Awesome PM Alt + ESC = Fun

[taylorp035]

I saw this video the other day that I think all of you will enjoy.

He has a PM alternator wired up to I think 6 Electronic Speed Controllers (the stuff I used in my battlebots), and this thing has some serious power.

Here is a link to both of this 1 min videos.

http://www.youtube.com/watch?v=hy6jZEW9uxc

http://www.youtube.com/watch?v=u0I0Tg8sxYw&feature=related

[willib]

I cant tell ya how many times i've wondered how well a PMA would do as a motor.

And the first one had just a single magnet rotor , i think.

very cool!

[wooferhound]

I tried to run my single phase genny off of a 6 volt transformer at 60hz

It's 6 sets of coils and magnets so it should do 20 turns per second or 1200 rpm

I wrapped a rope around the shaft and pulled it spinning before I applied the power

But everytime I tried, it would just quickly stop as soon as the power was on

I think it would run if I could spin it faster before applying the power

[12AX7]

YIKES

looks like body parts could fly!

I think besides the ear muffs he should have on body armor!

[boB]

Very curious on how they are driving these PMGs.  Must be some multi-phase inverter of some sort ?

That first one looks like it's being driven off of  L-16 6 Volt battery.  Is that right ?  Lots of current, but low volts....  Not as simple as one would think, I would think, don't you think ?

boB

[David HK]

One has to admire the recklessness of youth and how this young man protected himself with the minimum of safety gear.

Were the aerofoils balanced and what glue did he use to stop the magnets hitting Venus?

David in HK

[Volvo farmer]

Holy mackerel! Did you see that guys other video with the homebrew gas turbine? That would scare the crap out of me!

[dnix71]

Nice. How did you balance the blades?

You could market that here in south Florida. The airboats here use big V8's, but an electric version would be cool if you could make it small and light.

[Ungrounded Lightning Rod]

Shows a shot of the guts.  It's dual.  But with plywood rather than steel backing so weaker than it needed to be.  (More than adequate, though.)

What drove me nuts was that his mount was all rectangular.  No triangles.  Enormous forces near the joints due to leverage.  One crack and that prop would have taken off, twisted around on the partially-broken mount, hit something, and shattered.  And if the crack was in the back mount while he was standing in front of it, it would have thrown him into the spinning wreckage.

[Ungrounded Lightning Rod]

I take that back.  He did have diagonal braces and it was just his arm in front of the back plate.

[taylorp035]

he using what is called an ESC, or electronic speed controller.  They are widely used in the rc car/plane/boat market for "brushlees" motors.  The advantage is that these motors usually put out 2-5x more power per weight than a brushed dc motor.  

For his, it said 3 x 12v = 36 volts @ 600 amps... wow.

[taylorp035]

I think the blades are meant for an ultralight, which usually has at least 30hp.  3000 rpm doesn't seem too bad, I once got one of my windmills going that fast!

[richhagen]

Great, now I've got this mental image of the magnets letting go like machine gun fire at a thousand feet.  Rich

[taylorp035]

This is nothing.  The motors on my battle bots have 2" rotors that spin at 12k rpm and a 1 1/2" at 20k rpm.  My small brushless motors go over 100,000 rpm (1/2hp) before the magnets shatter.

I have seen some 15 lb battle bots that spin their weapons at 20k rpm at a 6" diameter.

I built a 18" diameter weapon that spins at 2.5k, could go to 5k.

That fastest weapon is on the robot called nightmare.  A 4 ft disc that spins at 3-4k, which is claimed at 340 mph or about 400ft/ sec with 120lbs.