Quote from: Jim on 08/12/2015 12:04 amQuote from: Raj2014 on 08/11/2015 09:29 pmHas NASA thought of using aerospike engines for the core stage instead? No, the whole point of the SLS design is to use derivatives of shuttle propulsion elements (SSME and SRB's). SLS will fly only one to two times a year. Not enough to justfiy a new engine development program. These questions are the same as those on Orion. SLS and Orion are not designed to push the state of the art or to reduce operational costs.Interesting, I also read that during the use of the SLS it will be improved, is this true? Why not reduce operational costs? I understand with what you have said Jim, that they are re-using technologies but will that not reduce the costs as well?
Quote from: Raj2014 on 08/11/2015 09:29 pmHas NASA thought of using aerospike engines for the core stage instead? No, the whole point of the SLS design is to use derivatives of shuttle propulsion elements (SSME and SRB's). SLS will fly only one to two times a year. Not enough to justfiy a new engine development program. These questions are the same as those on Orion. SLS and Orion are not designed to push the state of the art or to reduce operational costs.
Has NASA thought of using aerospike engines for the core stage instead?
Interesting the free hydrogen is still an issue
Quote from: Rocket Science on 08/18/2015 02:16 amInteresting the free hydrogen is still an issueThanks for pointing that out. In truth though has gaseous hydrogen ever been a concern for any group other than ASAP? In what way has the concern ever been quantified? I ask because sure, fireballs around e.g. Delta IV liftoffs have looked frightening, but have they ever had an impact on mission success? In particular for crew safety, suppose some disasterous contingency scenario were to occur -- isn't that what pad abort systems are designed to handle?
Quote from: Rocket Science on 08/18/2015 02:16 amInteresting the free hydrogen is still an issueThanks for pointing that out. In truth though has gaseous hydrogen ever been a concern for any group other than ASAP? In what way has the concern ever been quantified? I ask because sure, fireballs around e.g. Delta IV liftoffs have looked frightening, but have they ever had an impact on mission success? In particular for crew safety, suppose some disastrous contingency scenario were to occur -- isn't that what pad abort systems are designed to handle?
Quote from: sdsds on 08/20/2015 07:11 amQuote from: Rocket Science on 08/18/2015 02:16 amInteresting the free hydrogen is still an issueThanks for pointing that out. In truth though has gaseous hydrogen ever been a concern for any group other than ASAP? In what way has the concern ever been quantified? I ask because sure, fireballs around e.g. Delta IV liftoffs have looked frightening, but have they ever had an impact on mission success? In particular for crew safety, suppose some disastrous contingency scenario were to occur -- isn't that what pad abort systems are designed to handle?Following STS-41-D's pad abort free hydrogen that leaked from the engine cause a fire. Had the normal evacuation procedure been followed the crew would have encountered the fire. While Orion has a LES and Discovery didn't there are still situations where it would be preferable to get the crew out of the capsule rather than activate the LES.
Quote from: notsorandom on 08/20/2015 01:12 pmQuote from: sdsds on 08/20/2015 07:11 amQuote from: Rocket Science on 08/18/2015 02:16 amInteresting the free hydrogen is still an issueThanks for pointing that out. In truth though has gaseous hydrogen ever been a concern for any group other than ASAP? In what way has the concern ever been quantified? I ask because sure, fireballs around e.g. Delta IV liftoffs have looked frightening, but have they ever had an impact on mission success? In particular for crew safety, suppose some disastrous contingency scenario were to occur -- isn't that what pad abort systems are designed to handle?Following STS-41-D's pad abort free hydrogen that leaked from the engine cause a fire. Had the normal evacuation procedure been followed the crew would have encountered the fire. While Orion has a LES and Discovery didn't there are still situations where it would be preferable to get the crew out of the capsule rather than activate the LES. They did change the procedures after the 41D RSLS abort to include the immediate activation of the Base Heat Shield (BHS) water deluge system (this is the water system that showers the engines after a RSLS abort). For 41D and earlier, the procedure was a manual activation and it was only in short bursts. After 41D they made it automatic as well as continues which kept the engines and the aft watered down for a good 15 minutes or so.
Quote from: DaveS on 08/20/2015 01:32 pmQuote from: notsorandom on 08/20/2015 01:12 pmQuote from: sdsds on 08/20/2015 07:11 amQuote from: Rocket Science on 08/18/2015 02:16 amInteresting the free hydrogen is still an issueThanks for pointing that out. In truth though has gaseous hydrogen ever been a concern for any group other than ASAP? In what way has the concern ever been quantified? I ask because sure, fireballs around e.g. Delta IV liftoffs have looked frightening, but have they ever had an impact on mission success? In particular for crew safety, suppose some disastrous contingency scenario were to occur -- isn't that what pad abort systems are designed to handle?Following STS-41-D's pad abort free hydrogen that leaked from the engine cause a fire. Had the normal evacuation procedure been followed the crew would have encountered the fire. While Orion has a LES and Discovery didn't there are still situations where it would be preferable to get the crew out of the capsule rather than activate the LES. They did change the procedures after the 41D RSLS abort to include the immediate activation of the Base Heat Shield (BHS) water deluge system (this is the water system that showers the engines after a RSLS abort). For 41D and earlier, the procedure was a manual activation and it was only in short bursts. After 41D they made it automatic as well as continues which kept the engines and the aft watered down for a good 15 minutes or so.If I'm not mistaken they also added butcher paper in various places so that the cameras on and around the pad could see if there were a fire.
If SLS were being built without want for use of STS hardware, would it stage sequentially like Saturn V did?
If SLS were being built without want for use of STS hardware, would it stage sequentially like Saturn V did? Or is there benefit to horizontal staging where even in absence of STS hardware it would look like Delta IV with boosters on the side of a big core?
Couple of links; first, this appears to be a recent SLS blog:https://blogs.nasa.gov/Rocketology/Second, the NASA Advisory Council link was fixed and this PowerPoint deck (presented at the end of July at the JPL meeting) has some good information on development/status and recent schedule forecasts:http://www.nasa.gov/sites/default/files/files/2-Hill-Exploration-Systems-Development-Status-ESD-Status-NAC_Hill-July-28_Final.pdf
When completed, SLS, NASA's new rocket, will be one of the biggest, most powerful rockets ever built.
Quote from: catdlr on 09/02/2015 07:31 pmWhen completed, SLS, NASA's new rocket, will be one of the biggest, most powerful rockets ever built.Having been around when the Saturn-V was flying I am constantly irritated when I see statements like this. Everybody is always insisting that we compare apples to apples rather than apples to oranges, EXCEPT when it comes to showcasing the SLS - as if there is nothing else out there that compares favorably. Here's where us "old-timers" step in to set the record straight and keep the SLS proponents honest. The configuration of SLS above includes two (2) solid side boosters, and then they compare it to the Saturn-V without side boosters. Well for everyone's information there were side booster versions of the Saturn-V being developed that used a pair of 120 inch diameter solids strapped to the side of the core. This vehicle would deliver in excess of 180 tonnes to LEO. If one wants to compare the SLS to Saturn, then compare it to this side-boosted variant. If one does not want to compare to this Saturn variant then delete the SLS solids and compare core to core. Keep it apples to apples. Either way SLS will always come out less than the Saturn.For those who would say that the solid-boosted Saturn never actually existed I would say that neither does an actual SLS. But I would say that both vehicles were at a similar stage of development. That makes them completely comparable. I'm not bashing the SLS by any means. What I am bashing is misleading statements about the SLS.
For those who would say that the solid-boosted Saturn never actually existed I would say that neither does an actual SLS. But I would say that both vehicles were at a similar stage of development. That makes them completely comparable.
Quote from: catdlr on 09/02/2015 07:31 pmWhen completed, SLS, NASA's new rocket, will be one of the biggest, most powerful rockets ever built.Having been around when the Saturn-V was flying I am constantly irritated when I see statements like this. <snip>I'm not bashing the SLS by any means. What I am bashing is misleading statements about the SLS.
KSC shopping for Liquid Hydrogen solution ahead of SLS debuthttp://www.nasaspaceflight.com/2015/03/ksc-shopping-lh2-ahead-sls-launch/