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Post by Moon Man on Apr 7, 2006 14:37:37 GMT -4
Well explain this.
If the chemicals ignited on contact how many pounds needed to burn before it lifted off?
You peeps must have nice jobs in order to have time to post while you work.
How
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Post by LunarOrbit on Apr 7, 2006 14:40:09 GMT -4
You peeps must have nice jobs in order to have time to post while you work. I personally don't have a nice job which is why I'm available to post in the afternoon. I work evenings and weekends mostly.
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Post by scooter on Apr 7, 2006 15:03:13 GMT -4
School bus driver here, head out for the afternoon run in a short while...
The thrust buildup in the AS engine was quite rapid. It's a smaller engine, and the combustion stabilizes quickly by design (kinda like a great big RCS thruster, only gimballed). That's another reason the helium pressurized hypergolic version was chosen. I suspect if you did some research on the engine (which I'm going to do for myself), some figures are probably available.
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Post by JayUtah on Apr 7, 2006 15:44:58 GMT -4
Who says we're posting while we work?
Rated thrust for the APS is about 15,500 N. Liftoff occurs when thrust has built to 7,700 N, or about half rated thrust. The ignition transient for the APS is about 300 milliseconds in duration. The nominal APS mass flow rate is about 3.7 kg/s.
Assuming constant mass flow rate and a linear approximation to transient thrust over time, liftoff occurs approximately 150 milliseconds after ignition, during which approximately 0.6 kg of propellant has been expended.
Numbers are from memory and may be wrong. But that's how you figure the problem.
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Bob B.
Bob the Excel Guru?
Posts: 3,072
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Post by Bob B. on Apr 7, 2006 15:46:41 GMT -4
Well explain this. If the chemicals ignited on contact how many pounds needed to burn before it lifted off? Liftoff occured as soon as the thrust exceeded the ascent stage's weight, which was about 7.8 kN. This occured within a fraction of a second. Once steady-state operation was achieved, the ascent engine burned propellant at a rate of about 5.1 kg/s.
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Post by Fnord Fred on Apr 7, 2006 16:22:59 GMT -4
Why do I get the feeling he's still going with the 'big burst of fuel' theory? Arg.
To answer the 'cushy job' question, I'm a tutor. If I'm not tutoring, then I get to use lab computers so I don't go brain-dead before another tutee comes in.
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Post by nomuse on Apr 7, 2006 17:29:12 GMT -4
It's the only horse he's got at the moment. Whatever facts he has to stretch to make that "big burst of fuel" happen, he'll stretch them. Already, I can sense him fumbling around for another unlikely reason why it has to be "a big burst of fuel." Because, of course, it is pretty easy to understand why you can't get 500 GPM through a 1" pipe (or however he has the numbers now).
And it isn't like he has to actually argue about it. Instead, he just drops in every few days with "The pipe was too small, NASA can't pay you enough to say different. By now peeps."
I hope he doesn't argue that way in court. "Ladies and Gentlemen of the jury; the extensive testimony of the expert witnesses you have just heard is of course silly nonsense. They're just making this kaka up because they are doodoo heads. All scientists are in the pocket of big business anyhow. And besides...when have you ever heard of heavier-than-air flight? They must think we are all such morons to try to pull one like that."
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Post by JayUtah on Apr 7, 2006 18:01:56 GMT -4
That's what so funny about all this. His argument is classic reductio ad absurdum. His version of the LM propulsion system requires a patently and provably impossible fuel delivery rate. And you wouldn't have to be an engineer to see that. In a normal train of thought, that would raise a red flag that the argument is somehow wrong. A normal person would think, "Wait, 5,000 lbm fuel in 6 seconds? That can't be right." The other day I did a computation that resulted in 200 cfm for a small fan assembly. Reality check: the answer should have been much lower. Turns out I had made a simple order-of-magnitude error on the whiteboard and the real answer was a much more credible 20 cfm.
But in conspiracy Bizarro-World an absurd outcome isn't a signal to go back and verify the underlying facts. It's the clearly "inconsistent" condition you were hoping for all along.
Why is this so funny? Because lawyers can't think like this and be successful. You can't present an argument to a jury and have the opposing counsel score a major victory by being the one to reveal its extreme absurdity. Even if it's on a minor point, your loss of credibility with the jury will pretty much sink you. More than anyone, lawyers have to be extremely critical especially of their own arguments. They need to have already thought of the various ways in which they can be undermined.
If one arrives at the conclusion that an impossible fuel flow rate must have been acheived, then a lawyer would have gone back to verify his premise that there was only one propellant feed system, and in this case would have discovered his error. This is simply not the kind of argumentation I associate with lawyers. Lawyers are much smarter and more cautious than this.
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Post by scooter on Apr 7, 2006 18:54:36 GMT -4
Darn it nomuse, now I'm wiping beer off my keyboard...you big doo-doo head!! Ciao peeps, peace, out...
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Post by twinstead on Apr 7, 2006 20:52:38 GMT -4
I think Reductio Ad Absurdum would be a good name for a rock band.
Well, most fans wouldn't get it I suppose. How about RAA?
Rock on RAA, rock on!
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Post by JayUtah on Apr 7, 2006 22:58:09 GMT -4
Red Herring could be the warmup band.
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Post by Fnord Fred on Apr 8, 2006 1:25:41 GMT -4
With a cameo appearance by Slippery Slope Fallacy!
Oh crap, I think we just invented logiccore rock. Emo kids with nothing better to do are going to start carving "Socrates" onto their arms.
What have we done!?!
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reynoldbot
Jupiter
A paper-white mask of evil.
Posts: 790
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Post by reynoldbot on Apr 8, 2006 3:03:14 GMT -4
I am an art student, which means that I can get online and check the site pretty much any time I want. I have the funny feeling that after I graduate I will have the same amount of goof-off time due to not getting any work.
Jay as usual makes a good point. I thought the sole purpose of a lawyer was to be a convincing debater. I sure hope the people you are representing never stumble onto this forum. Actually, for their sake, I kind of hope they do.
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Post by james on Apr 8, 2006 6:25:19 GMT -4
I am an art student, which means that I can get online and check the site pretty much any time I want. I have the funny feeling that after I graduate I will have the same amount of goof-off time due to not getting any work. ^What he said. Especially the 'not getting any work' part. If I ever had a lawyer that said 'peeps', I think I'd rather try to defend myself thank you very much.
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Post by Count Zero on Apr 9, 2006 22:20:24 GMT -4
The other day I did a computation that resulted in 200 cfm for a small fan assembly. Reality check: the answer should have been much lower. Turns out I had made a simple order-of-magnitude error on the whiteboard and the real answer was a much more credible 20 cfm. But in conspiracy Bizarro-World an absurd outcome isn't a signal to go back and verify the underlying facts. It's the clearly "inconsistent" condition you were hoping for all along. In your above example, a CT would point out that first you said 200, then you said 20. The fact that you changed your story proves that you are dishonest. Either your first number was a lie, or TPTB made you change it because they want people to believe it's 20. "Calculations" and "checking your work" are irrelevant. Don't try to confuse the issue with "mathemagic".
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