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« on: 07/23/2007 03:15 PM » |
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PhalanxTX
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« Reply #1 on: 07/23/2007 03:30 PM » |
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Thanks for the heads-up on that!
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CFE
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« Reply #2 on: 07/25/2007 06:19 AM » |
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Very exciting stuff indeed.
The S-IC flyback booster option really changes the shuttle equation, with pluses and minuses.
Pros: a safer first stage that can be shut down. Liquid propellant and sequential staging prevent Challenger-style failures. No changes needed to MLP used in Apollo program.
Cons: a heavier and taller shuttle system. Probably costs more than SRB's to develop, and cost savings associated with runway landing are negated by need to replace F-1's after every flight. Sequential staging means that SSME's need to be air-started.
A flyback booster was probably a "bridge too far" in 1972. The best option for the shuttle design probably would have been liquid-fuel boosters that would be mounted parallel to the ET and be recovered after parachute-assisted splashdown.
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collectSPACE
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« Reply #3 on: 07/25/2007 07:31 AM » |
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Reminds me of an 18-page booklet prepared by Boeing in the late 60s/early 70s proposing the recovery and reuse of the S-IC...
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Jim
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« Reply #4 on: 07/25/2007 11:31 AM » |
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CFE - 25/7/2007 2:19 AM
No changes needed to MLP used in Apollo program.
. Big changes were needed. The wings were in the way
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zerm
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« Reply #5 on: 07/25/2007 12:12 PM » |
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That's TERRIFIC- I bought it on the spot, and they use PayPal too- which is handy for me!
For a long time I've been considering doing a flying model version of this for my Dr. Zooch Rockets line.
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Generic Username
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« Reply #6 on: 07/27/2007 03:44 AM » |
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collectSPACE - 25/7/2007 1:31 AM
Reminds me of an 18-page booklet prepared by Boeing in the late 60s/early 70s proposing the recovery and reuse of the S-IC...
The original Model 922 flyback S-IC was designed in the same program that produced those splashdown versions. Big trades study to find the cheapest launcher possible from Saturn V components. For limitted numbers of flights, the splashdowns were lower cost. But once you started launching two or three flyback S-V's per monmth for a span of ten years, the flyback option becomes cost effective. And, yes, they were serious about launch rates like that.
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tankmodeler
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« Reply #7 on: 07/27/2007 01:44 PM » |
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Generic Username - 26/7/2007 11:44 PM
But once you started launching two or three flyback S-V's per monmth for a span of ten years, the flyback option becomes cost effective.
And, yes, they were serious about launch rates like that. Of course, the question is, "Who was serious about launch rates like that?" I wouldn't think you'd have to go too far up the managerial food chain to find people who knew for a fact that there would never be that kind of money available. Also, you can be serious abuot something without believing it. If my boss tells me to devise a system based upon ridiculous assumptions, I can devise it and be serious about it without beliveing for a minute that it will come to pass. It would be very interesting to see who actually belived that there might ever be that kind of space funding available, especially as, by that time, actual costs for this scale of effort would be relatively well known. Paul
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Generic Username
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« Reply #8 on: 07/27/2007 03:23 PM » |
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tankmodeler - 27/7/2007 7:44 AM
It would be very interesting to see who actually belived that there might ever be that kind of space funding available, especially as, by that time, actual costs for this scale of effort would be relatively well known.
In 1962, when these studies were done, the Apollo funding boom was still building, and the future seemed limitless. This was the same time period that resulted in the Sea Dragon design for a TSTO booster that was 75 feet in *diameter*, used simple pressurized engines and was to deliver a MILLION pounds of payload... and at the same time as the Boeing MLLV design, the core vehicle of which was a million-pound payload SSTO, and could be bumped up to three and a half million pounds by strapping on 12 260" diamter solid rocket boosters. In the very early 1960s, yes, lots and lots of launches seemed a reasonable expectation for the future. When the notion came back in '72, it was for the Shuttle program... and remember Shuttle was sold as flying once a week (don't ask me who believed *that,* but clearly lots of people *wanted* that to be the case).
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Generic Username
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« Reply #9 on: 07/27/2007 03:54 PM » |
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This is Boeings Shuttle-launcher, the Model 979-061A. A *lot* more about this design in the actual article. ![]("<a) http://www.up-ship.com/eAPR/images/v1n2ad6.gif" />
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CFE
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« Reply #10 on: 08/09/2007 05:14 AM » |
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One of Boeing's concepts is an almost-unmodified S-IC that makes a ballute-assisted splashdown. I am wondering how Boeing expected to stabilize the S-IC in the attitude depicted in the drawings. Operational experience showed that the burned-out S-IC took an engines-first profile as it descended (the CG moves towards the heavy engines as the propellant is depleted.)
I'm assuming that the enlarged fins on the recoverable S-IC were designed to move the center-of-pressure aft, to get the stage oriented with the upper dome in the direction of travel. I still don't understand why Boeing would want to blow the upper dome off, though. Perhaps they wanted to ensure that the S-IC would sit vertically in the water, with no risk of seawater corrosion in the engines.
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meiza
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« Reply #11 on: 08/09/2007 12:57 PM » |
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meiza
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« Reply #12 on: 08/09/2007 01:14 PM » |
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Were the F-1 engines on the flyback booster supposed to be reusable? And if, what changes were necessary? I guess I should buy the article.
The later SLI RS-84 would use oxygen rich combustion instead, I guess to avoid coking, to reach reusability. Materials (at least not in the USA) were not good enough for that in the sixties or seventies.
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CFE
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« Reply #13 on: 08/10/2007 05:05 AM » |
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Astronautix.com reported that the F-1's would not be reusable. I would assume that the baseline engine would need a lot of mods in order to be reusable, anyways. That might explain why it would take so many flights of an S-IC to break even on the development costs--if you're just reusing the tanks, you're not saving that much.
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Generic Username
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« Reply #14 on: 08/12/2007 07:43 AM » |
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CFE - 8/8/2007 11:14 PM
One of Boeing's concepts is an almost-unmodified S-IC that makes a ballute-assisted splashdown. I am wondering how Boeing expected to stabilize the S-IC in the attitude depicted in the drawings. Notably larger tailfins. I still don't understand why Boeing would want to blow the upper dome off, though. When you blow the forward dome off and hit the water nose first, you hit the water not so much with structure, but with a large trapepd air volume. Smaller blow-out doors near the base of the forward tank (which would be closer tot he "top" at splashdown) would pop out as the air in the tank would compress and pressurize. Hitting nose-first means you are going to lose the forward dome. It'll simpy, be crushed. So, rather than letting it be randomly crushed while attached to the booster, sever it and use the LOX tank as a pneumatic shock absorber.
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