| T O P I C R E V I E W |
| bigkat |
Posted - 22/03/2008 : 18:23:31
well... I got it up... and the motor is not going to work... I am only getting 5v at full windspeed... but I got a rig ready for a motor that works...
 |
| 15 L A T E S T R E P L I E S (Newest First) |
| bigkat |
Posted - 26/03/2008 : 22:47:01
fungus... the original specs on the motor was 2.5 hp 95V trendmill motor... that is off the top of my head... I will have to pull it down to get whats on the motor... which I am going to do in the next couple of days...
|
| fungus |
Posted - 26/03/2008 : 14:56:43
Back to the original poster ..
Do you have the specifications of the original motor?
One quick way I've made PVC blades before without getting into any complicated shapes is to get PVC pipe , or guttering, and cutting it in half to make a 180deg. segment, then simply (IIRC this was with 4" pipe) , measuring in about 35mm[IIRC] - about 1 1/2 inch in from one side, marking then doing the same on the other side on a diagonally opposite corner, linking them and cutting along the line, that gets you two blades and you can get two more from the other half. Then just measure in 1/2" from the inner (uncut) line and drill two holes about an inch apart to mount them to. You could probably make them better but they worked well for me on a dynohub and are simple enough to make without any template. I'd still choose carved wooden blades for an ametek any day. |
| bigkat |
Posted - 26/03/2008 : 14:24:10
MattM... no problem... I like it...
We have two sides... for two different blade systems...
for me and the other newbies/lurkers this is good material to decide on which direction we should persue...
and plus a little name calling just adds to the fun...
I mean the one thing that I do know... this isn't the first place on the intrawebz this has happen... :)
I know that ben has said move on... but as long as it stays in this thread... I don't see a problem with...
what if the telsa/franklin had the opportunity to argue like this... do you still think that we would have been on DC instead of AC...
|
| fungus |
Posted - 26/03/2008 : 12:59:16
http://www.fieldlines.com/story/2005/8/22/123113/162
http://www.detronics.net/airx_report.pdf -- In a VERY good wind location
Theres a couple links to read through ..
Yes, they are LOUD-google the otherpower board for some more reports of peoples experiences.
And yes, I am comparing a Rutland 913 to it as they were both in the approximate same location with same windspeeds and the rutland was spinning and producing power when the air-x was totally still.
'Testing' a blade design does not equal chucking it onto a bearing in a freewheeling condition and seeing how fast it spins. Nothing like it. That only tells you speed and without a sensible alternator actually attached to it means pretty much nothing IMHO.
About the age .. dont think its relevant in any way to the discussion as thats just getting into personal attacks and not answering any of the arguments in any way, all the points I made are valid and sound, I know people who at 30 can hardly brush their own teeth and people at 10 that are smarter than me .. :D
Finito.
|
| gotwind |
Posted - 26/03/2008 : 12:06:33
O.K guys.
Lets draw a line under this now and move onto something more productive.
Ben. |
| MattM |
Posted - 26/03/2008 : 12:00:01
The funny thing is that Air-X was designed for just that 400W in a 28mph wind, so it does what it advertised. It was not meant to be the cure all. But its popularity of course speaks volumes against your average low volume hand built units designed to be more like hotrods. And from all the reading I've done on the different Air-X revisions, the loud ones were the first two revisions that suffered tail flutter. But you already made your mind up that the design was just supposed to be noisy. And screech? Wow, just wow. Using an inflammatory word like 'screech' to describe a non-mechanical braking system. That must be loud...
And now you want to compare something that is rated at half of the Air-X using twice the number of blade? C'mon, fungus. It doesn't take a rocket scientist to figure out that something like a Rutland 913 is actually much lighter AND because it is using more blades it's going to be more sensitive to the wind.
Funny how I've spent the time to test and verify yet I'm rejected by a few fellas who don't know me and spend their time repeating stuff they simply 'know' because it just is that. I should be hurt. Fortunately my parents raised me many years ago to have thick skin. Fungus, perhaps if you weren't fifteen years old I'd give you less benefit of the doubt.
Sorry to meander in your thread, BigKat.
Go Huskers! |
| fungus |
Posted - 26/03/2008 : 05:19:28
I'd rather stay out of this but ..
If you ask anyone who has ever owned an Air-x or anyone who knows anything about small windpower you'd know it really does suck for any power output in reasonable conditions, it has carbon fibre blades that are very flexible and it uses this to limit power output, but thats where it gets called a banshee as it makes huge amounts of noise in actual operation, and as soon as it gets up to windspeeds where it can make power, the regulator shorts the output making it screech to a halt.
They were originally designed to be put on boats where high winds are common and power requirements arent huge, and it might work well with this where other stuff probably makes more noise .. but the simple fact is it will not work well in a reasonable average wind site.. I was once at a fair where an Air-x was there, and it simply didnt make a revolution the whole day when there was a rutland 913 making about 0.5A into a battery consistantly ..
They can get away with a small alternator by having very fast blades, fast=loud pretty much ..
And about your 'blades' which are freewheeling on a test stand and you call them 'good' .. well I wouldnt call any blades that I'd be happy to stand next to freewheeling in any reasonable winds as 'good' for producing power ..
JMHO-YMMV ...
|
| MattM |
Posted - 26/03/2008 : 01:44:25
Poor ghurd got his feelings hurt a long time ago and he continues to carry on to this day. And to think he is taking an opportunity to knock on poor old Air-X, the #1 seller of wind turbines across the world, they obviously don't know that their 400W rated wind turbine was supposed to make well over 1kW...
Go Huskers! |
| bigkat |
Posted - 26/03/2008 : 00:15:03
ghurd... don't worry about it... it was a point of view and it was passionate...
to me that what makes a great website especially when it is to reach a goal that we are...
but on other news... I hooked a battery to my ginny it was dead as a doornail this morning...
well I am glad to report that I have 8v of charge on it this evening...
that's pretty cool imho!!!
:)
|
| ghurd |
Posted - 25/03/2008 : 21:12:19
I am told the above falls short, and was overly intellectual to the point of frightening for most readers.
I apologize to anyone who is confused.
G-
|
| ghurd |
Posted - 24/03/2008 : 06:16:30
Albert Betz is rolling in his grave.
When working within a format that has no chance of being a perfect airfoil, make it as easy and funtional as possible.
It works.
The Air-X blade is a well marketed half-assed stop-gap measure designed to bend out of power before the windings melt, much like your blades are doing now.
It is not efficient. It is loud. It is nearly useless in most wind conditions. It matches no mathematical logic.
It is rare to hear an owner of an Air-X reach 400W under extreme conditions, while owners of other blades (49" dia) can reach over 1KW.
A simple Ametek with PVC blades designed for low wind can put power into a battery before an Air-X is even turning.
To actually make power it would be best to follow published blade designs suited to the situation, or hints from people who have actually charged a real live battery, instead of guesses based on things that simply spin.
Some people propose wishes, based on pipe dreams.
I'm done.
|
| bigkat |
Posted - 24/03/2008 : 04:31:19
hahahahah... thank you guys... you are to good!!!
|
| ghurd |
Posted - 24/03/2008 : 04:18:49
That sketch was just to show the trailing edge, related to the bolts related to the flat area of the hub. Seemed easier than words to explain it. Do Not imply anything into the proportions of that sketch.
Proportions are vital. As is length. It changes with every use. Everything is a balancing act.
Rounding the leading (curved) edge helps. Sharpening the trailing edge helps too (at least for noise).
Might buy a set of Ben's blade plans. Dandy place to start, and may work perfect as they are.
G- |
| MattM |
Posted - 24/03/2008 : 04:14:11
Ghurd's example is a good compromise between simplicity and ease of duplication. When you work with pvc it just doesn't pay off to get fancy.
Be sure to check out Gotwind's visitors' pages that have a lot of pvc ideas: http://www.gotwind.org/visitor_1.htm
Air-X is a good example of what you can do if you want to get fancy: 
The blade in this case is not actually fixed in pitch, I am alluding to the general tapering. Air-X uses a nosecone on their turbines, which is why the blade has the thin flange to mount with, otherwise it probably would be wide there, too. Notice how the blade shape's curve is not a straight line. The material is only so strong and so as the blade moves out from the center it tapers on an elliptical curve to the point where the thickness is relative consistent only the last few millimeter of its length. Like ghurd related in his picture, the red line in that case is where your pitch should be nil. The trailing edge in the latter Air-X example actually uses a trailing edge pitch, forming an fairly flat S-shape (ogee) if you look at it from the tip on in. Too bad your pvc is so thick of material that it is not realistic to attach a downward curving trailing edge extension. The blades also thin down in camber as you move from center to tip, another unrealistic expectation for pvc. Camber (front-to-back thickness of the blade) is the least of your worries when working with pvc, because it is virtually nothing in your case. Again, the Air-X is a pretty damn fine blade if one wants to get real fancy.
Go Huskers! |
| bigkat |
Posted - 24/03/2008 : 03:21:51
righton ghurd... that makes alot of sense... I will try to re-work my blades... but I had a set on there that kinda look like that design... but they're not as wide as that one...
I still only get 5v... so I think that motor is just not going to work...
|
