|
Post by scooter on Nov 17, 2005 12:34:35 GMT -4
You haven't read, I mean really read, so many of the posts nor the links...The LM is not thrusting in an atmosphere...there is no conductive heating to speak of while the engine is firing...any heat would come from direct impingement of the exhaust on the LM structure, which is basically nil. (there actually was just a fringe bit, bet you can't find it in the links....I ain't spoonfeeding you anymore). Anyway, the temperature of the exhaust is a non-issue. There is also a LM diagram in the links that shows the descent batteries on the outer portion of the truss structure, it's there if you look. You are not doing your homework, and looking at the initial start of your suit post, you are researching nothing and learning nothing. Your "arguments" are based on ignorance, not research. The answers are there. Dave
|
|
Bob B.
Bob the Excel Guru?
Posts: 3,072
|
Post by Bob B. on Nov 17, 2005 12:45:52 GMT -4
Thank you for posting the temps in regards to 3000 lbs of thrust. Can you tell me what you think the temp would be with respect to 10,000 pounds of thrust..? Throttling the engine changes the temperatures very little. This Web page gives some information on the TR-201 engine, which was the direct descendent of the LM's descent stage engine. Using this data I can estimate some temperatures. The pertinent data is: Propellants: N2O4/Aerozine-50 Thrust(vac): 4,275 kgf Isp: 301 sec Chamber Pressure: 7.00 bar Area Ratio: 46 Oxidizer to Fuel Ratio: 1.59 Furthermore, I estimate the specific heat ratio to be about 1.23. From the thrust and Isp, I calculate a propellant flow rate of 14.2 kg/s at 100% thrust. At the lower thrust level (~3,000 lb) the propellant flow rate would be reduced to about 4.4 kg/s. From this data I calculate a combustion chamber temperature of 3,054 degrees K (5,037 F) at 100% thrust. Given the section ratio of 46, the pressure at the nozzle exit is about 0.01084 bar. The temperature of the exhaust gas at the nozzle exit will be about 1,000 K (1,340 F). The exhaust temperature continues to drop rapidly after leaving the nozzle as the gas expands into the vacuum of space; below is a sample: P = 0.01 bar ....................... 981 K (1,306 F) P = 0.001 bar ...................... 597 K (615 F) P = 0.0001 bar .................... 336 K (145 F) P = 0.00001 bar .................. 196 K (-107 F) At a propellant flow rate of 4.4 kg/s, the chamber pressure is reduced to 2.141 bar and the temperature to about 2,949 K (4,848 F). The gas pressure at the nozzle exit reduces to 0.003315 bar and the temperature remains about 1,000 K. These numbers are based on my own calculations, so please do not consider them authoritative. Edit: changed wording to make more clear (I hope).
|
|
|
Post by sts60 on Nov 17, 2005 13:29:27 GMT -4
Here's another one. Why, in a fusion reactor, is it so important to keep the plasma away from the physical walls of the chamber? Hint: it's not to keep the plasma, which is millons of degrees in any temperature scale you care to name, from damaging the chamber!
I point this out because I think Moon Man is working towards a comment about the LM DPS exhaust should have melted the lunar regolith.
Nope.
|
|
Bob B.
Bob the Excel Guru?
Posts: 3,072
|
Post by Bob B. on Nov 17, 2005 14:36:50 GMT -4
I point this out because I think Moon Man is working towards a comment about the LM DPS exhaust should have melted the lunar regolith. I anticipate the same. I'm pretty sure MM has already mentioned this somewhere (probably at BAUT).
|
|
|
Post by nomuse on Nov 17, 2005 15:13:48 GMT -4
Here's another one. Why, in a fusion reactor, is it so important to keep the plasma away from the physical walls of the chamber? Hint: it's not to keep the plasma, which is millons of degrees in any temperature scale you care to name, from damaging the chamber! I point this out because I think Moon Man is working towards a comment about the LM DPS exhaust should have melted the lunar regolith. Nope. Turbulance leading to no thrust, perhaps? (Okay...I cribbed that from Shlock Mercenary)
|
|
|
Post by JayUtah on Nov 17, 2005 19:14:51 GMT -4
I imagine it's to keep the chamber walls from damaging the plasma through cooling or contamination.
|
|
|
Post by Moon Man on Nov 17, 2005 20:08:51 GMT -4
I point this out because I think Moon Man is working towards a comment about the LM DPS exhaust should have melted the lunar regolith. I anticipate the same. I'm pretty sure MM has already mentioned this somewhere (probably at BAUT). Why do they call BA's board BAUT..? What does the UT stand for..? Thanks
|
|
|
Post by JayUtah on Nov 17, 2005 20:12:44 GMT -4
BA = Bad Astronomy. UT = Universe Today.
They were separate boards until a few months ago, then merged to cut down administration effort.
|
|
|
Post by hplasm on Nov 17, 2005 21:54:55 GMT -4
Consider also a cold gas in a sealed container which is heated up. This has become a very real hazard for firefighters at car fires, since gas struts are used more than ever in cars. Good old PV = nRT at work again; when T goes up greatly due to the fire, so does the pressure in the strut cylinder, and they fail all too often. One FF had a hood strut rocket off right through his leg at a car fire (he recovered). OO- thanks for that- completely OT, I know, but I've always harboured a certain suspicion about the shady cousin of the suspension strut- The Gas Spring.... they just don't seem... well...natural, somehow.. yes-I'm odd....
|
|
|
Post by hplasm on Nov 17, 2005 21:57:36 GMT -4
I point this out because I think Moon Man is working towards a comment about the LM DPS exhaust should have melted the lunar regolith. I anticipate the same. I'm pretty sure MM has already mentioned this somewhere (probably at BAUT). True. Volcanic temperatures..
|
|
|
Post by hplasm on Nov 17, 2005 22:04:33 GMT -4
I imagine it's to keep the chamber walls from damaging the plasma through cooling or contamination. Indeed, until recently ( what I call recently, probably 20 yrs or so since I last looked into it the main problem in sustaining a fusion reaction was kinking in the plasma stream, which hit the wall of the containment, and made it go out. from 600000000K * to 0 in 0 flat. ** * maybe too many '0's **(possibly 0#- I'm not a jazz-fusion physicist... ) Like driving a Skoda through a tiny puddle,
|
|
|
Post by Moon Man on Nov 17, 2005 23:37:22 GMT -4
BA = Bad Astronomy. UT = Universe Today. They were separate boards until a few months ago, then merged to cut down administration effort. Thanks Jay. Dave, there are over 2000 messages posted since I joined BAUT and here last Saturday. I read all of them. I might've missed a few on BAUT. There have been hundreds of links as there are links within links. I have not read all of those. It's not possible. If the landings are real then every HBer is ignorant, so why would you expect me to be any different..? I have a theory on certain issues that would prove it to be a hoax. If people can debunk it, great, but I wish the insults or personal attacks would stop. It's human nature that one would want to strike back. I think I've done a pretty good job at avoiding that so far. The discrepencies on NASA's site that I've point out thus far, from my READING, have been ignored by everyone but Jay. Anyway, just so you know, I am reading as much as possible Dave. There are hundreds of links and 10,000 scientist, or whatever, worked on this with over 2 million man hours involved, or whatever, so you can't expect a lay person to read or figure everything in 5 days. It's not humanly possible. Cheers!
|
|
Bob B.
Bob the Excel Guru?
Posts: 3,072
|
Post by Bob B. on Nov 17, 2005 23:43:52 GMT -4
... but I wish the insults or personal attacks would stop. It's human nature that one would want to strike back. I think I've done a pretty good job at avoiding that so far. You have done well to avoid that, which is a point in your favor. I agree insults do no one any good.
|
|
|
Post by bazbear on Nov 18, 2005 0:02:40 GMT -4
BA = Bad Astronomy. UT = Universe Today. They were separate boards until a few months ago, then merged to cut down administration effort. I have a theory on certain issues that would prove it to be a hoax. If people can debunk it, great, but I wish the insults or personal attacks would stop. It's human nature that one would want to strike back. I think I've done a pretty good job at avoiding that so far. The discrepencies on NASA's site that I've point out thus far, from my READING, have been ignored by everyone but Jay. Discrepencies do not automatically mean there's a hoax, MM! I could show you discrepencies between accounts in just about every historical event I've read about in any detail, covering subjects all the way from the battle of Gettysburg to the sinking of the USS Indianapolis. People do not have perfect memories, and people make honest mistakes. The personal attacks come from posters who's frustration levels over your apparent willful ignorance have reached the boiling point. I try to avoid that myself, but I do understand their frustration with you.
|
|
|
Post by Data Cable on Nov 18, 2005 1:59:53 GMT -4
Re: Would a glass of water in space freeze or boil?Is there anything you don't understand about it?I understand the premise when I read it but if you asked me to explain it to you I couldn't do it yet without reading it again. Do you understand why water boils and freezes in a vacuum? Do you understand that it is due to the absence of air pressure, and not the "temperature of space"?
|
|