Author Topic: Fly weight governer on 20 foot machine (Read 23313 times)

Royalwdg · « **on:** February 27, 2012, 12:34:44 PM »

Last summer I completed my fly-weight governer on my 20 foot machine. Not a new concept except for it's application. I have a problem with the unpredictability and inconsistent furling of the tail waggers. I wanted rpm control regardless of the electrical load. My goe222 Royal Wind blades are carved at 10 degrees. When it furls it pitches forward 22 more degrees. I tuned it on my welding bench with a huge flat belt reaching from my old lathe. Adjusting the weights and springs give me a lot of room to play. The test was done without blades. The weight of the blades caused more resistance to furling so needless to say it ran a little fast first time up on the tower. Brought it back down and moved the weights out on hole and it helped. It still runs a little fast. I often see 280 rpm with 6200 watts output. I'm using this for heating right now. I stays right in the wind and no more swinging around except for wind directional changes. Dave M

Ungrounded Lightning Rod · « **Reply #1 on:** February 27, 2012, 12:54:17 PM »

Cute design.

When I first looked at it I thought "How does that even work? The weights are pivoted at right angles to the radius." Then I realized that they were offset from the centerline, so they end up farther from the center when they rotate away from the camera.

Increasing force-per-rpm with distance, compensated by the sine curve function of the pivot.

Royalwdg · « **Reply #2 on:** February 27, 2012, 01:17:01 PM »

This method gives the turbine a little time to slow down before it unfurls. It works very smooth. At times I've heard it hanging at about half way. Of course you can't see anything going on. It's pretty much all in what it sounds like and watching the rpm stay the same or back off as the wind increases. Dave M

DanB · « **Reply #3 on:** February 27, 2012, 04:22:32 PM »

it looks quite brilliant!

oztules · « **Reply #4 on:** February 27, 2012, 04:29:16 PM »

I just love these things....if you have more time and pictures.... feel free to use both...

.................oztules

cdog · « **Reply #5 on:** February 27, 2012, 04:50:15 PM »

So would it be feasable to let it pitch enough so you don't need furling at all??

Flux · « **Reply #6 on:** February 27, 2012, 04:50:27 PM »

I always found it difficult to see how the controlling force was derived with the normal layout with the fly weights out at the blade root ( Dunlite etc). It seems much more obvious when you move them in close to the centre. I like it.

Flux

fabricator · « **Reply #7 on:** February 27, 2012, 07:00:55 PM »

Was it just a geometry problem that caused two legs of the spider to need short legs to get 120 degrees between them?

cdog · « **Reply #8 on:** February 27, 2012, 07:25:30 PM »

Three legs....eight bolts....

? Id say thats y....

Royalwdg · « **Reply #9 on:** February 27, 2012, 09:37:29 PM »

Thanks everyone for the comments. Yes the 8 bolt pattern blending with the three blade system took a little finagalling. Computers and old paper and pencil is all it took. One thing I didn't forsee was that this blade profile is high lift. At 10 degrees pitch my lift vector is tilted 10 degrees in the direction of travel. When it pitches forward the lift vector also tilts to 30 degrees toward the direction of travel. That keeps things moving along better than I wanted with high torque besides. At least my first flight wasn't too far out of wack so it survived until adjustments were made. Dave M

Ungrounded Lightning Rod · « **Reply #10 on:** February 28, 2012, 01:19:03 AM »

Quote from: cdog on February 27, 2012, 04:50:15 PM

So would it be feasable to let it pitch enough so you don't need furling at all??

Changing the pitch IS furling. So is turning away from the wind. So is shortening the blades (hard to do with a propeller-style but easy with sails). So is anything else that reduces the power intercepted by the turbine.

I presume you meant "So it would be feasible to furl enough by changing the pitch that you don't need to also furl by turning away from the wind?"

cdog · « **Reply #11 on:** February 28, 2012, 05:15:38 AM »

Yes that is exactly what i meant....

jlt · « **Reply #12 on:** February 28, 2012, 11:04:36 AM »

That is one cool governor.
Any chance we could more info on the size of things.

jlt

Royalwdg · « **Reply #13 on:** February 28, 2012, 12:30:24 PM »

I tend to overbuild. A little. The back plate is 1/2" thick 24" in diameter. 1 1/2" solid CRS through the pillow block bearings. 1/4" plates making up the blade mounts. I am currently building a smaller unit for 12' diameter machines aiming at some of my Wincharger customers. But the back plate bolt pattern can be drilled to adapt to anything. The cover is 18 ga. steel to keep the weather off. Dave M

cdog · « **Reply #14 on:** February 28, 2012, 01:13:27 PM »

Beautiful job!

midwoud1 · « **Reply #15 on:** February 28, 2012, 01:59:47 PM »

Hi Dave .
Very nice piece of work . Craft. I'm a fan of pitchcontrol.
How do you bring your tower down?, please more pictures and videos.
Are you using sliprings?
All the best.
Frans.

fabricator · « **Reply #16 on:** February 28, 2012, 06:54:23 PM »

It's hard to tell without any real perspective but it looks like you have about 1/2" travel in the spider, how much movement does that give you on the blade shafts?

Royalwdg · « **Reply #17 on:** February 28, 2012, 09:23:49 PM »

Hey fabricator, yes the travel on the spider seems short, but the weight arm is already starting at 45 degrees. I'm getting 22 degrees rotation on the blade shaft. The weights actually hit the cover when fully furled. So the cover is probably acting as my stop. Dave M.

cdog · « **Reply #18 on:** February 28, 2012, 09:26:56 PM »

I have to ask again.......with more pitch range of motion allowed would you still feel the need for a furling tail?

RP · « **Reply #19 on:** February 28, 2012, 09:33:57 PM »

Looking at the 2nd picture (no blades, laying on it's side), I'd say there is no furling tail.

There's no offset, no angle on the tail bracket and no obvious pivot mechanism for the tail so I believe he's relying only on the governor system to manage over-speed.

fabricator · « **Reply #20 on:** February 28, 2012, 09:57:18 PM »

Really cool, it's similar to the older flyweight Jacobs design but more refined.

Royalwdg · « **Reply #21 on:** February 28, 2012, 10:12:09 PM »

The tail is not self furling. Yes it's on center on a straight hinge. I'm using farm hay rake springs to keep it straight when flying. The springs hold it out like the old Winchargers. The cable, pulled from the boat winch at the bottom of the tower, over comes the spring to park the machine with tail folded. Quick wind direction changes in one direction actually pushes the tail against the springs and dampens the movement, which I didn't expect but I like it now that I've seen it in fast changing winds. The other direction just keep the tail against the stop. Dave M.

Valalvax · « **Reply #22 on:** February 29, 2012, 02:01:46 AM »

:/ could someone explain to me how this works? Use really little words

Flux · « **Reply #23 on:** February 29, 2012, 03:16:18 AM »

The big rectangular blocks are weights and as the speed increases they try to move to the farthest point. In doing so they rotate the blade shafts to feather the blades. The force due to cf on the weights is balanced by the three springs on the centre linkage.

This centre part rotates via the 3 jointed links and forces the 3 blades to move in step.

Up to a certain speed the force on the weights can't overcome the pull of the springs but at a critical speed they do and the blades turn to reduce the prop output and maintain near constant speed.

If you can find a diagram of the Jacobs flyball governor you may find it easier to understand how the weights cause blade rotation but the idea is the same.

Flux

midwoud1 · « **Reply #24 on:** February 29, 2012, 03:52:33 AM »

Hi Dave.
The blades can be feathered 22 degrees. There is no auto furling tail.
What happens if the wind picks up suddenly ?
With a prop diam 20 foot you can't stop it with the electrical brake switch.
You have no time to change or to park the tail with the boat-winch.
No problem with full feathered blades.

- Frans -

Menelaos · « **Reply #25 on:** February 29, 2012, 08:38:21 AM »

really nice Job!

Maybe its just me...but What scares me are the bearings used to hold the blade. They are not made to take a lot of axial forces and the centrifugal forces of those heavy blades are really high in good winds. Not sure how long those ball bearings survive.
Also what I have discovered from my own experiences ( I also started with this kind of bearings in my early designs) is that after some time, the balls in the bearings will wear out on one side as they always stay in the same position. Vibrations and the thrust radial forces to the bearings, flatten the balls. After some time they will not turn properly anymore or at least it will become harder to turn them.

Thats what happened to german tanks in worldwar II. They put those tanks on trains to drive them to russia. When they arrived, all the bearings were damaged and the tanks were not abe to move as the vibrations on the train damaged the balls...

Just my 2 cents ;-)

Max

Royalwdg · « **Reply #26 on:** February 29, 2012, 08:41:27 AM »

Frans, The pitch change is fairly quick. It is a smooth, non-banging, type of reaction. Sometimes it even hangs about half way totally depending on RPM. So far this system is proving itself. I've let it go on days with wind warnings of gusts to 50 mph. My wind only topped out at 45 that day. If I here those kind of weather reports I usually park it for the day. I've repaired a lot of damage. It's not only costly but discouraging. I have let it run with no electrical load in a 20 mph wind. The blades pitched as normal. It just gets up to furling rpm a lot sooner. Dave M.

Royalwdg · « **Reply #27 on:** February 29, 2012, 08:57:05 AM »

Max, I hear ya on the bearing wear issue. That is one of my concerns that I'll adress after about a years worth of operation. Unlike the tanks on the train I'll never have to rotate my bearings more than their wear area. As far as side load goes, my friend Dean Williams informed me of angular set bearings. I think thats the term he used. These are made for side loading more than standerd bearings. I don't have those. I'm currently using a cam follower bearing to take my side load. It is screw into the 1 1/2 blade shafts in between the pillow blocks. This goes up against a stop block. You can see in the pictures the back side if the hole where the cam follower is mounted. Dave M.

ChrisOlson · « **Reply #28 on:** February 29, 2012, 05:22:42 PM »

Quote from: Royalwdg on February 29, 2012, 08:57:05 AM

As far as side load goes, my friend Dean Williams informed me of angular set bearings. I think thats the term he used.

Dual row angular contact ball bearings, made by Svenska Kullagerfabriken AB (SKF) in Gothenburg, Sweden. These are the bearings I use on the mainshaft in my turbine gearboxes.

http://www.skf.com/portal/skf/home/products?maincatalogue=1&lang=en&newlink=1_3_1

However, I wouldn't use them on blade shafts because this type of bearing needs to run for proper wear and lubrication because they rely on hydrodynamics to properly lubricate them. As Max stated, they will "hammer out" - what really happens is that the contact surfaces in the bearing aren't moving, and consequently hydrodynamic lubrication does not work. So the balls and races push the lubricant out and they go metal on metal in one spot and fail.

I would use a regular flange type thrust bearing with a nylon or teflon thrust bushing designed for the job.
--
Chris

cdog · « **Reply #29 on:** February 29, 2012, 05:34:31 PM »

Do commercial turbines have pressurized bearings like an auto crankshaft?

fabricator · « **Reply #30 on:** February 29, 2012, 08:13:19 PM »

I'm sure they have pretty high tech bearings and they are certainly lubricated.

Menelaos · « **Reply #31 on:** February 29, 2012, 09:14:36 PM »

What people just will not believe but what works grat as a bearing for that kind of use are standard threaded rods. A friend of mine that lives in Luxembourg has used that kind of "bearing" already 25 years ago and those turbines are still running in the carebian sea until now. I did already post pictures of that mechainism on this discussion bord before withour great nitice. Anyway, using a threaded rod is a great idea for this purpose and time has shown that it works out well. This is as well the type of bearing I now use on my designs for the passive pitch mechanisms.

Max

kensue49 · « **Reply #32 on:** February 29, 2012, 09:26:49 PM »

Could you post a link to that post.
I haven't found it yet Max.
Kenneth

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Author Topic: Fly weight governer on 20 foot machine (Read 23313 times)