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Remote Fired Powder Cannon

Posted: Tue Dec 11, 2012 4:30 pm
by wrath144
Been a member here for a long time, never made anything worth posting. Figured this one would be worth it ;)

Purpose:
Design and build a remotely fired powder cannon for use in airsoft games as an IED simulator or remote mine.

Design Specifications:
Self contained unit with minimal external wires or failure points. Simple operation by an individual with minimal training. Safe to fire directly at people from point blank. Reusable components with minimal and inexpensive consumables.

Basic Design:
Based off a combustion potato cannon. Propellant is added to a chamber and ignited with the resulting explosion propelling the powder out of the device.

Design Problem:
Remote ignition with minimal electronics experience.

Research:
Research indicated ignition point of propane, the intended propellant, to be 470 degrees Celsius. During research, found this video with a demonstration of a wireless detonator using nichrome wire. Further research on nichrome wire found that the wire will melt at about 2 amps of current. Melting temperature was determined to be around 1400 degrees Celsius. Bingo.

Design:
Largely based off the design from the ChuKoNu1's Youtube video for a wireless detonator. A wireless relay hooked up to a nichrome heating wire. Mated his concept to a combustion potato cannon and came up with a working prototype.

Parts:
1-1/4" PVC pipe
1-1/4" PVC female threaded adapter
1-1/4" PVC threaded plug
1-1/4" PVC slip coupler
1Ch wireless relay and transmitter
Firefox 11.1v 1100mah 15C lipo airsoft battery
Deans connectors
Screws
2" Masking tape
32AWG Nichrome heating wire
18AWG automotive wire
PVC Primer
PVC Cement

Construction:
First I constructed the chamber with a length of pipe, the threaded adapter and slip coupler. I then inserted the screws into the plug. Next, I soldered all the necessary wires to the relay, battery connectors and electrodes. I cut an extra length of pipe as the "barrel".

Firing Procedure:
1. Remove plug from chamber.
2. Wrap nichrome wire 5 times around one electrode, and then five times around the other electrode with only a single strand in between.
3. Put masking tape over one end of the barrel and clean up the edges so it fits in the slip coupler.
4. Fill the barrel with about half a cup of powder and cover with another piece of masking tape.
5. Insert the barrel into the slip coupler.
6. Give the chamber about a 1/4 - 1/2 second shot of Static Guard and replace the plug as fast as possible.
7. Connect the battery when the device is in place.
8. Slide down safety on remote detonator.
9. Press the red button to fire. Release immediately after device fires.

Testing:
The first test was just the plug and relay circuit outside of the chamber. Nichrome wire was haphazardly wrapped around the electrodes, the battery was connected and the button was pushed. The nichrome wire immediately glowed red hot and melted. It worked. After the fumes from the PVC cement and primer dissipated, the device was tested with some Static Guard as propellant with only some masking tape over the end of the chamber, no projectile or powder. It worked, first try. After this, I begun to document testing as seen in the Youtube video below.

Future Plans:
I want to put the whole electronics assembly into either another pipe or project box. This will clean up appearance and ensure wires don't get snagged on anything. I'd also like to paint the whole device to camouflage its appearance. I plan to add another connector between the electrodes of the chamber and the relay simply to modularize the device. With a quick swap I can go from firing the Powder Cannon to igniting fireworks to remotely firing an airsoft gun. As far as the powder cannon goes, I'm thinking of adding a 90 degree elbow to the barrel to change the angle of fire. The device would be much easier to hide laying down rather than standing up.

Youtube Video:

Posted: Tue Dec 11, 2012 6:09 pm
by Zeus
As I said on Youtube, a blowtorch will solve your problems, or use this guide from JSR.

Posted: Wed Dec 12, 2012 12:41 am
by jackssmirkingrevenge
[youtube][/youtube]

Very nice, as Zeus suggested fuel metering will help both power and reliability.

Posted: Wed Dec 12, 2012 1:01 am
by Technician1002
For a re-usable ignition, look to a hobby shop and pick up a glow plug for a model airplane engine. Feed it a 1.25 volts from a Nicad and removal between each shot is not needed.

Posted: Wed Dec 12, 2012 1:17 am
by jackssmirkingrevenge
Of you could just use a thicker wire that doesn't burn out ;)

[youtube][/youtube]

From here: http://www.spudfiles.com/forums/clear-c ... 22067.html

Posted: Wed Dec 12, 2012 2:50 am
by wrath144
I'll admit, we ordered the nichrome wire for something a little bit more sinister and probably too dangerous for airsoft. We changed our mind and this is the product of what we had on hand.
I'll be looking in to all the suggestions posted, thank you.

Posted: Wed Dec 12, 2012 5:39 am
by Technician1002
To adjust the current on your wire to prevent burning it in two, use a longer piece and shorten it just enough to get it to glow. Then you can use it to ignite Propane without burning it out.