Savonius ready for 3D

[Stonebrain]

One day loking at my tower,thinking about what to put on it

I heard a voice:

"Thou should place a mill on it"

Ok just thinking of it,but what kind?

"A Savonius"

Hey didn't you read the posts on otherpower.It can not be done.

"Thou stupid boy,don't you know space have three dimensions?"

Hey what do yopu mean?

But the voice didn't answer anymore

I took a chunk off clay and my hands started make form as if

guided by invisible forces.

Hey! 3D,quite obvious,should have thought of it before.I call it Torkmaster.

Time had come to make Torkmaster1

Started with a wooden mold.

Just hammer a sheet of alu on it

Hell,must give this up

Try it with stinking glassfiber-polyester.

Went through the horror of glasffiber sticking to allmost everything.

And the more you get nervous the faster it hardens.

Anyone has a better technique?

 



the birth of Torkmaster1

Well I hope you can see the shape.

It's a 2'x2' rotor

It was up the  10' tower for a few weeks.I nearly got a lotec

dynamometer working,when a strong wind blew the tower to the ground

At that time I didn't have an anemometer,but I estimate it a 70 km/h.

One of the blades broke and the shaft bended.Next time better put

some weight on the feet of my tower.

Also I must find out the tecnique of getting the bubbles

out of the polyester (behind the glassfibercloth) to make it

smoother,better looking.Anyone has suggestions?

It spinned at  very low winds,well below tsr1,but I can't say

much more until I have Torkmaster2 flying and the dynamometer working.

I'd like to stress some advantages of the Torkmasterdesign.

Easy tower mounting

The 3D shape of the airfoil gives a great deal of stiffness

to a tiny sheet of material.So,they can be made extremely light and cheap.

No reinforcement of the structure needed,so nothing that

hinders airflow

The airodynamics is speculation but I think it has low

negative drag,when moving against the wind.

Need to find the tecnique to scale it up without making

a giant mould.

Well this was it.

cheers,

Stonebrain

[coldspot]

stonebrain-

Very nice !!!

"sticking to allmost everything"

Wax, lots of it. Automotive works fine.

"tecnique of getting the bubbles

out of the polyester"

A roller that has spiked wheels,

to puncher the bubble and press air out.

[hvirtane]

Very nice indeed.

I really like the way you made the mold.

I think that many kind of wax can be

used to clear the wing from the mold.

You might need some kind reinforcement

inside the vanes? Steel maybe.

Piano strings?

- Hannu

[electrondady1]

 i want to see it move . when it up again please post a little video !

[alcul8r]

Your Beehive mold looks like the sandpile we are making to make a clay oven.  you could coat it with 4-6 inches of clay and the first load of wood is already in place.

Seriously, it is good to see what people are trying, and even nicer of you to show us failures.  I think we can learn a lot that way.

Rex

[stop4stuff]

cool stonebrain

I've made molds and reproduction car body panels using grp.

The release agents I use are poly vinyl alcohol and beeswax, besswax on the metal, then coated with pva... I apply a gel coat first (allowing a short cure time) then resin coat and glass fibre mat, as many coats of resin and glass fibre as needed. Allow time for the resin to start curing (20 mins or so) between coats. I use a ribbed metal roller, similar to a paint roller, to work the resin into the glass mat and to get air bubbles out whilst the resin is still wet. Uncured resin can be cleaned off tools with acetone. The resin can be made to cure slower by using in a cooler environment (at night) or using less catalyst.

[harrie]

Very interesting, looks like you did a lot of work makeing that mold, and looks like the scoops will really catch the wind, keep up the good work, Harrie

[Stonebrain]

Coldspot,

Yes,a roller with spiked wheels.

Next time I will have something like this at hand.

Thanks

[Stonebrain]

Hannu,

In fact I put some ironwire reinforcement,but I dont

think it is necessary(as long as the tower don't fall over!)

I have lots of old guitarstrings,don't like to throw

away anything,but it's steel and maybe difficult to put

in place

[Stonebrain]

electrodad,

The camera I used is scrap...free present buying other thing.

I was lucky to finish my photos because it stopped working

right after.

Will be an investment of 200 Euros or so.

I can't make a mill with it but it's so good to share experience!

[Stonebrain]

Rex,

I forgive you talking about burning my mold,because your

idea of the sandheap is excellent for a giant mold,the

surface hardened with cement will be ready for resin-moldsing

I'd love to see some photos of your clay oven.

[Stonebrain]

stop4stuff,

your right,have to go right away,before the summer is getting hot.

[Stonebrain]

harrie,

Certainly the mould is the most impressive part of f

this project.

When I have finished the torkmaster1 series,Iwill probably

sell it at an art-gallerie

thanks you all for comments.

Cheers,

Stonebrain

[Ungrounded Lightning Rod]

Looks great but too thin.  If you make it 'way thicker then if the tower comes down again the blade will just dig its way into the ground as it comes to a stop.  B-)

Of course that means working at it longer as you add more layers of fiberglass and epoxy.  But think "boat hull" instead of "pinwheel" and you see what I'm driving at.  It will be heavy so you'll need a thrust bearing.   But that shape should have plenty of strength.

LOVE the shape - especially the narrow middle so the side force from wind loading is near the bottom bearing and you don't need a second bearing above the rotor - with all the support structure that implies.

It might be interesting to modify the curve so it droops slightly and puts the center of effort even with the tower bearing rather than above it - or perhaps slightly below.  Then your second bearing (below the top of the tower) will mostly be dealing with small errors rather than fighting the torque on the shaft from the wind loading being centered above the upper bearing - and your shaft will have little flex loading as things spin.

[WXYZCIENCE]

For speed you need to use a chopper and spray the resin. But that is cost. More acetone  , try wetting cloth with a little to break the glass glue bond. I don't glass without a gallon of acetone. Use thin strips for your second coat. Use a good roller. No less than 3 layers and extra on edges from hub out to at least half way to main body. I agree boat not pinwheel. Use oscar mold wax, 2 coats, polish well before glassing. PVA is also good. Joe

[Stonebrain]

ULR,

>especially the narrow middle so the side force from wind loading is near the bottom >bearing and you don't need a second bearing above the rotor - with all the support >structure that implies.

You got it

>It might be interesting to modify the curve so it droops slightly and puts the center >of effort even with the tower bearing rather than above it - or perhaps slightly >below.  Then your second bearing (below the top of the tower) will mostly be dealing >with small errors rather than fighting the torque on the shaft from the wind loading >being centered above the upper bearing - and your shaft will have little flex loading >as things spin.

I've been thinking about this,indeed if you extend the blades more downwards,

the equilibrum on the bearing right below the blades can be nearly perfect.

The counterpart is that the wind forces on the blades won't

be equilibrated(if this word exists) relatif to the fixation

on the shaft.Maybe best is a compromise of the two.

underneath this bearing I put a thrust bearing so if you want to get

dizzy you can hang on the shaft:)

In fact this rotor is ment to stir water in ponds.

Sure this one will be excellent for that(I did some testing)

.I don't regret my efford for the mold because I will make a couple of them.

Making the 6'x6' maybe even 8'x8'Torkmaster2 for electricity will

be another story.

cheers,

Stonebrain

[Stonebrain]

WXYZ,

" More acetone , try wetting cloth with a little to break the glass glue bond. I don't glass without a gallon of acetone."

I don't grasp this very well.Wat is "glass glue bond"? Glassing is what you

do at the end with acetone to make it shiny?

I suppose you can put colors in the polyester to make it even better looking,but I didn't find it in the shops.

I understand I must learn from boatbuilders,but the sea is quite a way from here

They talked about that roller on the polyester-drum.But no way to find it

in the shops over here.Might be long to find.

What about making a wheel with spikes?

I bit of ashamed of it,but I put machinegrease on the wood with a plastic film

on it.(Advise of the vendor).Better wash the grease off with white spirit for the wax and pva?

Thx,

Stonebrain

[WXYZCIENCE]

The rule is in fiber-glassing, keep trying. You can make a roller easy by stacking two different size washers on an old roller bar till you get the length you want. Use say 3/4" diameter and 1/2" alternatively 5" long. Bull cloth is the woven stuff and it is hard to use. The mat type is held together by glue that lets go when you add your resin. Try a test with a small piece of the mat. Lay it on a curved surface wet the roller with acetone. Now you can curve the mat easer before you add the sticky stuff. I love your  design. You got me very interested. I would use your first cast to make an inside mold  . They are not as hard to use. Like filling a bowl instead of balancing the stuff on the curved bottom of one. One of my favorite saying around this place: "Failure is an option." Keep posting the results. Joe  

[Buck L]

Try window screen in layers. I built a auto fender like that one time and it was very very strong.

[Experimental]

Hi Stonebrain,

     That looks like a really good idea, but a couple of things you might try !!

    First, fibreglass mat is great for building thickness, but very poor for strength. However, if you use one layer of cloth first, then mat, then one more layer of cloth -- the strength will be much better,, (I would only use cloth)

    A tool for working out air bubbles, is available from fibreglass suppliers -- it looks like many washers, spaced apart, but is actually a machined aluminum "wheel" pulled back and forth across the material -- available from -- "Aircraft spruce and specialties", in Los Angeles, California -- just punch in Aircraft spruce, on the web...But, if you use cloth, you probably won,t need one...

    As mentioned, use paste wax for a mold relese, but let each coat of wax "dry", for at least 4 hours, between coats, and use 3 to 4 coats !!

    BIG suggestion -- don,t work resin in sunlite, do it in the shade and you will enjoy much longer working time -- use a little less catalist, when it,s warm weather and mix small batches as large batches "Exatherm", and can get so hot it can smoke and burn !!

   One other thing -- use "bonding resin", not finishing resin --as you can add another layer of cloth, even after the bonding resin has cured -- but, finishing resin, has a wax in it and you have to sand, between coats.

   Hope thes suggestions are helpfull -- Bill H..

[Stonebrain]

Thanks for the suggestions

Interesting,the idea of casting them.

Only some questions:

What material do you want to cast in it?

If no reinforcement with fibers->less strenght->blades must be thicker.

How do you want to fill and get all the air out?

[Ungrounded Lightning Rod]

If you get close enough to putting no cross-axis torque on the shaft you can kill the residual errors with the separation between the two bearings in a motor conversion or an automotive-axle based radial alternator.  You'd have a very simple device then.

You might do a motor conversion on a motor that's designed to mount vertically and support a fan, rather than add an explicit thrust bearing.

Of course an automotive axle bearing set is designed for enormous along-axis force (which would support the rotor's weight) - because it gets those in turns, as well as large cross-axis torque (which would support center-of-effort errors) - because it gets those from the vehicle's weight and hitting road bumps.

Main issue will be that you'll need a lot of poles and a non-trivial genny radius to compensate for the low RPM of a VAWT.  Fortunately this design can clear a significant amount of radial alternator - or you could just put the radial below the rotor on a long shaft.  B-)

[Stonebrain]

A direct drive motorconversion-HAWT is a very interesting

project.

But forget it with the Torkmaster.It's defenitly a savonius.

I would rather do it with a feather-weight bambooframe with sails fast

darius-H-rotor.You can equilibrate it like the torkmaster.

And when a sail gets off,it won't be dangerous as a regular

H.

Have to cut bamboo sticks whenever I can.

And for the torkmaster I would rather try to get a gear then

make a 2' 64 pole axial flux.

cheers,

stonebrain

[Stonebrain]

oops,I meant to say motorconversion-VAWT

[Experimental]

Hello again,

    As I mentioned above, I would use cloth fibreglass fabric -- three or four layers will be much stronger than mat and you probably won,t need a roller to get bubbles out, all layers can be done without stopping !!

    PVA, is one of the best mold release agents -- but I don,t advise putting it over wax -- as it "beads" up, just like water on wax and needs to be sprayed on the mold in several light coats -- it is water soluable, and can be washed off with water, after the part is removed -- PVA is usually green in color..

    Automotive paste wax, works fine if allowed to dry completely between coats -- 3 to 4 coats recommended..

   Acetone is great for keeping your brush from hardening, between coats and I always use it for that purpose -- but to get a good shiny coat on the outside of the part -- just a couple of resin layers, after the part has cured will do that..

   One other thing I will mention -- your parts will still be "green" after removal from your mold -- it will take some time for them to completely cure, after removal, and placeing them in hot sunlite, can soften them and they can change shape-- I normally , leave parts in the mold, for a couple of weeks, if I can..

   If you note, most composite parts, are usually painted white, to protect from hot sun softening, unless oven cured...

  Fibreglass, is easy stuff to work with -- have fun, Bill H.....

[Stonebrain]

Thanks,Bill

[Stonebrain]

you mean the film you can stick on glass-panes?

And you build a wing with that?

interesting,if you spend a few more words on it

I will be reading with interest.

cheers,

Stonebrain

[Stonebrain]

Hey again bill

I bought some mat allready,cloth is nearly

two times as expensive but if it's two times stronger and easier

to apply I would have better take only cloth.

But anyhow I have mat now.

So,the procedure will be:

1) cleaning the mould and put some applications of polyvinylalc that's what I

found in the shop.

2. gelcoat Only if I find it,will have to go out for it tomorrow
   
3. resin-cloth-resin and working bubbles out with the homemade
   
   

 washer-roller.Cant find that roller over here,and not even on internet

 in whole france.So try this

4. mat-resin,working bubbles out
   
5. cloth-resin-resin,working bubbles out
   
6. polish after curing
   
7. finish paint (maybe need something special?)
   
   

Must be doable,say me if I'm wrong somewhere.

cheers,

Stonebrain

[Experimental]

  Sounds fine Stonebrain,

    And glad to hear you have PVA (poly vinyl alcohol) spray that on in thin coats and let it dry detween coats (drys very slowly in damp weather)

   The mat should be fine under most circumstances, but 8 to 12 ounce boat cloth would be lighter, and easier to work with -- one trick I have used, to make the matt easier to work with, is to just wad it up and kind of "mash it together" -- it makes it softer and easier to form !!

    The roller made of small and larger washers, works well -- (have made them that way) -- just dip it into the acetone often, to keep the washers from sticking together!!

I looked to see if I still had an old roller, but could not find one -- if I had, I would have sent it to you..

   As  all I build these days, is aircraft parts -- I don,t use mat any more, just cloth -- it also puzzles me, that mat would be more expensive there, than cloth.   But, I wonder if what you are speaking of, might be what we call "roving"??

   Roveing, looks like woven cloth, but the material is very thick -- while the cloth I,m speaking of, is thin and of rather fine weave, more like a shirt might be made of, with a little coarser weave !!

   Anyway, the mat should be just fine, and can be painted with automotive primer, espically if you use an epoxy primer, then top coated with standard automotive, acrylic enamel -- this gives a long lasting durable finish...

   Good luck to you, and we want to see the finished product -- Bill H...

[Stonebrain]

ok,thanks again bill

Will keep the board informed,

hope to come up with something good.

cheers,

Stonebrain