Falcon FLOC IX Rediculously Heavy

I should probably quit picking on the Falcons, but the possibilities are too much fun to leave alone. In January of 2008, Jon posted an article on Fleet Launched Orbital Craft, or FLOC. InĀ  the article, it is suggested that many identical bimese craft launch simultaneously from one general area. As one of the bimese craft is drained, it is dropped leaving the other fueled twin to carry on. The fully fueled twin mates with one of the other launched craft and begins propellant crossfeed anew until it is empty. The empties drop off and the full twin keeps going in a series of dockings and propellant transfers followed by another staging. The article mentioned up to 32 units taking off with a series of up to five dockings/transfers/staging events, depending on how one counts. 32,16,8,4,2,1. payload potential was enourmous.

The FalconIX Heavy is projected to have a payload of 53 tons. The SLS is supposed to eventually launch 130 tons at a time. If the FIXH reaches its’ target performance, then someone will still be screaming that we desperately need a larger payload for exploration or something. With the FLOC concept, three FIXH could launch at once. When the outer two cores were dropped from each vehicle a couple of minutes into the flight, the two non-payload cores would maneuver to a docking with the payload core crating a new trimese vehicle similar to the ones that just staged. All the mating gear and cross feed plumbing is still in place from the original trimese launch and the cross feeding begins again.

It would seem that a payload of 159 tons should be possible with a simple tripling of the FIXH projected payload. If this could be done, then how would the SLS justify continued existence?

 

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johnhare

johnhare

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.
johnhare

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johnhare

About johnhare

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 Falcon FLOC IX Rediculously Heavy

  1. George Turner says:

    Could you put eight Falcon 9H boosters around a Delta IV core?

    Assuming the boosters are stretched about 10% to give them a 200 second burn time (instead of 180), they’d have an empty mass of maybe 32,000 lbs and a wet mass of about 974,000 lbs [educated guesses]. Then take a Delta IV CBC (both stages) and add 150 metric tonnes of payload (330,000 lbs), to give a core/payload mass of 895,000 lbs.

    Arrange the boosters around the core in a square so that the engines at north & south are sustainers, cross fed from the corner engines just like a matched pair of Falcon 9 Heavies, and the engines at east and west are just stand-alone stap-ons. That gives you a lift-off mass of about 8.8 millon lbs and a lift-off thrust of 10.5 million lbs (from the 72 Merlin 1D’s on 8 boosters). The initial acceleration is 1.2 G’s.

    The corner engines burn out after 150 seconds, with the stand-alone boosters still having 25% fuel and the cross-fed sustainers having 75% fuel, and the total vehicle mass is 3.038 million pounds. The thrust prior to cutoff is about 11.5 million lbs (vacuum) and the acceleration would be 3.81 G’s, so you might want to throttle back a bit before that. The potential delta V to that point should be around 3 km/sec.

    After corner booster separation the vehicle mass drops to about 2.91 million pounds and the thrust is 5.78 million pounds (36 Merlins), so the acceleration drops to 2.0 G’s. At this point the vehicle is an X or a + configuration.

    At 200 seconds the stand-alone boosters burn out while the sustainers still have 50% fuel, with a vehicle mass of 1.97 million pounds. It would’ve been accelerating at 2.94 G’s prior to cutoff, and the potential delta V for that 50 second segment (leg 2) was 1.3 km/sec. After separation the mass is 1.9 million pounds and the thrust is 2.89 million pounds, giving 1.5 G’s.

    At 300 seconds the sustainers burn out. The vehicle mass was 960,000 lbs and the acceleration was back up to 3 G’s. After separation the mass is just the 0.895 million pound core stage (with the attached 150 tonne payload). The potential delta V for the 150 second leg 3 is about 2 km/sec, and the total delta V to that point is about 6.38 km/sec.

    Then the RS-68 on the Delta lights up with 785,000 lbs of thrust, producing 0.75 G’s. At about 543 seconds the main core stage burns out. The vehicle mass is down to 446,600 lbs and the acceleration was 1.7 G’s, and after separation the weight drops to 385,000 lbs. The delta V from the RS-68 was 2.8 km/sec, and the total to that point is 9.2 km/sec.

    Finally the little tiny RL-10 on the Delta IV upper stage adds 0.56 km/sec to bring the total delta V to 9.7 km/sec, which is at the high range of what it usually takes to get a rocket into LEO. If I run the numbers with a 200 tonne payload my simple spreadsheet shows 8.9 km/sec delta V.

    It would be interesting to run some real numbers through some actual software, with an additional allowance for the increased structural weight on the Delta IV to support such a large payload at 3+ G’s, and ditching the expensive RL-10 second stage entirely.

  2. Paul451 says:

    John Gardi (aka Tinker) had a similar proposal to George’s. Except the eight cores were extended RP-1 tanks only, around a single central LOx tank. Symmetrical pairs of cores would burn out in stages, cross-linking keeping the final two cores fully fuelled at last staging. (The downside is that two full sets of F9 engines are burning from launch right through to orbital insertion, which seems harsh.)

  3. Paul451 says:

    (Oops, forgot to say, in Tinker’s scenario, the tank is the primary payload. The additional few hundred tonnes of payload is to fit it out, a la Wet-Lab or ET-station.)

  4. Chris (Robotbeat) says:

    This isn’t exactly a very good argument against SLS. This might be a good NIAC proposal, but has a host of engineering headaches associated with it. First of which is, assuming you can make it work, it wouldn’t be very reliable. If we assume there’s some significant risk associated with each staging event, then this would be a quite risky way to launch things. At least if you have a lot of engines, you can mitigate it with engine-out. With this scenario, a single staging problem (and there are something like 2n-1 staging events if you assume n biamese craft, and that’s assuming rendezvous is easy!) would take down the entire payload.

  5. George Turner says:

    Not just staging events, but even a tiny hold on launch would doom the payload.

    The issue I see with using eight Falcon 9H boosters is the man- power of checking out and test firing 72 Merlins (and an RS-68) prior to each launch, which would limit the flight rate even if the boosters were re-usable. If you used something like six RD-170’s you’d have more total thrust and only six booster engines to check out.

    An unrelated thought I have is for a stage zero lift engine using something like the turbine stage from the RD-170 turbopump (or an SSME LH turbopump) hooked through a gearbox to the extremely lightweight fan from a GE 90-115B from a Boeing 777. That should make an extremely powerful ducted fan producing about 100,000 lbs thrust at sea-level with a 30 to 50 to one thrust to weight ratio. The RD-170 turbopump produces quite a bit more power than the GE-90, the SSME LH turbopump somewhat less. You’d have to carry oxidizer but the weight savings would give you nine to twelve minutes of run time before your fueled takeoff weight exceeded that of the conventional jet engine, and more importantly the final stage-weight would plummet. In theory it would also cost much less per engine. A small test model would probably make a nifty ducted-fan jet pack.

  6. Neil Shipley says:

    I believe Elon’s working on his next heavy vehicle – MCT, which I think, is why he wants LC-39A. FH due to fly 2nd quarter 2014.

  7. Paul451 says:

    Musk’s original plan was to develop a larger engine (Merlin 2), which would replace all 9 engines of the F9. So a Falcon Heavy MkII would have three single engined cores. The next step would be to build a wider core with all three engines. Falcon X. Then develop a triple-core Falcon X-Heavy. [The last step was to build a yet bigger stage with 9 Merlin 2 engines. Falcon XX.]

    So with Merlin 2’s, a six or eight core F9-based Super-heavy would only have 6 or 8 engines. (Or eight cores in a ring around a ninth. Coz tradition.)

  8. Pete says:

    The Merlin 2 and Falcon XX proposals were put together during the Ares meltdown and intended to inject sanity into NASA. It was a doomed effort from the start and buried well by SLS. MCT isn’t going to be anything like those. Remember that FXX was only ridiculously cheap when compared with SLS. When compared to equivalent F9, the single engined version was 2 times more expensive! Merlin 2 could only make sense in NASA economics.

  9. Neil Shipley says:

    The current engine development within SpaceX is, I believe, Raptor. This engine is reputably a Methalox SG engine with sea-level thrust in the order of 650klbf.

  10. Krishna Kattula says:

    I don’t think you make SLS unnecessary by sticking rocket stages together like Legos, in a Rube Goldbergian scheme.

    You do it by asking what possible payloads can’t be divided into two or three 53 tonne pieces.

    SLS can at least make a case versus the perceived complexity of 15 to 20 EELV launches plus assembly. Not so much against FH.

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