Quote from: rcoppola on 12/30/2015 06:40 pm[...]Specifically disruptive to Human BEO exploration plans. Scimemi, the ISS director for NASA, says he wants to build the HAB Congress just directed NASA to study and have a prototype ready for 2018. Why would we do that, when for a fraction of the cost, we could send up a prototype BA330 on a FH? (that's a rhetorical question)[...]A Hab would really have to be tested in EML1/2 space. LEO is very different from deep space. For example, you have 45min of hotness and 45min of coldness. In deep space you have a hot side and a cold side, permanently. So the thermal environment is completely different. You have to worry about MMOD and free oxygen in LEO which are not an issue in deep space. You have a lot less radiation, which you actually want to prove the hab design. You need completely different comm system. And a long list of requirements.Why I'm saying this? Because for such an Hab, unless you are also including a SEP tug (which has no budget), you are going to worry about the C3=-1kmē/sē performance. How much could the Falcon Heavy do? If it can, in fact, do 13 to TMI, then it should be able to do between 17 and 20 tonnes to TLI. The problem is, SLS can do something like 45tonnes with EUS and well more than 25 tonnes with the ICPS. So the prototype would have to have less than half the mass of the final hab if it were to fit into a FH.And I didn't get into the fact that SLS will have an 8.4m fairing (7.5m internal) vs the 5.2m (4.7 internal) of the FH. I rather see FH as an opportunity to send something commercial to LEO very cheaply or a Cygnus derived module to TLI, rather than the full Hab.
[...]Specifically disruptive to Human BEO exploration plans. Scimemi, the ISS director for NASA, says he wants to build the HAB Congress just directed NASA to study and have a prototype ready for 2018. Why would we do that, when for a fraction of the cost, we could send up a prototype BA330 on a FH? (that's a rhetorical question)[...]
You also didn't get into the fact that the FH will be ready in six months and the SLS with 8.4m fairing and EUS will be lucky to be ready in six years(and $20B). And conveniently didn't get into the fact that only one system will be affordable to operate.
Quote from: AncientU on 12/31/2015 04:19 pmYou also didn't get into the fact that the FH will be ready in six months and the SLS with 8.4m fairing and EUS will be lucky to be ready in six years(and $20B). And conveniently didn't get into the fact that only one system will be affordable to operate. Actually, you started talking about using FH for the Hab prototype. The Hab will fly with SLS/EUS, this is the current plan and thus it will be sized accordingly.And regarding affordability, it's not what you believe to be but what US Congress is actually willing to pay. And in the 2016 budget, US Congress actually decided that NASA is not spending enough on SLS. Also, they added quite a few millions to start up the EUS effort. So the definitive Hab will fly on SLS/EUS and will be more than six years. The issue is the prototype and how representative it will be.
I stated that it would be perfect for a Cygnus based hab or, may be, a lightened BA330 sent to TLI. Who knows what they meant by a prototype by 2018. That's not even clear if it would be orbital.
Happy newyear everybody and i wish you a good 2016.Who knows how weight an upgraded FH can sent to TLI in 2018 ? I have a question; A spacestation like the BA330 that is designed to withstand the rigors of space for years cannot survive the three first minutes of launch ? I mean considering the shape and size is it not possibele to adapt the design a bit so that the fairing might not be needed thus saving a lot of weight ?I do not know if the size increase of S2 was optimized for F9 or FH. Perhaps they made a compromise but i have the feeling that it was for F9. Maybe later they could incease it again for FH but i remember that Elon some time ago said that he was afraid of bending.
Is it out of the realm of possibility for the center core of the falcon heavy to RTLS by completing an orbit?
Quote from: Dante2121 on 01/03/2016 03:05 amIs it out of the realm of possibility for the center core of the falcon heavy to RTLS by completing an orbit?Yes
Quote from: Arcas on 01/03/2016 03:08 amQuote from: Dante2121 on 01/03/2016 03:05 amIs it out of the realm of possibility for the center core of the falcon heavy to RTLS by completing an orbit?YesI set myself up for that answer. I'm looking to understand why not. How much faster would it have to be traveling?
Either way, I have a few observations you might find interesting:Ground costs are extremely important. It is a very significant part of the costs. In my second scenario, more than half of the Reuse Index goes to ground costs. If we want orders of magnitude in savings, this will need to be practically 0. Spaceports will really need to operate like airports to even have a shot.The next biggest chunk is rebuilding the second stage, or in general : Fru. Trading off Cru to increase Fru is worthwhile as long as Cru * ( 1 - Fru ) decreases (if refurbishment costs remain the same, i.e. Crf goes down proportionally so that Crf * Cru stays the same). The initial cost of the rocket is divided by n, so as more launches happen this goes to zero. If we can make a fully reusable rocket at 10x the cost that can fly hundreds of times, it is totally worth it. This is pretty much the idea behind SSTO spaceplanes.Refurbishment costs should be low, but aren't the dealbreaker as long as they don't exceed 25% of the total rocket price (so closer to 35% of the first stage price). Spending several million on refurbishing per launch is totally doable. Using Cru = 1.2, Fru = 0.7, Crf = 0.25 and Cground = 0.2 (more realistic value from ULA tweets), you still get a 20% drop in costs after 10 flights. This would be a failure according to SpaceX, but still a significant and worthwhile competitive advantage.The F factor from ULA barely makes a difference. It increases the costs by 0.03-0.04 index points even at 20 launches. This is because the reduced production volume only counts for the first stage, not the entire rocket! At 20 launches you may pay almost 60% more to build the first stage, but that obviously only means a 3% increase per launch. I've actually found a mistake in my formula here: I apply this factor to the entire cost of the reusable rocket, while I should only apply it to the fraction that is reused. The first term should be (F * Fru * Cru + ( 1 - Fru ) * Cru ). This would reduce the impact even more. This term can pretty much be ignored unless the rate exponent goes down significantly.These observations may be more useful than what I originally wrote. It shows a part of the business model behind the Falcon Heavy: If they can achieve second stage reusability with it and cut production costs enough to make it worthwhile (second bullet point above), they have the winning formula. We can also see why Elon isn't exactly worried about refurbishing costs: Even at 25% there is a strong business case to be made. Building the Merlins from scratch to be reusable without significant maintenance is the killer breakthrough here. Everything hinges on that. I'm very interested to see the static fire because that will pretty much be the deciding factor according to my analysis. If they end up needing STS levels of disassembly, refurbishment, testing and reassembly... That's pretty much lights out for reusability then. Maybe the Raptor engines can save the day but it would still suck.
There's a very interesting post on r*ddit called "Recalculating the ULA reusability analysis in context of SpaceX" that goes into quite a lot of detail on the various costs of reusable rockets. One of the responses by the original poster was of particular interest:QuoteEither way, I have a few observations you might find interesting:Ground costs are extremely important. It is a very significant part of the costs. In my second scenario, more than half of the Reuse Index goes to ground costs. If we want orders of magnitude in savings, this will need to be practically 0. Spaceports will really need to operate like airports to even have a shot.The next biggest chunk is rebuilding the second stage, or in general : Fru. Trading off Cru to increase Fru is worthwhile as long as Cru * ( 1 - Fru ) decreases (if refurbishment costs remain the same, i.e. Crf goes down proportionally so that Crf * Cru stays the same). The initial cost of the rocket is divided by n, so as more launches happen this goes to zero. If we can make a fully reusable rocket at 10x the cost that can fly hundreds of times, it is totally worth it. This is pretty much the idea behind SSTO spaceplanes.Refurbishment costs should be low, but aren't the dealbreaker as long as they don't exceed 25% of the total rocket price (so closer to 35% of the first stage price). Spending several million on refurbishing per launch is totally doable. Using Cru = 1.2, Fru = 0.7, Crf = 0.25 and Cground = 0.2 (more realistic value from ULA tweets), you still get a 20% drop in costs after 10 flights. This would be a failure according to SpaceX, but still a significant and worthwhile competitive advantage.The F factor from ULA barely makes a difference. It increases the costs by 0.03-0.04 index points even at 20 launches. This is because the reduced production volume only counts for the first stage, not the entire rocket! At 20 launches you may pay almost 60% more to build the first stage, but that obviously only means a 3% increase per launch. I've actually found a mistake in my formula here: I apply this factor to the entire cost of the reusable rocket, while I should only apply it to the fraction that is reused. The first term should be (F * Fru * Cru + ( 1 - Fru ) * Cru ). This would reduce the impact even more. This term can pretty much be ignored unless the rate exponent goes down significantly.These observations may be more useful than what I originally wrote. It shows a part of the business model behind the Falcon Heavy: If they can achieve second stage reusability with it and cut production costs enough to make it worthwhile (second bullet point above), they have the winning formula. We can also see why Elon isn't exactly worried about refurbishing costs: Even at 25% there is a strong business case to be made. Building the Merlins from scratch to be reusable without significant maintenance is the killer breakthrough here. Everything hinges on that. I'm very interested to see the static fire because that will pretty much be the deciding factor according to my analysis. If they end up needing STS levels of disassembly, refurbishment, testing and reassembly... That's pretty much lights out for reusability then. Maybe the Raptor engines can save the day but it would still suck.So maybe the primary motive behind the FH was not that it could put massive payloads into LEO in expendable mode (since as many people have pointed out, these payloads are few and far between), but that it could put a future reusable second stage with its increased weight, plus an F9-sized payload, into LEO and still RTLS. If the first stage core and booster plus the second stage and payload fairing are all reusable at a reasonable maintenance cost, then the cost per kg to orbit can drop like a stone. F9 alone would not have the capacity to do this, you need the FH.Of course SpaceX's plans may have changed since the decision to develop FH.
Quote from: Mongo62 on 01/03/2016 03:49 pmThere's a very interesting post on r*ddit called "Recalculating the ULA reusability analysis in context of SpaceX" that goes into quite a lot of detail on the various costs of reusable rockets. One of the responses by the original poster was of particular interest:QuoteEither way, I have a few observations you might find interesting:Ground costs are extremely important. It is a very significant part of the costs. In my second scenario, more than half of the Reuse Index goes to ground costs. If we want orders of magnitude in savings, this will need to be practically 0. Spaceports will really need to operate like airports to even have a shot.The next biggest chunk is rebuilding the second stage, or in general : Fru. Trading off Cru to increase Fru is worthwhile as long as Cru * ( 1 - Fru ) decreases (if refurbishment costs remain the same, i.e. Crf goes down proportionally so that Crf * Cru stays the same). The initial cost of the rocket is divided by n, so as more launches happen this goes to zero. If we can make a fully reusable rocket at 10x the cost that can fly hundreds of times, it is totally worth it. This is pretty much the idea behind SSTO spaceplanes.Refurbishment costs should be low, but aren't the dealbreaker as long as they don't exceed 25% of the total rocket price (so closer to 35% of the first stage price). Spending several million on refurbishing per launch is totally doable. Using Cru = 1.2, Fru = 0.7, Crf = 0.25 and Cground = 0.2 (more realistic value from ULA tweets), you still get a 20% drop in costs after 10 flights. This would be a failure according to SpaceX, but still a significant and worthwhile competitive advantage.The F factor from ULA barely makes a difference. It increases the costs by 0.03-0.04 index points even at 20 launches. This is because the reduced production volume only counts for the first stage, not the entire rocket! At 20 launches you may pay almost 60% more to build the first stage, but that obviously only means a 3% increase per launch. I've actually found a mistake in my formula here: I apply this factor to the entire cost of the reusable rocket, while I should only apply it to the fraction that is reused. The first term should be (F * Fru * Cru + ( 1 - Fru ) * Cru ). This would reduce the impact even more. This term can pretty much be ignored unless the rate exponent goes down significantly.These observations may be more useful than what I originally wrote. It shows a part of the business model behind the Falcon Heavy: If they can achieve second stage reusability with it and cut production costs enough to make it worthwhile (second bullet point above), they have the winning formula. We can also see why Elon isn't exactly worried about refurbishing costs: Even at 25% there is a strong business case to be made. Building the Merlins from scratch to be reusable without significant maintenance is the killer breakthrough here. Everything hinges on that. I'm very interested to see the static fire because that will pretty much be the deciding factor according to my analysis. If they end up needing STS levels of disassembly, refurbishment, testing and reassembly... That's pretty much lights out for reusability then. Maybe the Raptor engines can save the day but it would still suck.So maybe the primary motive behind the FH was not that it could put massive payloads into LEO in expendable mode (since as many people have pointed out, these payloads are few and far between), but that it could put a future reusable second stage with its increased weight, plus an F9-sized payload, into LEO and still RTLS. If the first stage core and booster plus the second stage and payload fairing are all reusable at a reasonable maintenance cost, then the cost per kg to orbit can drop like a stone. F9 alone would not have the capacity to do this, you need the FH.Of course SpaceX's plans may have changed since the decision to develop FH.100% agreed. I personally think we'll be seeing a lot of FHs flights for exactly this reason, and mission specific reusable second stages (LEO satellite deployers, tankers, etc)
That would be a second FH launch inside 2016. That's...eh..very optimistic of him...