Hubs for a 10 footer

[Pyro]

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

[Flux]

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

[bob golding]

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

[Pyro]

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