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Nichrome wire as the ignition source ?

Post questions and info about combustion (flammable vapor) powered cannons here. This includes discussion about fuels, ratios, ignition systems, safety, and anything else relevant.
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Unread postAuthor: jimmy101 » Sun Mar 28, 2010 11:05 am

Go for it then. Still, i suspect that drawing enough power from a 9V battery to get a piece of wire to go incandescent is going to kill the battery pretty darn quick. I would suspect the battery to go dead within tens of seconds. Figure each firing is at least a second or two of power and ...

Interesting though, and worth a shot. When the wire is hot it's resistance will go about by something like a factor of ten or a hundred. At room temp the resistance will be something like an ohm, when hot perhaps tens to hundreds of ohms.
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Unread postAuthor: Coodude26 » Sun Mar 28, 2010 11:15 am

jimmy101 wrote:Go for it then. Still, i suspect that drawing enough power from a 9V battery to get a piece of wire to go incandescent is going to kill the battery pretty darn quick. I would suspect the battery to go dead within tens of seconds. Figure each firing is at least a second or two of power and ...


Yes, although 9v batteries seem pretty handy, I outgrew them pretty quick. They weren't very reliable, they have less capacity than a AAA battery, and very few electronics will run on 9vDC. I went with rechargables (NiMh, LiPo are both good IMO. You can pull 50+ amps from a good lipo at 11.1v)


Interesting though, and worth a shot. When the wire is hot it's resistance will go about by something like a factor of ten or a hundred. At room temp the resistance will be something like an ohm, when hot perhaps tens to hundreds of ohms.


Yes. I've been working with the stuff for over a year and the electrical properties of this stuff still confuse me. I really can't figure it out, other than "electricity make fancy wire go hot" :D

Also, I hope this isn't shameless advertising for my video, but I think that anyone who doesn't really know what we're talking about might want to check this out:

[youtube]http://www.youtube.com/watch?v=BK2_nHQUKus[/youtube]
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Plumbers have a funny definition of half an inch...


[quote=chinnerz]once my and one of my mates spent a whole day modding a nurf pistol.... it ended up shooting 1 extra meter and had an awesome paint job. (not rly worth it) [/quote]

/\why I don't like Nerf...
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Unread postAuthor: tatfree » Sun Mar 28, 2010 12:17 pm

What voltage is that and what's the gauge of the 8 strands ?

Seems to light really slow, that's why I'm asking.
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Unread postAuthor: tatfree » Sun Mar 28, 2010 12:21 pm

jimmy101 wrote:Go for it then. Still, i suspect that drawing enough power from a 9V battery to get a piece of wire to go incandescent is going to kill the battery pretty darn quick. I would suspect the battery to go dead within tens of seconds. Figure each firing is at least a second or two of power and ...

Interesting though, and worth a shot. When the wire is hot it's resistance will go about by something like a factor of ten or a hundred. At room temp the resistance will be something like an ohm, when hot perhaps tens to hundreds of ohms.


I get a good 150 fast red hot lights with a single 9 volt battery then it just takes a little longer to get red hot after that but still glows red to at least 200 shots. All of these lights are no less than 1 second, so I guess that means 200 seconds of light from a single battery. However I am guessing that is due to only going a second at a time then waiting a second or two for the next light. Myabe if you held it on there for that long it wouldn't last long, but that isn't going to happen when dealing with lighting chambers.
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Unread postAuthor: Coodude26 » Wed Mar 31, 2010 10:44 pm

tatfree wrote:What voltage is that and what's the gauge of the 8 strands ?

Seems to light really slow, that's why I'm asking.


8.4v, 32ga. I dunno if it was totally charged at the time, but I got some thicker stuff (21ga i think) and a new power supply, so I think I'll do another test soon/tomorrow.
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Plumbers have a funny definition of half an inch...


[quote=chinnerz]once my and one of my mates spent a whole day modding a nurf pistol.... it ended up shooting 1 extra meter and had an awesome paint job. (not rly worth it) [/quote]

/\why I don't like Nerf...
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