A quick Raptor Comparison.
Quote from: Khadgars on 09/27/2016 10:05 pmQuote from: JasonAW3 on 09/27/2016 08:46 pmQuote from: Space Ghost 1962 on 09/27/2016 08:38 pmQuote from: edkyle99 on 09/27/2016 08:22 pmFor me, the real question is how will SpaceX use these technologies (Raptor and carbon fiber tanks) to improve its current business (GTO and LEO satellites of reasonable size that don't require a 10,500 tonne rocket)? - Ed KyleDon't think that's the plan. He alluded to using the ITS SC to orbit/service payloads and ISS and other NASA needs.Holy... With that kind of payload, he could launch a whole new ISS in one launch!Isn't the whole issue with SLS that there isn't any payloads to put on it because its too big? The ITS is many times bigger, outside of shuttling people to Mars, who would use it?OK, forget completely the mass/bulk of a SC. You build what you need, as big/heavy irrespective, focusing more on systems engineering/test/qualification. He's got a few dozen boosters and perhaps a few thousand ITS SC that sit idle for half the time, and a repurposed like a trucking system to kick them out the door on appropriate orbit and return (likely automated).The time saved in rapid prototyping means years less time in design and fabrication, and less special purpose HW just to "hand in glove" fit need. So SC systems become more common and less special purpose, and so volume and reuse start to matter in meeting mission requirements on budget."Crazy Elon's Massive Launch Services, his prices are insane ..."Get the picture?
Quote from: JasonAW3 on 09/27/2016 08:46 pmQuote from: Space Ghost 1962 on 09/27/2016 08:38 pmQuote from: edkyle99 on 09/27/2016 08:22 pmFor me, the real question is how will SpaceX use these technologies (Raptor and carbon fiber tanks) to improve its current business (GTO and LEO satellites of reasonable size that don't require a 10,500 tonne rocket)? - Ed KyleDon't think that's the plan. He alluded to using the ITS SC to orbit/service payloads and ISS and other NASA needs.Holy... With that kind of payload, he could launch a whole new ISS in one launch!Isn't the whole issue with SLS that there isn't any payloads to put on it because its too big? The ITS is many times bigger, outside of shuttling people to Mars, who would use it?
Quote from: Space Ghost 1962 on 09/27/2016 08:38 pmQuote from: edkyle99 on 09/27/2016 08:22 pmFor me, the real question is how will SpaceX use these technologies (Raptor and carbon fiber tanks) to improve its current business (GTO and LEO satellites of reasonable size that don't require a 10,500 tonne rocket)? - Ed KyleDon't think that's the plan. He alluded to using the ITS SC to orbit/service payloads and ISS and other NASA needs.Holy... With that kind of payload, he could launch a whole new ISS in one launch!
Quote from: edkyle99 on 09/27/2016 08:22 pmFor me, the real question is how will SpaceX use these technologies (Raptor and carbon fiber tanks) to improve its current business (GTO and LEO satellites of reasonable size that don't require a 10,500 tonne rocket)? - Ed KyleDon't think that's the plan. He alluded to using the ITS SC to orbit/service payloads and ISS and other NASA needs.
For me, the real question is how will SpaceX use these technologies (Raptor and carbon fiber tanks) to improve its current business (GTO and LEO satellites of reasonable size that don't require a 10,500 tonne rocket)? - Ed Kyle
Astonished. You get to ask ONE question to EM, the day of his LIFE speech on Mars. and what's your pick? toilets?#speechless.
Quote from: billh on 09/28/2016 12:49 amSomeone else already mentioned the question of insulation up-thread. That was my big question, too. I keep wondering how you can build a vessel that uses subcooled propellants and expect to keep them subcooled all the way to Mars? That would seem to require not only good insulation, but active cooling as well.I would think subcooling is only needed to escape the Earth's gravity. You don't need it in space or on Mars.
Someone else already mentioned the question of insulation up-thread. That was my big question, too. I keep wondering how you can build a vessel that uses subcooled propellants and expect to keep them subcooled all the way to Mars? That would seem to require not only good insulation, but active cooling as well.
I still feel excited and skeptical at the same time.- I expected the integrated second stage + transfer vehicle to be a cylindrical lifting body.- Need to improve cost for a trip to Mars by 5,000,000% (30:15). Compare that with Kankoh-maru, another ambitious proposal that was a Japanese LEO tourism SSTO which was planned to bring prices down to $20,000 with a market of 1,000,000 passengers per year (a factor of 100,000% compared to the $20+ million one might pay to get into LEO today). (Might TSTO have made things more efficient?)- Very large windows might be a structural weakness (or contribute a significant amount to dry mass)- Vertical integration, with a crane, on the pad! What is a VAB even for, then? He also mentions the booster and spacecraft being constructed in the Gulf States (1:27:34), so there will be water transport. Also, absolute precision required for RTLS landing.- If a "Mars Colonial Fleet" (44:03) needs to be gathered in LEO, ITS tankers acting as depots might be necessary in between the 2-year launch windows to Mars, so a crewed ITS can refuel soon after launching and the ECLSS can be prioritized for the transfer and not the loitering. (also note the reference to "Battlestar Galactica," which used to be used derisively for the expendable, expensive 90-Day Report architecture)- The deployment of cargo such as rovers for water mining an issue. How big would those rovers need to be, anyway? There's an unpressurized cargo area, but there don't seem to be any cargo bay doors. The payload would be at the very top, as well (was expecting it to be below the tanks, like this). A crane would be needed, but how does the crane get to the surface in the first place?- 300 (reusable) to 550 (expendable) tonnes to LEO, Sea Dragon-class! But how will acoustics be managed during launch?(also, does 300 include the dry mass of BFS [150 t] itself?)- I wish he would have gone into more detail about how the in-situ water extraction systems would work.- Ship and booster testing is supposed to begin in 2018-2019, Mars flights in late 2022 (1:14:30). A huge technological leap from Red Dragon to Heart of Gold in less than 5 years. Not sure if they will meet this on time, but it'll be very impressive if they do. At least they already have 12 meter tanks, so there's that.- "Planet-hopping" with ISRU facilities everywhere (1:23:58) will be used to get to the outer planets (e.g. Mars to Jupiter). But what about all that radiation? Much worse than a Earth -> Mars trip.- (1:48:34) When talking about interstellar travel, "very tricky" is an understatement. And so is "going from a Wright Flyer to a 747."- Most of the Q&A was dumb but one thing that could be taken away was that Musk doesn't want SpaceX to be a monopoly on interplanetary transport (1:54:25).
I think Musk and SX would would like to have a few successful launches of this to Mars and the US public to start asking the question "Why have we spent 10s of $Bn on something that's nowhere near close to this achievement?" An interesting question in this vein would be would they get ITS the EELV contract list?
I guess that the SCs won't have much downtime between returning from Mars and refurbing for the next opposition. (I'm assuming that early missions will need a fair bit of maintenance.)
But new-build SCs could do the "milk run" to the Moon before the window opens up for their first Mars run - and Elon was talking about building a lot of spacecraft.
Quote from: francesco nicoli on 09/28/2016 12:05 amAstonished. You get to ask ONE question to EM, the day of his LIFE speech on Mars. and what's your pick? toilets?#speechless.ECLSS. Success of it absolutely critical to the survival of the crew, and mass/reliability of it absolutely critical to the cost of the project.But the question was worded incredibly badly.cheers, Martin
Take the landing for example, the landing gear is quite narrow on a vehicle that will be top heavy, if just one leg compresses the surface more then expected at touch down or the ground suffers subsidence due to subsurface ice melt the vehicle could easily tip over. Their also seems to be no provision for the intense thrust directed at the unconsolidated regolith and back splashing that would result, all indicative of the assumption of flat concrete landing pads.
QuoteI'd say very unlikely. F9 seems as big as it needs to be to capture the market SX want it to. A Raptor engined US might be an option but SX really don't like split supply chains. Now there are 2 engine lines to track instead of one. If they went with a CF US that's 2 stage mfg lines to track, not forgetting the CH4 infrastructure you need solely for the USIt is already known that SX plan to introduce a new upper stage for F9 engined by raptor due to documents released regarding USAF mission requirements for missions on F9 in the next few years. And yes there are now two engine lines, that is the problem. Merlin has no reason to exist anymore once raptor has some flight reliability behind it. It is more powerful, more efficient (loads more), and roughly the same size. Why continue building an obsolete engine? SpaceX in the past has always opted to phase out duplicate systems (for example no need for f1 and f9), in favor of better ones once they have better ones. I would be very surprised if they don't move toward a raptor F9 at some point beyond just the upper stage. Doesn't make sense to keep Merlin around, IMO, especially if the timeline for ITS comes true or even partly true.
I'd say very unlikely. F9 seems as big as it needs to be to capture the market SX want it to. A Raptor engined US might be an option but SX really don't like split supply chains. Now there are 2 engine lines to track instead of one. If they went with a CF US that's 2 stage mfg lines to track, not forgetting the CH4 infrastructure you need solely for the US
Quote from: FinalFrontier on 09/28/2016 12:58 amQuoteI'd say very unlikely. F9 seems as big as it needs to be to capture the market SX want it to. A Raptor engined US might be an option but SX really don't like split supply chains. Now there are 2 engine lines to track instead of one. If they went with a CF US that's 2 stage mfg lines to track, not forgetting the CH4 infrastructure you need solely for the USIt is already known that SX plan to introduce a new upper stage for F9 engined by raptor due to documents released regarding USAF mission requirements for missions on F9 in the next few years. And yes there are now two engine lines, that is the problem. Merlin has no reason to exist anymore once raptor has some flight reliability behind it. It is more powerful, more efficient (loads more), and roughly the same size. Why continue building an obsolete engine? SpaceX in the past has always opted to phase out duplicate systems (for example no need for f1 and f9), in favor of better ones once they have better ones. I would be very surprised if they don't move toward a raptor F9 at some point beyond just the upper stage. Doesn't make sense to keep Merlin around, IMO, especially if the timeline for ITS comes true or even partly true.I've thought this for a while now, but I see zero chance of Raptor being used as the upper stage on Falcon 9. Merlin was already oversized for Falcon 9 and this would be increasing the thrust by 3x again making it ridiculously oversized. Additionally, the engine bell for a vacuum Raptor is 14 feet while the Falcon 9 is only 12 feet in diameter. They'd have to crop the engine bell just to make it fit. This is all sorts of awkward design that doesn't make any sense.
Obviously landing on unprepared surfaces will be risky, and something only done for the first landing at a specific site. The risk is going to mitigated significantly by the very large feet of the legs. Once the first equipment is delivered, semi-prepared pads would presumably be available. Your other complaints are just gripes due to a lack of specificity on technical details that were unlikely to be covered at an event of this type. Human factors of disembarking? Do you really think he needed to cover how to use lifts, cranes, or ladders? Or show details on ISRU? C'mon.What he showed here was exactly what he hinted at before. Your ideas of multi-stage landers, solar powered transfer stages, high orbit TMI, LMO propellant depots were just that, your ideas that he doesn't share. If you think this is technically unfeasible, contact SpaceX and let them know. Or you have economic concerns, do the same. Who knows, you might prevent them from making a massive mistake.
As for landing the ITS booster back on its launch mounts -- what happens if you need to clear the pad (for a variety of reasons) after the last ITS launch of the day? You just land the booster back at the pad and then wait while you crane it off and back to storage, or wherever it's headed?
I would bet there will be some landing facilities away from the launch pad with the same type of launch mounts that the ITS booster will be expected to land on when they do land it back onto the pad. ... I'd truly have to believe SpaceX will test the landing sequence away from the pad before they risk the launch pad itself.
Also, F9 uses a hoverslam maneuver solely because the landing stage cannot achieve a hover, due to lower throttle limits on the Merlin and the weight of the nearly-empty stage. Using only a few of those Raptors, throttled to around 30%, wouldn't you be able to achieve a stable hover and relatively slow final landing sequence with the ITS booster? In other words, with just a few more seconds to clean up your attitudes and orientation, I'd think landing the thing into the launch mounts may not be as difficult as it appears at first glance.
Quote from: Space Ghost 1962 on 09/28/2016 04:41 amQuote from: pippin on 09/28/2016 03:17 amHm... whole fleet but only one or two pads. That means months of loiter time...Keep in mind the high cadence implied. If daily and a hundred in fleet, two pads could handle it in a few months.If the top off tanker load also brings crew, your loiter is 50 days, assuming all depart at start of MOI window. Now add a few days of bad weather per year and a few other delays and you've got months of loiter time, don't you?That's pretty much what I said.
Quote from: pippin on 09/28/2016 03:17 amHm... whole fleet but only one or two pads. That means months of loiter time...Keep in mind the high cadence implied. If daily and a hundred in fleet, two pads could handle it in a few months.If the top off tanker load also brings crew, your loiter is 50 days, assuming all depart at start of MOI window.
Hm... whole fleet but only one or two pads. That means months of loiter time...
If I felt they had a plan for these things I wouldn't be half as concerned, the problem is I don't think they have a plan.
As for contacting them, do you really believe that your so important that I spend all my time communicating on this forum, of course I've emailed them my thoughts, have you sent them yours too. Or is this just a rhetorical question for flippancy purposes?
Quote from: Star One on 09/27/2016 07:39 pmWhat happens if the booster and/ or tanker has an issue are all those colonists left twiddling their collective thumbs in orbit.Smart move is to reverse the launch order. The fuel doesn't get quite so impatient as the passengers.
What happens if the booster and/ or tanker has an issue are all those colonists left twiddling their collective thumbs in orbit.