Rotor Disk Failure
By phil b, Section Wind Posted on Tue Oct 26th, 2004 at 04:07:09 PM MST
unproperly secured hub

Here is an example of why the blades, wooden hub and blades must be securely attached to the generator. Last weekend, the wind was blowing in gusts, at a guess, 40 mph. The unit should have been able to take the jolts and would have, if I had made the hub to generator a little stronger. The blades are 6 feet in diameter with 8 inch center wooden hub on both sides of the blades. The blades are glued and screwed into the hub. The depth of blade into soil is 17". That takes a lot of power to drive it that far into clay/rock soil! Live and learn, just don't stand tooooo close to the generator on windy days!

Rotor Disk Failure | 7 comments (7 topical, 0 editorial)

Re: Rotor Disk Failure (3.00 / 0) (#1) by DanB (danb@*no spam*otherpower.com) on Tue Oct 26th, 2004 at 05:41:37 PM MST (User Info) http://www.otherpower.com/

Wow.. neat picture! A good week of interesting failures if nothing else. Can you describe how the blades were fastened to the alternator?

Re: Rotor Disk Failure (3.00 / 0) (#2) by iFred (ifred2006@yahoo.com) on Tue Oct 26th, 2004 at 07:01:38 PM MST (User Info)

Well, Thats a first. I have seen single blades go into ground, myself included. But the entire peice intact, wow!!! Did it come out in one peice? LOL, just curious... Live and learn... >> all energy used to produce this comment or post came from solar and wind energy! It works!

Re: Rotor Disk Failure (3.00 / 0) (#3) by JW on Tue Oct 26th, 2004 at 07:34:43 PM MST (User Info)

I suspect all blades came out intact. Noticing the relatively small diameter anchoring, to the genny and (center to)blade hub assy, such a result, could be easily expected, since this 'hub to the blades' does not feature a 5in 5 bolt pattern(whatever) automotive type fastening system... (a)[solid]Wood(hub) simply does not feature the compressive strength necessary to be fastened with the necessary thrust torque at 1 1/2 thread diameter[single center bolt]. Carbon fibre maybe, but not wood. "The five(small 1/2in) bolt pattern" evenly spaces the necessary thrust torque requirments 'evenly' across the hub bolt circle radius(5in?)(possibly with a steel reinforcement plate?). Effectivly reducing the need, for excessive compressive strength requirement, of the hub material. JW [ Parent ]

Re: Rotor Disk Failure (3.00 / 0) (#4) by juiced on Tue Oct 26th, 2004 at 10:09:08 PM MST (User Info) http://www.juiced.ca

Do you think disc brakes off a mountain bike would suffice? Canada's -Debatable- A.E./R.E Debate Site News, discussions and debates! www.juiced.ca [ Parent ]

Re: Rotor Disk Failure (3.00 / 0) (#5) by nobicus on Tue Oct 26th, 2004 at 11:11:42 PM MST (User Info)

Do you realise that on pre-WWII aircraft with wooden props the fit was a push fit on a cone?  The impressive looking boltup on the front was merely to stop it coming off.  The foot/lbs on the bolts is not all that great. [ Parent ]

Re: Rotor Disk Failure (3.00 / 0) (#6) by JW on Wed Oct 27th, 2004 at 05:28:05 AM MST (User Info)

Juiced,  Sure, if you have you have the disc brake plates for mountain bikes just laying around, why not incorperate them into your design. Im not sure what the diameter is on those, but if it matches your bolt circle, why not. You may want to remove the hardness from the rotors before drilling them. JW [ Parent ]

Re: Rotor Disk Failure (3.00 / 0) (#7) by phil b (philb7369at-no-more spam-yahoo.com) on Wed Oct 27th, 2004 at 07:28:08 AM MST (User Info)

The blade hub was attached to the generator with a 2 1/2" that came with the unit. I drilled and tapped it in 2 places 180 deg opposite with 5/16"x3" bolts and put JB Weld on the threads. The idea worked fine with a 3'and 5' prop. The 6 footer was too much for it. I would have never guessed the prop would  still be in 1 piece after being slung from a 30' tower at high RPMs. LOL The entire setup, including the tower was intentionally made rather small to help learn where to beef things up. Now I know. The Leeson does not seem to have suffered any damage.

Login

Make a new account Username: Password:

Total Views

103 Scoop users have viewed this posting.

Related Links

· Also by phil b