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PARACHUTE anyone ?

Posted by ARHEXA on March 27, 2011 at 7:50am

3689396321?profile=originalMaybe someone has encountered a small scale parachute ?

I'd like to add a safety parachute to the Arducopter !! help me decide....

 

 

As part of the project is to use an expensive DSLR on the copter,

My GF said i must have some kind of emergency parachute... after joking at it, i thought deeper -

I'd rather feel much safer having a parachute as backup to all electronics (even though i plan on 6 or 8 motors)

 

Just imagine an emergency button that will immediately turn off all motors and shoot a parachute.

 

questions:

as parachute takes some time to open (=some free fall height), the benefits are sure and obvious for a 100m fall.

but if i'm around 5m above ground, (which can still be nasty to the DSLR) - would i have enough "falling time" to open the parachute and having enough braking force ?

 

think i better make one by myself ? is it rather simple as cutting and connecting wires to a cloth,

or it is more complex design that i could hardly achieve and i better get a ready one ?

 

i came across this as the only parachute i could find:

http://cgi.ebay.com/NEW-40-SPEED-RUNNING-POWER-CHUTE-training-parachute-/220760637799?pt=LH_DefaultDomain_0&hash=item33665c0167

 

It looks sturdy and well balanced & stuff... it's totally affordable !

they say the 40" version has 7KG resistance. i'm safe on this side, i dont want a much bigger one.

 

how about the opening technique ?

i could stuff it in a small plastic tube attached to the top of the dome, using a small solenoid or servo to kick it out...

how do i ensure it opens reliably ? i guess it depends on the folding inside the storage tube...

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Comments

  • cholo March 28, 2011 at 8:14am

    but do we realy need parachutes ;)

    just look at the vid where all engines are out at 700m height (and stayed disabled till the ground):

    https://www.youtube.com/watch?v=ZkO-nhApgVA

  • ARHEXA March 28, 2011 at 5:59am

    @Martin-

    right, but then i have to add 4 small relays (or 2 double pole) to switch the signal off the APM.

    i've seen a warning somewhere to NEVER disconnect an ESC from the APM while running. (that could damage APM)

    I really prefer the electronics disconnecting option...

    i guess i will have to experiment what happens to the ESC in that case...

  • ARHEXA March 28, 2011 at 5:55am

    I think of getting this one.

    http://cgi.ebay.com/48-Red-Model-Rocket-Parachute-Quality-Rip-Stop-...

     

    the description says 'slow descend' for 1.5kg and moderate speed descend with ~2kg...

    my copter will be more than 2kg, so i think there's no chance i'll try some smaller than 48"....

    on the same hand, i hope 48" will be enough...

  • Overwatch March 28, 2011 at 5:52am
    You could ground the signal wire, but that will initiate the brake after a delay (about one second). A more involved option would use a simple rugged PWM generator that would output 50% duty cycle (zero throttle) that you would switch all signals to. This would stop the motors instantly.
  • Moderator
    Gary Mortimer March 28, 2011 at 5:39am
    Springs work as well

    http://vimeo.com/8904576
  • ARHEXA March 28, 2011 at 5:36am

    for sending 0% throttle i have to use the copter code, and at the moment of truth i rely on the electronics.

    if the quad fails because of the electronics, i cant use the software to turn off the motors...

    i must have an aggressive and simple way to switch to emergency state, like disconnecting the motors or the APM

  • Overwatch March 28, 2011 at 5:36am
    With Turnigy ESCs (and others) you can enable the "Break" option. What it does is it forcefully stops the motors if you command 0 RPM (lowest calibrated PWM value). They stop from hover speeds to zero in a second or so.
  • Overwatch March 28, 2011 at 5:33am
    My mother's a seamstress so I had a bunch of 1-meter square chutes made from extremely fine cotton. 55 grams each. I haven't tested them yet, so I'm flying them with the pyro disconnected. Can't wait for the summer :-)
  • I.S. March 28, 2011 at 5:29am

    you could also send 0% throttle to the ESCs instead of disconecting them.

    With no signal, and ESC not having any failsafe function, should stop

  • ARHEXA March 28, 2011 at 5:29am

    Here i found a successful one, @ 0:40

    https://www.youtube.com/watch?v=NbQryfscr-U

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