Awesome manned electric multicopter takes off, crashes

 

This may be the most amazing thing we've ever posted here. DIY Drones member Brad Hughey built an electric multicopter capable of carrying a person (him), and then actually tried to fly it in his driveway (without a helmet!). Let's just say it didn't end well. But he's figured out what went wrong and he's going to give it another go.

 

In an email to me, he explains:

History was indeed made on August 10th, 2011 when the Revelation PoC prototype crashed unceremoniously in my driveway.  It did briefly leave contact with the Earth, and one could argue that you have to fly in order to crash, but I do not have the audacity to declare a success out of this debacle.  A root cause analysis has determined that multiple Magically Obliterating Smoke and Fire Emitting Transistor (MOSFET) failures are to blame.  If you listen real closely, you can hear the power rail line inductance ringing (a bit of electronics levity).  I wasn't laughing at the time, but an important lesson is finally learned; MOSFETs fail shorted (full throttle).  One failure in the back started the pitch forward, then three in the front failed, catapulting me down the drive perilously close to a parked car, missing a rotor strike by mere inches.

 

The resolution isn't great due to the use of USB instead of FireWire to copy it off of the camcorder.  That said, I'd rather this didn't go "viral", as it is a bit embarrassing.  Such is the nature of invention.  I proffer it mainly as a veracity enhancer; this effort is real and very close to success.

 

It is interesting to note that half the array out of ground effect managed to push the whole craft with me in it dragging against the asphalt for almost 20 feet before I managed to shut everything off.  The power is certainly there.  It's all a matter of control now, and the first thing to do next is make the power MOSFET stage for each thrust unit "bullet-proof".

 

The damage isn't as bad as it looks.  The real work involves a total redesign of the power stage including FUSES for each thrust unit.  There are much better MOSFETs around now, considering this iteration is seven years old. 

New changes frantically being applied include:

  • Higher current and more modern MOSFET devices
  • A resistor-capacitor snubber network across every MOSFET to help mitigate ringing overvoltages
  • Transient voltage suppressors (zener diode-based technology) across every MOSFET
  • A complete rewiring to minimize power rail inductance
  • FUSES on each motor as a fail-safe
  • Larger decoupling capacitors on the outrigger thrust units

We're a couple weeks away from another run at it. 

Yours in Daring Invention Progress,

 

Brad

Views: 13690

Comment by estebanflyer on August 27, 2011 at 3:35pm

plus a helmet.

Comment by Jeremy on August 27, 2011 at 3:49pm

What did the neighbors think when you rolled that out of the garage? I get strange looks when flying AC2 in the driveway.


Moderator
Comment by Gary Mortimer on August 27, 2011 at 3:59pm
I think there are awards for that sort of thinking.

But as much as I think he is foolish, I think trying is very important.

Feint heart never won fair maiden.

Make scale models and build them up slowly, don't leap to manned!
Comment by Brent on August 27, 2011 at 3:59pm

Awesome!

Comment by Knuckles904 on August 27, 2011 at 5:31pm

Seriously envious and in awe. Amazing work. I'd definitely say spring for a trailer and take it to an open field next time tho, lol. Are you documenting the build anywhere? If not, pleeze do!


T3
Comment by Rory Paul on August 27, 2011 at 5:58pm

@Gary

What awards....the Darwin awards? Needless to say very impressive although I would sub out the test pilot work.

Comment by Rhett Walker on August 27, 2011 at 7:08pm

it'd be cool to have an arducopter version of this magnitude; I think i'd want to sit in it as well =)


Developer
Comment by Randy on August 27, 2011 at 7:57pm

I wonder what code he's running on that?  Did he write both the hardware and software?  I would definitely recommend testing it with a regular transmitter & reciever before actually climbing into it!!!

Comment by Nigel Conliffe on August 27, 2011 at 8:18pm

Might I also suggest a master power off switch (aka The Big Red Button) at least at first.

 

Another trick I've seen when testing experimental helicopters is to chain it down, with about 3' - 6' of "play".

This lets you get it off the ground, although still in ground effect, and satisfy yourself that it is stable in all axes in sustained hover. 

Comment by nubli hashim on August 27, 2011 at 8:44pm
I would agree with TX-rx at early stage. replace man with 150 # sand bags.. and in the open field.. amazing though..

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