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Hubs for a 10 footer
By Pyro, Section Wind Posted on Sun Oct 11, 2009 at 12:05:00 PM MST
10 and 12 footer hub i'm contemplating

I hope this dosnt repost, its been a while and I re submitted it.
The first wrighting I thought I had 3/16in plate on double checking it is 1/8 in and might be to light for this but I would like you'r thoughts.
I don't like wood at all so I was wondering if somthing like the Dans 17 and 20 footer hub mounts would fly on my 10s.
I would like to run the hub and magnet plates as usual then instead of the 1/4 inch plate then plywood I was looking at adding a stainless nut and lockwasher to the outer disk, then a 16 or 17 inch 1/8in steel plate with the 3 spars with 5- 1/4 in bolts through the blades conecting another 1/8in matching 3 spar hub and finishing it off with a lock washer and ny lock.
If the blades come loose the lock nut on the hub would be a backup to the rotors and stator being damaged.
Like the larger units just downsized, weight and sizing is a concederation at this point.
Please excuse the spelling my spell checker is at church, and the spell check on here...
Bob

Hubs for a 10 footer | 3 comments (3 topical)

Re: Hubs for a 10 footer (3.00 / 0) (#1)
by Flux on Sun Oct 11, 2009 at 12:34:31 PM MST

I think the idea is ok but not sure if 1/8" is thick enough. It certainly won't stand the bending on its own but with a plate on the front, the front one is in tension. If the bolts, blades and both plates remain a unit then I think it will be ok. If there is play in the bolt holes then you may loose the advantage of the tension and the blades may bend back.

I think I over engineer these things but I would prefer to see a decent thickness disc at the back of perhaps 12" diameter rather than thin spars further out along the blades.

A 5/16 thick disc at the back with a similar disc of perhaps 1/8" at the front would seem to me to be far better.

I have mainly used plywood discs but always glued them to the blades as well as using plenty of screws. I don't think the ply is inherently strong but the complete sandwich when glued and screwed is very strong indeed. I have built all steel hubs for variable pitch blades and they have been fine but as I say they are probably over engineered and weigh far too much for convenience. I have seen many half baked ideas fail so there is indeed a large force bending these blades back. My initial worries was that cf forces would throw the blades off but all failures I have seen have been from bending.( probably during yaw from gyro forces).

Flux

Re: Hubs for a 10 footer (3.00 / 0) (#2)
by bob golding on Sun Oct 11, 2009 at 03:15:13 PM MST

hi,
i just use 1/2 standard ply on my turbine. on this new one i have changed the design somewhat, and have a 1/2 inch disc of ply hard up against the rotor with holes large enough for the nuts to go though. on the front i have an ally plate. i must say in five years of experimenting this is the one bit that hasn't ever given me any trouble. i use 2 nuts locked against each other to secure the blades. seems to work fine. no sign of anything coming loose,yet. i am using 5 stud Volvo hubs,and have changed all the hardware to stainless steel as i live in a marine environment.

bob golding

Re: Hubs for a 10 footer (3.00 / 0) (#3)
by Pyro on Sun Oct 11, 2009 at 04:53:46 PM MST

Hey thanks Guys
I had forgot about the gyro affece.
I rember its streingh now when I had a test pole on a truck with a 5 footer on it.
Standard exterior ply helps a lot.
I would have figured putting the wood disks streight onto the magnet rotors would have combined them too close and the blades would have had more of a chance of flexing the 1/4 steel magnet plates.
i'm not questioning the generator construction at all it's my ability to work with wood.
To me 1/4 in is .250 not like in wood where I have to settle with 10k diffrences,
and then I think i'm doing good.

All the input is realy apreciated, Thank's

Bob

If you see me running...try to keep up.
[ Parent ]

Hubs for a 10 footer | 3 comments (3 topical)

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