Just a quick thought for fun.

Suppose some execs got together and had a solid commercial business case for heavy launch ASAP. ATK supplies well tested Shuttle four segment SRBs to mate with current Falcon 9 equipment. Two SRBs are mated with a Falcon 9 core and two strap on stretched  tanks built with Falcon 9 tooling.

At launch the assembly weighs more than the Shuttle stack did and has lower acceleration than the traditional stack even with the Falcon 9 core thrust. At SRB burn out, the falcon 9 and two partly empty strap on tanks mass about 2.4 million pounds and are on a lofted trajectory to compensate for the less than 1 T/W ratio. From the 1,500 m/s or so velocity at separation, the mass ratio to orbit should be around 8. Considering the strap on tanks are dropped three or four minutes after SRB separation, mass in orbit should be on the order of 280,000 pounds.

Your 140 tons is in orbit. How much of it would be usable payload?


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I do construction for a living and aerospace as an occasional hobby. I am an inventor and a bit of an entrepreneur. I've been self employed since the 1980s and working in concrete since the 1970s. When I grow up, I want to work with rockets and spacecraft. I did a stupid rocket trick a few decades back and decided not to try another hot fire without adult supervision. Haven't located much of that as we are all big kids when working with our passions.

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10 Responses to SFalconLS

  1. Pingback: Space-for-All at HobbySpace » The FrankenFalcon rocket + Navy railguns as lunar mass drivers

  2. ken anthony says:

    Always thinking, eh John? Join ’em rather than fight ’em.

    It could happen if there were a payload. How about all those politicians that think it’s a good idea to spend $3b to $4b a year during this economic time?

  3. ken anthony says:

    I couldn’t decide ‘SLS’ or ‘on nuthin’ so I left both out, duh!

  4. john hare says:

    Kicking out a fun piece is not joining. This would be quite theoretically possible if I were allowed to cherry pick allowable data. I’m sure I could sub that cherry picking out to one of the solid rocket fanboys. OTOH it could be done if risks were accepted and a boatload of safety regs were ignored with an over riding need for heavy lift right now.

    I think Clark nailed it with FrankenFalcon. It truly would be a monster.

  5. ken anthony says:

    Sorry, didn’t mean an insult. I don’t think FrankenFalcon has quite the marketing ring to it? đŸ˜‰ You could just stick with the way they’ve been going and just call it Falcon SLSX? SLSX for short of course.

  6. Dick Eagleson says:

    Sorry to be late to this party, but I have a few thoughts anent your modest proposal.

    Really interesting idea, but it fails the ASAP test because of infrastructure issues. It would require vertical assembly and therefore massive mods to the Kennedy VAB and one of the Apollo/Shuttle crawler-transporters to get it to the pad and support it there. It would also require significant mods to one of the 39-complex launch pads.

    Consider a more readily buildable HLV. Clustering seven complete F9’s – 1st and 2nd stages – would involve relatively trivial engineering changes to the SpaceX hardware, somewhat less trivial mods to the control software and then you’d have a vehicle that could put 200K lbs. into LEO. To take full advantage of the lift capability, it would need a new, single, very large diameter payload support and shroud structure (ca. 33m minimum) to cover the circle swept by seven clustered cores.

    On the infrastructure side, you’d need a wider, higher-bay version of the horizontal integration building SpaceX already has at Canaveral. Interior fitments, except perhaps overhead crane capacity, could be the same as those in use now. The rocket pieces to be lifted won’t weigh any more, there will just be more of them. Moving a single large payload in one chunk, though, might need extra crane muscle.

    Also needed, either a complete new bespoke launch pad or massive mods to one of the 39-complex sites. This is maybe the only place where the SFalconLS proposal might score better.

    Finally, it would need a transporter-erector appreciably more muscular than what F9 or even Falcon Heavy will need, but still – even starting from a clean sheet of paper – likely a lot less bother than a conversion job on one of the Canaveral monster crawlers. Nice thing about liquid fuel rockets is you can haul them out empty and fill them at the pad; SRB’s, not so much.

  7. john hare` says:

    it was just a fun post mostly. The FrankenFalcons’ main advantage if this were a serious post would be the additional political support from the solid fuel crew. Actually. I still have some problem understanding why it takes Dirksens and decades to do an LV out of supposedly mature Shuttle components.

  8. Dick Eagleson says:

    I grok the “modest proposal” aspect of FrankenFalcon – which, by the way, would be a great name for a vehicle designed to launch Sen. Al Franken into space and leave him there – but I digress.

    My F9x7 response wasn’t really a serious proposal either, just an alternative “modest proposal.” As for why, as Heinlein famously put it, “everything takes longer and costs more,” I think Tom Heppenheimer put his finger on it decades ago when he noted that the one absolutely sacrosanct engineering requirement of any government project is “to keep the parking lots full.” Whether anything useful, or anything at all, really, gets accomplished beyond that is quite secondary.

    Personally, I think the coming year or so looks likely to be the time when NewSpace accelerates decisively past Legacy Space. A decade hence, “the space program” will consist mainly of whatever today’s and tomorrow’s entrepreneurial space companies are doing. NASA, to the extent it still exists, will be a sideshow. I think even most space-based astronomy and robotic planetary exploration missions will be NewSpace-based by then.

  9. john hare` says:

    Well said sir.

  10. steven says:

    I think the MCT or Mars Colonial Transport is a Falcon core stage carried all the way to orbit!
    refueled with tankers the last of which is your LO2 and a propositioned cargo

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