Calcium CArbide

Post questions and info about combustion (flammable vapor) powered launchers here. This includes discussion about fuels, ratios, ignition systems and anything else relevant to launchers powered by igniting things like hairspray or propane.

Postby jimmy » Mon Dec 11, 2006 4:57 pm

<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote">Originally posted by DR
[br]<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote"><b>Originally posted by jimmy</b>
Exactly what advantages does calcium carbide have over right gaurd, propane, butane ... anyway?

[disadvantage blah-blah]****[/disadvantage blah-blah]

So exactly why would you use carbide other than to see if it works?
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

Because the measured peak explosion pressure of acetylene is 10.6 bar, which is a significant increase over ther peak explosion pressure of propane!
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
So you didn't answer the question.

And 10.6BAR vs. 9.3ATM (stoich. propane in air) ain't all that much. Enough of a difference considering the spud will (usually) launch at a significantly lower pressure? Besides, the peak pressure in the chamber is pretty irrelevant in a standard combustion, the spud leaves when the pressure gets high enough. Doesn't matter a hair off'a DR ass what the closed chamber peak pressure might be, the spud is gone. If the good DR new anything he would have quoted on the burn velocity or the specific impulse and not the basically irrelevant peak pressure in a closed chamber.

Are the "advantages" of using bangsite enough to justify having to add water to the chamber? Enough to justify having calcium hydrodxide sloshing about in the gun every time you point the muzzle down?

So, again, what advantage does bangsite have over propane, butane, rightgaurd ... ?

Natadine can do what ever he wants. Hopefully some nine year old won't see his posts here at Spudtech and decide to shove a spud into the barrel of a bangsite cannon that their grandpa bought 50 years ago and has been sitting in the barn rusting since 1963 ...
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Postby SpudMonster » Mon Dec 11, 2006 8:57 pm

Natanddiane, I have tried my best to keep myself under control, but I must say that you are one stupid son of a bitch. Did you even READ the posts that people have made in this thread? Do you know what we are discussing here? Do you have the faintest idea how hotheaded and concetied you have made yourself look? I, myself, would like to know how far you got in school. Even I, at a mere 14 years old, can completely see the points that the forum members who have posted in this topic have tried to get through your head. I can see that you are going off your own half-assed guesses. I can see how idiotic and foolish your logic is in each of your posts, and I can see that you have no desire to listen to and heed anything we say, unless it corresponds exactly with your preexisting point of view.

I'd say we have one of <a href="http://redwing.hutman.net/~mreed/warriorshtm/ferouscranus.htm">THESE</a> on our hands here.
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Postby pbmann123 » Mon Dec 11, 2006 10:02 pm

You know, just use the damn carbide cannon, I recommend shoulder firing the beast. Hey I also hear dwv is acetylene resistant, and is even acetylene + oxygen safe. It is the strongest cannon material we know of, we just don't want that power to fall into the wrong hands. Please build dwv cannon, and shoulder fire it with acetylene and oxygen. :D
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Postby BewareOfDog » Mon Dec 11, 2006 11:13 pm

<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote"><b>Originally posted by jimmy</b>
So you didn't answer the question.

... What[intercourse]ingever...

If the good DR new anything he would have quoted on the burn velocity or the specific impulse and not the basically irrelevant peak pressure in a closed chamber.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

The burning velocity of acetylene (in air) is 157 centimeters per second.

Specific impulse? Please enlighten me as to what the specific impulse in seconds of propane or acetylene, as it is (admittedly) beyond my comprehension.

The peak pressure <b>IS</b> in fact, "relevant" when talking about detonation of a specific fuel in an enclosed chamber. - Which is the only reason why I brought it up when trying to make my point.

<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote">
Are the "advantages" of using bangsite enough to justify having to add water to the chamber? Enough to justify having calcium hydrodxide sloshing about in the gun every time you point the muzzle down?
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

Nope. - If you had read one of my previous posts, you would have seen that that I <b>also</b> denounced its use, because it was "messy".

<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote">
So, again, what advantage does bangsite have over propane, butane, rightgaurd ... ?
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

Nothing, really- except that it would make a louder bang?

<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote">
Natadine can do what ever he wants. Hopefully some nine year old won't see his posts here at Spudtech and decide to shove a spud into the barrel of a bangsite cannon that their grandpa bought 50 years ago and has been sitting in the barn rusting since 1963 ...
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

natandianne (Little ditty, 'bout natandia- ane... two amercian kids blowing up in the heartland. Natty gonna be a [intercourse]ed retard. dianne debutante, then she FUBAR...)

- Hey everyone: There is NOTHING wrong with using "bangsite" as a fuel for a combustion cannon.- So long as you are fully aware of ANY possible hazard which <b>may</b> occur. Other than that, I'm stickin' with propane.
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Postby jimmy » Tue Dec 12, 2006 3:42 pm

DR

That values for acetylene in air seems kind of low. Propane in air is usually quoted at 400 to 450 cm/sec. (Deflagration at 1ATM)

<i>The peak pressure IS in fact, "relevant" when talking about detonation of a specific fuel in an enclosed chamber. - Which is the only reason why I brought it up when trying to make my point.</i>
I don't believe that is correct. The peak pressure in <U>detonation</u> is higher than it is in <u>deflagration</u>. I don't know the numbers for acetylene but for propane in air the deflagration P<sub>max</sub> = 9.3 ATM, for detonation P<sub>max</sub> = 17.5 ATM (according to GasEQ). I would expect that acetylene would also give a higher P<sub>max</sub> in detonation versus deflagration.

<i>Specific impulse? Please enlighten me as to what the specific impulse in seconds of propane or acetylene, as it is (admittedly) beyond my comprehension. </i>

Impulse is force times the length of time that it acts. That is not what I was thinking of. I probably should have said "shock" instead of "impulse". A rapid change in pressure can cause a pressure spike that is higher than the actual "peak pressure" (where "peak pressure" is a thermodynamic quantity calculated without taking into account how long the reaction takes). A high rate of change of pressure per unit time can causes a pressure spike that can be greater than the "peak pressure". Similar to water in a pipe, when you close a faucet quickly the pressure at the faucet spikes higher than the supply pressure.
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Postby BigBang » Tue Dec 12, 2006 7:38 pm

Humm, I didn't realize till now that GasEq could do detonation. Another interesting find!!!

So, after playing with GasEq's CJ-Detonation calculations a bit, and after reviewing chapter 6 of the <a href="http://www.gexcon.com/index.php?src=handbook/GEXHBcontents.htm">Gas Explosion Handbook</a> it appears that to a first approximation the pressures encountered during a detonation are about what we would expect from a 2X hybrid mixture. And, previous fiddling with GasEq indicated that peak deflagration pressures for acetylene are about that we would expect for MAPP.

This seems to jive with my general recollection of the few failures I found with with bangsite fueled spudguns. Repeated 2X shots might eventually cause an end cap to blow out, or a chamber to crack. Most, however, would not expect a 2X mix to cause a catastrophic failure in a well built SCH40 gun.

At this point my conclusions would be:
1) Up to the point of ignition, there are no transportation or handling safety issues involved with acetylene derived from Bangsite.
2) 1X bangsite derived acetylene/air mixtures are much more likely(maybe 10 times more likely based on cell size)to detonate than are mixtures of propane or MAPP.
3) I doubt catastrophic failures would result from repeated use of Bangsite in a well designed gun. However, I do suspect that over the long haul you will ruin a nice cannon. A poorly built gun, however, might fail in such a way as to cause grave bodily injury.
4) If reasonable safety precautions are taken - the same as you would employ if shooting a hybrid - then doom and gloom may not be the future of those who wish to play with Bangsite. I would consider remote ignition a must!!!!
5) I would not even think of playing with hybrid mixes of Bangsite derived acetylene. The 2X detonation pressure factor just gets multiplied to the point where chamber failure is very likely.
6) Due to the mess of using Bangsite, and due to the fact that if all goes well it is likely no better than more common fuels, Bangsite is off my radar screen as a fuel.

I think this topic has largely run its course. Does anyone else agree? I would suggest that natanddiane study chapter 6 of the Gas Explosion Handbook, and play with GasEq himself a bit. If after this he is comfortable with proceeding with experimenting with Bangsite, then so be it.

Nat: If you proceed, eyes wide open, I'd like to see a pretty standard 4" chamber SCH 40 gun with a 1.5" barrel and <b>remote ignition</b> tested. Shoot 200-300 rounds of spuds, taking video and plenty of pictures. If possible record velocity data. Then report back to us both successes and failures. If there have been no failures of any sort, I'll be the first to offer to eat my spoonful of crow. If there have been chamber failures or explosions, please let us know that too - we will all learn something. Just be safe. No matter how annoyed some may be with you, no one really wants you to get hurt.
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Postby BewareOfDog » Wed Dec 13, 2006 3:19 am

jimmy,
I certainly wasn't asking for you to give me a defintion of the word "impulse"! I was <b>specifically</b> asking if if <b>you</b> knew what the <b>specific impulse</b> of acetylene was, seeing as how you were making comments about me not knowing.

You know;
EVERYONE I come across seems to have a very difficult time answering any given question. Not just here, but in my everyday life as well. I sometimes begin to question my own intelligence, as you have to give people the benefit of the doubt; They are either [intercourse]ing with me on purpose, or are completely [intercourse]ing stupid.- I am beginning to believe the latter.
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Postby boilingleadbath » Wed Dec 13, 2006 7:55 pm

DR, he answeared that he mearly misspoke and acctualy ment something else... and as the specific impulse of C#C / O=O is irrelevent to our discussion, he didn't enbark on a (most likely fruitless) search for such values.
(there are surely crazy rocket technicians, but probably not very many that'd use acetelene as a fuel, and fewer that will publish their numbers on the web... although, IIRC, CC#C (component of MApp gas) is used as a rocket fuel.)

Oh, and I like SMILES.
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Postby BewareOfDog » Thu Dec 14, 2006 1:32 am

boilingleadbath,
You've proved my point! [:(!]

Take a peek at the previous page: <a href="http://localhost/forums/viewtopic.php?t=15165&whichpage=3">Calcium CArbide Page 3</a> ...

jimmy stated specifically:

<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote"><b>Originally posted by jimmy</b> Posted - Dec 11 2006 : 15:57:51

If the good DR new anything he would have quoted on the burn velocity or the <font size="3"><b>specific impulse</b></font> and not the basically irrelevant peak pressure in a closed chamber.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

..But he <b>answered</b>... that he <b>merely mispoke</b>... and <b>actually meant something else</b> ?????

What in the <b>@#$%</b> is that supposed to mean?- And how in the nine hells did <b>you</b> come to this conclusion? - Holy friggin' shit!

And <b>if</b> he did not wish to embark on a (most likely) fruitless search for such values.. then why in the <b>@#$%</b> did he denounce me in that quoted reply because I didn't ???

You like smiles, huh? - I've got a big ear-to-ear one for 'ya right here: <a href="http://www.eirefirst.com/clipart/gifs/Leprechaun%20Mooning.gif">**:mrgreen:**</a>
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Postby boilingleadbath » Thu Dec 14, 2006 7:27 am

I shouldn't have abreviated "simplified molecular input line entry specification"...

"what the c1[ONO2]c[C]c[ONO2]cc[ONO2]c1 is that supposed to mean?"
To speak in your typical overstated language, it means that he's a friggin' dumbass and failed to differentiate between "specific impulse" and "shockwave force". (or whatever you want to call it)
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