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Where do you find a solid surface to land on except in Russia and China? You would like to fly across water or at least unpopulated areas in case a problem dev
by HarryHirsch 12y ago
Where do you find a solid surface to land on except in Russia and China? You would like to fly across water or at least unpopulated areas in case a problem develops during flight and range safety needs to go for self-destruct. The USA, Europe, India and Japan all do that, because no one wants a re-run of the Long March desaster in 1996.
Flying back the opposite direction is no good because you are fighting the rotation of the Earth and are paying with extra fuel to carry the fuel needed to go back, besides coastlines are always the most densely settled areas of any country.
I can't imagine that the economics will work out, but perhaps someone else has genuine numbers to prove me wrong.
- washedup 12y agoSpaceX owns some land in southern Texas. It seems that the initial idea is to have a spaceport in Brownsville, TX, and use Cape Canaveral, FL, as the landing location. In the mean time, they can practice by using floating platforms in the Atlantic. http://www.faa.gov/about/office_org/headquarters_offices/ast/environmental/nepa_docs/review/documents_progress/spacex_texas_launch_site_environmental_impact_statement/media/SpaceX_Texas_Launch_Site_Draft_EIS_V1.pdf http://www.faa.gov/about/office_org/headquarters_offices/ast...
- Shivetya 12y agooh I am sure there are a few islands out there both inhabited and not so much that would present some opportunities. Much easier to deal land on something that isn't moving up and down, let alone side to side.
- washedup 12y agoIf launched from Texas, would they have to move side to side to land the first stage in Florida?
- Chronic29 12y agoNo. The earth moves them..
- Shivetya 12y agomy apologies for not be clearer, while the movement of the Earth is a concern I was replying to the idea of trying to land on a floating platform which I do not see as feasible. Both from the standpoint of trying to find such a small location to the fact it is not going to be a stable landing area because of wave action
- coob 12y agoWould an old oil rig work?
- rspeed 12y agoIt would require significantly more fuel to get the stage to even the Gulf coast of Florida (much less the Atlantic coast) than it would take to return to Brownsville. Additionally, Brownsville launches will almost certainly be aimed between the southern tip of Florida and Cuba, in order to avoid traveling over any populated areas.
- seanflyon 12y agoIf you can deliver a payload and recover and fully reuse the rocket then your costs drop by an order of magnitude. I can't imagine that the economics won't work out.
- timdiggerm 12y agoDepends on cost of refurb
- vajrabum 12y agoThey're shooting for no refurb on per mission basis and potentially to fly it the next day. Apparently the first stage is about 70% of the total $60M mission cost.
- Nogwater 12y agoI'm pretty sure they're planning to fly the first stage back to the launch site (Cape Canaveral in most cases for now). It wouldn't return to the same tower, but somewhere at the Cape.
- dredmorbius 12y agoThing is, for orbital flight, you're adding a lot of sideways translation in order to achieve orbital speed. In the case of the Saturn V, the first stage (S-IC) sequence completed after 2 minutes 41 seconds, at an altitude of 42 miles (68 km) a speed of 6,164 miles per hour (9920 kph). It continued ascending ballistically to an altitude of 68 miles (109 kilometers), ultimately landing 340 mi (550 km) downrange. https://en.wikipedia.org/wiki/Saturn_V#S-IC_sequence https://en.wikipedia.org/wiki/Saturn_V#S-IC_sequence
- InclinedPlane 12y agoReusability trumps everything. EVERYTHING. When you throw away the entire rocket every flight you throw away tens of millions of dollars in hardware. If you can recover and re-fly stages you can get away with a lot of compromises elsewhere. Especially since the first stage, for SpaceX anyway, represents 3/4 of the hardware cost of the launch vehicle. Even reusing the first stage once means cutting the overall hardware cost of a flight by nearly 1/3. For SpaceX that translates to about $20 million per flight in savings. And that's from one and only one reuse flight of the first stage. In comparison the fuel is nothing. In comparison even a massive payload hit is acceptable. As long as the payload reduction is less than the cost reduction, everything is golden, and the rest is profit margin. For 2 reuses (3 total flights) the hardware cost per launch drops to 1/2 of current costs. For 5 or more uses per first stage the cost drops below 40%. SpaceX's launches are already cheaper than the competition, dropping below 1/2 of their current cost floor makes it impossible for the competition to keep up and would enable them to own the launch market.
- ufmace 12y agoWhich would then force anybody else who wants to be in the launch biz to develop their own version of the technology. Sounds like a win for humanity.
- krschultz 12y agoI think they're talking about a barge or floating platform of some sort out in the Atlantic, at least for the initial tests.
- sitkack 12y agoIceland, Bahamas or Canary Islands?
- greglindahl 12y agoSpaceX has said that they want to fly the booster back to the launch pad from the first announcement of their reusability plans. Yes, the rocket launches with 30% extra fuel - Falcon 9 v1.1's first stage was made bigger to accommodate that need. Fuel is a small cost relative to everything else.
- HarryHirsch 12y agoFuel is a small cost relative to everything else. But the extra weight is a concern, it limits payload to orbit. Try flying the first stage back to the launchpad in Kerbal Space Program while delivering a useful payload to orbit! It's instructive. KSP really develops your intuition for rocketry, everyone commenting in this thread ought to buy a copy.
- greglindahl 12y agoYou did note that the OG2 flight 1 payload was about 1/4 of the max? And the next 2 flights aren't going to try landing because they need all the fuel to get a big payload into GTO[1]? SpaceX seems to have all this under control, even if you can't imagine that it will work out. [1] http://www.spacex.com/news/2014/07/22/spacex-soft-lands-falcon-9-rocket-first-stage http://www.spacex.com/news/2014/07/22/spacex-soft-lands-falc...
- XorNot 12y agoYou also always have the option of just building a heavier lift rocket - which is what SpaceX is starting to spin up for. I'd imagine the F9H's successor/bigger brother is going to be designed with provisions for the same type of return profile.
- InclinedPlane 12y agoAccording to SpaceX the Falcon Heavy will only fly with reusable first stages. That will bring the payload down but the payload was very high before. The Falcon Heavy should still be able to lift more than 20 tonnes to LEO, which is equivalent to the Delta IV Heavy. And with reusability it should be able to do so at a cost comparable to or cheaper than today's expendable Falcon 9s.
- ChuckMcM 12y agoIf they launch from their Vandenberg launch complex they can "easily"[1] land in the high deserts of California or Nevada. Although I believe the plan is to return to the existing pad. And in answer to the expense question, 9 merlin engines are pretty pricey compared to just fuel costs. [1] scare quotes because I know its never easy to land and California or Nevada east of Vandenberg for minimal delta-v requirements.
- washedup 12y agoVandenburg AFB is used for placing payloads in polar orbits, which means they launch north/south. However, because of the population centers north of the AFB, they generally launch all vehicles south. This mean launches will happen over the Pacific Ocean, and they would not recover the first stage in the high deserts of California or Nevada.
- seanflyon 12y agoUnless they did something different from what others normally do.
- ChuckMcM 12y agoAs washedup accurately points out they only launch south because in the event of a scrub they are over the ocean. And while Spacex could request an eastward flight plan, its unlikely the FAA would grant such a request because it is unlikely that SpaceX could assure them adequately that Bakersfield would not be at risk. For grins and giggles I confirmed this with the Air Force (their response was "Safety concerns restrict the available launches from this facility." Interestingly SpacePort America (http://spaceportamerica.com/ http://spaceportamerica.com/) has a similar problem, although if you look (https://www.google.com/maps/place/Spaceport+America/@33.0125641,-106.9475644,9z/data=!4m2!3m1!1s0x0:0x55de8b938eb3dc17?hl=en https://www.google.com/maps/place/Spaceport+America/@33.0125...) you will see there isn't much east of it.
- InclinedPlane 12y agoYou just fly back to the launch area. It's immanently feasible to fly that route and always have a buffer of assurance that the rocket's trajectory will not head towards populated areas. If, for whatever reason, that changes then they press a button, the rocket zips apart and falls in pieces into the Atlantic ocean. As for cost, fuel is cheap, it's one of the cheapest things in the whole operation. Think about the fact that every commercial airliner has the capability to make an unpowered landing and to save fuel doing so, why don't they? Because operational complexity adds cost much more than using up fuel does. By the same token, the greatest costs in orbital launch come from throwing away the hardware after every flight and operational complexity. If using extra fuel enables them to more easily reuse the stages and get more launches out of them as well as reduce overall operational complexity, then it makes economic sense.
- jccooper 12y agoI would suspect SpaceX has the numbers. I don't think they're just guessing that what they want to do will work. Rocket engineers are big on numbers. They intend to do a return to launch site--at least eventually. There will be several intermediate steps to prove the system. If it proves unworkable, always landing on a barge is better than not, I guess. RTLS will certainly require a good deal of margin (by rocketry standards), but first stages usually have some margin already, and SpaceX will have a nice range of options once the F9H comes on line so that they don't have to fly a rocket "fully loaded" except for certain extra-large payloads. I imagine they can also optimize most flight profiles for RTLS, by sending the first stage more than usually straight up--which is close to the case anyway. Lateral velocity is mostly the job of the second stage. While it's never been done before, it's not an unheard-of concept. One of the potential evolutions for the STS was "fly-back boosters".
- Gravityloss 12y agoReturning to launch site doesn't require that much fuel as the first stage is really light after separation. Barnaby Wainfan patented an interesting alternative: after staging, re-enter, then do a burn and fly ballistically back to launch site. This kills the horizontal speed with air resistance instead of propulsion, potentially saving fuel. You have to regain the altitude though.