tank will disengrate, good news it fuels are hydrogen and oxygen so it doesnt matter... > In the event of an RTLS abort, are there shut off values on the > umbilical lines to prevent remainning fuel to leak out of the tank once > the orbiter separates? I could see leaking fuel being a danger at that > moment, not to mention pollution in the water. What pollution? The ET contains cryogenic iquid oxygen and cryogenic liquid hydrogen. > Also, when the tank hits > the water, would it remain intact or break apart? I'd think it would be squashed a bit on impact. ;-) Seriously though, I think if you're performing an RTLS, you end up burning most (all?) of the fuel in the ET in order to do the powered turn around maneuver, but there are others here that know better than I. Jeff  Signature"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) > > In the event of an RTLS abort, are there shut off values on the > > umbilical lines to prevent remainning fuel to leak out of the tank once [quoted text clipped - 19 lines] > safety" > - B. Franklin, Bartlett's Familiar Quotations (1919) Stupid me...what happens to super-chilled liquid hydrogen and oxygen when it warms up. Duh! I do wonder how long after SRB SEP that the shuttle stays with the tank. Maybe most of the fuel is indeed burned off? the srbs cant seperate till they burn out, at just over 2 minutes I'm aware of that. My question was how long after that separation does the orbiter stay with the tank during an RTLS abort. > I'm aware of that. My question was how long after that separation does > the orbiter stay with the tank during an RTLS abort. I think during RTLS the Orbiter takes about 20 minutes after shedding the SRBs to get turned around and headed back, and that burns off most of the fuel. Mike Ross >I'm aware of that. My question was how long after that separation does >the orbiter stay with the tank during an RTLS abort. How long the Orbiter stays on the Tank depends on when the RTLS Abort order is given. They'll burn the SSMEs until ET depletion, which means at least 8 minutes of powered flight, longer if an engine-out is the reason for the RTLS. So the actual RTLS flight profile will be designed to get to ET depletion at the same time the Shuttle achieves the necessary velocity to get back to KSC, and that depends on vehicle weight, launch azimuth, etc. By the way, a lot of that SSME burning will be into the velocity vector, slowing the Shuttle's downrange progress and eventually reaching a zero velocity point before the Shuttle starts accellerating back to KSC. It would be, shall we say, very exciting. Brian how many really think its survivable? > how many really think its survivable? Who cares, as long as its better than the alternative. --Chris doesnt matter if the crew dies anyway............ probably another feel good safety measure thats known as not effective... >>I'm aware of that. My question was how long after that separation does >>the orbiter stay with the tank during an RTLS abort. [quoted text clipped - 11 lines] >reaching a zero velocity point before the Shuttle starts accellerating >back to KSC. It would be, shall we say, very exciting. Nobody really believes it will work, do they? But they have to do SOMETHING... > Nobody really believes it will work, do they? But they have to do > SOMETHING... Many people do in fact think it will work, though it's risky enough that it's not worth risking an orbiter and crew just to test it. SignatureJRF Reply-to address spam-proofed - to reply by E-mail, check "Organization" (I am not assimilated) and think one step ahead of IBM. >> Nobody really believes it will work, do they? But they have to do >> SOMETHING... > > Many people do in fact think it will work, though it's risky enough that > it's not worth risking an orbiter and crew just to test it. I'm one of those people. If they every have to do one, it will be one exciting ride. >>> Nobody really believes it will work, do they? But they have to do >>> SOMETHING... [quoted text clipped - 4 lines] > I'm one of those people. If they every have to do one, it will be one > exciting ride. ..and exciting to see too. Lets hope it doesn't happen. I'm secrectly hoping for a realistic 3D animation / CGI graphics from the vantage point of a cape tracking camera to see how it would look like on NASA TV, though. SignatureMika Takala > >>> Nobody really believes it will work, do they? But they have to do > >>> SOMETHING... [quoted text clipped - 13 lines] > -- > Mika Takala I'd imagine the crew runs through the scenario in simulations...any word how they typically do? -A.L. >> >>> Nobody really believes it will work, do they? But they have to do >> >>> SOMETHING... [quoted text clipped - 14 lines] > I'd imagine the crew runs through the scenario in simulations...any > word how they typically do? They almost always survive. The few times they don't, it's usually because the training team threw in extra malfunctions that combined with the RTLS in ways the crew and/or flight control team failed to anticipate. SignatureJRF Reply-to address spam-proofed - to reply by E-mail, check "Organization" (I am not assimilated) and think one step ahead of IBM. >> I'd imagine the crew runs through the scenario in simulations...any >> word how they typically do? > >They almost always survive. The few times they don't, it's usually because >the training team threw in extra malfunctions that combined with the RTLS >in ways the crew and/or flight control team failed to anticipate. Are any simulations regularly run in which the odds of survival aren't so good? Seems like that would be pretty demoralizing, but if there is a way to increase their chances through simulations... Dale >>> I'd imagine the crew runs through the scenario in simulations...any >>> word how they typically do? [quoted text clipped - 7 lines] > so good? Seems like that would be pretty demoralizing, but if there is > a way to increase their chances through simulations... Integrated sims are always scripted with at least one way out. They can still end badly if the simulator misbehaves, if the script scenario turns out to be unsurvivable because a novice training team fails to recognize all the interactions between the malfunctions in the script, or if the crew or flight control team fails to see a solution or otherwise makes an error. So the "odds of survival" of a given sim depend to a large extent on the skill level of the crew and flight control team. SignatureJRF Reply-to address spam-proofed - to reply by E-mail, check "Organization" (I am not assimilated) and think one step ahead of IBM. >>By the way, a lot of that SSME burning will be into the velocity >>vector, slowing the Shuttle's downrange progress and eventually >>reaching a zero velocity point before the Shuttle starts accellerating >>back to KSC. It would be, shall we say, very exciting. >Nobody really believes it will work, do they? But they have to do SOMETHING... Would you rather face certain death, or possible death? Brian > Nobody really believes it will work, do they? But they have to do SOMETHING... Its sort of like ejecting from a military aircraft where its your last desperate chance to maybe live but your quality of life might not be 100%. I remember Navy pilots use to refer to it as committing suicide to prevent being killed. JD > Stupid me...what happens to super-chilled liquid hydrogen and oxygen > when it warms up. Duh! I do wonder how long after SRB SEP that the > shuttle stays with the tank. Maybe most of the fuel is indeed burned > off? Yes, the goal is to burn almost all of it off so that the tank is near empty at ET sep. ET sep for RTLS occurs at lower altitude than nominal and propellant slosh would create some very unfavorable dynamics. SignatureJRF Reply-to address spam-proofed - to reply by E-mail, check "Organization" (I am not assimilated) and think one step ahead of IBM. |
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