A multirotor flight is very critical: if it happens an ESC, motor, propeller, RX failure or even if you get a lot of vibrations in the flight controller, the multirotor will crash. That's why I created a parachute and attached it to the quadcopter. This was the first test I've done with a parachute for quadcopter:
It had a stick so it kept the parachute away from the propellers. The problem is that the CG is difficult to keep in the center of the quadcopter and also because if the quadcopter hits the stick on the ground when it lands it's going to break the stick.
Therefore, I positioned the parachute on the back of the quadcopter without a stick. I've done a "wind tunnel" test (lol ;D) to check if the parachute would open:
As you can see, it seems to work, so I tried it in field:
Although it didn't land well, nothing was broken because the quadcopter arms are foldable and the ground was soft (grass).
The parachute is activated with a receiver channel and a servo. So when I get in trouble I press a button in my transmitter and it will release the parachute.
Currently i'm projecting a parachute launcher with springs, so it will be launch vertically and thus it will open faster. Another option would be using a small rocket/gunpowder to pull the parachute, but i'm still thinking on the positioning to avoid unwanted burn to the parachute and the multirotor
Cheers!
Comments
@bernardo,
I'm afraid that I also don't know how I'll be launching it. The "springy arm" is only a concept at this point. I gather from some of the comments above that you might be able to attach 1 (or maybe 4) springy poles to the arms of your quad and some how use a servo to make them spring up and launch the parachute into the air above. Below is a concept drawing.
That's interesting esteban ;) i'm thinking about using a needle or something sharp
Randy, that's a nice parachute! How will you do to launch it? Do you know where I can get more info about the "springy arm"?
It's hard to see the scale from my picture above. it's 14cm x 14cm x 3cm (5.5 x 5.5 x 1.2 inches).
I've just received this parachute from opale-paramodels although there are other cheaper options out there like this one. I can modify the arducopter code to do something smart like monitor the desired attitude vs actual and move a servo when they become to far apart for too long (and also cut the motors) but like many others here it's the physical deployment that I'm unsure about. This seems to have a very long drawstring attached to it. I guess the idea is that I somehow wrap the black part around the copter and then somehow push the whole red bad and parachute off the copter. I guess the springy arm idea proposed above is the way to go. It's all looking a little more difficult than I was hoping.
this pump has a mechanism that punctures the co2 cartridge:
http://www.amazon.com/Genuine-Innovations-2425-Ultraflate-Plus/dp/B...
Craig, thank you very much for the informations! ;) I'll take a look on this Nomex cloth.
I was doing some parasheet size calculations for my octo and it would be almost 4m of diameter for a smooth decent hhauhauhauh
^ Somebody, somewhere in this blog (months ago), demonstrated a chute using the "bent springy rod" technique...seemed to work just fine.
Alternatively, the hobby rocketry technique of blowing out a chute from a tube using a small black powder charge (easy to ignite with simple/cheap electronics) is very reliable and long-proven. Nomex cloth or fireproof tissue paper (I think it all is in North America these days) protects the chute. A chute that won't get ripped to shreds when the shrouds are jerked upon violent deployment is somewhat heavier than you might think. Even a typical 3D quad is heavier (with battery) than most model rockets, you're getting into the low end of "High" Power Rocketry payload weights so more thought is required than for typical Estes rockets, even the larger ones.
Hi FD, thanks for the tip ;) I didn't understand very well. What's going to launch the parachute? If you put it under a arm you'll have to counter balance this weight but that will reduce the angular acceleration of the quad.
Hi all, following the discussion, I am imagining a very lightweight / thin carbon fiber rod (thanks Gary) pulling out the parachute upon releasing it (thanks Muhammad). Considering a quad for the sake of the argument, could the rod be mounted on a motor arm pointing outward and then bent over to pull out a small, neatly packed parachute from a neighboring arm (or a tube mounted alongside it?
This would eliminate the problem of soft fabric compression that Bernardo mentioned using a spring and at the same time hold the center of the chute in a defined area away from entanglement. Just an idea.
Thanks for the tip Muhammad! ;)
I was thinking about getting a CO2 cartridge pierce by something sharp so it will free the stored gas hhehe
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