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
Comments
I suggest him to buy " Complete Idiots Guid to Flying and gliding" from amazon.com
Finally fly from inside.
For this case I think an octocopter 8 blades is best being failsafe to one or two motors. Blades must be protected to avoid damage to the pilot...
An specification in this sense should be done in advance.
You might be doing it wrong when:
Awesome! It's not for the faint- hearted.
Don't do it in the driveway. What do you do if you actually manage to take off? Land on the roof?
Are there large enough brushless motors available to simplify the mechanical design?
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.
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!!!
it'd be cool to have an arducopter version of this magnitude; I think i'd want to sit in it as well =)
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