I can appreciate the blackout zone argument, however I'm not groking the load limits statement. Seems to me that 2 Centaurs should provide a gentle ascent. Even at max thrust it shouldn't exceed 3 g's
Maximum acceleration is 3.5g, not 3g as has been reported. Listen to the audio at 1:08:25 of the NASA livestream.
So I'm stumped why they did this. Any thoughts?Once around automatic safe abort. Plain and simple.
- Ed Kyle
My problem is that I can't game out a case where once-around is actually safer than aborting to orbit.
My problem is that I can't game out a case where once-around is actually safer than aborting to orbit.Progress 59, spacecraft spinning out of control upon separation.
CRS-2, spacecraft separated with no RCS for some time, solar arrays could not deploy, etc.
Etc.
Big trouble sometimes happens - has happened - right at spacecraft separation. Better to have a safe passive abort than to leave helpless astronauts spinning in space with no way out.
- Ed Kyle
Spinning out of control is fatal if you don't fix the problem before reentry.
Lack of an RCS system is likely fatal if you don't fix the problem before reentry.
Spinning out of control is fatal if you don't fix the problem before reentry.
Lack of an RCS system is likely fatal if you don't fix the problem before reentry.I'm not sure about these. These capsules are supposed to be aerodynamically stable during reentry. Without RCS, they could oscillate and cone, etc., but would still generally point heat shield first (CG versus CP and all that). Of course for all this to happen, the service module needs to separate and, in the end, the parachutes need to deploy.
- Ed Kyle
Right. Not all the way around. Safe abort to Indian Ocean.
- Ed KyleDo they have rescue assets placed there or nearby? Wondering how long the capsule is good for if it aborts and has to await assets to travel some distance.The US Navy usually has some ships in the Indian Ocean. There is the base at Diego Garcia. It may not be too big of a problem to have some ship nearby just in case.
RCS absolutely stone dead: SWAG PLOC at reentry: >95%.
RCS absolutely stone dead: SWAG PLOC at reentry: >95%.
Far too high an estimate, IMO. Starliner is a new vehicle, but out-of-control entries have happened before. See Soyuz TMA 01, 10, and 11. The "worst" of these, due to separation failure of the service module, caused the capsule to re-enter hatch-side forward. Even so, the re-entry module eventually broke free and successfully reoriented itself. Very far from ideal, but also far from a certain death sentence.
A loss of control on Starliner would likely result in ballistic re-entry rather than a lifting re-entry, as it did in the TMA flights. You'll land far off-target, and it'll be a very uncomfortable ride down, but the trip back should be inherently survivable. Important to remember that in an emergency situation, it's more important to get the crew back alive than to get them back comfortably and without injury. Things like re-entry corridors are pretty much an afterthought at this point.
This spring, Ferguson was back in the cockpit of the simulator, training to fly again.
...
The shuttle had wings, like a plane. His new spacecraft was a thimble-shaped capsule, far more difficult to control. In this particular test, he’d be facing a worst-case scenario: Every computer of the autonomous spacecraft would be out, meaning he’d have to fly it manually, hitting the atmosphere at Mach 25, or 25 times the speed of sound, then, somehow, bring it down for a soft landing. Two of the four NASA astronauts who had attempted it had failed, losing control of the spacecraft so that it tumbled, and Ferguson was eager to get in some extra practice.
...
He was struggling with what he called the “pitch worm.” If the spacecraft pitched too much, it would start a tumble almost impossible to recover from. He was also having a hard time seeing the screen in front of him because it was so close.
...
The spacecraft started oscillating at 120 kilometers high.
“Oh, here we go,” Ferguson said, gripping the joystick, firing the thrusters in short bursts so that the spacecraft stayed level. “Game on.”
Behind a glass wall, a pair of evaluators were observing.
“He makes it look easy,” one said. “But it goes from easy to hard really fast.”
The spacecraft was now tearing through the thickening air, flying Mach 17 at 60 km, then Mach 13, then Mach 6.5. Ferguson was in the groove, talking to himself and firing the thrusters to steady the spacecraft.
“Just keep beating back the pitch worm,” he said calmly to himself. “Beat it back.”
“He’s looking really good,” said one of the evaluators behind the glass wall. “You can see he’s fighting the pitch.”
Altitude: 50 km, then 40 km, then 30 km.
Finally, the parachutes deployed. The spacecraft splashed down. Ferguson delivered his line, rehearsing the coda that would usher in a new Space Age:
“Houston, we have landed.”
Things like re-entry corridors are pretty much an afterthought at this point.
Things like re-entry corridors are pretty much an afterthought at this point.A reentry corridor is the range of trajectories and flight path angles that result in the vehicle not skipping off the atmosphere and not burning up and/or squishing the crew.
NB: "Skipping off the atmosphere" is likely the same as "burning up": You have even less C3 than you started with, and the next time you enter you're going to hit steeper, and probably go splat/sizzle.
Starliner isn't all that stable.
Yes, but that's more of a concern with an Apollo-like return trajectory rather than Starliner's suborbital trajectory. Think of Starliner as being delivered directly into a survivable re-entry corridor, which it escapes from using it's own systems if things go right, and comes back home if things go wrong.
The corridor is the acceptable path through the atmosphere, not the trajectory that leads it to entry interface.
A reentry corridor is the range of trajectories and flight path angles that result in the vehicle not skipping off the atmosphere and not burning up and/or squishing the crew.
RCS absolutely stone dead: SWAG PLOC at reentry: >95%.
Far too high an estimate, IMO. Starliner is a new vehicle, but out-of-control entries have happened before. See Soyuz TMA 01, 10, and 11. The "worst" of these, due to separation failure of the service module, caused the capsule to re-enter hatch-side forward. Even so, the re-entry module eventually broke free and successfully reoriented itself. Very far from ideal, but also far from a certain death sentence.
A loss of control on Starliner would likely result in ballistic re-entry rather than a lifting re-entry, as it did in the TMA flights. You'll land far off-target, and it'll be a very uncomfortable ride down, but the trip back should be inherently survivable. Important to remember that in an emergency situation, it's more important to get the crew back alive than to get them back comfortably and without injury. Things like re-entry corridors are pretty much an afterthought at this point.
Starliner isn't all that stable.QuoteThis spring, Ferguson was back in the cockpit of the simulator, training to fly again.
...
The shuttle had wings, like a plane. His new spacecraft was a thimble-shaped capsule, far more difficult to control. In this particular test, he’d be facing a worst-case scenario: Every computer of the autonomous spacecraft would be out, meaning he’d have to fly it manually, hitting the atmosphere at Mach 25, or 25 times the speed of sound, then, somehow, bring it down for a soft landing. Two of the four NASA astronauts who had attempted it had failed, losing control of the spacecraft so that it tumbled, and Ferguson was eager to get in some extra practice.
...
He was struggling with what he called the “pitch worm.” If the spacecraft pitched too much, it would start a tumble almost impossible to recover from. He was also having a hard time seeing the screen in front of him because it was so close.
...
The spacecraft started oscillating at 120 kilometers high.
“Oh, here we go,” Ferguson said, gripping the joystick, firing the thrusters in short bursts so that the spacecraft stayed level. “Game on.”
Behind a glass wall, a pair of evaluators were observing.
“He makes it look easy,” one said. “But it goes from easy to hard really fast.”
The spacecraft was now tearing through the thickening air, flying Mach 17 at 60 km, then Mach 13, then Mach 6.5. Ferguson was in the groove, talking to himself and firing the thrusters to steady the spacecraft.
“Just keep beating back the pitch worm,” he said calmly to himself. “Beat it back.”
“He’s looking really good,” said one of the evaluators behind the glass wall. “You can see he’s fighting the pitch.”
Altitude: 50 km, then 40 km, then 30 km.
Finally, the parachutes deployed. The spacecraft splashed down. Ferguson delivered his line, rehearsing the coda that would usher in a new Space Age:
“Houston, we have landed.”
https://www.seattletimes.com/nation-world/nasa-trained-and-boeing-employed-chris-ferguson-hopes-to-make-history-as-a-company-astronaut/
RCS absolutely stone dead: SWAG PLOC at reentry: >95%.
Far too high an estimate, IMO. Starliner is a new vehicle, but out-of-control entries have happened before. See Soyuz TMA 01, 10, and 11. The "worst" of these, due to separation failure of the service module, caused the capsule to re-enter hatch-side forward. Even so, the re-entry module eventually broke free and successfully reoriented itself. Very far from ideal, but also far from a certain death sentence.
A loss of control on Starliner would likely result in ballistic re-entry rather than a lifting re-entry, as it did in the TMA flights. You'll land far off-target, and it'll be a very uncomfortable ride down, but the trip back should be inherently survivable. Important to remember that in an emergency situation, it's more important to get the crew back alive than to get them back comfortably and without injury. Things like re-entry corridors are pretty much an afterthought at this point.
Starliner isn't all that stable.QuoteThis spring, Ferguson was back in the cockpit of the simulator, training to fly again.
...
The shuttle had wings, like a plane. His new spacecraft was a thimble-shaped capsule, far more difficult to control. In this particular test, he’d be facing a worst-case scenario: Every computer of the autonomous spacecraft would be out, meaning he’d have to fly it manually, hitting the atmosphere at Mach 25, or 25 times the speed of sound, then, somehow, bring it down for a soft landing. Two of the four NASA astronauts who had attempted it had failed, losing control of the spacecraft so that it tumbled, and Ferguson was eager to get in some extra practice.
...
He was struggling with what he called the “pitch worm.” If the spacecraft pitched too much, it would start a tumble almost impossible to recover from. He was also having a hard time seeing the screen in front of him because it was so close.
...
The spacecraft started oscillating at 120 kilometers high.
“Oh, here we go,” Ferguson said, gripping the joystick, firing the thrusters in short bursts so that the spacecraft stayed level. “Game on.”
Behind a glass wall, a pair of evaluators were observing.
“He makes it look easy,” one said. “But it goes from easy to hard really fast.”
The spacecraft was now tearing through the thickening air, flying Mach 17 at 60 km, then Mach 13, then Mach 6.5. Ferguson was in the groove, talking to himself and firing the thrusters to steady the spacecraft.
“Just keep beating back the pitch worm,” he said calmly to himself. “Beat it back.”
“He’s looking really good,” said one of the evaluators behind the glass wall. “You can see he’s fighting the pitch.”
Altitude: 50 km, then 40 km, then 30 km.
Finally, the parachutes deployed. The spacecraft splashed down. Ferguson delivered his line, rehearsing the coda that would usher in a new Space Age:
“Houston, we have landed.”
https://www.seattletimes.com/nation-world/nasa-trained-and-boeing-employed-chris-ferguson-hopes-to-make-history-as-a-company-astronaut/
That sounds terrible!
Two of four astronaut/pilots failed at flying a Starliner reentry?
That would mean that the inability to activate the RCS thrusters within 30 minutes, like CRS-1, would be fatal.
I hope this is just shabby writing and that Starliner flies itself in all but the most serious system failures.
Even the unstable X-29 could be flown with computer control.
Can someone please verify that this is the case?
But even Soyuz is passively stable.
A passive reentry is unpleasant, even injurious, but to date uniformly survivable.
Why would it be an advance to build an inherently unstable capsule for crew?
https://www.seattletimes.com/nation-world/nasa-trained-and-boeing-employed-chris-ferguson-hopes-to-make-history-as-a-company-astronaut/
That sounds terrible!
Two of four astronaut/pilots failed at flying a Starliner reentry?
That would mean that the inability to activate the RCS thrusters within 30 minutes, like CRS-1, would be fatal.
I hope this is just shabby writing and that Starliner flies itself in all but the most serious system failures.
Even the unstable X-29 could be flown with computer control.
Can someone please verify that this is the case?
But even Soyuz is passively stable.
A passive reentry is unpleasant, even injurious, but to date uniformly survivable.
Why would it be an advance to build an inherently unstable capsule for crew?
Starliner seems to be a cross between Shuttle and Apollo, but just because either did something doesn’t say it’s optimal.
Is there an advantage to a capsule that is unstable rather than bring passively stable?
That's literally the exact opposite of what you just said.
Starliner seems to be a cross between Shuttle and Apollo, but just because either did something doesn’t say it’s optimal.
Is there an advantage to a capsule that is unstable rather than bring passively stable?
Remember that the issue we started with is whether a thrusters-out reentry was likely to succeed. Doesn't really matter if the computers are out if they can't command anything to do what they want.
Starliner seems to be a cross between Shuttle and Apollo, but just because either did something doesn’t say it’s optimal.
Is there an advantage to a capsule that is unstable rather than bring passively stable?
Remember that the issue we started with is whether a thrusters-out reentry was likely to succeed. Doesn't really matter if the computers are out if they can't command anything to do what they want.Unless they have the ability to go RCS Direct as with the Apollo CM...