# FLYTHERED.COM

### Help Support HomeBuiltAirplanes.com:

#### pictsidhe

##### Well-Known Member
Quite a few car propshafts now have rubber couplings that may be useful. Lovejoys aren't rated for many RPM.

#### TFF

##### Well-Known Member
I have owned eight Alfa Romeos, and I have several hundred thousand miles driving them. I love my Alfas. I would not put one of their rubber doughnuts on a plane.

#### Vigilant1

##### Well-Known Member
I have owned eight Alfa Romeos, and I have several hundred thousand miles driving them. I love my Alfas. I would not put one of their rubber doughnuts on a plane.
"Giubo" doughnut. Sorry!

#### Turd Ferguson

##### Well-Known Member
My 23 year old grandson engineer has his name on a patent that has something to do with electro- magnetic coupling. My brain is to small.

My '60's (?) Graziano Italian lathe has an electromagnetic coupling in the drive line. It's pretty cool in that the motor only turns in one direction but the spindle can turn forward or reverse and change direction of rotation instantly if desired. Smooth as silk, no gear grinding or metal clunking.

#### pictsidhe

##### Well-Known Member
I am presently waiting to load $500,000 worth of resin. Just thinking about the newly available 4500-5000 rpm VW. I would like to discuss in a civil manner, the use of Aeromentum's PRSU. Is it professionally engineered? Its availability,$1500 or so, is tempting me to adapt it for type1 VW use.
This PRSU and viking's PRSU seem to use the same principle.
I haven't heard anything negative, but that is meaningless.
I think I would go to an Aluminum engine case, and eat the weight gain.
Would this be a good fit?
H-Minus
NOBODY has yet managed to redrive a half-VW. Several have tried. Assuming that you can just fit one engineered for a different engine may be a trifle rash. Feel free to try it, though. I'd recommend plenty of ground testing.

#### proppastie

##### Well-Known Member
Log Member
Having owned many bikes and even one Harley. Neither the VW or Harley name impresses me.

#### pictsidhe

##### Well-Known Member
I've heard that harleys are a lot better than they used to be. The Japs were killing their sales so they updated. I wasn't too smitten with the innards of an 80s one.

#### lr27

##### Well-Known Member
My 23 year old grandson engineer has his name on a patent that has something to do with electro- magnetic coupling. My brain is to small.
I have seen ideas for magnetic reduction drives! At one point, I even sorta understood how they were supposed to work. Allegedly used, of all places, in oil drilling rigs to speed up and reduce the size of the tube driving the drilling head. I suspect that the electro-magnetic coupling works by eddy currents. If you have a rare earth magnet, try sliding it down a steeply inclined, conductive but non magnetic ramp like a large aluminum pan. Or try sliding it down a steeply slanted copper pipe. It's amazing how slowly they can go. For comparison, try sliding the same magned down a plastic tray or something. So I think if you put an aluminum disc on one side and a bunch of magnets almost touching the disc, arranged in a symmetrical fashion on the other side, you could have a reasonably non-slip coupling with lots of damping. Depending on how much it slipped, the aluminum disc would have to dissipate more or less heat.

NOBODY has yet managed to redrive a half-VW. Several have tried. Assuming that you can just fit one engineered for a different engine may be a trifle rash. Feel free to try it, though. I'd recommend plenty of ground testing.
It's not as necessary. If you're maintaining the same horsepower to disc area ratio, the diameter of the prop for the half VW will be 29 percent smaller, meaning 29 percent slower tip speed at the same rpm.

I've heard that harleys are a lot better than they used to be. The Japs were killing their sales so they updated. I wasn't too smitten with the innards of an 80s one.
Well, there are always the imitation Harley's. Doesn't Honda have one?

#### pictsidhe

##### Well-Known Member
I think all the japs have harley-esque models.
Personally, I think that aero engines are best with OHV heads. They don't rev high so anything else is just extra weight. That means Harley is a top choice as the Japs have gone OHC.
I did wonder about a 90 degree harley case, but the crank sucks for hanging a prop off, so you'd need a new one of those too by which time it was getting a lot of machining.