the Otherpower.com Discussion Board || blade to hub connection for variable pitch

Front Page - [Homebrewed Electricity-- (wind) (solar) (hydro) (steam) (controls) (storage) (mechanical)] - Classifieds - Site News
Everything - Newbies - [Remote Living-- (housing) (heat) (light) (water)] - Rants & Opinion - Diaries - Our Products

blade to hub connection for variable pitch
By jacquesm, Section Wind Posted on Thu Oct 28th, 2004 at 05:37:06 PM MST
blade to hub connection for variable pitch suggestions

After six weeks of plodding we finally have three blades.

Now that that has finally been completed we are ready to move on to the next portion of the project, the fibreglassing and the connection of the blades to the hub.

The fibreglassing we have under control, nasty work, but no surprises there.

Connecting the blades to the hub is another kettle of fish though, this being a variable pitch machine you can't sandwich the blades in between two layers of plywood or so to hold them together, each blade must revolve on it's individual shaft.

The shaft is a 1" 'superior shaft' standard mechanical grade that you can buy just about everywhere, the blade is a 2" thick piece of pine at the root. It will need some kind of reinforcement (I'm thinking 1/8 stainless or so) to have something to tie in to, and then we have to go from that sheet to the shaft.

Any hints on what the possibilities are here would be greatly appreciated !

blade to hub connection for variable pitch | 11 comments (11 topical, 0 editorial)

Re: blade to hub connection for variable pitch (3.00 / 0) (#1)
by cevonk (cevonk(atsignhere)aol.com) on Thu Oct 28th, 2004 at 06:12:44 PM MST
(User Info)

Two general designs that I came up with (the concepts are by no means original.)

Re: blade to hub connection for variable pitch (3.00 / 0) (#4)
by Chagrin on Thu Oct 28th, 2004 at 07:31:28 PM MST
(User Info)

If the blades pitch to a different extent at any time (whether by failure or imperfect precision in construction), won't you create a bladeset that has uneven wind pressure across it? I'm pretty sure this could cause a bit of havoc.

[ Parent ]

Re: blade to hub connection for variable pitch (3.00 / 0) (#2)
by cevonk (cevonk(atsignhere)aol.com) on Thu Oct 28th, 2004 at 06:17:03 PM MST
(User Info)

Ooops. Forgot text.

First one was actually a design for a centripetally powered system to move the parts of the dynamo apart so that it would be easy to start, and then move them back together as the blade got up to speed. This still might be an alternative to feathering a prop.

You could modify this to turn the shafts of the prop blades instead of moving the parts of the dynamo.

Second one is a recent plan for automatic centripetal feathering. As the prop rotates faster, the blades are forced outward against springs that try to push them inward. In the course of moving outward, the shafts are forced to turn by lugs that engage an circumferentially angular groove. As the prop slows, the springs pull the blades back inward and they rotate back to a less feathered position.

Re: blade to hub connection for variable pitch (3.00 / 0) (#3)
by monte350c on Thu Oct 28th, 2004 at 07:21:11 PM MST
(User Info)

Hi Jacques,

Great rig for blade production - a real thumbs up.

As far as attachments go, you might consider sinking the superior shaft into the root of the blade, and pinning it through the stainless sheet on each side.

Try epoxy instead of fiberglass. There is no smell, and you can mix very accurately with the pumps (1 pump resin and 1 pump hardener) the mix comes out perfect every time. Plus it's stronger. It does have to be coated against UV though.

Spend a bit of time here: http://www.westsystem.com/ there's a lot of good info at this page, including lots of application info and a few projects people have done.

Let us know when you're accepting blade orders!

Ted.

monte350sms at yahoo.com

Re: blade to hub connection for variable pitch (3.00 / 0) (#7)
by Flux on Fri Oct 29th, 2004 at 01:58:52 AM MST
(User Info)

I did a small 2 blade prop and this was the bit that I was least happy with but it worked well.

I pressed a piece of steel plate into a u shape so that the end of the prop fitted into it. I then cut a slot in the flat piece at the back so that the shaft fitted and welded the shaft to the plate.

I bolted it to the end of the prop with a flat steel plate sandwiching the prop between this and the u plate and also put screws through the sides of the u into the edge of the prop. I covered the whole thing with epoxy before bolting together in the hope that would help.

The thing was heavy but otherwise ok. I used a grade of steel that was intended for welding, I considered this more important than actual strength. I have no idea what your shaft is made of so I can't comment on the chances of it welding without special rods and heat treatment. Fatigue cracking of the weld is something that worries me.

The Elektro used a similar idea, without the sides but it was a steel forging.

From pictures it doesn't look as though Jacobs used anything very complicated, perhaps I was over engineering things.

Flux

[ Parent ]

Re: blade to hub connection for variable pitch (3.00 / 0) (#5)
by Electric Ed on Thu Oct 28th, 2004 at 08:15:43 PM MST
(User Info) http://www.electric-ed.com

Here is a basic sketch of a hub we built years ago. It worked quite well, except for some "hunting", which I was convinced could have been corrected with the proper combination of weights and spring tension.

Unfortunately, it was wrecked before the adjustments could be made, due to the "temporary" tower collapsing. You are no doubt aware of the "got to test it now" syndrome. :-)

The sliding collar keeps the three blades pitch syncronized.

Re: blade to hub connection for variable pitch (3.00 / 0) (#6)
by gibsonfvse on Thu Oct 28th, 2004 at 10:34:11 PM MST
(User Info)

There was another thread on pitch control here on Otherpower.com. It may be a good starting point; I think we batted around a few good ideas :)

Re: blade to hub connection for variable pitch (3.00 / 0) (#8)
by Walt (captainws(at)valornet(dot)com) on Sun Oct 31st, 2004 at 12:03:47 PM MST
(User Info)

jacquesm

If I understand your comment correctly what you are trying to do is attach the 1" rod to the blades. The best way to accomphish this, I think, would be to bore a hole in the root of the blade and then add a angle iron peices on either side of the blade and weld them to the shaft to prevent the blade from moving around the shaft. Then through bolt the angle iron to hold it in place.
Just one option.

Walt

Re: blade to hub connection for variable pitch (3.00 / 0) (#9)
by Walt (captainws(at)valornet(dot)com) on Sun Oct 31st, 2004 at 12:06:29 PM MST
(User Info)

I should have said: bore a 1" hole into the blade and insert the shaft for added support.

Walt

[ Parent ]

Re: blade to hub connection for variable pitch (3.00 / 0) (#10)
by twombo on Fri Nov 5th, 2004 at 11:23:13 AM MST
(User Info)

A takeoff on the roller and swashplate design.

Thoughts on feathering?

Plus a composite blade design. 45" blades are maybe 1.2 to 1.5 lbs.

Re: blade to hub connection for variable pitch (3.00 / 0) (#11)
by jacquesm (j@ww.com- I run a whitelist, add 'stjoes' to msg) on Fri Nov 5th, 2004 at 01:56:35 PM MST
(User Info) http://www.greenbits.com/

do yo have some more details about that governor, perhaps a much larger image ?

It sure looks more organized than mine :)

www.greenbits.com
[ Parent ]

blade to hub connection for variable pitch | 11 comments (11 topical, 0 editorial)

Menu

� create account
� How to use the board
� FAQs
� search the board
� Google search the board
� Old Otherpower Board

Login

Make a new account

Username:

Password:

Total Views

��84 Scoop users have viewed this posting.

Related Links

� finally have three blades
� Also by jacquesm

You must be a registered user to post here. It's easy and free, and the link is on the upper right side of your page.
All trademarks and copyrights on this page are owned by their respective companies. Postings are owned by the poster, but may be deleted or moved at the ADMIN's sole discretion. The Rest � 2003 Forcefield.
You can Email the board ADMIN here. PLEASE include the username you signed up with!