Blade weight
By JW1111, Section Wind Posted on Thu May 8th, 2008 at 11:38:33 PM MST
Blade weight

I just finished carving my 24" blades to go on my Ametek motor.  I used schdule 40 6" pvc.  They are 4" at the root and 2" at the tip.  They look pretty sweet.  They each weigh exactly 7 ounces.  Is this too heavy?  I can easily take some more off if need be.  Thank you.

Blade weight | 13 comments (13 topical, 0 editorial)

Re: Blade weight (3.00 / 0) (#1) by ghurd on Thu May 8th, 2008 at 06:56:05 PM MST (User Info)

The weight really doesn't matter much. Make sure they are very well balanced.

Re: Blade weight (3.00 / 0) (#2) by ghurd on Thu May 8th, 2008 at 07:28:38 PM MST (User Info)

After thought... With 6" pipe, and a 4" root, something must be pointed the wrong way. Part of the blade is fighting another part of the blade. The 2" tip has me wondering too. Maybe I am wrong, but weight seems to be the least of the problems. G-

Re: Blade weight (3.00 / 0) (#3) by TomW on Thu May 8th, 2008 at 07:58:14 PM MST (User Info)

Yeah, seems odd. This is where a couple pictures could tell the tale easier than text. Tom Contact: IRC [ Parent ]

Re: Blade weight (3.00 / 0) (#7) by clflyguy (sidney.raiford@gmail.com) on Fri May 9th, 2008 at 06:39:16 AM MST (User Info)

Ghurd, It sounded about right to me so I layed it out real quick and it looks pretty good- especially if the trailing edge got raked back at the tip like I've shown in the drawing [ Parent ]

Re: Blade weight (3.00 / 0) (#8) by ghurd on Fri May 9th, 2008 at 07:02:56 AM MST (User Info)

Looks a lot better than it sounded. G- [ Parent ]

Re: Blade weight (3.00 / 0) (#4) by valterra on Thu May 8th, 2008 at 08:16:17 PM MST (User Info)

The large blades that I made from a plastic barrel (12"(?) at root) were VERY heavy for their size. My wooden blades (24" diameter dual-blade carved on a single 2x4) came out VERY light.  So light that they feel like you could snap them in half. Either set spun like crazy.  The guys are right about balance.  And strength is another factor.  Be sure the blades can't bend backward at the tips and strike your pole at 500 rpm (72 mph?).

Re: Blade weight (3.00 / 0) (#5) by kurt on Fri May 9th, 2008 at 06:23:37 AM MST (User Info)

clflyguy, image posting rules do apply to you. please keep your images under 640 x 480 pixels and under 150 KB. i removed your comment because it was the only way to remove your over sized image. http://www.reresource.org/ IRC

Re: Blade weight (3.00 / 0) (#6) by clflyguy (sidney.raiford@gmail.com) on Fri May 9th, 2008 at 06:26:17 AM MST (User Info)

Sorry Kurt- forgot to check before sending- will dial it down and re-send [ Parent ]

Re: Blade weight (3.00 / 0) (#9) by JW1111 on Fri May 9th, 2008 at 08:17:31 AM MST (User Info)

That picture is very helpful.  It is almost spot on.  Except for the 3/8" off set between the tip and root.  I can see you did this for more twist.  I did not do this, I ran my leading edge line parellel with the tube, but I still have nice twist, just not as much as that.  I was able to get a nice foil, and then sanded it flat out the end.  I will post a picture if I can figure out how.   [ Parent ]

Re: Blade weight (3.00 / 0) (#10) by JW1111 on Fri May 9th, 2008 at 09:07:59 AM MST (User Info)

The edges are smooth but they look rough here.

Re: Blade weight (3.00 / 0) (#11) by JW1111 on Fri May 9th, 2008 at 03:53:53 PM MST (User Info)

I made a make shift hub and hung them up and they spun like mad. But I think they are a little heavy.  The start up seemed to be bogged down by the weight, but once they started to get some lift they went ballistic.  Not bad for my first try.  I'm hooked.   [ Parent ]

Re: Blade weight (3.00 / 0) (#12) by jmk on Fri May 9th, 2008 at 08:12:03 PM MST (User Info)

Plastic from barrels well change shape in the sun. They are soft and well work for a while till they do what they want. jmk

Re: Blade weight (3.00 / 0) (#13) by JW1111 on Sun May 11th, 2008 at 03:13:48 PM MST (User Info)

I got my turbine up and running today.  It has exceeded my expectations both in performance and how easy it is to make.  Thanks alot to Ed Lentz for the motor and brackets. In 15-20mph winds it is slightly out performing the Air-x only 10 feet away.  I am getting 3 amps in 20mph.  But the big difference is that it is very very quiet.  I am going to build another one and will have some more questions.  Thanks for all your help. [ Parent ]

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