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Post by banjomd on Jun 23, 2010 11:18:49 GMT -4
Were the F-1 and J-2 engines test-run before being installed?
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Bob B.
Bob the Excel Guru?
Posts: 3,072
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Post by Bob B. on Jun 23, 2010 11:27:22 GMT -4
I believe they were, but my memory isn't good enough to be trusted.
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Post by banjomd on Jun 23, 2010 11:41:05 GMT -4
I ask because a Grumman engineer says (in the "Moon Machines" DVD) that the LM ascent engine, because of the hypergolic propellants' corrosivity could not be tested and each one's MAIDEN RUN was from the lunar surface! (Well, that holds true for the DPS engine but death would've been less likely if it failed.) Got me thinking about which engines would be run before installation.
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Post by Jason Thompson on Jun 23, 2010 11:59:35 GMT -4
If I remember from the books I have about the Saturn V, the early launches used engines that had been static test fired, but a few of the later ones used engines that were not previously static tested, once the process was considered mature enough to roll them out and use them right off production. I'll double check. I'm pretty sure that only applies to something like the last three launches anyway.
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Post by gwiz on Jun 23, 2010 12:04:03 GMT -4
I think everything was tested at least twice, with the engines being tested individually before fitting to the stages and also as a stage.
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Post by Obviousman on Jun 24, 2010 3:05:47 GMT -4
Each stage was subject to a static test firing prior to NASA acceptance for many of the initial flights but the cost was enormous - the biggest cost in the Saturn V programme if I recall correctly. The static firing were later discontinued after confidence in vehicle reliability was high.
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Post by gwiz on Jun 24, 2010 4:53:48 GMT -4
I've checked with Alan Lawrie's books on Saturn V and Saturn 1/1B and the facts are that every Saturn V first and second stage was static fired, including the two unflown sets that are now on static display. The third stages were static tested up to the 11th (Apollo 16). For the earlier Saturn 1 and 1B vehicles, all first stages were static fired and all second stages up to the 9th 1B, making the Apollo 17 and ASTP launches the only ones where the S-IVBs weren't static fired as complete stages.
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Post by banjomd on Jun 24, 2010 6:04:50 GMT -4
Thanks, everyone. I re-read and want to clarify: The Grumman engineer meant that the flying APS engine was never tested, not the APS engine family as a whole. Now, does anyone have a link to S1 test firing video? ;D Nevermind... www.youtube.com/watch?v=iIuM_cI5yQs&feature=related
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Post by clipperride on Jun 25, 2010 16:35:43 GMT -4
The LM assent engine used a fuel and oxider combination that exploded on contact with each other. Whilst it meant that they could use a simpler engine (no igniter needed) and that the fuel and oxider could be stored for longer, they where very toxic and corrosive. Once fired, the exhaust gases where so corrosive that the engine started to degrade. It wasn't a big issue as once fired, the LM would only be used for a few hours before being jettersoned. It did mean that a completed engine could not be test fired and then used on a flight. It must have been a tense moment for all those involved when the first time an mission engine was fired was the "all-or-nothing" lift off from the Moon.
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Post by Jason Thompson on Jun 25, 2010 16:44:56 GMT -4
I see gwiz has already checked, and it seems my memory was in error. Still, that's nothing new.
I'm curious about the LM engine though. I know that the fuel was very corrosive so it couldn't be fired or they'd be heading into space with a partly corroded engine right at the start, but presumably each engine system could still be checked even without the fuel being used (essentially test that the fuel and oxidiser flow valves open, those being about the only moving parts the engine actually needed). Can anyone confirm if the engines were 'fired without actually being fired' in testing, so to speak?
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Bob B.
Bob the Excel Guru?
Posts: 3,072
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Post by Bob B. on Jun 26, 2010 10:24:35 GMT -4
Whilst it meant that they could use a simpler engine (no igniter needed) and that the fuel and oxider could be stored for longer, they where very toxic and corrosive. Once fired, the exhaust gases where so corrosive that the engine started to degrade. I don't agree with this statement. Although the liquid fuel and oxidizer was very toxic and corrosive, the exhaust gases were not worse than any other rocket engine. After nitrogen tetroxide and Aerozine are burned, we're left primarily with water vapor, nitrogen, hydrogen, carbon monoxide, and carbon dioxide. Although I haven't really studied this issue very closely, I suspect the degradation problem was related to the fact that the thrust chamber was ablatively cooled. Firing the engine caused erosion of the engine's ablative lining meant to protect the chamber/nozzle wall from the high heat of combustion. Although this is a form of corrosion, it is due to high temperature rather than unusual chemical corrosiveness of the gases.
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Post by capricorn1 on Jun 26, 2010 12:28:52 GMT -4
I ask because a Grumman engineer says (in the "Moon Machines" DVD) that the LM ascent engine, because of the hypergolic propellants' corrosivity could not be tested and each one's MAIDEN RUN was from the lunar surface! I watched that one - episode 4. I wondered if the Astronauts knew this! If they did, that is a huge leap of faith.
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Post by scooter on Jun 26, 2010 13:01:14 GMT -4
Those engines were the perfect example of simplicity. Tank pressure and valves...thats it. I would imagine the actual plumbing could have been tested ahead of time, but otherwise, pressurize the helium tanks, open the valves and presto...rocket power.
Now, that broken engine arm circuit breaker, there's a real show stopper. (did they put guards over those things on later LMs?)
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Post by drewid on Jun 26, 2010 17:51:52 GMT -4
I ask because a Grumman engineer says (in the "Moon Machines" DVD) that the LM ascent engine, because of the hypergolic propellants' corrosivity could not be tested and each one's MAIDEN RUN was from the lunar surface! I watched that one - episode 4. I wondered if the Astronauts knew this! If they did, that is a huge leap of faith. Not that huge. The engine design had been tested numerous times on earth, and there certainly were elements that would have been tested with the engine in an unfueled state.
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Post by capricorn1 on Jun 26, 2010 19:16:15 GMT -4
I watched that one - episode 4. I wondered if the Astronauts knew this! If they did, that is a huge leap of faith. Not that huge. The engine design had been tested numerous times on earth, and there certainly were elements that would have been tested with the engine in an unfueled state. Probably better to say leap of courage, than faith. Just seeing them all tense at mission control, just before they hit the button said enough. I've had a lighter that fired pretty much every time, every now and again it didn't! Courage.
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