Quote from: Ictogan on 05/21/2017 06:39 pmWell, two out of two reused boosters have taken several months to refurbish so far. And I'd imagine that SpaceX is going to reduce those times gradually, not suddenly.Don't confuse time to re-fly with time to refurbish. The booster can't re-fly until there's a customer willing to re-use.
Well, two out of two reused boosters have taken several months to refurbish so far. And I'd imagine that SpaceX is going to reduce those times gradually, not suddenly.
Block 3/4 boosters sound like candidates for expendable launches. The marginal cost of a couple of weeks refurbishment of a single core would very low, even if they have been written off for regular relaunches. Of course block 5 FH refurbishment costs would presumably be even lower, but using an expendable block 3/4 core would save one flight's portion of lifetime on three FH cores.
Quote from: Mongo62 on 05/21/2017 07:53 pmBlock 3/4 boosters sound like candidates for expendable launches. The marginal cost of a couple of weeks refurbishment of a single core would very low, even if they have been written off for regular relaunches. Of course block 5 FH refurbishment costs would presumably be even lower, but using an expendable block 3/4 core would save one flight's portion of lifetime on three FH cores.I see your argument about expendable flights. But those will not be many. Assume only 10 block 5 cores built before reuse becomes standard. Assume only 10 reflights per core. Assume there will still be a few customers like NASA and DoD who want new cores for a while. They will soon have 20 cores worth 200 flights. That is enough to last them well into beginning to launch the constellation in 2019.
There is always the possibility that the 100 flight target proves optimistic. Look, even 10 reflights mean a revolution in the cost of access to space, so that would not be a disaster. But I can see a scenario where cores get reflown 10 times, or maybe 20 o 30 times, rather than 100 times.
This is someting I've been pondering on. Specifically, the difficult decision of when to stop reusing Block 3 and 4 boosters because Block 5 is available. On the one hand, just throwing away a perfectly reusable booster seems a waste of tens of millions of dollars. On the other hand, they cost more and take longer to refurbish than the Block 5 with its optimized reusability features.So come next year, they will have a dozen or so Block 5's in operation, but also have maybe a dozen or more Block 3 and 4 landed cores still sitting in storage, some of which have been reflown once, and some which haven't been reflown at all.So how to decide when to stop using pre-Block 5 cores that are still available?
No Human operator. It was a big computer sitting on the ground. Something that was way to heavy for a rocket to lift but was fast enough to do high accuracy navigation steering and engine cutoff timing. It could have been sufficient for a computer controlled landing on a landing pad. This accuracy was why it was still in use up to the 1990's.
The ICBM version was designed such that the X band tracker up-link would capture the Atlas in-flight during the sustainer phase and issue SECO that would then result in the warhead hitting the specified target. The Atlas's were launched at ~1min intervals to be able to give the shared guidance station the ability to acquire and guide each of several missiles. The main reason that Atlas was not made into a reusable LV was that it was a throw away weapon system. That after they were launch there was no reason to recover and use then again. Possibly even the probable no facilities left standing either.One of the first engines the F-1 was so good that it could have been reused. Also the RL-10 was so good as well that it could have done a dozen restarts in-space if they could figure out how to get a dozen restart cartridges on the engine. The RL-10 actually has 4 cartridge start ports for use and has been used for 4 in-space starts. So there were engines in the mid to late 1960's that could have been used to create fully reusable LV's. In fact they were almost used on shuttle. But because development funding was limited the cost of operations was sacrificed for lower development costs.Added:Now back from history to the effect of reusability on costs. Reusability has been the goal since the 1960's but has been only partially successful if even that until now. SpaceX tells us that their solution will lower their costs and has offered customers a lower price for use of used boosters. But only once their use of used booster exceeds that of new ones can it be said that their reusability solution has become successful.
The Atlas D,E,F,G, and H all used pressure fed vernier engines for steering. ,,,The Atlas vernier engines produced 2,000lbs thrust each. And had the option for its own small shared turbo pump for independent operation after SECO (sustainer engine shutdown). A modified Atlas design with 4 verniers landing legs and some areosurface controls could have in the 1960's done a VTVL. ...
The following post on the Bulgariasat Update thread implies great reduction in cost of refurbishment.http://forum.nasaspaceflight.com/index.php?topic=42913.msg1681755#msg1681755This is that between these two that the refurbishment costs reduced by ~factor of 4. If the SES-10 refurbishment cost 50% that of a new booster, the Bulgariasat-1 cost ~12% that of a new booster. Even if a new booster cost $30M (this is actually the highest estimate for what a new booster cost to manufacture) then the refurbishment cost is <$4M. If the cost of a new booster is $20M (this is the low end for the estimated cost to manufacture) then the refurbishment cost would be <$3M. This puts the savings of at least $17M up to as much as $26M for this launch.Even if the reduction factor is only ~3 then the savings become from $16M to $25M. Only a variation of $1M from the higher reduction factor.
Don't confuse elapsed time with effort required.... that 4 months go by between flight and reflight doesn't imply that there was 4 months of continuous effort. (much less if it was one person or a standing army of 1000... )When we see SpaceX say "we can't reuse on this flight, we don't have a booster ready" then we'd know that they don't have effort down low yet....
Quote from: Lar on 05/23/2017 03:48 pmDon't confuse elapsed time with effort required.... that 4 months go by between flight and reflight doesn't imply that there was 4 months of continuous effort. (much less if it was one person or a standing army of 1000... )When we see SpaceX say "we can't reuse on this flight, we don't have a booster ready" then we'd know that they don't have effort down low yet....I guess I didn't think of it that way. Although, I'm assuming that similarly with airplanes, they technically "lose" (not really) money by having the core on a hangar and not helping to deliver a payload into orbit, which is what I was thinking about. So at this point, they could have greatly reduced how much it costs to refurbish a core because it takes less effort do so presumably, and now they're going to aim to maximise the revenue that they get from each core. This will done by reducing the turn around time by making refurbishment quick and cheap (or eliminating it altogether), and by ensuring the core has high durability.Cue in block V...
Quote from: tvg98 on 05/23/2017 04:02 pmQuote from: Lar on 05/23/2017 03:48 pmDon't confuse elapsed time with effort required.... that 4 months go by between flight and reflight doesn't imply that there was 4 months of continuous effort. (much less if it was one person or a standing army of 1000... )When we see SpaceX say "we can't reuse on this flight, we don't have a booster ready" then we'd know that they don't have effort down low yet....I guess I didn't think of it that way. Although, I'm assuming that similarly with airplanes, they technically "lose" (not really) money by having the core on a hangar and not helping to deliver a payload into orbit, which is what I was thinking about. So at this point, they could have greatly reduced how much it costs to refurbish a core because it takes less effort do so presumably, and now they're going to aim to maximise the revenue that they get from each core. This will done by reducing the turn around time by making refurbishment quick and cheap (or eliminating it altogether), and by ensuring the core has high durability.Cue in block V...Airplanes are built and operated assuming they will spend more time flying and earning money than on the ground.Rockets are (until now) built and operated assuming they will be used once and that's it. You can't use the same financial model for both and expect sensible results.
Launch cadence.One of the biggest impacts to per launch costs is the crew at the launch site. If there is not a launch they do not have much work to do. Their time (from the standpoint of the company) is being wasted. Also for a flow not everyone is involved with every step of the process. So unless there is an assembly line setup to LV processing at the launch site, again wasted manpower. If SpaceX with 2 pads can launch a little less than every 2 weeks, they can share personnel between pads too as long as the launches are staggered (about one a week) between the two pads. So at a rate of 1 a week (once every 2 weeks per pad) SpaceX would be spending almost the same in labor as they would be to launch off of 1 pad every 2 weeks.But this higher cadence and assembly line like launch processing is a result of rapid reusability. If spaceX can get there. There will be several costs savings in various other places than just in refurbishment costs. Generally the cost of launch (even for a new booster) will decrease because of higher cadence.Now as far as my estimates on the relative costs of refurbish ment between SES-10 and Bugariasat-1 is that SpaceX stated the cost of refurbishment for the SES-10 booster was 50% that of a new booster. The next item is statements that refurbishment on later vehicles would be 1/8 the the cost of the SES-10. What I was showing is that it seems that Bulgarisat-1 shows that SpaceX has yet to reach that 1/8 the cost of SES-10. But as Lar states we do not know if they are simply counting time (a mixture of storage and active work) or the work of a certain size crew or crews for a period. But the costs have gone down. The exact amount is not known but even just cutting the costs in half from that of SES-10 is significant ($5M or more in additional savings).
Airplanes are built and operated assuming they will spend more time flying and earning money than on the ground.Rockets are (until now) built and operated assuming they will be used once and that's it. You can't use the same financial model for both and expect sensible results.
So they're getting a better bang for their buck by effectively increasing productivity. Would they move the work force responsible for manufacturing new first stages to other projects to keep costs low and productivity high? Like you said, it is in their best interests to keep the crew busy and not have them standing around and doing nothing.
Obviously they would. First thing they'll be doing? Making more second stages than 1:1 with first stages. They already have made at least one more, presumably, and are about to have made 2 more (discounting test articles)