Are you seriously equating manufacturing cost with reburbishment costs. Really?93143 wrote:Mitigating the manufacturing costs doesn't get rid of all the other costs associated with launch vehicles, and all of those also scale with the size and number of stages. In fact, post-flight servicing/refurbishment is a whole new cost that expendables flat-out don't have, and it scales with size and number too, probably more than manufacturing cost does. So to first order, your scheme doesn't scale any better for reusable stages than it does for expendables.
My example was more numerous, but also increased the payload.Then consider that the reusability requires those stages to put out more impulse in order to do the same job, meaning either they have to be bigger or more numerous (= more expensive to have, use, and refurbish) or the Isp has to be better. Or both.
The zeroth stage booster would be easier to return to launch since they would run dry and get jettisoned much quicker. The pair of boosters would not be more difficult if it allowed an easier down range retrieval. Get high enough and you might just get a circumglobal retrieval for the core.In fact, your scheme would result in the main boosters and especially the core ending up much faster and further downrange by the time they had to drop off and go back, making the problem worse.
Nobody assumed "free", just cheaper. The fuel cross connect concept used by F9H in conjunction with fly back boosters may just make space flight affordable for common business.You can't just assume reusable = free and throw ganged cores at the problem. Or more sequential stages for that matter; each unique stage you add requires its own DDT&E and special manufacturing and handling treatment, which could rapidly eat up the advantage of reusability.