And anyone know what the buyout of PWR by Aerojet means for SLS LRB's?
Quote from: Lobo on 08/30/2013 06:10 pmAnd anyone know what the buyout of PWR by Aerojet means for SLS LRB's?Aerojet Rocketdyne controls RD-180, the "AJ" derivatives of NK-33, RL10, RS-68, RS-25, J-2X, and anything F-1 related. In other words, this company controls access to primary liquid propulsion for every U.S. launch vehicle except Falcon 9 and the Minotaur/Taurus/Pegasus series. Why NASA would also want to hand this company the keys to the SLS boosters is beyond me. - Ed Kyle
Aerojet could now put the kaibosh on F-1B, if they want to promote their AJ series kerolox engines.
Quote from: Lobo on 08/30/2013 10:35 pmAerojet could now put the kaibosh on F-1B, if they want to promote their AJ series kerolox engines.My guess is they can't. When Corporation A buys Corporation B, it typically must legally honor all contracts previously signed by Corporation B (unless there are bankbuptcy or other issues-which there are none that I know of). As I said above, a corporation like Dynetics is going to have lawyers good enough to put those kinds of conditions in contracts it signed with PWR, guaranteeing access to F-1B technology. I am pretty sure that Dynetics is the lead corporation of the F-1B project anyway; PRW was not. And thus Dynetics would still have all the rights it had before.
Very simple. Whoever has the best, most cost effective proposal get's it. If that is AR, so be it. They don't exactly produce junk. Sometimes monopolies do have the best product, sometimes not.
Quote from: newpylong on 08/31/2013 01:04 pmVery simple. Whoever has the best, most cost effective proposal get's it. If that is AR, so be it. They don't exactly produce junk. Sometimes monopolies do have the best product, sometimes not.Aerojet Rocketdyne builds good hydrogen/oxygen engines (RL10, RS-68), but it hasn't built a main propulsion kerosene/LOX engine in roughly a decade, it hasn't developed an upgraded high-thrust kerosene/LOX engine model since the late 1980s, and it hasn't developed an all-new high thrust kerosene/LOX rocket engine since the early 1960s. - Ed Kyle
Quote from: edkyle99 on 08/30/2013 07:52 pmQuote from: Lobo on 08/30/2013 06:10 pmAnd anyone know what the buyout of PWR by Aerojet means for SLS LRB's?Aerojet Rocketdyne controls RD-180, the "AJ" derivatives of NK-33, RL10, RS-68, RS-25, J-2X, and anything F-1 related. In other words, this company controls access to primary liquid propulsion for every U.S. launch vehicle except Falcon 9 and the Minotaur/Taurus/Pegasus series. Why NASA would also want to hand this company the keys to the SLS boosters is beyond me. - Ed KyleATK will play that card and that's why advanced boosters for SLS will remain solid IMO. My prediction is that IF we ever see advanced boosters on SLS, they will be the 'black knights'.
These new contracts are funded under an NRA risk mitigation effort and acquisition. There will be a future competition for design, development, testing and evaluation for the SLS advanced booster. This future competition is planned for 2015 and will be acquired through a separate solicitation. The 2015 competition will not be limited to awardees announced in this NRA. Successful offerors to this NRA are not guaranteed an award for any future advanced booster acquisition.
Quote from: edkyle99 on 08/31/2013 03:18 pmQuote from: newpylong on 08/31/2013 01:04 pmVery simple. Whoever has the best, most cost effective proposal get's it. If that is AR, so be it. They don't exactly produce junk. Sometimes monopolies do have the best product, sometimes not.Aerojet Rocketdyne builds good hydrogen/oxygen engines (RL10, RS-68), but it hasn't built a main propulsion kerosene/LOX engine in roughly a decade, it hasn't developed an upgraded high-thrust kerosene/LOX engine model since the late 1980s, and it hasn't developed an all-new high thrust kerosene/LOX rocket engine since the early 1960s. - Ed KyleRespectfully, that does not mean they can't and don't know how.
If you had to quantify the level of nefarious activity of ATK and Aerojet Rocketdyne one would barely register while the other would be off the chart.
Excuse me if I'm missing something, but this discussion seems a bit premature? AFAICT SLS Block 1A with SRBs will be flying through the early 2020's and possibly mid-to-late 2020's. Given a nominal five year lead (?) that suggests a decision is several-to-many years in the future, and a great deal can change between now and then.
Quote from: TomH on 08/31/2013 06:44 pmQuote from: edkyle99 on 08/31/2013 03:18 pmQuote from: newpylong on 08/31/2013 01:04 pmVery simple. Whoever has the best, most cost effective proposal get's it. If that is AR, so be it. They don't exactly produce junk. Sometimes monopolies do have the best product, sometimes not.Aerojet Rocketdyne builds good hydrogen/oxygen engines (RL10, RS-68), but it hasn't built a main propulsion kerosene/LOX engine in roughly a decade, it hasn't developed an upgraded high-thrust kerosene/LOX engine model since the late 1980s, and it hasn't developed an all-new high thrust kerosene/LOX rocket engine since the early 1960s. - Ed KyleRespectfully, that does not mean they can't and don't know how.I look at it this way. Where does the country's current top hands-on knowledge of high thrust kerosene/LOX rocket engines reside? The answer: not at Aerojet-Rocketdyne, but rather in the hands of some folks at Hawthorne and McGregor. Now a follow-up question. Who is more likely to succeed at developing a new super-high thrust kerosene/LOX engine? The folks who shut down their production years ago, or the folks who are building them, right now? - Ed Kyle
Respectfully, I have to disagree. The F-1B is actually not an entry by Rocketdyne; it is an entry by Dynetics. Further, those solids are the poorest choice possible on every level, regardless of how many times Chris calls them the "favorite". They have the lowest Isp. They incur high weight on the crawler. They are toxic and place limitations on VAB operations. In case of an in flight abort, they cannot have the engines turned off, and if they have to be detonated they will spew pyrotechnic debris throughout the sky, debris that would be very dangerous to the parachutes. Though the upper end of the cylinder could be blown, NASA didn't do that on STS and likely wouldn't do so on SLS. ATK has already said they can't reach the 130 mT requirement without a 5th RS-25 on the core. That would require the LUS with J-2X of Block II. NASA has said they are not going to add that 5th RS-25. They seem to want DUUS as it can do circ., TLI, and LOI burns, or a TMI burn. The advanced solids just do not meet the requirements. (I know some here think they can do the calculations better than ATK and that Dark Knights can meet the specs. I find it highly doubtful that others are right and ATK's own engineers are wrong.)This competition needs to be decided on merit, not politics, and not by ATK playing a victim card of, "Oh poor us. Those guys have a monopoly, therefore you have to give this contract to us." That's balderdash.
I look at it this way. Where does the country's current top hands-on knowledge of high thrust kerosene/LOX rocket engines reside? The answer: not at Aerojet-Rocketdyne, but rather in the hands of some folks at Hawthorne and McGregor. Now a follow-up question. Who is more likely to succeed at developing a new super-high thrust kerosene/LOX engine? The folks who shut down their production years ago, or the folks who are building them, right now? - Ed Kyle
Heavy Lift is an absolute necessity for the beginning of any serious BEO exploration mission profile, but that vehicle won't see a reasonably consistent launch rate for many years to come, making it very expensive to build and use. But that level of expense can be brought down, provided the boosters chosen for it are LRBs, and those LRBs are designed to be able to function alone in combination with an upper stage as both a CLV and a general purpose LEO launch vehicle in their own right. As such they will fly far more often than the HLV they support, driving their cost per unit down and, as a result, driving down the cost of the HLV when that vehicle is employed.
Strapping 3 boosters together? Unlikely. Any potential HLV replacement would need a LOX/LH2 core and Kero/LOX or Meth/LOX boosters. The boosters need to be hydrocarbon-based for their raw power in the lower atmosphere where isp is not an issue and the core needs to be LH2/LOX because it will burn most/all the way to orbit where isp is very important, thrust not so much.
But again, we need to stop falling into the trap of optimizing for performance vs. optimizing for cost.
They do have the poorest ISP, but remember, these are boosters. ISP isn't all that big of a hit for short burn boosts like SRB's or LRB's would do. They are only burning for around 2 minutes or so, so thrust is the major driver for most of that boost...
It's not just the raw thrust; it's also the T/W (thrust to weight ratio). As I understand it, those SRBs are so heavy that most of their liftoff thrust goes into just lifting themselves, and not as much of the thrust is being transferred to the thrust beam. With the KeroLox boosters, while the Isp density is high, the pure volumetric density is not (if I understand correctly) as high as the solid propellant. This means the liquids are contributing more of their thrust to the thrust beam on the core.
Those advocating HydroLox boosters are forgetting one important factor: width of the VAB doors. Due to horizontal clearance, boosters are limited to 5.5 meters. The very low density of LH requires much more volume. To get the equivalent thrust that an RP-1 booster would give, you would need boosters as wide as or wider than the core. (I know you have proposed a 8.4 m common HydroLox core, but that won't work. The core can't even support its own weight at liftoff; it depends on the structural strength of the boosters to support it from the beam.) HydroLox boosters are just not possible on SLS because they would be far too large to fit through the doors. There's also the issue of what engine you'd put on them. Six or seven RS-25s for a two minute burn; I don't think so. Eight or nine RS-68-As? I don't want to even think about the complications of that.RP-1 is just the only fuel that makes sense for this application.
Something tells me ATK will win this easily. So with liquids (F-1B) you get..A new high-thrust kerolox engine program, 8000kn (!), that's 10x a Merlin.A new core which must be strong enough to transfer all this raw thrust to the upper attachement.4 additional liquid engines at launch which can fail.With AJ-1E6 you have 6 SC kerolox engines in addition to the 4 RS-25. So in total 10 engines without engine out capability (correct me if I'm wrong about that one).
Quote from: Oli on 09/03/2013 02:27 amSomething tells me ATK will win this easily. So with liquids (F-1B) you get..A new high-thrust kerolox engine program, 8000kn (!), that's 10x a Merlin.A new core which must be strong enough to transfer all this raw thrust to the upper attachement.4 additional liquid engines at launch which can fail.With AJ-1E6 you have 6 SC kerolox engines in addition to the 4 RS-25. So in total 10 engines without engine out capability (correct me if I'm wrong about that one).Well, if ATK wins, it will probably have more to do with cost than technical merit (or politics). IF ATK can make the composite casings cheaply, then the infrastructure to get the segments to KSC and assemble them there will already be in place. The SLS ML will already be set up for it.I don't know that engine count will be a big deal, unless SpaceX proposes a booster with 25 Merlin 1D's on it or something. Then they might start thinking that could be detrimental.I would think you -would- have engine out capability depending on where the engine fails. But that's the same as the stages on Saturn V, and on STS. Any engine failure too early one them would have caused a LOM abort.And as far as engine failures go, at least typically an engine failure of F-1B or AJ-1E6 would not be a catastrophic failure. But an SRB failure would be fully catastrophic failure. or a failure on the pad...or in the VAB....etc...I think LRB's probably have the advantage over SRB's in terms of overall safety. Dunno about reliability as F-1B, AJ-1E6, and advanced solids will all be new engines...so we won't really know until there's a track record.If reliability is the concern, then go with an engine already proven like RD-180 or RS-68.
Of course, if you actually look at the stats regarding the Shuttle's SRBs, they were only at fault in one instance in 135 flights. Once the O-ring issue was resolved I can't say I ever heard of another moment when the SRBs were ever a significant issue from a safety perspective. My guess is aside from ground handling safety, SRBs will be neck-and-neck with LRBs in terms of flight safety risk. They're certainly more proven, though obviously there is no engine shutdown option with solids unless you engineer something into the SRB. I get the feeling that will not happen with ATK emphasizing the low cost of their "Black Knights".
I think the SLS program is an opportunity for developing components for a new ELV. The RL-60 engine for example would be nice to have, I heard about NASA and air force cooperating on this one. So we have...F-1B engine for a first stage a la Falcon 9. Sounds interesting, although manufacturing such a huge engine could be expensive. With its low first stage ISP it would also require early staging and a relatively powerful second stage engine (e.g. Merlin).
AJ-1E6 as a RD-180 replacement. I think NASA does not want 6 SC kerolox engines on SLS, also manufacturing them in the US could be too expensive for an ELV.
An Ariane 6 style launcher with monolithic solids. ATK's SLS solids would share similarities with those developed for A6. Approx. the same diameter, composite casings and electrical TVC. Unfortunately the infrastructure for casting the solids would have to be set up in Vandenberg and at the Cape.
RS-68 with higher thrust. Potentially allows for getting rid of the solids on Delta IV (if that is a big cost factor). Requires a regen nozzle for SLS. Just a thought.
Edit: This may have been mentioned before in another thread, but what about adding 4 strengthened Falcon 9 cores as boosters? Does it have to be 2 boosters?
F-1B engine........manufacturing such a huge engine could be expensive.
This may have been mentioned before in another thread, but what about adding 4 strengthened Falcon 9 cores as boosters? Does it have to be 2 boosters?
Yes, it has to be 2 boosters due to the configuration of the thrust beam. 4 F9s are not enough thrust. Lobo had an entire thread about connecting 3 per side at the single attachment point using a strongback; that gets really complicated. You were just talking about too many engines. Now you're talking about 54 engines just on the boosters.
Quote from: Oli on 09/03/2013 01:35 pmThis may have been mentioned before in another thread, but what about adding 4 strengthened Falcon 9 cores as boosters? Does it have to be 2 boosters?Yes, it has to be 2 boosters due to the configuration of the thrust beam. 4 F9s are not enough thrust. Lobo had an entire thread about connecting 3 per side at the single attachment point using a strongback; that gets really complicated. You were just talking about too many engines. Now you're talking about 54 engines just on the boosters.
Quote from: TomH on 09/03/2013 05:31 pmQuote from: Oli on 09/03/2013 01:35 pmThis may have been mentioned before in another thread, but what about adding 4 strengthened Falcon 9 cores as boosters? Does it have to be 2 boosters?Yes, it has to be 2 boosters due to the configuration of the thrust beam. 4 F9s are not enough thrust. Lobo had an entire thread about connecting 3 per side at the single attachment point using a strongback; that gets really complicated. You were just talking about too many engines. Now you're talking about 54 engines just on the boosters.4 F9's not enough thrust? Not that I advocate using F9 boosters, but the F9v1.1 core has ~50% more thrust than an RD-180 on an Atlas V core, and ~80% more thrust than an RS-68A on a Delta IV core. How in the world is *thrust* the problem?
This thread made me think about something additional.Aerojet owns Rocketdyne, so they own the rights to the RD-180 now?RD-180 would very directly compete with the AJ-1E6, even moreso than the F-1B.I understand existing contracts must be honored, but again, I've also seen parent companies force changes to susidiary companies to streamline and standardize competing lines after mergers and buy outs.I could very much see someoneone thinking they don't need two engines so close together in performance, and might negotiate a change to Atlas V to take the AJ-1E6 engine. Perhaps make it a good enough of a deal to make it worth ULA's while to do so. Essentially sell a block of AJ-1E6's at a cheap enough cost to cover the modification costs to Atlas.Or just tell ULA they must change after the existing contracts are filled.How could/would that work, anyone know?I have no clue what sort of deal/contracts there would be that would allow that or prevent that.
Quote from: clongton on 09/01/2013 06:18 pmStrapping 3 boosters together? Unlikely. Any potential HLV replacement would need a LOX/LH2 core and Kero/LOX or Meth/LOX boosters. The boosters need to be hydrocarbon-based for their raw power in the lower atmosphere where isp is not an issue and the core needs to be LH2/LOX because it will burn most/all the way to orbit where isp is very important, thrust not so much.Not necessarily true... Weren't there calculations that showed that Delta IV based boosters would be just as effective (if not more) than Atlas V based boosters?But again, we need to stop falling into the trap of optimizing for performance vs. optimizing for cost.
Quote from: edkyle99 on 08/31/2013 03:18 pmQuote from: newpylong on 08/31/2013 01:04 pmVery simple. Whoever has the best, most cost effective proposal get's it. If that is AR, so be it. They don't exactly produce junk. Sometimes monopolies do have the best product, sometimes not.Aerojet Rocketdyne builds good hydrogen/oxygen engines (RL10, RS-68), but it hasn't built a main propulsion kerosene/LOX engine in roughly a decade, it hasn't developed an upgraded high-thrust kerosene/LOX engine model since the late 1980s, and it hasn't developed an all-new high thrust kerosene/LOX rocket engine since the early 1960s. - Ed KyleOther than the RS-27A you mean.
Quote from: Downix on 09/04/2013 05:19 pmQuote from: edkyle99 on 08/31/2013 03:18 pmQuote from: newpylong on 08/31/2013 01:04 pmVery simple. Whoever has the best, most cost effective proposal get's it. If that is AR, so be it. They don't exactly produce junk. Sometimes monopolies do have the best product, sometimes not.Aerojet Rocketdyne builds good hydrogen/oxygen engines (RL10, RS-68), but it hasn't built a main propulsion kerosene/LOX engine in roughly a decade, it hasn't developed an upgraded high-thrust kerosene/LOX engine model since the late 1980s, and it hasn't developed an all-new high thrust kerosene/LOX rocket engine since the early 1960s. - Ed KyleOther than the RS-27A you mean.When was the last RS-27A (or RS-27) built?
Quote from: edkyle99 on 08/31/2013 03:18 pmAerojet Rocketdyne builds good hydrogen/oxygen engines (RL10, RS-68), but it hasn't built a main propulsion kerosene/LOX engine in roughly a decade, it hasn't developed an upgraded high-thrust kerosene/LOX engine model since the late 1980s, and it hasn't developed an all-new high thrust kerosene/LOX rocket engine since the early 1960s. - Ed KyleOther than the RS-27A you mean.
Aerojet Rocketdyne builds good hydrogen/oxygen engines (RL10, RS-68), but it hasn't built a main propulsion kerosene/LOX engine in roughly a decade, it hasn't developed an upgraded high-thrust kerosene/LOX engine model since the late 1980s, and it hasn't developed an all-new high thrust kerosene/LOX rocket engine since the early 1960s. - Ed Kyle
Quote from: Lars_J on 09/01/2013 06:30 pmQuote from: clongton on 09/01/2013 06:18 pmStrapping 3 boosters together? Unlikely. Any potential HLV replacement would need a LOX/LH2 core and Kero/LOX or Meth/LOX boosters. The boosters need to be hydrocarbon-based for their raw power in the lower atmosphere where isp is not an issue and the core needs to be LH2/LOX because it will burn most/all the way to orbit where isp is very important, thrust not so much.Not necessarily true... Weren't there calculations that showed that Delta IV based boosters would be just as effective (if not more) than Atlas V based boosters?But again, we need to stop falling into the trap of optimizing for performance vs. optimizing for cost.Slightly better performing actually. If it were not for the human-rating issue, the Delta CBC would have been used in the AJAX writeup. Ironic that issue has since been shelved.
Quote from: Downix on 09/04/2013 05:23 pmQuote from: Lars_J on 09/01/2013 06:30 pmQuote from: clongton on 09/01/2013 06:18 pmStrapping 3 boosters together? Unlikely. Any potential HLV replacement would need a LOX/LH2 core and Kero/LOX or Meth/LOX boosters. The boosters need to be hydrocarbon-based for their raw power in the lower atmosphere where isp is not an issue and the core needs to be LH2/LOX because it will burn most/all the way to orbit where isp is very important, thrust not so much.Not necessarily true... Weren't there calculations that showed that Delta IV based boosters would be just as effective (if not more) than Atlas V based boosters?But again, we need to stop falling into the trap of optimizing for performance vs. optimizing for cost.Slightly better performing actually. If it were not for the human-rating issue, the Delta CBC would have been used in the AJAX writeup. Ironic that issue has since been shelved.How has it been shelved? Are there any plans to launch people on a Delta? I thought both CST-100 and DC were looking at Atlas?
How has it been shelved? Are there any plans to launch people on a Delta? I thought both CST-100 and DC were looking at Atlas?
Since the Aerojet booster is to have 4, 1.1 million pound engines, couldn't the Pyrios booster engines later be upgraded from 1.8 million pounds, to 2.2 million pounds.The Aerojet booster is to have 4.4 million pounds of thrust. The ATK booster is expected to produce more than the 3.5 million pounds of thrust of the 5 segment RSRM. The Dynetics booster is to have only 3.6 million pounds of thrust. Couldn't the Dynetics booster engines later be made larger, with more fuel, and 4.4 million pounds of thrust. New and improved booster, with 22% more thrust! The 4 engine SLS core, was made with upgrades in mind!
Same here. I thought I'd heard four, but then the paper someone (was it Steven?) pulled up recently showed three engines per booster, each with twin nozzles for a total of six nozzles per booster.
Quote from: TomH on 11/08/2013 10:43 pmSame here. I thought I'd heard four, but then the paper someone (was it Steven?) pulled up recently showed three engines per booster, each with twin nozzles for a total of six nozzles per booster.Yes, the paper Steve posted on the thread about AJ-1E6 progress is the one I was thinking of. That's about all I've seen on the Aerojet booster. You don't need as much fuel if the ISP of the engine is higher, which means less mass and less thrust needed to get it off the pad and moving.If AJ-1E6 had the same ISP as the NK-33, the three RD-180's with their higher ISP might get pretty clos eto four AJ-1E6's, even though they have less thrust. The boosters wouldn't need quite as much propellant mass.
Quote from: Lobo on 11/09/2013 01:52 amQuote from: TomH on 11/08/2013 10:43 pmSame here. I thought I'd heard four, but then the paper someone (was it Steven?) pulled up recently showed three engines per booster, each with twin nozzles for a total of six nozzles per booster.Yes, the paper Steve posted on the thread about AJ-1E6 progress is the one I was thinking of. That's about all I've seen on the Aerojet booster. You don't need as much fuel if the ISP of the engine is higher, which means less mass and less thrust needed to get it off the pad and moving.If AJ-1E6 had the same ISP as the NK-33, the three RD-180's with their higher ISP might get pretty clos eto four AJ-1E6's, even though they have less thrust. The boosters wouldn't need quite as much propellant mass.I remember us having this discussion back on an SLS thread a year or so ago. Lobo was lamenting the relative lack of thrust on the Aerojet booster. Then I ran across an article talking about there being four of those engines on the Aerojet boosters. Downix said I'd gotten that detail right and now here we are, and suddenly the Aerojet boosters have only 3 engines. Either they've changed the design or perhaps the source is wrong. I'll have to dig up that post and find the link.
Any chance of conformal tanks and hydrogen peroxide as the oxidizer for either an Aerojet or Dynetics LRB that is optimized for cost?
Quote from: HappyMartian on 12/24/2013 08:31 amAny chance of conformal tanks and hydrogen peroxide as the oxidizer for either an Aerojet or Dynetics LRB that is optimized for cost? Yes. Buckleys and none. :-) The US does not have experience with large keroxide (a term for kerosene/hydrogen peroxide propellants invented by Lobo) engines, while there is plenty with kerolox. So when a choice is made, its nearly always for kerolox. The British were building up this experience with their Black Knight and Black Arrow launch vehicles, but when they pulled out of the launch business in the early 1970's, this experience was lost.You know all those troubles that SpaceX has had with LOX? What was the main cause of the problem? Its the cryogenic temperatures that makes things stick. Thus, if a launch provider ever wants to have true reliability where they always launch on time, I believe keroxide is the best solution for the first stage (upper stages are a different story). Its higher impulse density also implies that it has greater performance than kerolox for the same volume first stage.
That discussion should continue there. http://forum.nasaspaceflight.com/index.php?topic=33280.30Steve, I'm very intrigued by that staged combustion thing. Keroxide (great name!) specific impulse is around 310 - 320 but I wonder, could staged combustion bring it to 350 ? That would make a huge difference...
Any speculation as to what engines may be included in the proposals submitted for liquid versions of the SLS advanced boosters? Upgraded single RD-170 or RD-171, a pair of RD-180s, built by Glushko or under U.S. license? Will PWR pull out the F-1A; will it be upgraded? Will SpaceX offer a Falcon of any type with Merlin II? Other ideas?
Well, if ATK wins, it will probably have more to do with cost than technical merit (or politics). IF ATK can make the composite casings cheaply, then the infrastructure to get the segments to KSC and assemble them there will already be in place. The SLS ML will already be set up for it..........I think LRB's probably have the advantage over SRB's in terms of overall safety. Dunno about reliability as F-1B, AJ-1E6, and advanced solids will all be new engines...so we won't really know until there's a track record.If reliability is the concern, then go with an engine already proven like RD-180 or RS-68.
http://www.dynetics.com/news/377Dynetics Meets Milestone on Advanced Booster Work
Quote from: Lobo on 09/03/2013 05:49 amWell, if ATK wins, it will probably have more to do with cost than technical merit (or politics). IF ATK can make the composite casings cheaply, then the infrastructure to get the segments to KSC and assemble them there will already be in place. The SLS ML will already be set up for it..........I think LRB's probably have the advantage over SRB's in terms of overall safety. Dunno about reliability as F-1B, AJ-1E6, and advanced solids will all be new engines...so we won't really know until there's a track record.If reliability is the concern, then go with an engine already proven like RD-180 or RS-68.Considering how the average firecracker and SRB share some basic principles...yeah I can't help getting images of a swarm of rocket scientists fleeing the VAB the day a SRB malfunctions. Still, despite being potential bombs in tin cans, they only caused grief for ill-fated Challenger, not so much the production floor. If ATK does win the advanced competition, they should teach their boosters some new tricks befitting a next-gen solid.The liquid boosters at least wouldn't be explosive until fueled at the launch pad as you imply Lobo. More chances to evolve and tweak performance too. Aside from streamlining a solid all you can otherwise do is pack it with more flamboyant firecracker material (putting it bluntly of course).
Did you ever watch closely the Challenger explosion? The SRB's did not explode, even while the hydrogen and LOX filled ET was doing exactly that right next to them. They continued to fly until detonated by the Range Safety Officer.And they can't "malfunction" inside the VAB. Malfunction means operating incorrectly and inside the VAB they are not operating at all. They are not even "functioning". They are just sitting there doing nothing.
Correction regarding Challenger: the O-ring leak effectively blowtorched a hole into the ET. The vehicle already exploded by the time the range officers destroyed the SRBs. The damage was done.I acknowledged they haven't been a danger while just sitting on the production floor. However, the VAB no longer has active offices inside it because the threat remains that the SRBs are inherently fueled versus liquid boosters that are empty until safely on the launch pad. And the imagery of fleeing rocket scientists refers to the fact of IF something went wrong; had engineers anticipated ice damage in Florida Challenger's fate could have been different, but 90% of the time ice doesn't even exist in Florida.
And they can't "malfunction" inside the VAB. Malfunction means operating incorrectly and inside the VAB they are not operating at all. They are not even "functioning". They are just sitting there doing nothing.
Your story does not seem to mesh with the safety precautions taken in the VAB when dealing with solids. Perhaps the precautions were excessive, but the point remains that an element that comes pre-packaged with the propellant *and* oxidizer is always going to be more risky than one that contains neither at the time of handling.
If Russia stops exporting RD-180s to the US in retaliation for sanctions, and so US production of the engines is started for national security reasons, wouldn't that change things a lot? There would be a desire to find other uses for the engine to share the costs among and it would save NASA the cost and trouble of developing a new liquid engine, making the liquid option more attractive relative to solids as well. Four RD-180s per booster should be enough to get to 130 tons with four RS-25s in the core.
Quote from: clongton on 04/04/2014 08:53 pmAnd they can't "malfunction" inside the VAB. Malfunction means operating incorrectly and inside the VAB they are not operating at all. They are not even "functioning". They are just sitting there doing nothing.Your story does not seem to mesh with the safety precautions taken in the VAB when dealing with solids. Perhaps the precautions were excessive, but the point remains that an element that comes pre-packaged with the propellant *and* oxidizer is always going to be more risky than one that contains neither at the time of handling.
enough solids have their place, look at Orbital and their use in Antares.
reduce the risk and improve technical maturation of a liquid oxygen and kerosene oxidizer-rich staged-combustion engine. The company will fabricate a representative full-scale 550,000-pound thrust class main injector and thrust chamber, and prepare to conduct a number of tests measuring performance and demonstrating combustion stability.
These are good questions, questions I'd like to have answered as well. Maybe something that Chris might want to pursue in an update article.I doubt SpaceX is interested, but a Raptor entry would be interesting. It could at least give them some extra research money.
But let's be frank, if SpaceX demonstrates just reusable boosters, the Advanced Booster competition will have a taste of obsolete.
Look. SpaceX has two cards that depend on demonstrating usability. The big one is designing a reusable BFR and thus making SLS obsolete after the four initial launches.
There is one reason I doubt Raptor boosters could be used on SLS: ISP Density of CH4 in relation to VAB door width. With the core having only 4 main engines, and with EUS being smaller than the J-2X LUS, the difference in the 130mt payload must come from potent boosters. 5.5m is the max width for boosters in relation to the VAB doors. I don't know if that volume of CH4 at its ISP density would be enough total thrust. Then subtract prop needed for RTLS, and 130mt seems exceedingly difficult.
Agreed. Which would mean that the program failed not for the reasons so many critics posit, but because superior technology was developed by someone else and thus the fabled heritage technology was swept away by the tide of progress. I would not at all be surprised if your scenario is exactly the way history unfolds.
CH4 is only like 19% less dense than RP-1, and that applies to only the fuel tank. The LOX tank would be the same size.
Quote from: Lobo on 04/25/2014 11:02 pmCH4 is only like 19% less dense than RP-1, and that applies to only the fuel tank. The LOX tank would be the same size.LCH4 has a density of 0.4239 kg/L while RP-1 has a density of 0.8 kg/L. Thus, LCH4 is 47% less dense than RP-1. However, methalox at a 3.6 to 1 oxidiser to fuel mixture ratio (MR) is 19% less dense than kerolox at a 2.8 MR.
Quote from: Steven Pietrobon on 04/28/2014 07:37 amQuote from: Lobo on 04/25/2014 11:02 pmCH4 is only like 19% less dense than RP-1, and that applies to only the fuel tank. The LOX tank would be the same size.LCH4 has a density of 0.4239 kg/L while RP-1 has a density of 0.8 kg/L. Thus, LCH4 is 47% less dense than RP-1. However, methalox at a 3.6 to 1 oxidiser to fuel mixture ratio (MR) is 19% less dense than kerolox at a 2.8 MR.Rule of thumb, for staged combustion, CH4 requires 30% more volume than RP-1. Which if you scale a tank in 3D mean an 9% longer dimensions. And the general 10extra seconds or so of isp usually mean very similar performance. Of course Russians and SpaceX appear to calculate that if you design the SC CH4 cycle taking advantage of the characteristics, like using the expander cycle for something, and thinking in terms of reusability, the CH4 is superior.BTW rocket engine with more restarts lowers development and certifications cost. You might need as little a 10 engines for development vs 100s.
Interesting. So do you mean a Raptor methalox booster would be about 9% longer than a comparitive RP-1 staged combustion booster like an RD-180 powered booster or an AJ-1E6 powered booster? Or that given Raptor's extra performance, it would mean the boosters would be similar in size?Also, roughly, assuming 5.5m diameter for both, how would a Raptor powered booster compare lengthwise to the Dynetics F-1B booster?
What I mean is that the F-1B is less efficient than a SC engine, but can have more thrust.