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| Saturn V launch |
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| Lew_Merrick_PE:
--- Quote from: AdeV on September 07, 2011, 03:55:53 AM ---Lew - one of the increasing problems with low-Earth orbit is, as I understand it, the ever increasing amount of "space junk"; apparently, the recent Chinese satellite-killer experiment plus an accident where a live satellite crashed into a dead one, has increased the number of small particles beyond NASA's ability to track them all? It seems to me, the next thing we need to be inventing, is a big orbital broom to sweep up the cr*p before it becomes deadly... it'd be a bit stupid if we got to the point where launching anything into orbit was impossible... --- End quote --- Ade -- and don't forget our (the US's) own "tests" of aircraft-launched anti-satellite missiles. Do you remember the mysterious "sonic booms" off the east coast of the U.S. in 1978 or how they stopped the two weeks before a Soviet satellite crashed in Canada (250 miles or so from the Alaskan border)? Thank God for coincidence, right? Yes, this is a major problem. However, it is one that can only be solved with a real and constant (and functional) presence in orbit. The International Space Station will, if it ever actually completed, have about 75% of the volume of a 747. The External Tank of the Space Shuttle (ET-STS) had 160% the volume of a 747. The only reason to have gone with the Shuttle was to use the ET's as building blocks for a space station! Instead, we spent more than $2,500,000 in fuel each and every Shuttle launch to crash them to Earth (burning them up). Seven of them in a polygonal "ring" were to be a "unit" (with a central "axis" for stacking them). I oversaw the tests of cutting and installing the "hatches" at the ends of the tanks in the pool at Houston in 1977. The gelatin that solidified in urine was developed as neutron shielding for that part of the program. (It is now dower property of Kimberly-Clark.) The "joke" about it was that the assembly crews would get free beer so long as they would pee where they were told. Yeah, tell me about it... |
| AdeV:
Lew, In 1978, I was still in short trousers & IIRC starting school.... I didn't have much interest in the space programme at that time (the last moon-walk finished before I was born). It always did seem to be a shame that the big Shuttle fuel tanks were just thrown away, how much extra fuel would they have needed to drag them into a stable orbit? I guess it can't be much, as the Shuttle itself didn't carry any main engine fuel did it? I guess we can only hope now that the private sector (e.g. Branson & his pals) develop to the point where they can take over the "drudge" work of getting stuff into LEO. Sad to say, I think the first man (or woman) on Mars will either be Chinese or Indian, at the rate the "western" world is going. |
| DMIOM:
--- Quote from: 75Plus on September 06, 2011, 02:12:47 PM ---....... The link is to an article about this engine, http://www.prnewswire.com/news-releases/nasas-new-upper-stage-rocket-engine-ready-for-testing-123740339.html --- End quote --- Joe, If the story is to be taken literally, I hope there aren't too many folk living within earshot of the test range! and they must have some seriously large fuel supplies, as it says: "... Beginning in mid-June, the engine will undergo a series of 10 test firings that will last several months...." Dave ::) |
| 75Plus:
--- Quote from: DMIOM on September 07, 2011, 05:09:16 PM --- --- Quote from: 75Plus on September 06, 2011, 02:12:47 PM ---....... The link is to an article about this engine, http://www.prnewswire.com/news-releases/nasas-new-upper-stage-rocket-engine-ready-for-testing-123740339.html --- End quote --- Joe, If the story is to be taken literally, I hope there aren't too many folk living within earshot of the test range! and they must have some seriously large fuel supplies, as it says: "... Beginning in mid-June, the engine will undergo a series of 10 test firings that will last several months...." Dave ::) --- End quote --- David, I think you can take the story literally. The full load testing has to be done before any thought of lift off. This is the same test facility that was used in the development of the original Saturn V engine. I once asked Marc how they simulated the vacuum of space and was told that they used water to maintain a constant vacuum. The quantities needed were mind boggling. Here is another link to pictures of the engine, http://www.nasa.gov/mission_pages/j2x/ Joe |
| DMIOM:
so they actually run the engine, without stopping it, for two months :jaw: I would have thought some components at 'the hot end' would have significantly lower life. Burns into orbit, I would have thought, would have been 10's of minutes. A couple of months is of the order of 90,000 minutes. I can understand stress testing and accelerated testing for components, and the need for margins of safety - but if the engine is capable of running for that length of time, then I would have though it might be somewhat over-"strong" and hence over-weight. I remember looking at calcs (when doing my physics degree in the 1970s) on the extra weight of fuel needed to lift each extra pound of payload; and because you were in turn lifting that extra fuel, and the bigger engine, off terra firma, I seem to recall it took maybe 5 or 10 lbs extra fuel to lift 1 lb of payload. Anyway, the citation from NASA shows your nephew is a great guy who gets on with it and you can pass on our congrats too. Dave |
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