I made my smaller 24 volt motor based on my "Electric Hubcap" design,
which I've titled the "Electric Caik" (ElectricCake.com being
already taken).
Then I put it in a Honda 75 (7.5HP) outboard shell with a fairly
steep pitch prop. I don't want to run it over about 2000 RPM and of
course there's that nasty 2.6(?) to 1 speed reduction in the foot, so
I couldn't run it flat out and the prop sits there "idling" away at
around 770 RPM.
But I put it on my 14' aluminum boat and tried it out on Saturday. I
couldn't tell the boat speed. A strong wind pushed the boat around
some.
Yesterday I put up video clips someone took:
http://youtu.be/zrtE6yHSFRw - rundown of the setup
http://youtu.be/jen-WpfaM4k - pulling out
http://youtu.be/-L3yHhgoFmE - a bit more
['Fraid they're pretty low rez. Another guy had a hi-rez camera but I
don't have his shots yet - if he took any. The batteries in my own
cam decided to die just before launch. I'll have a video showing the
makings of the Electric Caik soon, but it needs editing.]
The motor drew 50 amps getting up to somewhere around 2000 RPM. A
couple of times I got up a bit over that (2200?) with currents to
almost 60 amps.
60A * 24V = 1440 watts or 2 horsepower. The motor temperature only
rose 17ºc, so I imagine it would handle the full rated power
indefinitely.
Interesting efficiency notes: hitting 2000 RPM with the motor alone
took maybe 140 watts. Some if not much of that was friction from the
excessive grease in the needle bearings, and some has now oozed out
during running. Running it in the outboard in air 2000 RPM took 380 W
(1/2 HP), which shows how much friction there is in the outboard
mechanism - bearings & gears. It's probably pretty typical.
[Motor specs: 24V, 0-127A, 3KW(4HP), 0-2000RPM, axial flux, 8 -
1x2x.375" supermagnets on 7.5" O.D. rotor, 6 iron powder toroid core
coils coated with ilmenite in sodium silicate, molded
polypropylene-epoxy composite body parts, 9.25" O.D. x ~4", 15
pounds.]
Cheers,
Craig
Victoria BC
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