Using styrofoam blades for a VAWT?
By Derek, Section Wind Posted on Tue May 22, 2007 at 03:27:19 PM MST
Would they be resistant enough to stress over time?

I was about to go to sleep the other night at about 11pm, then suddenly a random idea popped into my head and I couldnt sleep for an hour.  I'm working on making my first VAWT, and was trying to figure out how to design a real sturdy, yet lightweight model.  For the blades wouldnt styrofoam be plenty strong enough and resist fatigue better than aluminum or steel blades?  They'd probably be a couple inches thick, and have a curve to them of course.  On a HAWT, no way they'd work being 20 feet long.  But with the design of a VAWT, I think it might work.... Two options for getting such a part into existence.  First, I could buy big blocks of styrofoam and cut them myself or have a company cut them.  OR, is there any type of stuff that could be sprayed into a mold that I could do myself?  I dont know anything about styrofoam, so.... But what I do figure is this.  If it lasts only 1 year, so what, they'd be cheap to replace.  Or if the unit was to self destruct, nobody would die either!  So are there any suggestions for sources on getting some styrofoam like that?  And do you think it'd work?

Using styrofoam blades for a VAWT? | 14 comments (14 topical)

Re: Using styrofoam blades for a VAWT? (3.00 / 0) (#1) by winston on Tue May 22, 2007 at 10:49:12 AM MST

I think this could be a good idea if you were to cover the foam with fiberglass this is used in experimental aircraft construction it is called 'flying the mold' the foam is cut into an airfoil shape with a hot wire then the foam is covered with several layers of fiber glass this makes a very strong structure good luck

Re: Using styrofoam blades for a VAWT? (3.00 / 0) (#2) by Derek on Tue May 22, 2007 at 11:54:50 AM MST

Oh well snap, that would work.  I seen on discover channel show "how its made" with hot wires cutting styrofoam, was pretty cool.  So I'd end up with a very strong, and incredibly lightweight blade for my VAWT wouldnt I?  Wonder why nobody has tried this before, or has nobody thought of it.... So where can I get some stryofoam either already cut, or some really big chunks? [ Parent ]

Re: Using styrofoam blades for a VAWT? (3.00 / 0) (#4) by Lumberjack on Tue May 22, 2007 at 12:54:17 PM MST

I have seen inch thick blue foam used on walls.... [ Parent ]

Re: Using styrofoam blades for a VAWT? (3.00 / 0) (#7) by vawtman on Tue May 22, 2007 at 04:30:31 PM MST

Hi Derek  I think foam/epoxy glassed blades would work fine for a small vawt.You can cut your desired profile out of a 1x4 or whatever and epoxy that to each end that will be your form to follow has well has end supports for mounting.  Plan on doing this for a rooftop turbine.  I built a foamcutter basically for free from the great help here.  Material list;  scrap pvc pipe  scrap emt  element from a junk milkhouse heater(with insulators streched out to~4FT  transformer from a junk pool robot  spring from a junk dishwasher  Worked fine with practice  Heres a pic of the beast   [ Parent ]

foamboard on a VAWT (3.00 / 0) (#3) by Norm on Tue May 22, 2007 at 12:34:55 PM MST

Well you can use foamboard on a small vawt like I'm doing....just slightly larger than lawn ornament.....44 inch diameeter. I put masking tape on edges then paint with poly urethane then regular paint for color. Just temporarily taped onto bikewheel (trying to see how it worked before the wind died down ....Nah ! too late wind stopped)   Made out of foamboard...Maybe neighbors knowing blades are made of foamboard will feel that it's not a hazardous machine.              ( :>) Norm. ( :>) Norm

Re: Using styrofoam blades for a VAWT? (3.00 / 0) (#5) by DanOpto on Tue May 22, 2007 at 02:59:53 PM MST

A local installer bought a chinese HAWT mill with styrofoam blades covered with fiberglass. It lasted one year. High winds of 110 mph broke them at the root. Ooops The manufacturer did not have replacements. The wind generator was replaced with a smaller unit.

Re: Using styrofoam blades for a VAWT? (3.00 / 0) (#6) by DanOpto on Tue May 22, 2007 at 03:09:04 PM MST

http://www.rcfaq.com/ANSWERS/modelbuilding/foamcutting.htm Here is a good link for foamcutting information

Re: Using styrofoam blades for a VAWT? (3.00 / 0) (#8) by thefinis on Wed May 23, 2007 at 08:20:20 AM MST

Don't forget that some type of blade structure must exist so that the blades have an attaching point or points. I thought that the resin for fiberglass would eat foam so you use epoxy for binder. Makes the cheap blades much more expensive. No one else has asked so I will, what type of vawt are you wanting to build? Type of blades drag or lift and size would help lots for making recommendations. There are many types of foam so a little research might pay off before buying. MEPS XEPS EPS(first 3 are types of expanded polystyrene) polyurethane and polyisocyanurate all are types of foam commonly available but with differing characteristics. Finis Texas born and bred

Re: Using styrofoam blades for a VAWT? (3.00 / 0) (#9) by SparWeb on Wed May 23, 2007 at 12:46:06 PM MST

This can be done. Here's my design from 2 years ago: Do a search on foam cutting with a hot wire.  There have been many posts here on that topic. Whatever you do, don't build it with just 2 blades like I did.  Or, if you must, use a much sturdier axle than the 1.5" that I used. Steven Fahey

Re: Using styrofoam blades for a VAWT? (3.00 / 0) (#10) by Derek on Wed May 23, 2007 at 08:42:55 PM MST

Thanks for the excellent help guys!  So it turns out foam blades isnt a new idea...  But I'm going for more of a drag type VAWT, but it will be shrouded and ducted to increase the air flowing through the unit.  From testing, I think what I'm working on is actually doubling the speed of the VAWT I've made. Well, I guess one of the next steps is to actually find a place to get styrofoam from.  Any ideas there? As far as the Chinese HAWT with styrofoam, depending on the cost and ease of replacing the blades, even a year of use wouldnt be too bad in my opinion!  Even $20 worth of foam wouldnt be a big deal to replace once a year to me.  The trade offs of it being light, cheap, and especially safe would be a good thing I think.  Attaching the thing, I think I've got some ideas worked out.  I'll get a 3D pic made soon to show my idea. [ Parent ]

Re: Using styrofoam blades for a VAWT? (3.00 / 0) (#11) by SparWeb on Thu May 24, 2007 at 12:42:50 PM MST

Hobby stores have small amounts, local hardware stores have large sheets of blue/pink house insulation foam panels, or find an industrial plastic product supplier and they could have lots of choice, too.  You can get laminating epoxy and the fiberglass fabric from the industrial plastic supplier, too. Steven Fahey [ Parent ]

Re: Using styrofoam blades for a VAWT? (3.00 / 0) (#12) by pepa on Fri May 25, 2007 at 07:34:43 AM MST

hi derek, check at a building supply center for rigid roof insulation, it usually comes in 4'x8' sheets and the thickness veries. i have used this rigid foam insulation  up to 8" thick. it will have a slight taper from one side to the other for roof slope on a builtup roof system. the material is very dense, durible and water proof, easy to cut and work with, pepa. [ Parent ]

Re: Using styrofoam blades for a VAWT? (3.00 / 0) (#13) by TheEquineFencer on Sat Jun 23, 2007 at 04:09:25 AM MST

It's funny I found this post when I did. I have freind taking classes for his air frame lic. for the FAA. The "foam" used is not the type sold at a hardware store, it's special foam with a differant structure used for airframes. He has made actual scaled down wings using composite materials, the idea is the same though. Monday he's going to ask his instructor to see about getting large sheets and the materials to build some for me. He says the stuff is awsome! You just cut it with a hotwire and lay the resin on and then lay a section of "fabric" on top and roll the bubbles out. If you use regular foam it melts. That's my .02 worth. F. Moore Farmville, NC [ Parent ]

Re: Using styrofoam blades for a VAWT? (3.00 / 0) (#14) by pepa on Sun Jun 24, 2007 at 02:56:40 PM MST

hi Derek, try a builder supply for rigid roof insulation for built up roofs. i have used it in 4x8 sheets and up to 8" thick. it does come with a slight taper form one 8' side to the other of about 1/2" for slope angle and may have to be special order, but you might find some damageded pieces at a good price. you could also find some of the dock floats in 2x2x4' sizes. pepa [ Parent ]

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