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Did Apollo really travel sideways?
I just watched Man Moment Machine featuring Apollo 13. In most of the
animations, the LM/CSM was traveling to the side. Is this right? I always assumed it traveled straight ahead with that big CSM engine nozzle to the rear. |
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Did Apollo really travel sideways?
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#4
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Did Apollo really travel sideways?
In article ,
David Findlay wrote: ...Many spacecraft do a bbq roll which is basically keeping the vehicle rolling so that no side of the vehicle gets too hot. A "barbecue roll" in fact isn't *that* common; most spacecraft are designed to handle being constantly one side to the Sun. Apollo did it not to keep things from getting too hot, but to keep one specific thing from getting too cold: it proved impossible to qualify the CM heatshield material for prolonged "cold soak" conditions, so a slow rotation with the spacecraft axis roughly perpendicular to the sunlight was needed to keep it within its temperature limits. Positioning the spacecraft axis roughly north-south -- which did indeed imply traveling sideways -- and rolling around it was a simple way of doing this, independent of the exact trajectory being followed and satisfying some other arcane constraints. -- spsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | |
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Did Apollo really travel sideways?
"Henry Spencer" wrote in message ... In article , David Findlay wrote: ...Many spacecraft do a bbq roll which is basically keeping the vehicle rolling so that no side of the vehicle gets too hot. A "barbecue roll" in fact isn't *that* common; most spacecraft are designed to handle being constantly one side to the Sun. Apollo did it not to keep things from getting too hot, but to keep one specific thing from getting too cold: it proved impossible to qualify the CM heatshield material for prolonged "cold soak" conditions, so a slow rotation with the spacecraft axis roughly perpendicular to the sunlight was needed to keep it within its temperature limits. Positioning the spacecraft axis roughly north-south -- which did indeed imply traveling sideways -- and rolling around it was a simple way of doing this, independent of the exact trajectory being followed and satisfying some other arcane constraints. -- spsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | On April 14th, 1970 the moon was in quarter phase, so the sun would have been at some angle less than 90 degrees from a north/south axis. RT |
#6
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Did Apollo really travel sideways?
Henry Spencer wrote:
A "barbecue roll" in fact isn't *that* common; most spacecraft are designed to handle being constantly one side to the Sun. Apollo did it not to keep things from getting too hot, but to keep one specific thing from getting too cold: it proved impossible to qualify the CM heatshield material for prolonged "cold soak" conditions, so a slow rotation with the spacecraft axis roughly perpendicular to the sunlight was needed to keep it within its temperature limits. Did Apollo 13 then give them that qual? rick jones -- portable adj, code that compiles under more than one compiler 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... |
#7
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Did Apollo really travel sideways?
Did Apollo 13 then give them that qual? I don't think so. Even though the service module was rendered dead (or at least not trustworthy) anymore, they still held onto it to protect the heat shield. And they still did the barbecue roll, as that didn't cost battery power or other consumables. On the ground tests probably showed that the heat shield would not qualify for a cold soak, but the barbecue roll was a workaround to get past that problem. We did have a deadline to meet.... |
#8
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Did Apollo really travel sideways?
In article ,
Rick Jones wrote: ...it proved impossible to qualify the CM heatshield material for prolonged "cold soak" conditions... Did Apollo 13 then give them that qual? No, even on Apollo 13, they made a point of putting the spacecraft into the thermal roll before shutting down after maneuvers etc. -- spsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | |
#9
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Did Apollo really travel sideways?
In article tYt8i.991$jW6.679@trnddc01,
Rocky Top wrote: ...a slow rotation with the spacecraft axis roughly perpendicular to the sunlight was needed... Positioning the spacecraft axis roughly north-south -- which did indeed imply traveling sideways -- and rolling around it was a simple way... On April 14th, 1970 the moon was in quarter phase, so the sun would have been at some angle less than 90 degrees from a north/south axis. Uh, the Sun is *always* at roughly a right angle to a north/south axis, because that axis is roughly perpendicular to the Earth's orbital plane. The position of the Moon is irrelevant. -- spsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | |
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Did Apollo really travel sideways?
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