Wind Turbine Transmission

[gsw999]

are these blades available online, I had a nose about and couldnt find anything.

[wolfie]

just curious, are the blades set with an attack angle? or parallel to the plane of the hub?

[ChrisOlson]

are these blades available online, I had a nose about and couldnt find anything.

I order them from here:
http://royalwindandsolar.com/index.php?option=com_content&view=article&id=48&Itemid=57

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Chris

[ChrisOlson]

just curious, are the blades set with an attack angle? or parallel to the plane of the hub?

The airfoil has angle of attack but the angle varies at each station along the airfoil because it has no twist.  The GOE222 is a strange animal and it was originally developed by the Gottingen Aerodynamic Research Center in Germany and used for years on the Winchargers that powered many American farms before the Rural Electrification Act.  It's a very high lift airfoil that appears to work well from zero angle of attack to over 17 degrees without a big change in performance.  This will give you an idea of what it looks like:
http://www.ae.illinois.edu/m-selig/ads/afplots/goe222.gif

The best way I can describe its performance is that it's about as close to having variable pitch on a fixed pitch turbine as you're going to get.  The TSR operating range where these blades will work is wider than anything I've ever run.  I found out by accident that they'll quite happily spool up to 10+ TSR unloaded in the blink of an eye and they'll pull like a mule at 3 TSR.  As far as "ideal" TSR I haven't really arrived at a conclusion on that.  So I've been running them around 5 TSR at 15 mph wind speed and they seem to work pretty good on either side of that.

The rotor on this geared machine is running at 102 rpm at 25 volt cut-in at 6 mph, which works out to 7.4 TSR.  At 12 mph it's pushing 330 watts and the rotor is at 140 rpm.  At 20 mph the rotor is only up to 215 rpm and it's right at about 1,200 watts.  At 24 mph where it starts to fold up and furl the rotor is running at 250 rpm and about 1,340 watts.

So the rotor only gains about 150 rpm from cut-in and hits 5 TSR right in there about 15-16 mph wind speed and only drops to about 4.6 TSR where it starts to furl.  I tried a one-day experiment on the second turbine I built with a set of PowerMax 131's  (13.1 foot rotor) on it and they wouldn't drive it.  It would've even get above 12 amps with the PowerMax blades on it, and it struggled to get that far.  The S809 airfoil used on the PowerMax blades is known as a high-torque airfoil with self-speed limiting capability in high winds, but they won't drive this beast.
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Chris

I'm going to modify this post to make a footnote here:
I designed this machine from the ground up to use these blades.  I did a lot of research on the GOE222 airfoil, and I did a lot of testing with generators at the gear ratio I selected to arrive at what it takes to match the power curve of the rotor.  I did my original testing with 12 volt stators and got a good match.  But the machine was an animal in higher wind speeds and the amps on 12 volt was just ridiculous - I had hot wires, rectifiers with fans blowing on them to keep them cool, and all sorts of problems.  So I took what I learned from the 12 volt testing and applied it to 24 volt and it still works.  The machine is not near the animal on 24 volt because it cut the amps in half.

So, taking what I learned from the original, I can't recommend building a 12 volt version of this machine anymore.  It works but no matter what I did to try to keep the power down it would still go well over 100 amps without even really trying, and start to fry everything hooked to it.  So I finally had to give up on the 12 volt.

[gsw999]

Thats some sweet blades there , Im just starting to learn about wind turbines so Im not gonna pretend I understand what half of the stuff means but hopefully will do eventually.

[wolfie]

just curious, are the blades set with an attack angle? or parallel to the plane of the hub?

The airfoil has angle of attack but the angle varies at each station along the airfoil because it has no twist.  The GOE222 is a strange animal and it was originally developed by the Gottingen Aerodynamic Research Center in Germany and used for years on the Winchargers that powered many American farms before the Rural Electrification Act.  It's a very high lift airfoil that appears to work well from zero angle of attack to over 17 degrees without a big change in performance.  
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Chris

I have followed your build with interest, you did an awesome job on this.  I am a machinist with some electrical background so understood all that...but i am a little confused on the blades...if there is no twist, how does the angle of attack change along the chord stations??

[ChrisOlson]

I have followed your build with interest, you did an awesome job on this.  I am a machinist with some electrical background so understood all that...but i am a little confused on the blades...if there is no twist, how does the angle of attack change along the chord stations??

The angle of attack is the difference between the centerline of the cord and the relative wind the airfoil "sees".  It's affected by pitch angle, but it's not the same thing as pitch.

When you have a blade with no twist the outer stations of the airfoil operate at higher angle of attack then the inner stations.  Theoretically, this should be a self speed-limiting blade since the airfoil at the tip should go into stall (exceed the maximum angle of attack where it can generate lift) at extremely high rotational speeds.  At this point, I don't know where that is with 12 foot GOE222's.  On a day when I have 40-50 mph winds to play with I'm going to try unloading one and see what it does in free-spin.
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Chris

[tanner0441]

Hi Crys

If you are going to run you blades unloaded I hope you video it. That is the same profile that came with my Chinese copy, they are pultruded fibreglass. I don't know what that means all I do know is that they are heavy, rigid, start in low winds, tolerate the turbine thrashing about in turbulent conditions, and with the turbine shorted out they still start up and want to keep turning in strong winds. (That's why my setup currently has a rope over it trapping one of the blades)

My turbine is 200W but reading the adverts they use the same blade size (2.2mt rs) on the 500W units.  I have seen on at least two occasions my system doing 480+ W and the acceleration is impressive.

Brian.

[ChrisOlson]

If you are going to run you blades unloaded I hope you video it.

Basically I want to find out how much self speed-limiting capability they have.  I've run them unloaded at 25 mph and they got to 580 rpm, which is slightly over 10 TSR.  Typically, a blade that runs 10 TSR unloaded will pull at 6-7 TSR loaded at optimum.  These don't - 5 TSR appears to be optimum.

I want to find out if they run at that same tip speed at 40 or 50 mph, or if the tip drag from the tips being stalled starts to limit their speed at some point.  My gut feeling is that they won't exceed much past 650-700 rpm @ 40--50 mph because a larger and larger portion of the outer stations on the airfoil will start to stall and just be along for the ride, creating drag.  I suspect that because they make their best power at 5 TSR.  Running them at 6 TSR @ 20 mph drops their power output by about 18% over what I get at 5 TSR, which tells me they're already starting to self limit their rotational speed due to excessive tip drag at high angle of attack at the higher speeds.

But I want to test that theory at more wind speed to see if it's right.
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Chris

[clintonbriley]

Hey Chris,
great description on the goe222 blades.  Do you think there would be much improvement in efficiency if they had a twist to them?
Clint

[phil b]

Hi Chris, I'm interested in seeing your test results. I made a set of blades close to the 222 design.

http://fieldlines.com/board/index.php/topic,138086.0/topicseen.html

I measured the freq. on mine to determine RPMs. few years back. It goes to 650 RPM (unloaded) before the wind wouldn't push it any faster. The harder it is loaded, the harder it pulls. The silicon steel strip in the stator  works well but, it can't be stopped from turning by shorting the generator wiring at the pole.
It's been down for a almost a year from transmission line issues and I haven't got back to it. It will get a brake of some kind during the downtime.

[ChrisOlson]

Hey Chris,
great description on the goe222 blades.  Do you think there would be much improvement in efficiency if they had a twist to them?

Hi Clint,

I really don't know.  I don't think the old Winchargers that used these blades had twist.  I only know that they're pretty much animals.  When I put in my 24 volt bus to get the amps down I figured when the bus switches to 12 volt to equalize banks that it would cut the turbine's output way down when it clamps the turbine from 24 volts down to 12.  It doesn't, really.  If it's putting out 20 amps on 24 volt and the bus switches because the one bank is full, it just jumps the ammeter to 35-40 amps on 12 volt with the rotor turning so slow you can count the blades going around.

So I'm tickled pink with them the way they are because they appear to me to be about as close as you're going to get to a variable pitch rotor with fixed pitch blades.

Possibly by putting twist in the blade profile you could get more top end out of it.  But "bragging numbers" in high winds aren't what gets the work done day in and day out to power your house.
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Chris

[halfcrazy]

I measured the freq. on mine to determine RPMs. few years back. It goes to 650 RPM (unloaded) before the wind wouldn't push it any faster. The harder it is loaded, the harder it pulls. The silicon steel strip in the stator  works well but, it can't be stopped from turning by shorting the generator wiring at the pole.
It's been down for a almost a year from transmission line issues and I haven't got back to it. It will get a brake of some kind during the downtime.

This was a question I had from my experience with this style of blade unloaded it will only spin so fast period. Has this proven true with this particular blade? Chris have you tried this? Also with the typical Otherpower alternator and a set of these blades undersized by say a foot or 2 compared to the size they run will the turbine stop when shorted like it does now. We will be trying a set on the 17ft machine that we are running at my neighbors as soon as they ship them and had anticipated making it a 15-16ft machine. Any thoughts on this?

[ChrisOlson]

This was a question I had from my experience with this style of blade unloaded it will only spin so fast period. Has this proven true with this particular blade? Chris have you tried this?

I did it at 25 mph one day and they ran pretty dang fast.  Faster that I thought they would.  Like I said, I need to try it at higher wind speeds to see what the real limit is.

Also with the typical Otherpower alternator and a set of these blades undersized by say a foot or 2 compared to the size they run will the turbine stop when shorted like it does now. We will be trying a set on the 17ft machine that we are running at my neighbors as soon as they ship them and had anticipated making it a 15-16ft machine. Any thoughts on this?

I can't really comment on that other that to tell you that they don't like to stop.  I calculated one day that my 12 foot blades were making right close to 100 lb-ft of torque at only 80 rpm when it's "clamped" down to 12 volt by my auto-switching bus.  That's a lot of torque at only 80 rpm from a 12 foot rotor - right around 1.5 hp worth.

There's a lot of meat in the airfoil at the tips and even at very slow rpm those tips are running fast enough to fly and make lift.  You combine that with what's a very high-lift airfoil in the first place, and place it way out on the end of a long lever (the blade) where it has the most mechanical advantage on the shaft, and you got an animal that's hard to tame.

My advice is don't build a machine with these blades on it unless you incorporate some other means to stop it other than shorting the generator or you're going to have a lot of smoke escaping from your stuff.
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Chris

[phil b]

Halfcrazy, Mine won't be going back up until I install something to shut the turbine down. It was reassuring that the blades would only go just so fast.

I tested them in increments of about 10 mph, up to about 50. My wind speed indicator maxed out there at 50. I'm sure the wind went higher, but the blade RPM did not.  It was not a very scientific test. I checked the wind speed, then the turbine speed. Just eyeballing the DVM's.

One curious thing occurred at high wind speeds. The turbine would speed up to to ~650 RPM then down to ~600 RPM. It was like an engine running on the lean side fishing for more fuel. I assume it was stalling because of higher noise levels when RPM's were going down from 650. Different loads didn't seem to make a hoot.

I bought a set of blades from the guy in Plano, Tx., windmax, I think. On the same unit, his wouldn't shut down totally either, but they would move at less than 50 RPM with the turbine shorted.

The 222 blades generated much more power. That's what I'll use after learning how to harness them.

[opo]

Interesting observations Chris, it would be nice if we could determine somehow which section (or percentage) of the blade is stalled.  In the following web page one can compare different or similar airfoils to the goe222.

http://www.worldofkrauss.com/foils/435

 I've been playing around with some primitive (airfoil close to a triangle) untwisted wood blades lately @ 4ft diameter and they seem to like an angle of attack between 10 and 20 degrees, actually closer to 20 for my setup (primitive motor conversion).  The blades really "follow" wind speed increases (gusts within gusts for example).

Cheers,

Octavio

[Harold in CR]

 Chris wrote
 

I don't think the old Winchargers that used these blades had twist.

 I'm not sure what "OLD Winchargers" refers to. Back in 1976, I had to climb a 100' tower, that had a 24V "Wincharger" dangling by 1 bolt. It could have broken loose and taken me out. What I found was, the "Airbrakes" that Wincharger used, had worn completey out, and the controlling rods had pulled through the mounts on the brake shoes. These are the BLADE actuated brake shoes.

 The drum brake had been pulled on so tight, it actually wore out the lining and wore through the metal drum, until IT became ineffective. This was the normal 5'+ one piece blade. It had the 222 shape. There was NO twist toward the ends of the blade tips. I also had to replace 2 other blades, on other machines. these were all 12 or 24 volt machines. We sold both voltages.

 This tells me that the blade speed CAN be over what is estimated and will run away, so to speak. I believe the only REAL way to control runaway, is, a blade feathering "Governing" hub, if these blades are used.

 I'm on the verge of building such a governor, and will start a new thread about it. It's NOT as difficult as everyone thinks.

[ChrisOlson]

This tells me that the blade speed CAN be over what is estimated and will run away, so to speak. I believe the only REAL way to control runaway, is, a blade feathering "Governing" hub, if these blades are used.

It's not the only way.  I've flown these blades unloaded and the machine will fully furl running unloaded at lower wind speed than it will furl running under load. It was still running at 580 (I got a tach on it) fully furled with the rotor unloaded.  Which is pretty fast for 12 foot blades.  But if it doesn't run much faster than that in higher speeds with no load, then I'm going to consider that it simply won't go any faster because the tips go into serious stall.

Reconnecting the generator at that speed brought it down to 260 rpm and it faced right back into the wind.  Cranking the tail at that speed reduced the power to about 200 watts.

Even a Jacobs turns pretty serious rpm's in big winds with the blades feathered to 60 degrees.  A Jake starts to feather at ~25 mph and reaches full feather (60 degrees) at 40-45 mph where rotor thrust finally overcomes torque on the gearbox and it turns to the side of the tower.  But even fully feathered and turned to the side it continues to scream wide freaking open.  It does not slow down because as soon as it does the blades flatten out and speeds it back up.

Jake men call that "runnin' up against the governor" but a Jake varies from the machines we build because the Jake does not use feathering to control power - only for overspeed control.  The Jake has a outbound excited generator and power is controlled with the field in the generator.

Cranking the tail on my machine with the generator connected slows it WAAY down even in pretty stiff winds.  I still have the desire to know what will happen with it unloaded in very high winds, though, just to satisfy my own curiosity.  If it won't go faster than about 650 then variable pitch feathering will not do much good.
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Chris

[Harold in CR]

 You are probably more correct than I am, Chris. My info is over 30 years old and I'm going from a foggy memory.

  I should also have stated, that, at high wind destruction, what happens is, the wood starts to seperate along the Growth ring lines. Those are actually summer-winter rings, and, the summer rings are softer. The harmonic resonance that gets transmitted through the tips, starts that separation.

 One 4KW blade we had blow, there was nothing bigger than chopsticks to be found, except for the hub piece. That machine also was hanging by one bent bolt. That was also a 1 piece blade, at 16' long. That machine had the small fan on top of the nacelle, that cranked the machine out of the wind.

 I believe a piece of Pine tree wood got slung into the machine, and jammed the fan Blade system. Can't remember the brand name of that machine. Damn, it's tough getting old. 

[opo]

Hey Chris,

Have you noticed any turbulence generated by the goe222 blades affecting the mill tail? like shackeing it for instace.

I hope this is not too off-topic.

octavio

[ChrisOlson]

Have you noticed any turbulence generated by the goe222 blades affecting the mill tail? like shackeing it for instace.

No - no shaking, no turbulence.  I know from when I was test running it on the forklift that the air behind the blades is pretty still even at 15-18 mph wind speed.
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Chris

[halfcrazy]

Chris can you give me some details on your blade hub. We are mounting 8ft blades and your idea looks interesting and of course would need to be up-sized a bit for a 16ft machine.

[ChrisOlson]

Chris can you give me some details on your blade hub. We are mounting 8ft blades and your idea looks interesting and of course would need to be up-sized a bit for a 16ft machine.

 My turbines have an input shaft and most here stack stuff on redi-rod, so this may be different than for redi-rod ones.

The hub sleeve pilots on 4.75" of the input shaft and is keyed at the rear of the hub.  The input shaft is drilled and tapped and a bolt screws into the end of the shaft to secure the hub, as well as four set screws in the sleeve.  The rear plate on the latest ones is 12" diameter x 1/4" thick.  The root on the RWS blades is 2" thick x 6.25" wide and there's 1-1/2" x 1-1/2" x 1/8" angle that cradles each blade root, and those are welded to the rear plate.  The front plate is also 1/4" thick and is welded to the sleeve.  The blades have to slide in the cradles in between the two plates.  There's three bolts at the root thru the front plate and the rear plate, two at the sides midway on the root thru the cradles, and three at the end of the root near the start of the airfoil thru the cradles, so each blade root has 8 bolts thru it.

There's no room for adjustment for tip spacing, so it's critical that the cradles be welded on accurately the first time.  Tip tracking adjustment is done with shims between the cradles and the blade root.

The hub weldment was 28" in diameter on the original machine.  On #'s 2-4 I've build them 36" diameter, the bare hub weighs about 40 lbs and is more than adequate for 16 foot blades.  I'm building machine #'s 5 & 6 right now and when I get the hub completed for one of those I can post a picture of the latest hub design.
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Chris

[ChrisOlson]

I'm building machine #'s 5 & 6 right now and when I get the hub completed for one of those I can post a picture of the latest hub design.

I remembered I had mentioned something about posting a photo of the latest blade hub for my 12G machine, and this is a photo I snapped of one on a machine sitting on the bench:



And another one a little closer:





And here's yet another photo of it laying on top of a garbage can:



It's basically the same as the prototype machine except that it's a bit heavier, a big larger diameter, and uses a 1/4" thick back plate with a 10 gauge front pilot plate.  On the prototype machine I used three-tang rear and pilot plates, but I've now gone to round plates because it takes less time to cut them out.  With this style hub I can remove the blades and re-install them and the tip spacing and tracking is perfect every time, with no adjustments required.  The hub pictured is white because it's for black blades on this machine that's going to Canada.

As to the original question for mounting 16 foot GOE222 blades from Royal Wind & Solar, this hub will easily handle 16 foot blades.  There's a lot of steel in it.  I weighed the hub in the photo and it's 42 lbs and cradles the blade root all the way out to where the airfoil starts.  A fully assembled 12.3 foot rotor weighs 75 lbs (ash blades) with all the hardware on it:


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Chris

[dlenox]

halfcrazy,

Here is the blade hub that I made up for my 17' wind turbine about 4 yrs ago.


The back portion of the hub is simple piece of 1/4" flat steel. The front piece is also 1/4" thick but has some steel plates welded to 'cradle' the blade root between the front and back plate.

Hope this helps.

Dan Lenox

[vawtwindy]

awesome Chris.

[spitfire]

Chris
I have no words. I can only say, congratulations, congratulations
SpitsFire

[ChrisOlson]

I have no words. I can only say, congratulations, congratulations

Well, I don't know what congratulations are for.  A gear drive turbine with a durable transmission was one of my projects that I wanted to do for a long time.  The prototype machine posted here came off the tower when it had about 2,000 hours of running time on it and was replaced with a new one with some of my improvements in it.  I stepped the gear ratio to .4375:1, am using a UHMW chain guide inside there now, narrowed up the case by an inch with the main and generator shafts going all the way thru the case and the bearing housings piloted in bores in the case, and several other improvements.  I took the cover off the prototype transmission case and inspected it to see how it was doing and there was zero wear to any of the drive components inside it.  So I decided to test it to failure to see what it would take.

I rigged up some PTO shafts and drove my M&W dyno with it with my 806 diesel tractor.

I ran the 806 at PTO speed with the input shaft at 565 rpm (driven by the 540 shaft on the tractor).  The dyno had been sitting out in the machine shed all winter so I warmed up the oil in the dyno for 20 minutes then started tightening it up.

The tach on the dyno said 1,210 rpm (output shaft speed of the gearbox) and it held 150 lb-ft of torque for over an hour without the case of the transmission even warming at all.  The gauge said 34.6 hp.  I tighten up the brake on the dyno and the chain finally broke at 308.7 lb-ft @ 1156 rpm.  67.9 hp.  Being a 12 foot turbine can maybe make 4-5 hp the transmission is pretty massively over-built.  But this one provided the most fun of any turbine I've flown.  And it sounds totally cool on the tower because the generator hums like a heavily loaded electric motor with absolutely none of the low frequency vibration inherent in direct drive turbines.

Geared machines are all I'm building now.
--
Chris

[Dave B]

Great information Chris, thank you for sharing your work and testing besides. Let us know how that locking max furling system works out too, I know we need some decent wind for you to give report on it. Thanks again,  Dave B.

[ChrisOlson]

Great information Chris, thank you for sharing your work and testing besides. Let us know how that locking max furling system works out too, I know we need some decent wind for you to give report on it. Thanks again

Will do Dave - I got one of those Canadian machines on my tower (complete with the big red maple leaf on it    ) with that furling system on it.  But it's just been dilly-dallying around at 1-1.2 kW and the wind has never blown hard enough to fully furl it.  If I got it adjusted right it should allow up to 75-80 amps (2.2 - 2.4 kWh) then lock and hold the machine furled.  I'll update on that as soon as I see it work (or not work).
--
Chris

[gsw999]

Awesome work

[defed]

out of curiosity, when you did your rpm vs wattage tests (chart on page 7), did you record the torque required for each output?  if not, do you have any idea of the torque on the generator shaft at given outputs?

the only torque readings i see are when you pushed the transmission to failure on the dyno!

[fabricator]

Besides being practically impossible for anyone but an extremely sophisticated testing laboratory what possible meaning would such readings have? Seeing as how he already has an rpm vs wattage plot.
I've never seen an input torque/rpm/wattage plot for any wind turbine, direct drive or geared.