Author Topic: PVC tower update (Read 6345 times)

taylorp035 · « **on:** March 15, 2010, 03:17:21 PM »

Today I went out there to try and charge my roughly 40 ah 12v battery with my pvc windmill. The paper said 7-14 mph from the NNE, which is the perfect direction for my back yard.

So a few minutes later, I trudged through the snow with my battery, many wires, diode, and a folding lawn chair (the folding chair was a good idea to set the battery on, except for when you try to unfold it while balancing a large 12v battery in the other hand so the cardboard box that the 12v is in wouldn't get wet). The blades were starting up on their own, so I knew there was some potential. Once I got her all hooked up, I stood there for about 75 minutes.

The peak amperage which I saw was 1.89 amps, which was a decent breeze, maybe 18 mph peak. The voltage on the battery was probably past 13v, as it was charged with my solar panel last week. So an estimated 25 watts would be fair.

Some of my observations included a moderate shake to the tail at 15+ mph, which means the blades must not be very well balanced. Also, the mud around the pole was pushed out about 4-5" from it leaning over. This concerned me a quite a bit, but not surprised as the water table was even with the ground. Maybe this summer I will pile some more dirt around the pole so it doesn't sway so much. The blades and the treadmill motor seem to be holding up just fine from the snow, ice and rain.

I am surprised that the 35+ mph winds haven't knocked it over, maybe the tower bends so much that it kind of self furls.

Hopefully spring will bring some stronger winds, as the blades have only spun on 4-5 days since January. It seems that start up is around 10v wind speed, which I would guess to be 10-12 mph.

I hope everyone had a happy Pie day yesterday!

taylorp035 · « **Reply #1 on:** March 15, 2010, 03:19:33 PM »

That should be a PVC tower in the first sentence. The blades are hand carved and 50" in diameter.

Rover · « **Reply #2 on:** March 15, 2010, 04:47:28 PM »

I would not be concerned about the "moderate shake to the tail at 15+ mph" , this is fairly typical in smaller machines like ours, especially when not up 30+ ft. You are dealing with rougher air, etc not a straight on continuous.

Keep it up ,I enjoy reading your posts.

taylorp035 · « **Reply #3 on:** March 15, 2010, 05:13:25 PM »

Well, ok.... I did balance it before I put it on the shaft 2 ways. 1st, I put a shaft through the center of the hub and balanced it the same way I balanced one of my battlebot weapons that spun at 2,500 rpm @ 18 inches

The 2nd way I balanced it was it put the whole windmill in the vice and hooked a 12v battery to it, so it spun at 300+ rpm. The results were very smooth, so I stuck it outside.

If I make my tower stronger, I bet I could hit 200+ watts. Currently, I think the tower would only hold up to maybe 100 watts. I saw it putting out 54 watts once and it was pretty scary (always stand up wind ). I could also put some guy wires on it, but that would look interesting with a tower that only sticks 8 ft above the ground.

greend88 · « **Reply #4 on:** March 15, 2010, 09:03:35 PM »

What Diameter is your tower? Have you thought about filling it with concrete and rebar maybe? Take a smaller diameter PVC pipe for a conduit for your wires if you ran them on the inside, and take some rebar and put it between the two pipes and fill with concrete. I bet it could withstand quite a bit of abuse then.

CmeBREW · « **Reply #5 on:** March 16, 2010, 05:47:42 AM »

HI,

Sounds good. I am going to try to use some 2" PVC pipe as a tower for my newest small 40" Hawt. I'm going for the good looks without guy wires also. What I am going to do is just sledge hammer a 1.25" diam steel pipe into the ground (6'long or so) and it will stick up a few feet and the PVC goes over it to support it better.

It will be just a simple little 'garden wind mill' decoration looking thing. (6 blade/ downwind hawt no tail)

You might consider the steel pole in the ground like this.

Keep up the good work.

ghurd · « **Reply #6 on:** March 16, 2010, 06:29:33 AM »

2" gets pretty floppy. 40" sounds pretty big for 2".

Might drop a piece of 1.5" in it for extra stiffness, but that creates issues for the wire drop.

G-

TomW · « **Reply #7 on:** March 16, 2010, 08:22:24 AM »

I would never use PVC here for anything structural!

Our temperatures run from -40F to +120F and I tried making a greenhouse with grey PVC and some of the white stuff. Neither stood the test of minor loading when summer hit. Stuff just got soft and was like a limp noodle. Seen the cold shatter it under deflection, too [snow].

I fully support use what you got methods but the PVC tower mast just spooks me.

Just tossing that out there.

I suppose you could fill it with sand or something too to stiffen it or concrete as mentioned. I have access to lots of surplus and that includes tube and pipe whicjh I would use.

Good Luck with it.

Tom

CmeBREW · « **Reply #8 on:** March 16, 2010, 08:42:38 AM »

Yeah, I was going to try the 1.5" inside also. And to try to make the steel pipe come up about 4', so that only 6' (out of 10' long) that is a bit 'flimsy'.

I forgot to mention my little Axial alternator practically weighs nothing. (so far just 8 lbs)

A heavy treadmill motor would as you guys say bend the flimsy 2" without guys easy.

I really just meant the idea of the steel pole in the ground for him so he could get the full 10' high. If I recall he was using the 4" diam anyway. Might just put a piece of treated 4x4 in ground and have that come up in the PVC pipe 4' or so for good support.

What i am making is VERY light weight and going for a stream-line thin unnoticable look like a garden decoration. Hope to get a covert 1-3 amps. If so, might make a few.

wooferhound · « **Reply #9 on:** March 16, 2010, 08:50:33 AM »

Yes I have seen PVC shatter in -20f weather with quick minor movements.

I work in a Concert Hall Theater and in June they are replacing the Fly System. This is the Pulleys, Pipes and Ropes used to raise & lower backdrops and scenery to the stage. The pipes are perfect for wind power masts cause they are 2 inch schedule 80, plus there are 60 of them at 60 feet long each.

However the theater is owned by the City and they are scared of any possibility of problems if these pipes and ropes get reused, so they are going to destroy everything by cutting it up and throwing it into a dumpster. Makes me sad, there are miles of cables that go down to the pipes that would be excellent for tower guy wires. A weight system that rides a huge grid of guide tracks made from long strips of 1/4" x 2" steel.

All going to the dumpster . . .

ghurd · « **Reply #10 on:** March 16, 2010, 09:17:20 AM »

Advice for TomW and anyone else in a -40 area: Move South!

We had 1" (?) PVC supporting a light weight tarp hood in the sugar house.

Seemed solid as could be, like hold up a Sherman tank kind of Really solid.

Until the fire was burning, when it became half as solid as overcooked spaghetti.

I doubt the temps at the pipes was all that 'hot', but it was enough.

I was not there at the time, but the stories are amusing.

G-

taylorp035 · « **Reply #11 on:** March 16, 2010, 01:36:12 PM »

My pipe is a 4" diameter, which is reasonably stiff. The wall thickness in only about 1/16"... The reason I used it was because I had a bunch of it laying in the yard, and it is very portable, as I plan on taking my windmill out to the beach one of these days with a 6ft tower or so and dig in for an hour. Hopefully the DCNR people don't get mad at me

If I wanted to, I have tons of scrap wood that I could possibly make a lattice tower any height I wanted. One other option that I have is that I have a 4" stainless steel pipe from an old nuclear plant, which would be infinitely strong, but it is not as portable nor is it stackable like pvc pipes (see video for demonstration:

http://www.youtube.com/watch?v=ZWfvyj8diug

I could easily put some guy wires on it at about 6ft up if I wanted to.

For people who want to use a 4' pvc pipe like I did, here are some suggestions:

Stick with one pipe tall, unless your blades are less than 24"
Don't go much larger than 4ft, as my 66" set was too much
Use the pipe that has holes in it, so when the water table goes above your foundation, the water can flow out.
Guy wires will increase the size or height possibilities
If there are no guy wires, dig at least 2 feet down.
Larger diameter pipe would be awesome, especially if you get your hands on some 6" or larger.
If you find your self holding the tower with your hands every time the wind blows, it's time to do some more thinking
Be careful about the blades hitting you in the head... some thing you don't think about with a short tower. Wearing a helmet can help for those people who don't learn as fast!

taylorp035 · « **Reply #12 on:** March 17, 2010, 08:55:22 PM »

Here are my two favorite tower bending videos of mine.

http://www.youtube.com/watch?v=-N0PWif6jtw#movie_player

http://www.youtube.com/watch?v=ZWfvyj8diug

Getting that top tube on top of the other one was very difficult and not recommended...

Perry1 · « **Reply #13 on:** March 18, 2010, 06:51:57 PM »

I don't understand why anyone would use PVC for a tower. It is probably one of the worst possible materials to use as a structural component in this situation. I understand it may be what you have on hand but why not spring for the $20 to buy 10 ft of 2" steel pipe? It just seems like a no brainer. You could get by with no guys and paint it white if that makes it look better for you.

I've fudged a few things in my time and by no means am I without fault but come on seriously, $10 for a PVC tower or $20 for a steel one.

Perry

dboller · « **Reply #14 on:** March 18, 2010, 07:56:41 PM »

Hey on all that good pipe cable, etc. getting cut up and thrown away by the city. I've been involved in local government enough to know that the whole thing runs on CYA of one form or another. They might be convinced that selling it at a surplus auction keeps them from being accused of failing to recover any value for the city that this stuff would have. Maybe that could outweigh their worries about someone being hurt by it. Besides, if they sell it they are washing their hands of it better than if they give it to someone. Usually the issue is fairness and recovering maximum value for the govt. entity. Just saying......

taylorp035 · « **Reply #15 on:** March 20, 2010, 12:13:08 PM »

My budget is usually $0, plus, the pvc pipe allows me to make a REMOVABLE windmill that I can bring into the garage when every I want. Assembly requires no bolts, it just slides right into the pvc pipe. My 4-wheeler doubles as my ladder to lift it high enough in the air.

You are right, PVC is one of the worst things I could of used, but I test it before I put my windmill up by clamping it into my wood vice and pushed the other end. I found it to be surprisingly stiff. PVC is stronger than most people think. I once saw a 4" pipe cut in half (like the letter C )with a length of 3", and a 250lb guy jumped on it and it did not break.

For $20, I could make a carbon fiber pole that would be 10x as strong as the pvc pipe.

Perry1 · « **Reply #16 on:** March 20, 2010, 05:59:10 PM »

But weren't you saying above that your pvc tower was bending and leaning over to the point of furling?

fabricator · « **Reply #17 on:** March 21, 2010, 05:40:11 PM »

Hey Woof, I have a hold harmless agreement that was drawn up by my lawyer, it has blanks for filling in the name of the party that needs to be indemnified, I could email it to ya if ya want to give that a try.

taylorp035 · « **Reply #18 on:** March 22, 2010, 04:15:03 PM »

I don't really know what happens to it in high winds. 3 months and the wind here has been sub par. The pole only bends about 4" in 20mph winds. Currently, the windmill is just free-wheeling, so if it hits 1,000rpm in 30mph, I don't care. If I was actually charging something 24/7, then I would make a better tower, as you said, PVC is not very good (of course an 8ft hub height isn't good either ).

taylorp035 · « **Reply #19 on:** March 27, 2010, 01:37:21 PM »

Yesterday (3/26) I got her up to 10 watts, but the winds were only good for 15mph or so. I have been considering making a new set of blades that are very wide for better start up and an angle at the tip that is closer to 3-5 degrees instead of 10 degrees. When I watch it get close to 12v, it seems like it is having a hard time getting enough rpm.

Do you guys think I should make a smaller diameter (42" maybe instead of 50" currently), or should I make wider blades ( currently 4" at the roots ). Or maybe I should make straight blades so there is no taper from 4" wide to 2" wide. Any expert opinions?

Perry1 · « **Reply #20 on:** March 27, 2010, 04:30:16 PM »

I don't think a wider root will really contribute all that much. I would back off on the dia as the quickest way to boost the rpm. Are you having trouble with the start up? You could cut the tips off your current blades to test the theory but once that's done, it's done, right.

Perry

ghurd · « **Reply #21 on:** March 28, 2010, 05:39:06 AM »

That 10 degrees has got to be a big part of the slowness.

The wood looks like 3/4" thick? It should start better with 1.5" thick.

Shorter is faster. Might try shortening them, and then reducing the tip angle if there is enough wood.

G-

taylorp035 · « **Reply #22 on:** March 29, 2010, 01:38:12 PM »

Ok, I will do that the next time I make a new set of blades. So probably two boards glued together + 46" dia + closer to 3-5 deg tip.

taylorp035 · « **Reply #23 on:** March 29, 2010, 01:41:20 PM »

My start up wind speed is higher than I would like it (about 10-12 mph), but then I don't hit 12v until 12-14 mph, so I am not loosing anything. as you suggested, I will go for a smaller diameter + less attack angle. I think right now that my airfoil it too thick also (about 3/8'+ instead of 1/4" )

taylorp035 · « **Reply #24 on:** April 01, 2010, 12:23:53 PM »

Today was windy and very warm so I went out and hooked the battery up. I ended up setting a new personal record of 62 watts! Estimated wind speed of 25 mph. When I was packing up for the day, a very large gust of wind came of about 30-35 mph which made the blades hit about 1500 rpm. I based this off of an earlier estimation when I hit 26v with no load. The pvc pipe bent about 16" from straight.

I hope you guys are still enjoying this thread.

ghurd · « **Reply #25 on:** April 01, 2010, 01:21:21 PM »

I though of this thread late one night...

Lowe's or Home Depot has pipe for chain link fences. CHEAP!

Might consider looking at it.

Not sure it would be good for a very sizable mill, but maybe it would limit the PVC from flexing so much?

I kind of plan on a second tower, with that fence pipe, bolted to a 4x4 fence post, for experimenting with some 1 meter class stuff.

It is in a safe place, and a crash is not a problem.

G-

taylorp035 · « **Reply #26 on:** April 01, 2010, 01:29:08 PM »

I am getting closer to getting that stainless steel pipe.

As for it crashing, it is pretty far out there. I think the blades will explode before the tower breaks ( only two 1/4" bolts holding the blades on ).

Also, it stays balanced at the higher speeds, which makes me happy.

ghurd · « **Reply #27 on:** April 01, 2010, 03:59:20 PM »

I meant MY planed test tower is in a safe place!

And MY experiments crashing would not be a big deal!

I would feel bad for you if your machine crashed,

even out in the boonies.

But do have a look at that fence pipe stuff.

It is not exactly round, or having any other nearly precise measurement,

but it looks pretty tough for the cost.

'Seems Like' the 2" stuff was cheaper than 4" PVC? There are a couple different diameters, and it was all really cheap.

The top rail (whatever?) could be had in pretty long lengths.

G-

taylorp035 · « **Reply #28 on:** April 01, 2010, 07:14:36 PM »

Sry about that.

I don't really care that much if mine breaks. I think I have broken at least 5 blades with the same set up so far. The only thing I have a hard time fixing is the hub, as I don't have any beefy plywood to make a new one out of.

Don't expect me to be fast with this pipe thing, it may be a few weeks unless the pvc pipe decides to fail. After watching it today, I think anything over 100w is going to require a stiffer pole and faster blades ( at least I will not stand behind it watching my amp meter at 1500 rpm ... ). I just don't have any open weekends to spend 20 hrs on a new set of blades. When school lets out on may 7th, things will get better

taylorp035 · « **Reply #29 on:** April 03, 2010, 01:13:39 PM »

I am watching the windmill right now from my window and it is bending every bit of 2ft+. I am going out there to at least take some video for you guys and maybe to break 100 watts!

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Author Topic: PVC tower update (Read 6345 times)