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By boyskeletor
Hey bondy,
Did you use the original plastic silencer as a mold for your carbon fiber one? It looks sweet!

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By Wagner24314
im thinking the same thing that looks great and what is the weight diffrence
By Bondy
boyskeletor wrote:Hey bondy,
Did you use the original plastic silencer as a mold for your carbon fiber one? It looks sweet!
Cheers guys,
The plastic ones don't have enough room between the carby and skid leg, the newer models have an offset motor for more clearance so I made my own. I've built a ton of surf skis, surf and sail boards so shaping one out of foam was no problem, wrapped it with duct tape, waxed and release agent, then laminated it with carbon, epoxy then peel ply and finished with gloss coats.
I added a red intake flange inside the silencer to atomise the fuel better and uni filter. Didn't weigh it but be less than 1/2 a pound after glassing, carbon is so light when done right. :) ImageImage
By tommy42
Hi all,

Looking for advice regarding picking a motor for an E-Help powered harness for a hang glider. From what I know so-far the formula for RPM is motor kv * motor voltage * losses .8 = RPM. Early E-Help systems use small propellers at very high RPM. More recent higher performing systems are using bigger propellers with geared reduction 1:285. All these designs seem to be using the Rotomax15cc 15kv motor at around 52 volts, which would yield 150 * 52 * .8 = 6240 RPM. After this motor RPM is geared down 6240 / 2.85 = 2190 RPM.

I would like to spec a motor that has high torque at 2000 – 3000 RPM whereby I do not need to add mechanical gear reduction to the design. E-Power Hobby has an 80kv motor that would produce 80kv * 52v * .8 = 3,328 RPM, which puts me within the direct drive range. This motor can actually take 70v, but I would have to add gear reduction. Plus I have had an electric airplane manufacturer mention that they can only operate their motors at 45%. If I run the E-Hobby motor at 52 volts then I am dropping the current by 20% and if I do not operate at full power, just enough power to achieve around 2300 RPM then I generally will not be running the motor at full capacity.

E-Power has a 50kv motor at twice the price and power (45hp). They publish the usage of this motor to be for para gliders. 50Kv * 70v * .8 = 2800 RPM. This may be a good motor to use direct drive if I could get one made at 18000Wt.

I do not know how to factor in propeller load as applied to RPM and motor load.

Any advice is appreciated.
Thanks Tom
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By Wagner24314
well i haven't updated this in a long time. here are some pics
v1 v2 v3.jpg
v1 v2 v3.jpg (238.51 KiB) Viewed 1092 times
20150929_183823.jpg (3.61 MiB) Viewed 1088 times
20150927_150129.jpg (2.93 MiB) Viewed 1088 times
20150407_070423.jpg (2.54 MiB) Viewed 1089 times
13975559_10157336457830593_5357811468112516315_o.jpg (249.54 KiB) Viewed 1093 times
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By DMarley
Nice stuff, Wagner.
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