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#1
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Used, beaten up rockets gaining popularity !
Snidely writes:
JF Mezei quipped: I sure hope Boeing/Lockheed has some skunkworks developping re-usable rocket ASAP. A future Vulcan upgrade is the SMART package, for engine recovery with mid-air snagging. See the wikiparticle. /dps This IS reusing the most expensive part of the rocket, however I don't see how this competes with either at sea or RTLS landing of the entire stage. Snagging the Vulcan engine assembly mid air will be a little more complicated (quite doable just more complicated) and still requires re-assembly of a new stage each time 'round. Once Starship is flying this will also become an economic dog by comparison. Dave |
#2
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Used, beaten up rockets gaining popularity !
David Spain writes:
This IS reusing the most expensive part of the rocket, however I don't see how this competes with either at sea or RTLS landing of the entire stage. Snagging the Vulcan engine assembly mid air will be a little more complicated (quite doable just more complicated) Complicated compared to throwing the stage away I meant, not more complicated than landing an entire stage! Sorry didn't make that too clear. Dave |
#3
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Used, beaten up rockets gaining popularity !
David Spain was thinking very hard :
Snidely writes: JF Mezei quipped: I sure hope Boeing/Lockheed has some skunkworks developping re-usable rocket ASAP. A future Vulcan upgrade is the SMART package, for engine recovery with mid-air snagging. See the wikiparticle. /dps This IS reusing the most expensive part of the rocket, however I don't see how this competes with either at sea or RTLS landing of the entire stage. Snagging the Vulcan engine assembly mid air will be a little more complicated (quite doable just more complicated) and still requires re-assembly of a new stage each time 'round. Once Starship is flying this will also become an economic dog by comparison. Meanwhile, Rocket Lab is going to try chuting a whole first stage, mid-November, a more definite date than anything ULA has mentioned. First iteration is trying for a wet recovery, with helicopters intervening on later launches. /dps -- "First thing in the morning, before I have coffee, I read the obits, If I'm not in it, I'll have breakfast." -- Carl Reiner, to CBS News in 2015. |
#4
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Used, beaten up rockets gaining popularity !
JF Mezei writes:
On 2020-11-06 13:37, David Spain wrote: Complicated compared to throwing the stage away I meant, not more complicated than landing an entire stage! Sorry didn't make that too clear. How complicated would it be to make a delta IV, Arianne 5 or other "legacy" rocket land? Not difficult at all. Most of them already do. It's mainly a question of velocity. :-) Obviously, add legs, grid fins and software. But realistically, how difficult is it to ignite main engines in flight during descent if they don't have igniters on board? Pretty difficult if there isn't someone on board with a match. You'd need hypergolic propellants if you aren't using igniters. Those present their own problems. Better off starting from scratch. Of the legacy rockets, perhaps you could most easily retro fit a Titan II. But the more I think about it, the more less it looks anything like a Titan II. If they want to catch Vulcan engines as they fall down, doesn't that imply engine separation mechanism and likely parachutes for engines? Wouldn't it be simpler to just have it land? Nope. Since there's no propellant for it to combust. If it it's coming down on chutes it's coming down fast enough to damage itself if it were to make contact. I assume it's also not buoyant so that kinda rules out a water landing. Sea water is notoriously bad for rockets engines anyway. See: https://spaceflightnow.com/2015/04/1...of-new-rocket/ Nice chart here that shows all. Dave |
#5
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Used, beaten up rockets gaining popularity !
With a quizzical look, JF Mezei observed:
On 2020-11-07 08:28, David Spain wrote: Pretty difficult if there isn't someone on board with a match. Question remains: how difficult is it to put an igniter in an engine? Since turbopump no not near the engine bells, igniting that "engine" requires a spark generator that is already in there, doesn't it? Do these rockets really requite sparks that are created by GSE? If so, what it is mean when T reaches 0? The rocket sends command to ground equipment to generate the sparks? What is so difficult about igniting the engine from within? Nope. Since there's no propellant for it to combust. Surely, they can do like SpaceX, and return launchers where there is spare fuel, and expand the ones that push the limits and have no fuel left? What is so different with Falcon9 that allows it to ingnite its own engines that nobody else can do? Designed for restarts from the beginning. Most second stage engines are also so designed, plus the shuttle main engines. I don't know if SLS has retained that capability, but Wikipedia suggests that the RS-25 has it still ... dual-redundant spark igniters in the injectors of the preburners. Merlins start with a canister of ugly goops (TEA and TEB) that go bezerk when mixed. Raptors use spark plugs to light torches that then light the preburner and the main chamber. Vulcan will use BE-4 engines, which are supposed to be restartable during flight. Head pressure restarts the turbopumps, but WP doesn't explain what igniters are used. Blue Origin's demonstration of powered landings with the BE-3 engine may have been too late in the Vulcan design cycle to give ULA confidence in the approach. The BE-3U variant is going into the Vulcan, though, as the upper stage. New Glenn will use the same combination as Vulcan, it seems. /dps -- "That's a good sort of hectic, innit?" " Very much so, and I'd recommend the haggis wontons." -njm |
#6
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Used, beaten up rockets gaining popularity !
"Snidely" wrote in message news:mn.3d6c7e4b28a58571.127094@snitoo...
With a quizzical look, JF Mezei observed: What is so different with Falcon9 that allows it to ingnite its own engines that nobody else can do? Designed for restarts from the beginning. Most second stage engines are also so designed, plus the shuttle main engines. I don't know if SLS has retained that capability, but Wikipedia suggests that the RS-25 has it still ... dual-redundant spark igniters in the injectors of the preburners. The SSME were not designed to have relight capability. I don't know the details, but a pad abort for example required them to do servicing. Since there was no real reason for inflight reignition ability, my understanding is they never put it in. -- Greg D. Moore http://greenmountainsoftware.wordpress.com/ CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net IT Disaster Response - https://www.amazon.com/Disaster-Resp...dp/1484221834/ |
#7
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Used, beaten up rockets gaining popularity !
Lo, on the 11/8/2020, Greg (Strider) Moore did proclaim ...
"Snidely" wrote in message news:mn.3d6c7e4b28a58571.127094@snitoo... With a quizzical look, JF Mezei observed: What is so different with Falcon9 that allows it to ingnite its own engines that nobody else can do? Designed for restarts from the beginning. Most second stage engines are also so designed, plus the shuttle main engines. I don't know if SLS has retained that capability, but Wikipedia suggests that the RS-25 has it still ... dual-redundant spark igniters in the injectors of the preburners. The SSME were not designed to have relight capability. I don't know the details, but a pad abort for example required them to do servicing. Since there was no real reason for inflight reignition ability, my understanding is they never put it in. Ooops. Or OMS. /dps -- "This is all very fine, but let us not be carried away be excitement, but ask calmly, how does this person feel about in in his cooler moments next day, with six or seven thousand feet of snow and stuff on top of him?" _Roughing It_, Mark Twain. |
#8
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Used, beaten up rockets gaining popularity !
"Snidely" wrote in message news:mn.458c7e4b01aa0c02.127094@snitoo...
Lo, on the 11/8/2020, Greg (Strider) Moore did proclaim ... "Snidely" wrote in message news:mn.3d6c7e4b28a58571.127094@snitoo... With a quizzical look, JF Mezei observed: What is so different with Falcon9 that allows it to ingnite its own engines that nobody else can do? Designed for restarts from the beginning. Most second stage engines are also so designed, plus the shuttle main engines. I don't know if SLS has retained that capability, but Wikipedia suggests that the RS-25 has it still ... dual-redundant spark igniters in the injectors of the preburners. The SSME were not designed to have relight capability. I don't know the details, but a pad abort for example required them to do servicing. Since there was no real reason for inflight reignition ability, my understanding is they never put it in. Ooops. Or OMS. :-) /dps -- Greg D. Moore http://greenmountainsoftware.wordpress.com/ CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net IT Disaster Response - https://www.amazon.com/Disaster-Resp...dp/1484221834/ |
#9
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Used, beaten up rockets gaining popularity !
JF Mezei writes:
On 2020-11-08 23:32, Greg (Strider) Moore wrote: The SSME were not designed to have relight capability. I don't know the details, but a pad abort for example required them to do servicing. Since there was no real reason for inflight reignition ability, my understanding is they never put it in. In a previous message, it was alluded that some nasty chemicals used to ignite engiunes (I assume hydrazyne, right?). Isn't it just a question to grow the tank and have the pump disperse finite amount such that theu can ignite 3 or 4 times during a flight? It was TEA (tri-ethyl aluminum) and TEB (tri-ethyl boron). https://en.wikipedia.org/wiki/Triethylborane According to the Wikipedia page above this is used as an igniter for both first and second stage for the SpaceX Falcon 9. But it is running very different fuel from the Space Shuttle. I'm not sure you can just inject this material into any old place on a LH2/LOX engine without it going ka-boom. The shuttle igniters (on the ground) shot sparks into the fuel flow POST mix at low rate. All key factors I'm sure. Do they need heat to get fuel/oxydizez to has to ignite? Or can they ignite either cold liquid H2 or Kerosene with liquid O2 with sparks? I don't believe for SSME they are strictly liquid phase post combination. My visual says a mostly a gaseous mixture at that point. So the answer to your question is yes, at least partially. If they need to pre-heat, how long are we talking about? less than a second, a couple seconds? 1 minute ? I'd guess it takes a second or so just based on the fuel flow, but that's just speculation on my part. Dave |
#10
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Used, beaten up rockets gaining popularity !
David Spain writes:
JF Mezei writes: On 2020-11-08 23:32, Greg (Strider) Moore wrote: The SSME were not designed to have relight capability. I don't know the details, but a pad abort for example required them to do servicing. Since there was no real reason for inflight reignition ability, my understanding is they never put it in. In a previous message, it was alluded that some nasty chemicals used to ignite engiunes (I assume hydrazyne, right?). Isn't it just a question to grow the tank and have the pump disperse finite amount such that theu can ignite 3 or 4 times during a flight? If you are interested in re-igniting a LH2/LOX engine go do a web search on the Saturn V third stage. It had to light both for Earth orbital injection as well as for Trans Lunar Injection. https://en.wikipedia.org/wiki/Rocketdyne_J-2 The above answers the question: to wit: spark plugs, ullage and pre-chill. Dave |
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