| T O P I C R E V I E W |
| Hefhoover |
Posted - 28/01/2008 : 02:12:30
Just spotted this on Fleabay, he's mated a gearbox from an angle grinder to the Ametek motor, with a PVC pipe fitting swivel as a pivot, quite an easy task for anyone with access to a lathe etc
http://cgi.ebay.co.uk/Wind-turbine-Generator-PMA-Ametek-40-PIVOT-HUB_W0QQitemZ150210086149QQihZ005QQcategoryZ41981QQssPageNameZWDVWQQrdZ1QQcmdZViewItem Hef  |
| 15 L A T E S T R E P L I E S (Newest First) |
| gotwind |
Posted - 06/02/2008 : 21:10:39
I think this discussion has been exhausted now - thankfully.
I have to admit that forum member Ghurd has always gone out of his way to help.
12 (or so) months ago he spent the time to draw up an LED diagram suited to the dynohub projects I was working on.
Help like this takes time and patience for no financial gain but is very much appreciated by me and all I suspect.
http://www.gotwind.org/images/Glenn_Hurd.jpg
The Futures Green - Getwind of it. |
| MattM |
Posted - 06/02/2008 : 14:38:01
Hefhoover's original post has me thinking how to turn an old 12v dc drill made for running off automotive batteries into a mini-generator. It has a 3/8" chuck on it that would probably come off easy enough. It just requires an incredible amount of startup torque to spin so it might not be all that useful in this case.
An update on sheet metal as a blade material:
So far my 26 ga. steel blades on the 5' diameter ten bladed have survived gusts of over 30mph. The 15' big guy did not fare so well, with one blade striking the pole and it is hopelessly bent. We didn't really think 26 gauge material was going to survive on either rig because its only 3/4 pound of material per square foot. I purposely overweighted the tail on the ten blade to keep it in the wind w/o furling yet its still happily churning today. The 16 ga. two blade design (actually built in a single piece) has survived much worse storms and we don't even have a furling system on it. Also surviving w/o any problems are a pair of 10' three blade systems using massive internal chord tapered to smaller tips, one of each aluminum and steel. I suspect the latter pair is heavy enough to survive twice the wind the way they are built reinforced; I stood on the steel one's hub and the blades handled my weight.
--------------------
Go Huskers! |
| Hefhoover |
Posted - 06/02/2008 : 08:17:46
"I am truely sorry to Hefhoover his question went in this direction."
On the contrary it's been a valid and interesting discussion. 
If anything, it's probably reinforced the fact that good quality Al blades are available, but so are inferior quality, but even if you had top quality Al the engineering work done to mount them must be of the highest integrity, whereas you will get away with being a lot more "sloppy" with wood (and this is meant as no reflection on anyone)
All the best to you all, Hef.
|
| MattM |
Posted - 06/02/2008 : 01:35:24
Get out while you got a hide left.
--------------------
Go Huskers! |
| ghurd |
Posted - 06/02/2008 : 00:07:32
Fungus,
Some poeple just need to have a Catastrophic Failure before they belive anything.
Notice how he changed from the cause was bending, to cheap AL, and even blamed race for the mix of silica and aluminum?
He never mentioned how much more he knew than the ME people at Comet or Boeing.
Seems like the ME or SE guys, even then, would understand AL.
And implies how he can determine the properties of AL alloy from a low quality JPG.
I simply new want people to understand aluminum blades are a real danger and not at all reliable.
Maybe he can show us detailed results of his working AL blades which were in servivice for a few years making some kind of power?
Gosh. Maybe he can make a tiny bit of power with the free spinning blades?
Until then, my photos of FAILED blades will satisify my interest.
I simply want to point out AL blades can be a serious danger.
A side note would be my family and myself fly in a 50+ year old de Havilland DHC-2 Beaver on a regular basis.
Thank the Lord it is not made of AL. (that's a joke. It is made of AL)
http://www.otherpower.com/images/scimages/2050/1stlook.jpg
I'm done now, and will not reply to this again.
I am truely sorry to Hefhoover his question went in this direction.
G-
|
| fungus |
Posted - 05/02/2008 : 16:37:04
I'd still trust wooden blades any day ; very low levels of fatigue, strong, cheap, easy to shape/carve, they dont bend but arent brittle etc etc ... |
| MattM |
Posted - 05/02/2008 : 03:30:17
Yep, you're right. And he also said he used the aluminums because the bad hub already destroyed a set of fiberglass blades and a tail. We haven't got any details from the Gill person how his bent set worked out. I have a strong feeling it will be similar to wllewellin's experience.
Those blades look awfully brittle; its probably are a cheap mix of silica and aluminum.
--------------------
Go Huskers! |
| ghurd |
Posted - 05/02/2008 : 03:11:34
You should notice the bent blades and the failed blades are not the same blades. Or owners. |
| MattM |
Posted - 05/02/2008 : 01:26:49
Go research the properties of extracted aluminum and it explains his experience. Extruded aluminum is not sheet aluminum. And drilling imperfect holes in aluminum is going to promote cracking, which is exactly the problem he had. A lousy grade of aluminum cannot be straightened out once bent. Look what he did, he took lousy aluminum, twisted it, over drilled, and literally hung it with hooks because that dead space in the blade allowed the blade to pivot freely.
If the guy knew what he was doing the blades would have worked fine.
I like how people blindly label imported blades from China as "Chinese blades" when it obviously came from some specific outfit. Calling them 'Chinese blades' is almost racist. I've met some real geniuses in my lifetime that swore they knew what they were doing then literally did everything completely opposite of conventional wisdom.
--------------------
Go Huskers! |
| ghurd |
Posted - 05/02/2008 : 01:01:26
I read it as the 1st set lasted 4 weeks and the 2nd set lasted 6 weeks.
Makes me afraid to get in a plane!
G-
|
| fungus |
Posted - 04/02/2008 : 16:34:59
http://www.thebackshed.com/Windmill/FORUM1/forum_posts.asp?TID=684&KW=fatigue
Look there. Right down at the bottom .. maybe they'll work for 5 months ... |
| ghurd |
Posted - 04/02/2008 : 15:14:44
I meant alternator cost to get reasonably efficient power from a 5'dia 100RPM at 8MPH blade set.
'fatigue'. Comet. 737. 747. 767... |
| MattM |
Posted - 04/02/2008 : 14:11:15
Yep. Wood is just as prone to fatigue in the weather and no amount of shellac or varnish is going to make it survive the elements indefinitely. Aluminum is more resistant to weather save high winds, easy to manufacture, resists breakage because it is flexible, plentiful in supply, extremely uniform in consistency, and its very lightweight. A good furling solution should help it survive most winds. If aluminum was such a terrible solution they wouldn't of replaced wood with it in airplane manufacturing; even in today's age of carbon fibers the subframes are still nearly all aluminum.
And I have a good understanding of cost, be it in time and material. For my costs the metal material is next to nothing because what I am using is mainly drops off larger projects. By the time I made up the same material in pvc or wood it is costing me much more of both.
--------------------
Go Huskers! |
| fungus |
Posted - 04/02/2008 : 00:17:31
Have you ever heard of a thing called 'fatigue'? |
| MattM |
Posted - 03/02/2008 : 22:45:48
It has yet to be proven good or bad on a metric, but the superficial results are exceptionally encouraging.
You're simply wrong on the latter point.
--------------------
Go Huskers! |
