More VAWT

[ffoegw]

Any VAWT needs a rotating base to sit on and take power off.

I'm thinking of taking a rear end out of a truck and cementing/bolting it into a support.

I imagine that power could be taken from a gear or pully bolted onto the hub studs or ..... taking power right of the drive shaft through the differential.

Any other ideas for doing it on the cheap?

Regards

Geoff

[thefinis]

What I am doing at the moment is using front wheel drive hubs from a chevy car that have a splined shaft. The bolts for the wheel rim point in and with a welded adapter, bolt to turbine base. This requires a stand and cross member to mount to and leaves the power shaft vertical but does away with losses from running the third member in the rear end. One problem I have encountered is that for all my careful layout the S rotor ends when mounted with hubs aren't quite straight flat something and the hubs want to wiggle a little. I may can shim it out but I am worried that a pipe or shaft is needed to align the bearings/hubs so it will run true enough for a hybrid vawt.

If you are just looking for convience then a truck rear end with one hub bolted to a plate/rim set in concrete the other hub to the turbine would have several advantages. Your power shaft will be horizontal and the rear end ratio should speedup the rpms. You even get drum brakes that are cable operated. The main problems should be power losses and oil leakage.

What type and size of vawt makes a difference in bearings and support. The S rotor needs a bearing top and bottom while the H vawt needs beefy bearings in the middle. The eggbeaters needed bearings top and bottom. Small turbines can use bearings off of lots of stuff but the bigger turbines start needing bearings that can handle the loads both horizonal and vertical like some automotive agricultural or industrial bearings.

Good luck

Finis

[ffoegw]

Thanks for the info Finis.

I am concerned about the cemented hub/axle trying to turn. Do I need to worry and if so is there anything I can do to eliminate it.

Oil leakage!

Maybe I can squeeze a pile of grease (or silicone or cement) in through the downward cemented axle which should help keep the gear oil from leaking through to the seal in the first place?

Having access to a ready made braking feature is an interesting thought and I think may overcome some necessary safety issues that inspectors may have.

What is the ratio limits in a rear end?

I think that for every 2-3 turns of the drive shaft the wheel turns once, so because I would be sending the power the other way I would expect to get 2-3 rpms for every turn of the VAWT.

Does anyone know?

I am also thinking that with the weight of the rear end itself and the cement there might be enough stability not to worry about securing the top of the VAWT.

How concerned should I be about this?

Power loss!

Perhaps instead of a truck rear end I could use a lighter vehicles rear end which has rear drive. I am imagining the inefficiencies of turning lighter gears would be smaller. Might be hard to find.

Any input appreciated.

thanks

Geoff

[kitno455]

check my diary, i have a section on this. i cant answer many RE questions, but i know a bit about cars.

the rear axle ratio will depend upon the weight/age/engine of the vehicle, but will range between 2.7 and 4.11 for most consumer equipment. large trucks may have a bull gear input, with ratios going up to 6 or 8. Rockwell 2.5 ton axles of that type are relatively common. you get lower (higher number) gears when you have weak engines and tall tires. suzuki samuri comes to mind...

you have a couple issues to be aware of:

1. full floating axles are stronger than semi-floaters (non-floaters) but they are heavier and more costly. they will also rob more power.
   
2. diffs are designed to be run in the normal position. this keeps the low mounted pinion gear and bearings in the lube. stand it on the end, and the lower axle tube will fill with lube, and there will be none in the diff. you will need a couple gallons of oil to fill it...
   
3. it has a diff in it. if you spin one axle, the other will spin in the opposite direction, and the pinion will not spin at all.
   
   

if you hold one axle shaft fixed to the housing and turn the other, the pinion will actually turn at a different rate than you would expect- since the diff will act as a gear train. those gears are small, and not really designed to carry alot of torque.

so what you want is to lock the diff so it cant differentiate. search online for lincoln locker or spool or mini-spool. they are used by drag racers and offroaders.

allan

[kitno455]

4. how about getting an axle and cutting one tube off, and weld a cap over it. then you wont need so much lube, and there will be less leaking.
   
5. diff gears are really designed to be driven by the pinion in one direction. you will be driving them in the coast direction, which is weaker, and if you drive them backwards, its even worse. that said- lots of trucks have 'backwards' running front axles, and they work out ok.
   
6. the farther up or down the pinion is from the centerline of the axle as compaired to the size of the ring gear, the more heat it will make. as an example, the ford 9" rear is offset enough to have a second bearing. they usually need a diff cooler in road racing applications. the chevy 12 bolt is similar size, but does not need the cooler, cause the pinion is a little higher.
   
7. watch out for axles with c clips holding the shafts in. i have seen an axle button come off on the trail. it was not pretty.
   
   

allan

[vawtman]

Hi jeoff what size vawt are you planning on?It seems lately that everyone wants to build these big dinosours without testing small models first.I dont know why.The wind puts tremendous pressure on these things.Multiple small vawts would be better and alot cheaper.A rearend is strong but whats your plan from there up?

[georgeodjungle]

how big is it gonna be?

my 2 drum s rotor sits on a washing machine and i use the drum shaft & tranny from it.

started with the stock belt but when't to cogs & chain from a 10 speed bike.

way better start-up.

it's about 6:1.

i think i could go to 8 or 10:1.

but that would kill cut-in a bit.

the frame is from moble homes.

the bearings are flange type.

from surpluscenter.com, napa has them to.

i don't think you have to worrie about c clips or spider gears.

stop one side on a open diff axle will spin 2x faster.

your not making the same hp, tork & rpm as a car, truck or washer.

lots of great sites with s rotors and axles.

mostly water pumpers.

she has only been up for only 4 months now.

so who knows?

ice has been a lil prob.

other than that still running good.

hope this helps ya...

[ffoegw]

Thanks for this Allan,

So it wouldn't work unless I did cement one axle.

Never gave this much thought until you brought it up.

"diffs are designed to be run in the normal position. this keeps the low mounted pinion gear and bearings in the lube. stand it on the end, and the lower axle tube will fill with lube, and there will be none in the diff. you will need a couple gallons of oil to fill it... "

Without more oil it would be running dry!

"those gears are small, and not really designed to carry alot of torque."

It should be able to handle the same amout of torque that a truck can?

350hp perhaps?

Or am I missing something?

what do you think?

Thanks

Geoff

[ffoegw]

how big is it gonna be?

Hey Georgeo,

This is my math using formula's provided by windstuffnow.

Please imagine 4 spokes with 4 -  2ft x 4ft panels each.

I multiply by two at the end and not 4 because while one panel is slightly furled the opposite panel is proportionately furled to equal what I believe would be the pressure on a 4'x2' panel/sail held directly into the wind.

I hope that makes sense?

Also I am not certain of efficiencies.

In a 10mph wind will the outside panels be traveling at 10mph?

Like a canoe paddle in the water I would expect some slippage through the wind.

The efficiency number in the below example is saying that in a 10mph wind I would only get 2 mph on the outside.

Don't know if this is right and would welcome corrections.

    Wspeed        RPM        Efficiency   

    10.00        754.2857143        0.2   

Inches per panel    Ft per Panel    Distance from Center    Wind Pressure     

24.                     2.00             8.00                    3.936   
    
48.                     4.00             10.00                    3.936   
    
72.                     6.00             12.00                    3.936   
    
96.                     8.00             14.00                    3.936                   
    
    

Ft/Lbs torque    HP    Watts

31. 488    4.522267436    3373.611507
    
39. 36    5.652834294    4217.014384
    
47. 232    6.783401153    5060.41726
    
55. 104    7.913968012    5903.820137
    
173. 184    24.8724709    18554.86329 -(Add all 4 panels on one spoke.)
     
346. 368    49.74494179    37109.72658 -Times 2 (not 4 even though there are 4 spokes)
     
     

So in a 10mph wind I am expecting 49.7 hp   and  346.36 ft/lbs torque.

Can a rear end handle this?

Geoff

[healerenergy]

The VWAT design I am working on will use a thrust bearing and 2 alignment bearings in the tower.  The head will be keyed or splined to the shaft.  With no bearings in the head the shaft head union will be stronger.

[Gordy]

Geoff,

Thoughs small gears Allan refered to are commonly called "Spider gears", They are what makes the diff a diff to alow the two wheels to turn at differant speeds when turning a corner. Otherwise they would bind or drag (working against each other) and make the vehicle hard to steer, ect.

I made a poor mans posi rear end (when a kid) by welding the spiders solid. It turned OK if you could get the rears spining

Most diffs will have the ring/spider carrier bearings bolted in. This will alow you to remove what will be the lower axle shaft and weld / plug it's hole at the diff housing, then weld the spiders.

As far as oil I think you have two options,

 1, is to drill a new fill hole just above the top carrier bearing and fill with oil. "I" would use the litest oil I could get. Because there's gona be a lot of drag with the ring and carrier totaly submerged in oil like that. Espesaly in cold weather.

 2, Rig a small pump and plumbing to dribble oil on what will be the top carrier bearing and the pinion bearings and gear, That way you would only need the lower bearing in the oil. Been thinking about this axle mount for awhile now and want to test one of thoughs cheap drill chucked pumps, for flow at low rpm's. Don't know if the plastic housing will hold up to the oil though.

$.oo2 worth,

Gordy

[wind4Reg]

The fwd hubs sounds like the way to go to me. The bearings in them are tapered roller bearings which are the type we are looking for. Plus the benefit of having a splined PTO is just what is needed for VAWTs. It couldn't get any simpler that this.

wind4Reg

[thefinis]

Looks like you got lots of great answers on the rear axle. I think that you might need to do a search of the board for sails for more info on this type setup. I am afraid that your math is off on how it will work. A drag based machine like the one you are describing will most likely run somewhere in the .3 tsr range or the sails will travel at 3 or 4 miles an hour. A sail or drag based unit will make no power if it is moving the same speed as the wind, to extract power it must slow the wind down. The amount of net power it makes is tied to how much power it loses fighting the wind on the furling side and how well it extracts power from the sail side.

The rearend should take the power I think that you will make but the next problem is if it will eat too much power especially when trying to start. For a unit the size you are talking about you can use much smaller bearings.

Good luck

Finis

[thefinis]

Allan or anybody else what rearend would you recommend for the least amount of heat buildup/power loss? I don't think that most turbines will reach loads above what a good rearend will handle except maybe in storm winds. Just to make sure I have it right on the ratio for back driving diff if it is a 3.54 rearend then the pinion will spin at 3.54 times what the hub is turned at even with one hub locked?

Thanks

Finis

[ffoegw]

Sorry guys, the math is way wrong here.

I calculated the RPM using 10mph which mean the revolutions are RPH. So divide by 60 to get the real RPM.

If the rear end ratio is 1:3 then I can multiply the RPM by 3.

The error doesn't make difference on the torque.

This should allow for gearing up and still reaping a decent horse power.

I am starting to go to sleep at night thinking about this stuff.

Is this a symptom of something I should be concerned about?

Still need to do more math.

Geoff

[ffoegw]

Vawtman,

I've been thing about the same thing.

The larger the size of the structure the more concern I have for it collapsing upon itself.

Have been looking at materials to build it with and the cheapest seems to be ABS or PVC pipe.

I am wondering also how I might attach a 12" diameter Pipe to the rear end hub or axle.

Then I could hang the smaller guage ABS spokes through the 12" center pipe.

I calculated the power on my spreadsheet above assuming that I would use a 12 foot section of pipe to start the spokes and then hang a 2ft by 4ft sail every 2ft 6in and eventually reaching about 15 feet from the center after hanging 4 sails.

This model could easily be  resized if I run into structural problems.

Perhaps starting with one sail on each spoke first and adding on until I run into structural problems.

look forward to more of your suggestions and concerns.

regards

Geoff

[ffoegw]

Thats more than 00.2c worth.

"Most diffs will have the ring/spider carrier bearings bolted in. This will alow you to remove what will be the lower axle shaft and weld / plug it's hole at the diff housing, then weld the spiders."

I was thinking of welding it shut at the hub end instead of the diff housing.

Thanks for the lube suggestions.

Geoff

[ffoegw]

Hello Finis,

You were right.

My math was wrong.

It's still not perfect because I am not certain about the inefficiecies.

You said:

"A sail or drag based unit will make no power if it is moving the same speed as the wind, to extract power it must slow the wind down."

I am thinking that my terminology is wrong.

Instead of "inefficiencies" it should be "load".

Without any load the VAWT should indeed turn at the speed of the wind.

So if I remove my wrongly termed inefficiency number from the equation I should end up with the maximum possible load required to completely stop the sails in Xmph winds.

If the load applied is less than this the VAWT should at least start.

There probably are some other factors which are presently eluding me.

regards

Geoff

[ffoegw]

So by changing the wind speed to miles per minute and using a 1:3 ratio rear end as well as removing my wrongly termed inefficiency number I calculate that a 10mph wind should give me about 12.2 horsepower at 172 RPM coming off the drive shaft.

There seems to be lots of torque (372 ft/lb) which might allow for gearing up.

This should be enough to turn a 5000w generator in 10mph winds.

I ran some wind speed through the spreadsheet and got the following:

5. mph = 1.52hp
   
10. mph = 12.2hp
    
15. mph = 41.2hp
    
20. mph = 97.7hp
    
25. mph = 190.8hp
    
30. mph = 329.8hp
    
40. mph = 781.7hp
    
50. mph = 1526.8hp
    
60. mph = 2638.4hp
    
    

Now I am thinking I should use at least 2 sails per spoke so that when the speed gets too fast I can use one of the sails for an aerodynamic brake.

This is where I get concerned about the structure.

regards

Geoff

[ffoegw]

By employing a centrigfugal clutch I could have another say, 10,000w generator start after 15mph wind acheived. 42hp should be plenty to run it.

HHHHHHHHHHmmmmm

Geoff

[kitno455]

once you start building a vawt, there is going to be less data to go by, and you are going to have to figure more of it out on your own.

if i were you- i would not use the whole axle. instead, switch to a front hub from a 4x4 truck. my mid 80's full-size k5 blazer with 10 bolt would do nicely. you will get two widely spaced bearings on a hollow, hardened spindle, with a beautiful drive shaft passing thru. you also get a brake if you can figure out how to use it. scrap the upright, the spindle unbolts. watch out for auto-locking hubs, you will have to disable that, but thats pretty easy. dont try to get this at the auto-parts store. get it used at the salvage yard.

you can either use the axle shaft as-is and put a tranny/gen at the lower end (ground?), or you could cut the ujoint off the stub-shaft, and hang a 2-speed transfercase right below that.

go spend some time in the auto salvage yard. there are thousands of ways to do this.

i recommend against front hubs from a FWD car, unless you keep the outer part of the axle shaft with the big nut on it. if you dont- it will come apart eventually. 4x4 truck is made for greater abuse...

you will want to add a zerk fitting somewhere...

allan

[kitno455]

oh- and dont concrete any part of the axle into the ground. you will want to fix it eventually, and it would be nice to move it back to the shop for that....

you've got me thinking. i might draw something up. i have a spare t-case in the shed

allan

[vawtman]

Maybe you could use twin or triple towers on the outside of the unit.Then you wouldnt need the axle and you would have more freedom with gearing at the base.You could run supports across every 4ft with bearing and 1in shaft.Is this going to be in a wide open area?Im thinking swirling winds could cause problems.Not sure and good luck.

[thefinis]

Hey Geoff

Your figures look much better now but I haven't put a calculator to it yet. Your unit if drag based will never turn at tsr 1 except for decelerating after a gust. Why is due to the loads already in the design. The turbine has to push half of the structure into the wind and bearings are never friction free. It is amazing how much of the power available is lost to parasitic drag, friction, and inefficiencies. We base our math on making everything perfect no friction bearing, perfect airfoils, smooth flowing winds. To account for the real world an efficiency rating has to be figured in and it is usually just a good guess based on other machines of the same type.

Now there is hope due to the fact that a sail when tacking starts making lift and if that can be built into the sail design then you might could do tsr=1 unloaded.

Hang in there but I think you can start seeing why so many of the builders want to go bigger and bigger.

Keep going and good luck

Finis

[thefinis]

After more coffee and a little more thought I think that I am wrong. If you use lift to help a drag based machine to reach and hold tsr=1 even unloaded then it is a lift based unit because the working drag is gone at that speed.

Finis

[elvin1949]

Gordy

 For oiling the top carrier bearing,try something like the oil slinger on a vertical crank briggs lawnmower motor.

 Just a thought   not worth much

later

elvin

[elvin1949]

Geoff

V8 chevy   4 to 6 times that much horsepower

later

elvin

[ffoegw]

vawtman,

I plan to use 4 spokes with 4x    2ft x 4ft panels on each spoke.

The math for the output is in this thread somewhere.

If it works I might then go with straight  4ft x 8 ft plywood panels.

Regards

Geoff

[vawtman]

Hi geoff is there any way you could draw the idea up?I just cant picture how flat panels in any configuration would work well.A savonius still needs some curvature just to grab wind on one side and deflect on the other.Tsr1 sorta like a aneometer.Aneometers are lucky because they cover a small area and wind changes with height wont effect them.Plus they dont have to do any work other than keep track of how fast ther going.With a lift type vawt the blades dont care where the winds are coming from.They can achieve tsrs similar to hawts with tsrs over 6 and weigh alot more.But can also selfdestruct like a hawt if uncontrolled.I tried an idea I had by using 2 2ftx2ft panels mounted on each side of the rotor 8ft apart.They where set up like an open v.The thinking was that the it would grab the air compress it and would speed up.Didnt do crap at least at that time I could say I tried.Good Luck and it takes time.

[ffoegw]

Vawtman,

I am in the process of drawing a flash animation and will post when complete.

Maybe with some words I could bring you closer to what I am thinking of.

Imagine a sailboat with a rigid sail instead of a cloth sail.

It should still sail shouldn't it?

Now imagine what the sails have to do to keep the boat moving towards its destination no matter what direction the wind is in.

They would have to do the same on a vawt.

The only time the boat cannot make at least even a small amount of progress towards its destination is when the wind is directly in front.

Granted at angles close to the oncoming wind it is also difficult because the boat may capsize however, with a rotational and earth bound vawt the tolerances can be closer.

Therefore some forward movement from a rigid sail should be realized during at least 359 degrees.

I am giving away only one degree where there is not any desired motion towards the destination which, in the case of a vawt is rotational however even this might be too much.

It's like calculus, there is a point where there is no power obtained but its approach is infinite.

With 4 spokes it means that while one sail is reaching that point where it gets no power from the wind the sail on the opposing side is reaching the point where it gets maximum power from the wind.

The combined power realised from 4 rotational sails should therefore equal the power which could be realised with the wind directly behind 2 sails.

Try to think of something far simpler than your expectation.

Regards

Geoff