I know that people have discussed this before, but I have yet to see anyone declare that they built a worthwhile system or create any documentation.  I did see some youtube videos using pyro charges, but that makes me nervous.  I want to use CO2.  If anyone has any information or observations I would love to hear it as I start this project.  I am throwing all my ideas out there to see what people would do differently, or to find out if it is a pipe dream (pun intended).  So here we go!

Goal:

Develop a lightweight and independent failsafe system for multicopters.

Idea Summary:

Use an Arduino micro with an accelerometer to trigger the ejection of a parachute.  The system will have to be independent of all other power and mechanical systems on board so it will have it's own power source.

Detail:  

This would be primarily designed for multicopters carrying a large and expensive payload like a DSLR.  The goal is to slow the copter down enough so that the payload is less likely to be damaged if an emergency occurs.  The independent power source must be small and light weight.

I researched different methods to see if anyone had tried to worked with Arduino and pressurized CO2.  Unfortunately, there were only unanswered questions or some hypothesis with no follow up.  While brainstorming I thought about paintball and thought that a solution might exist there since they use electric triggers in many of the markers.

I picked the CO2 system from the Tippman Tipx pistol because it was built around CO2 cartridges, instead of a refillable bottle system.  I think I can use the puncture valve assembly from this marker to interface with the CO2 cartridge.  I need to figure out if the puncture valve assembly will actually act as a valve, or if it only provides the breach.  I also need to find out if the an e-trigger solenoid provides enough force to puncture the cartridge, or if it has to be manually punctured.

The Solenoid will be triggered by an e-trigger assembly, this assembly will be hooked up to an arduino micro with an accelerometer.  The accelerometer will trigger the solenoid when either the multicopter tips past a certain point or the rate of descent reaches a specified velocity.

The gas from the CO2 cartridge will travel through a pipe into the adjacent tube that is packed with wadding and a parachute.  I will need to run some tests to see how big the chute needs to be, but I am sure it will be significant.

Reference:

Tipx Exploded Diagram: http://www.tippmann.com/pdfs/manuals/TiPX%20Schematic%208-11.pdf

Valve Puncture Assembly: https://www.pbsports.com/Tippmann-TiPX-Puncture-Valve-Complete.html

Solenoid & e-trigger: https://www.pbsports.com/Virtue-Redefined-Tippmann-A5-Upgrade-Board...

Arduino Micro: https://www.adafruit.com/products/1086

Accelerometer: https://www.adafruit.com/products/1018

Here is a really rough draft of what I am thinking:

So lets hear what you think!

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Check out these CO2 Ejection Kits for High Power Rocketry, as a engineering reference

I've seen this referenced in a few other posts, but it seems really hard to find a place that sells the hardware.  I just need the 12gram hardware, all I can find are the full kits.  Do you know of a good place to find these?

Also, I am trying to stay away from any kind of explosive charge.  I would prefer electronically (though that my be impossible).

Also, don't these rely on being stuck in a trapped space?  I might try to do some other stuff with the CO2 so I need it to be piped.  These don't seem to have any fittings for that.

I think these are expensive too, at $185 for kit, maybe AeroTech (RouseTech) will sell only CO2 cart size you need?

Maybe consider building a refillable air bottle (air compressor) with solenoid valve, maybe plastic Pre-peg used to make small 6 oz soda pop bottle? kind of large, but should be easy to make.

No, using compressed air won't work for anything more than blowing up a small kid's balloon.

Co2 is used because it is stored as a liquid which expands when released, greatly increasing the efficiency.

Nitrogen, butane, freon, and propane, etc are other examples of gases stored as liquids which each expand at different rates, usually dependant on temp.

You can get lightweight cylinders and air lines and even the solenoid valves from paintball suppliers.

 

Parachutists, as of 20 years ago, when I jumped a few times, used two different systems for releasing the chute manually (free-fall jumps, not static-lin jumps).

One is a smallish chute, which is kept in a piece of tubing, usually on the right hip/outer thigh

The other is a steel-wire with a handle at the left shoulder - this is the one you always see in movies.

The steel wire pulls out a pin, releasing a spring, which ejects the smallish chute, which, in turn, pulls the real parachute out.

I wonder if a spring-loaded system couldn't do the trick - and at least weigh a lot less?  It would definitely cost less.

Maybe some sort of mouse-trap trigger could release the spring, which ejects the parachute; so a small, not so powerful servo could "pull the handle" ?

A question: are you making some sort of free-fall detection in the "Arduino & E-trigger" blue box?

EDIT: in any case, a parachute has a minimum height, from where it will work, as it takes time to unfold. Depending on the job, of course, I would much more worry about "failures" that occur under the minimum height of the parachute, but still high enough to cause destruction to sensitive payloads. This makes me wonder, if some sort of leightweight (foam?) protection around the payload wouldn't do the job better, overall?

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