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Permalink Reply by Gerry Lichter on November 4, 2010 at 1:18pm

Any reason for explosive ignition vs. Co2/Nitrous oxide?

I imagine the second could be deployed by a firing pin+shear pin arrangement. Servo arm pulls the shear pin. Pack it in a tube with an ESTES parachute protection sheet.

I'd probably spring load a hammer and smack the cartridge on to the firing pin. This minimizes moving parts in between the parachute and the cold gas.

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Permalink Reply by Ersin Acar on November 4, 2010 at 1:54pm

hmm good idea! why i didnt think that :) now i need little gas tube maybe i can find at BB gun store and test it

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Permalink Reply by Johann Van Niekerk on November 4, 2010 at 1:56pm

Hi Ersin

I am also currently buzy with parachute design and experimenting with deployment ways .
Aldo im currnetly going with Gerry's way i looked into a other method of controling the CO2 ,I played paintball for couple of years on semi proffesional level and made two of my own guns , a Co2 paintball handgun has replacable canisters the usefull part is that you get cheap electric activated trigger circuits for these guns and you can use that to trigger the Co2 and simple install the main or pilot(small) chute in a round tube with co2 pipe connected at the bottom of the tube with a presis petrolum lubricated cork inlay undertheath the chute to insure a explosive effect on the chute . that is my idea anyway and will also post video of this process in near future .

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Permalink Reply by Ersin Acar on November 4, 2010 at 2:06pm

i really wanna see that electric activated trigger :)

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Permalink Reply by Johann Van Niekerk on November 4, 2010 at 2:23pm

I will see if i can find a diagram but any Paintball store will have Etriggers is what they called they can also be set to what rate you want co2 to be released and how many times

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Permalink Reply by Ersin Acar on November 4, 2010 at 2:54pm

hmm i can look for a paintball shop at the weekend. I will keep you in touch

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Permalink Reply by Gerry Lichter on November 4, 2010 at 11:19pm

I'm currently using motorcycle fuel injectors as my solenoid valve of choice, but I'm always on the look out for better alternatives. Please let us know if you have success with the paintball valve and at what price.

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Permalink Reply by Richard Hirst on November 4, 2010 at 11:31pm

I would look at an Electro-Magnet to hold the lid shut, then remove the current through the coil to release then hatch.
Also if power fails it will Open .

We used a 50Kg device on a Drone with great results.

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Permalink Reply by Gerry Lichter on November 5, 2010 at 2:14pm

Using a fail-safe electromagnetic deadman's switch is a great idea.(It works great for nuclear reactors.)

Although probably unnecessary, I really like the positive deployment of cold gas. If I end up building I'll probably borrow from your method and use a weak spring returned solenoid as a shear pin on the same hammer/Co2 mechanism.

If if I balance the solenoid strength and hammer spring: this might achieve a comparable energy consumption to a electromagnetic hatch.

If it's a problem: there's always fail secure servo retracted shear pin + independent power supply/RF deadman's switch.

Over-engineered? Probably. But as long as we're brain storming...(realistically: if your UAV isn't moving fast enough for a electromagnetic hatch to work well: is a chute even necessary?)

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Permalink Reply by Ersin Acar on November 5, 2010 at 12:17pm

i really dont know how CO2 tubes works. need to work on it :) i will let you know if i success

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Permalink Reply by Ravi Gaddipati on November 5, 2010 at 1:45pm

I think a container with a cap would be best. The cap can come off with a small charge (perhaps something like the putty charges).

This is lighter, almost foolproof, not mechanically intensive, and is easy to implement redundancy.

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Permalink Reply by Ersin Acar on November 6, 2010 at 12:02am

I found a company that making parachute for drone systems. and a test page at their website
http://www.butlerparachutes.com/pia99.htm

there are photo sequences like here. i will make a research on this photos. there is one chance for air test. if i fail, my all works and money gone :). Maybe i can make a launcher mechanism like UAV launcher. so i can test it with fake loads :) (or just find a high building and throw it xD )

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