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Did Apollo do a burn prior to re-entry?
At the risk of sounding like a smart aleck, I think the answer is yes . . . or perhaps more accurately, it depends. It probably depends on the angle at which the reentry had been attempted, vechicle velocity, and the weight of the vehicle, which increased as more and more samples were brought back. I suspect that it would be a funny- shaped earth orbit, but maybe someone more proficient at orbital mechanics can tell us for sure. I can picture it losing enough velocity that it travels outbound from the Earth to a very high altitude, stops, and then falls straight into the atmosphere and burns up. Pat I hate the word "skip". Makes it sound like the atmosphere gives it some sort of push back up. In fact, of course, the atmosphere just slows it down, and if not enough, then the ship's speed is enough to allow it to increase it's distance from the earth. I presume it would go into some highly eccentric orbit, and re-enter the atmosphere perhaps the next few passes, depending on how far outside the re entry window they were. |
#12
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Did Apollo do a burn prior to re-entry?
On Mar 5, 1:53 am, Pat Flannery wrote:
John wrote: Pat, At the risk of sounding like a smart aleck, I think the answer is yes . . . or perhaps more accurately, it depends. It probably depends on the angle at which the reentry had been attempted, vechicle velocity, and the weight of the vehicle, which increased as more and more samples were brought back. I suspect that it would be a funny- shaped earth orbit, but maybe someone more proficient at orbital mechanics can tell us for sure. Take care . . . John I can picture it losing enough velocity that it travels outbound from the Earth to a very high altitude, stops, and then falls straight into the atmosphere and burns up. Pat The heat shield would have withstood 2 additional reentries (skip +final), but I don't know whether the oxygen whould have run out or not. Anyone care to enlighten me regarding O2 supplies on Appolo? |
#13
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Did Apollo do a burn prior to re-entry?
Which brings up the question: What would happen if it did skip off the atmosphere? Does it go into some odd orbit around Earth, or does it go clean out of orbit and into solar orbit? It wouldn't make solar orbit, but it might bounce into a long looping orbit that would return it to the upper atmosphere a day or two later. Bad news for the astronauts, as the command module only has supplies and oxygen that lasts for only a few hours. |
#14
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Did Apollo do a burn prior to re-entry?
Hyper wrote:
On Mar 5, 1:53 am, Pat Flannery wrote: John wrote: Pat, At the risk of sounding like a smart aleck, I think the answer is yes . . . or perhaps more accurately, it depends. It probably depends on the angle at which the reentry had been attempted, vechicle velocity, and the weight of the vehicle, which increased as more and more samples were brought back. I suspect that it would be a funny- shaped earth orbit, but maybe someone more proficient at orbital mechanics can tell us for sure. Take care . . . John I can picture it losing enough velocity that it travels outbound from the Earth to a very high altitude, stops, and then falls straight into the atmosphere and burns up. Pat The heat shield would have withstood 2 additional reentries (skip +final), but I don't know whether the oxygen whould have run out or not. Anyone care to enlighten me regarding O2 supplies on Appolo? Only good for a couple of extra hours. You really don't want to skip off the atmosphere. This assumes that the capsule doesn't flip around and expose the top part to the searing reentry heat. |
#15
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Did Apollo do a burn prior to re-entry?
In article .com,
Hyper wrote: The heat shield would have withstood 2 additional reentries (skip +final), but I don't know whether the oxygen whould have run out or not. Anyone care to enlighten me regarding O2 supplies on Appolo? Power, cooling, oxygen, etc. all were good for only a few hours after separation from the SM. -- spsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | |
#16
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Did Apollo do a burn prior to re-entry?
wrote: I hate the word "skip". Makes it sound like the atmosphere gives it some sort of push back up. Actually that's what happens. The CM was designed to generate lift on the atmosphere as it came in, by angling its heat shield so it wasn't face-on into the airstream: http://content.answers.com/main/cont...-Apollo_cm.jpg Originally the intention was to have it hit the atmosphere, and skip out again as it lost velocity, then do its final reentry. This plan got ditched, and what it ended up doing was using its lift to extend its reentry's length while staying in the upper atmosphere to decrease G forces: http://www.nasm.si.edu/collections/i...RES/Fig22d.jpg The Soviet Zonds returning from looping the Moon on the other hand did use a lifting skip reentry technique that had the spacecraft bounce out of the atmosphere and then do a second reentry. And it was some bounce... it would ether come in over Antarctica and then do its final reentry over the Indian Ocean for a water landing, our come in over the U.S. and then fly over the Arctic for a ground landing in the Soviet Union. So both sides owed a little something to Eugene Sanger and his Antipodal Bomber idea that used atmosphere skipping to increase range, although in this case the idea was to decrease G loads. Pat |
#17
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Did Apollo do a burn prior to re-entry?
In article ,
Pat Flannery wrote: So both sides owed a little something to Eugene Sanger and his Antipodal Bomber idea that used atmosphere skipping to increase range, although in this case the idea was to decrease G loads. Although range was part of it, too -- the reason you do the full Zond-style skip, rather than the less drastic Apollo reentry, is if you really need to stretch the reentry out, to get somewhere that a normal reentry can't reach. Apollo dropped the skip partly because it also dropped its original requirement for a landing in the continental US. -- spsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | |
#18
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Did Apollo do a burn prior to re-entry?
Henry Spencer wrote: Apollo dropped the skip partly because it also dropped its original requirement for a landing in the continental US. I've never seen a drawing of it, but I once ran into a mention of a Rogallo wing equipped Apollo. Pat |
#19
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Did Apollo do a burn prior to re-entry?
Pat Flannery wrote:
Henry Spencer wrote: Apollo dropped the skip partly because it also dropped its original requirement for a landing in the continental US. I've never seen a drawing of it, but I once ran into a mention of a Rogallo wing equipped Apollo. Would not be surprised as Rogallo wings were the original idea for Gemini. My guess is that you are talking about a later block of Apollo capsule. Maybe a design concept from about 1967-69 for Apollo upgrades? |
#20
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Did Apollo do a burn prior to re-entry?
In article ,
Pat Flannery wrote: Apollo dropped the skip partly because it also dropped its original requirement for a landing in the continental US. I've never seen a drawing of it, but I once ran into a mention of a Rogallo wing equipped Apollo. There were a number of ideas for just how to bring an Apollo down on land, and if you read early Apollo papers, you can find details and even some test results -- for example, there was substantial testing done on braking rockets for touchdown. -- spsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | |
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