I've been working for the last few weeks on developing a parachute recovery system for E382s to reduce the need for manual flying. I know from my own experience that any time a human is at the controls, the risk of crashing is significantly higher. Parachutes have been made for small aircraft before but they're often implemented in an expensive or complicated way. The idea here is to make a simple, working parachute that reduces the overall risk of damaging the aircraft, is simple to use and cheaper to install.

Building the parachute itself was pretty easy, I used this gore size calculator by Scott Bryce and just printed the gores out as patterns. I accidentally printed the pattern out on 8.5x11 instead of 11x17 so this parachute is actually only 22" diameter - much smaller than what it should be for this weight. The gores are cut out of black rip stop nylon and just sewn together. The lines are attached at 8 points, with the lines simply tied through button holes. The line I used is too thin to be sewn into the material but I prefer the thin line, made of kevlar, for its weight and size.

20130630_181911

Next I ran a few tests using some dummy mass at about the same weight as an E382, 1.70 kg, to see how quickly it would fall and if it would even open up properly. The first few tests were done with the parachute already pretty much deployed as it was from a pretty low altitude off my building's fire escape.

WeightToss1.Still001

 

I thought the speed it hit at was slow enough, despite the smaller chute size, to not significantly damage an airframe and decided to move on with the tests. So I attached the parachute to a light-weight (1.5kg) airframe to see how it would fall and if the wings would affect the speed significantly. Because of the smaller size of the parachute, the airframe was actually still had almost enough lift to fly itself. So as it fell and built up speed, it would begin to pull out of the dive, then the parachute would slow its horizontal movement and it would stall, then presumably repeat until it hit the ground. In a few of the tests, the parachute line also got caught under the horizontal stabilizer, further complicating the problem.

Plane2.Still001

Not wanting to call it a day, I pressed on to simulate the actual deployment. Ideally, the parachute would deploy on its own, be near the center of gravity and allow the plane to fall down roughly level and impact the ground on its belly. That all points to a deployment from on top of the wings, right in front of the motor. On the first try, I loosely packed the parachute on top of the wing and just tossed it. This allowed it to catch wind almost immediately which promptly pushed it straight back into the tail, where it lodged itself, allowing the plane to crash at high speed.

Plane123.Still001

But I tried again, packing the parachute more tightly so it would roll out past the tail in a compact ball before opening up and catching wind. That did the trick! The dive/stall issue is still there but that should be fixed with the next parachute build.

Plane4.Still001

 

All four tests above plus one more live deployment test on a flying plane are in the video below.

Would you ever use a parachute as your primary recovery mechanism? Why or why not?

Views: 6671

Comment by Scott Berfield on July 1, 2013 at 10:50pm

100KM
Comment by keeyen pang on July 1, 2013 at 11:02pm

Expensive staff......defeat to purpose of low cost. But anyway I did ordered one for trial. I'm impress with their quality

Comment by johnkowalsky on July 2, 2013 at 3:59am

Why use co2 if you can use butane or propane(in cold climate)??

Comment by Kenny on July 2, 2013 at 11:58am

Wouldn't bother with any kind of compressed air or pyro. This is a perfect candidate for a good old fashion spring - and a clever cam mechanism on a servo for release.

Comment by Will Snodgrass on July 2, 2013 at 12:59pm

When I fist got into Arducopter I was playing around using one with a some sort of mini self (9V) powered arduino para shoot that would go into a rather small cylindrical (I'm thinking like the the round boxes they ship posters in, but cut into small lengths 3 to 5"s? So say main power drops out a simple and barometer tells the craft is in a dead drop......then cue the small charge to pop out of the chute. It may not leave it completely undamaged.........But at least it will stave off a completely disastrous situation!

Comment by Euan Ramsay on July 4, 2013 at 12:06pm

Note to self: Stay away from the mad rockerteers...especially if they smell like melted ping pong balls!...:-D

Comment by Euan Ramsay on July 4, 2013 at 12:08pm

oh, his post is gone???


Moderator
Comment by Nathaniel Caner on July 4, 2013 at 12:20pm

Hey!! I don't smell like ping pong balls! And I'm most certainly not mad.....a bit eccentric maybe...but not mad

And my post is on the first page....

Regards,

Nathaniel ~KD2DEY

Comment by Rob Bartlett on July 5, 2013 at 8:05am

@keeyen

I don't know about that. It seems to me that at the minimum you should be able to exercise full control over the basic flight operations of the aircraft-- take off, landing, level flight, etc.  It seems to me that flying a drone is more than just executing a mission.  You need to be able to deal with unexpected glitches.  Popping a chute at the first sign of trouble, or even when there is no trouble, seems to me makes a very poor pilot who arguably shouldn't even be in the air.

But then I can see the argument that a chute is just another flight mode.  Still, you should be able to FLY the thing no matter what, IMHO.

Comment by Leandro Gonçalves Santos on July 5, 2013 at 9:07am

Hi dears...

Bought 16g CO2 cylinders and try testing with solenoid valve for ejection chute. Pyrotechnics seems to be interesting for lightweight aggregate. I'll be here watching the topic.

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