http://www.e-volo.com/Home.html
Love the yoga ball as a soft landing device, can't believe the pilot trusted his life to an RC controller though and he never had covers for all those props which would have sliced him up like a blender if things went pear shaped.
Awesome stuff, just totally jealous as we are trying something similar and they flew first :-)
Comments
Awesome! We can fly to school and office later!
@Nick Mann: The efficiency effects of a coaxial configuration are indeed negative, causing an induced power increase of 25% to 40% depending on the separation gap. That's why some of the small, indoor model electric R/C coaxial copters have ridiculously large distances between the upper and lower rotors (larger gap being better). The only reason to have two rotors share the same axis is to counteract torque in a small space without the complexities of a tail-rotor. I cannot speak to the intentions of a potential competitor, but in my opinion, using conventional model airplane propellers instead of something more aerodynamically appropriate speaks to expediency rather than efficiency. Most of this group are experimenters themselves and can look at the pictures of the craft in question and probably cite the Hobby King or Tower Hobbies part numbers for almost all of it. That said, I applaud their resourcefulness and daring.
@Park Jungho
The people on this discussion did not build the craft. You should contact the people at E-Volo who did and ask them for more information. Then as a good citizen of this community, I hope you will then share that with us, in this discussion.
Check their site.
the web site says it has a empty weight of 80 kg. including batteries.
It's hard to estimate the weight of that frame, but that's about 70 pounds of batteries, about 150 pounds of aluminum, 180 pounds of pilot, 50 pounds of motors, hardware and wire, and a 5-pound rubber ball.
I assume the E-Volo craft is using 32 inch commercially-made props (the largest I've ever seen), so figuring the total weight of their craft is 455 pounds, I calculate an induced velocity at each disk of 32.72 ft/sec for an ideal power of 1,262 watts. The best figure-of-merit I've ever measured in static thrust for a model plane propeller is about .35, so we'll give them the benefit of the doubt and call it FM=40. That's 3,155 watts at the disk. Assuming the efficiency of the motor is about 80 percent until it gets VERY hot, that's asking for 3,944 watts from the battery. I remember someone saying that they saw two 6-cell 5800 2 li-polys for each motor, so that means a 20.4 volt rail under load at 193.3 amps. Not counting Peukert effect or other losses, that means they've a maximum of 3.6 minutes of flight time in out-of-ground-effect hover.
Yes, Chris, he had a helmet. This proves it can be done with off-the-shelf components (especially now that there are very high discharge rate batteries available). It will be interesting to see how they plan to scale that design. In any event, we are seeing the dawn of affordable personal aviation, and I look forward to healthy competition.
a chinese guy is already flying with a multi-copter using motorcycle engines... that one is nuts!!
This picture from the E-Volo web site reminds me of Ezekiel 1:16
"The appearance of the wheels and their work like unto the colour of a beryl: and they four had one likeness: and their appearance and their work as it were a wheel in the middle of a wheel."
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