Rotor hub for pulley end

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Mike von S.

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Pops (or anyone else building/having built a flywheel drive aero VW),
Are you installing a Bob Hoover style dynamo rotor drive hub on the pulley end? (pic below).
Is there a source for this (CNC machine shop or other) at a reasonable cost?
Thanks
UNADJUSTEDNONRAW_thumb_1311.jpg
 

Pops

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Looks like there used to be. Not going to restock.

But, why not buy on of these and unbolt the outer part ?

 

Mike von S.

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Looks like there used to be. Not going to restock.

But, why not buy on of these and unbolt the outer part ?

Ah, good idea!
Too bad the "hub only" is not longer available, but a pulley removable from its hub should be just as good (apart from a few extra $$).
Thanks!
 

Mike von S.

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Ah, good idea!
Too bad the "hub only" is not longer available, but a pulley removable from its hub should be just as good (apart from a few extra $$).
Thanks!
Actually, don't think this will work. I Hoover's hub is extended to provide enough room between the case and the hub face to mount a stator plate and stator (fixed), with the rotor bolted to the hub face.
 

Hot Wings

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Is there a source for this (CNC machine shop or other) at a reasonable cost?
I kind of doubt the price is much less than the $300 each mentioned in his blog back in 2007.
Keep in mind that RH used what was at hand and could improvise. Pick out the dynamo parts that are easy to source from a system with similar capacity to what is required and start drawing. Parts from a GY6 come to mind.

I'd be tempted to use an aluminum sand seal 'power pulley' as the base for a couple of simple lathe cut parts that bolt to each other to mount the spinning parts.
 

Mike von S.

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I kind of doubt the price is much less than the $300 each mentioned in his blog back in 2007.
Keep in mind that RH used what was at hand and could improvise. Pick out the dynamo parts that are easy to source from a system with similar capacity to what is required and start drawing. Parts from a GY6 come to mind.

I'd be tempted to use an aluminum sand seal 'power pulley' as the base for a couple of simple lathe cut parts that bolt to each other to mount the spinning parts.
Hotwings, thanks for the input.
The tricky part in his design, it now occurs to me, is the fact the the fixed element (the stator) is attached to the case. The hub, therefore, needs to be long enough to allow the rotor to spin just beyond the stator, but narrow enough to fit through the stator plate and stator.
I agree that it would not be hard to build extensions to a commercially available pulley hub, but how to do that in a way that fits through the stator/stator attach plate seems to be the challenge.
Perhaps, to use commercially available hubs, with built up rotor extensions, instead of Hoover's extended hub, I should be thinking of ways to "extend" (with a bracket, for example) the case? But in my project, room aft of the case is already very tight.
 

Hot Wings

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Keep your options open. Just because Hoover used an 'outrunner' doesn't mean that is the only option. There are versions that have the magnet inside the coils.

Motorcycle-charging.jpg
 

Mike von S.

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Ouch, hope that wasn't yours!
Great point, thanks.
Don't quite know where to go from here, but this VW community seems always ready to find a way!
This must say something about the flexibility of the basic design.
 

TiPi

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Just keep in mind that most of the motorbike alternator stators and rotors are designed for much higher rpm than the direct-drive VW. The output at your cruise rpm might be very disappointing.
The better option would be to look at the alternators from industrial engines as they deliver the rated output at 3,600rpm (many available from 10-20A). They mostly have outrunner rotors (permanent magnets running on the outside of the alternator stator), integrated in the flywheel. Getting a stand-alone magnet ring could be a challenge but can be made to fit one of the above prop hubs.
 

Hot Wings

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<< >> look at the alternators from industrial engines as they deliver the rated output at 3,600rpm (many available from 10-20A).
Good observation. The pic is just the first example I could find.

@ the OP - Wish I had a Ducati.
 

lakeracer69

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Great Plains uses a Harley stator and regulator. Maybe from a DYNA engine. If you go that route like I may, buy a REAL Harley setup, not something from JP cycles etc. (Chinesium)
 

Pops

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Small dia VW pulley and a John Deere alternator. If you machine the flywheel prop hub you could machine a belt grove on the outside.
 

Pops

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Flywheel prop hub with a alt pulley machined on the outside, using a JD alternator . On the pulley end of the VW engine a mag using a home made adapter ( no one sells a mag adapter for the pulley end). Then the heads drilled for lower spark plugs and a second ignition system using a stock VW parts. (cheap).
 

karmarepair

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Pops (or anyone else building/having built a flywheel drive aero VW),
Are you installing a Bob Hoover style dynamo rotor drive hub on the pulley end? (pic below).
Is there a source for this (CNC machine shop or other) at a reasonable cost?
Thanks
View attachment 109546
I bought one from Steve Bennett when he was still alive and running Great Plains Aircraft Supply Company. Later it seemed like they only wanted to sell the complete kit for the flywheel drive. This is Aluminum, and only the left hand threads (to "pump" oil back into the crankcase) and the keyway present any challenge at all to a Hobby Machinist, or a pro.

Try a post here: CAN YOU MAKE SOMETHING FOR ME?
 
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Vigilant1

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On the pulley end of the VW engine a mag using a home made adapter ( no one sells a mag adapter for the pulley end).
This would be one of the products GPAS or another niche VW aero conversion shop should sell (esp nice for a hand-propped flywheel drive).
 

Mike von S.

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Small dia VW pulley and a John Deere alternator. If you machine the flywheel prop hub you could machine a belt grove on the outside.
Pops,
You recommend the JD alternator presumably because it delivers its 20 amps at (relatively) low rpms?
I was hoping to avoid pulleys and belts, but this should be simple to install at the pulley end? (Hard to argue with pulleys where pulleys were designed to be).

Sorry if these are dumb questions.
 

Pops

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Yes, easy to drive an alternator from the pulley end, but for me, I was wanting to have the mag on the pulley end. It's still possible by designing a pulley into the mag drive.
 

Mike von S.

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Ok, got it.
I'm thinking Leburg ignition. Not sure I can fit a starter under the cowl at the front (flywheel) end, and I understand that for hand propping, particularly, the Leburg electronic ignition affords a much "softer" start.
 
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