Author Topic: Furling Video (Read 5235 times)

ChrisOlson · « **on:** March 30, 2010, 08:10:23 PM »

Here it is on a 10 foot 48 volt machine on my new tower. My little camera can only take 3 minutes of video before the card is full and I didn't catch a snip with it at full furl in the time allowed. But it demonstrates how smoothly the system works:

http://www.youtube.com/watch?v=NS_6OCZt7rI

I had the top extension tube down in the tower so I could more easily lower it to the ground to adjust the furling cylinder (it's a tiling, free standing tower). So it wasn't in ideal wind - sort of gusty and variable. Once I extended the center tube in the tower and got it up in clean air it flew straight and true and ran 50-100% furled the rest of the day in the 25-35 mph wind we had here.

I have the hard stops on the tail on these older machines set like a Bergey at 75° from the tail being straight in back of the rotor. On my newer machines I've gone to setting the hard stops from 5° to the anti-furl side to 80° from the tail being straight back - the tail can move 85° total swing.

I adjusted this one so it runs fully furled at 1,400-1,500 watts.

--

Chris

97fishmt · « **Reply #1 on:** March 30, 2010, 09:21:17 PM »

I would get rid of the spings and get a gravity furling system going.

Looks like good wind why are you trying to defeat the kiss system?

Tinbendr · « **Reply #2 on:** March 31, 2010, 05:09:40 AM »

Hey Chris,

Do us a favor and buy a cordless microphone for your camera.

They have inexpensive ones on EBay in the $9-$30 range.

Thanks for sharing.

ChrisOlson · « **Reply #3 on:** March 31, 2010, 06:36:18 AM »

I would get rid of the spings and get a gravity furling system going.

Been there, done that. I don't do things other people do just because everybody thinks it's the thing to do. Nor do I follow other people's plans when I build something. I invent and fly my own designs.

--

Chris

TomW · « **Reply #4 on:** March 31, 2010, 07:32:46 AM »

Chris;

Exactly the kind of action and attitude that pushes this whole show along. The doing it in new ways.

I think the "stick to the plan" approach is favored here because many [dare I say most] folks just want a build that works right off the bench. Not everyone has the time, resources and ambition to try new stuff. There is really no one way for all method since everyone has a different set of circumstances. Everything from those who cannot weld worth spit [myself] to master fabricators. That is a broad audience

You seem to have come up with a nice divergence from the common design here.

These bigger machines are a whole other animal, IMHO.

Thanks for the share. Hope it works long term for you.

Tom

youmanskids · « **Reply #5 on:** March 31, 2010, 07:58:31 AM »

looks good and smooth but the total tail travel only looks like 30-40 degrees, can you get good control of speed with this small amout of furling? my standard angle-hinge tail moves 85 deg.

I also wonder if your design would be better for the 17 footers ( more easily adjustable) where did you get the adjustable cylinder ? thanks and nice job. Roger

ChrisOlson · « **Reply #6 on:** March 31, 2010, 07:59:50 AM »

I think the "stick to the plan" approach is favored here because many [dare I say most] folks just want a build that works right off the bench

Right. I'm not the typical homebuilder. Most of the guys here just want to follow the plans and build a machine that works. I've already built plenty of turbines that work and it's no longer a challenge. So I like to try new things to make them work better.

I realize that most guys here are going to look at this and they're scared of it - or at the best, skeptical, because it's not in the plans. That's fine. I don't follow anybody's plans so my stuff is going to be different.

Back thru the eons of time, changing anything has never been well accepted by people. It's been called "reinventing the wheel". But if the wheel was never reinvented it would still be a round piece of wood and progress would come to a grinding halt.

--

Chris

oldculett · « **Reply #7 on:** March 31, 2010, 08:05:09 AM »

Thanks for sharing. Looks like it woorks good.

SparWeb · « **Reply #8 on:** March 31, 2010, 08:57:51 AM »

Hi Chris,

Always fun to watch these things run isn't it?!

I only see about 30 degrees of swing in the tail. I know it's easier to ask than to do, because the opportunities are rare, but a video of the tail tucked up behind the disk would open the sceptics' eyes much more. Even a photograph would do, really. I've got some pictures like these from my own, when I was tuning my machine's furling. I tied a streamer to the tail, too, which made the geometry pretty obvious.

What to you do for wind speed measurement/estimation?

ChrisOlson · « **Reply #9 on:** March 31, 2010, 09:17:20 AM »

This one actually moves 75° The hard stops are set so the tail can go from straight back from the rotor to 75° from straight back. I have another video from when I built the first one that explains it a bit better (I think this is the right link):

http://www.youtube.com/user/OlsonFarms#p/a/u/0/qgjwYP2OSz0

That 75° I picked, because it seems to work well for Bergey. But it didn't work well for me. On my 8 footer I've seen it run at well over (my) rated power for up to 15 seconds fully furled in powerful wind. The 10 footers seem to be more well-behaved and do not spool up as quickly as that little 8 footer when a powerful gust hits. The 8 can easily reach over 700 rpm in a heartbeat and push well over 1 kW, which is way too high for the generator, sustained. The 10's stall out over 400.

At any rate, I've changed that - I now have the hard stops set so the tail can go from 5° to the anti-furl side to 80° from straight back.

That seems to work fine. I've found that the tail never runs completely parallel with the wind with a good load on the tail during furling. The tail is just a wing with no airfoil to create lift. So when it has to counteract the rotor thrust the only way it can make enough lift to do it is to run at a slight angle of attack - about 10°

Liken this to holding a piece of plywood in the wind. Hold the piece of plywood edge-on in the wind and nothing happens. It creates no force either way. But tip it 10° to the wind and now you have force - lift. The tail has to do the same thing to be able to apply the required pressure to the offset point (or torque to the yaw tube) to fight the rotor's tendency to turn out of the wind.

This 10 footer has my old-style tail on it - my other 10 and new 13 that I just built both have the new-style with 85° of total tail boom travel.

--

Chris

ghurd · « **Reply #10 on:** March 31, 2010, 09:22:10 AM »

It sure is smooth.

A pic would help me!

It just doesn't look like it can furl a lot more because of the mechanical dimensions (the cylinder being too long when compressed), but I don't really know anything about how the cylinder works.

For people having a hard time with the basic furling concept, this Aermotor furling video is pretty cool,

http://www.youtube.com/watch?v=WOzDkIfzYlg

G-

ChrisOlson · « **Reply #11 on:** March 31, 2010, 09:30:56 AM »

What to you do for wind speed measurement/estimation?

I forgot to answer this, I guess.

I have (had) a little home weather station with an anemometer on it. It's a wireless unit and it transmits the data to a base station in my shop office. But the anemometer recently quit working on it. I bought the thing off eBay, and it wasn't all that expensive, but I've tried replacing the batteries in the sensor unit and the anemometer refuses to work anymore.

But I don't adjust my furling by wind speed anyway. I adjust it by generator output. If I design my generator to put out 1,000 watts I adjust the furling so it runs fully furled at 800, leaving a little "cushion".

The tail wagging method of controlling turbine output is NEVER 100% accurate. Those machines can get hit by a powerful gust and run fully furled, at over rated output, for a LONG time sometimes. Many people here have described it and it's always assumed it's something wrong in the setup. Chances are, in some cases it's not. The day I adjusted my 8 footer it was very well behaved and furled nicely at 60 amps (12 volt). Then I saw it push over 100 amps for 15 seconds one day when we had very powerful gusts here on the flats - and it was completely folded up - the furling worked fine - but getting it to stall and spool down didn't.

The only 100% accurate method (I think) to control output is a variable pitch governor. And I suspect that's why all the Big Boys have it.

--

Chris

ChrisOlson · « **Reply #12 on:** March 31, 2010, 12:19:12 PM »

I built the cylinders, Roger. If you look in my photo uploads there should be some photos of it in there on the bench, showing the internal parts.

It will easily work on a 17 (with the appropriate stroke and spring pressure). Jacobs has been using spring loaded tails on their machines for years, mainly to prevent damage to the boom assembly in side gusts, but also for initial furling before the prop governor starts feathering the blades. I just built a 13 with one on it that has 11" of stroke using Hillman #62 springs in it. I don't have that machine up yet - I'm working on building a tower for it.

The total tail travel on this one is 75°. My newer ones have 85° of movement. In the video it never got to fully furled. But when it does it turns the rotor at about 80-85° to the wind due to the tail itself running at approximately 10° to the wind direction.

I started working on this concept awhile back because I got tired of having the tail weigh a specific amount, and be limited on the length of the boom. This arrangement allows me to use whatever size (and weight) tail feather I want, and to fly a long tail boom that would otherwise not work with an angled hinge system.

Wind turbines work by having a higher pressure in front of the blades than they have in back. Without that pressure difference they wouldn't even run. Getting the tail further back, out of the wake turbulence and low pressure zone in back of the blades gives better steering control, keeps the rotor more accurately steered into variable winds and enhances total kWh output because the rotor maintains a more constant speed. Since I started doing this my ammeters no longer dance up and down the scale like they used to when I was restricted by the required design parameters of the old gravity tail.

On larger machines with gravity tails, builders go to great lengths to get the tail light enough to even work properly. With this, you don't have to worry about that.

The gravity/angled hinge tail is limited in what it can do. You don't see it on bigger machines, like the Jacobs, because things get too heavy and it won't stand up to the test of time and high winds. I'm just adapting what Jacobs has done to these smaller machines.

--

Chris

Ungrounded Lightning Rod · « **Reply #13 on:** March 31, 2010, 12:39:20 PM »

Hear hear! (Worked in the Auto Industry engineering: Detroit reinvented the wheel several times a year back in the day, and still does it to some extent. Not just cosmetics, either.)

I'm skeptical, too, but just from concern that an enclosed spring might have failure modes from dust in/through the sliding joint, rubbing in the enclosure, or just fatigue. The tilted pivot design works as long as the hinge does - for whatever value of "works" it does. Gravity doesn't wear out.

I bet your cylinder could also do a bit of damping if the airflow around the base of the spring support is restricted (though this would produce pressure differences where the rod enters, potentially pumping in dust). I've wondered if damping would help stabilize the yaw when the wind picks up a bit of turbulence and whether the aerodynamics of the tail provides some damping.

Thought about piston-into-cup designs (rather than bumpers) for cushioning and/or absorbing the energy at stops, but that dust issue comes up again, redoubled by the specter of the cup filling with rain, snow, or ice, followed by mud. Decided if I try any damping games I'd use magnets and a copper disk - which could be shaped to provide position-dependent damping. (Still symmetrical on direction, which probably wouldn't be an issue or might actually help in the "bumper" case. But it wouldn't tend to foul except if you have magnetic dust in the area, which would also be a problem for the axial flux alternators...)

Tapers in the cylinder changing the "piston" clearance (along with the triangle geometry of your cylinder setup) would let you play with position-dependent damping in your design. And you could use valves, or even fill it with oil ala a shock absorber. (I've imagined using a door closer - maybe with the spring swapped to the opposite end, in a geometry like yours.)

Flux · « **Reply #14 on:** March 31, 2010, 01:23:31 PM »

I agree with you that limiting movement to 75 deg won't work with most blades, there is something very different about Bergey blades. They work with much less offset then most blades need.

I use my tails to stop the machines manually and they do need to go to very near 90 deg. Stooping it at 75 deg would still let it running and producing serious power.

If you don't need the manual shut down then the fully furled position will still need to keep it below rated power in the highest winds.

Flux

Ungrounded Lightning Rod · « **Reply #15 on:** March 31, 2010, 01:37:17 PM »

I started working on this concept awhile back because I got tired of having the tail weigh a specific amount, and be limited on the length of the boom.

What limit on the length of the boom? I'm unaware of such a limit.

bob golding · « **Reply #16 on:** March 31, 2010, 03:20:53 PM »

hi chris,

looks good. i notice you say you have 8.5 inches offset on a 10 foot machine. this seems a lot. i only have 4.5 inches on mine. my turbine does dart around a bit, especially last night in 70 mph winds, but it is still there. i have noticed that the current does jump around a lot. i see up to 25 amps into 24 volts max which is fine and within design limits. i have a very short tail. i did try a longer tail but then it didnt furl at all,so went back to the tried and trusted method. i would like to experiment with this idea, looks interesting. i can see how the longer tail would help stabilise the whole system. as regards dust and stuff getting into the spring you could use steering rack gaiters from a car. seem to remember volvo ones are quite long.

i still have a gut feeling the blade design makes a lot more difference than is appreciated. i am planning a new set of blades for this summer. still deciding on the best design. the ones on there at the moment are windstuff now eds design. i am going to try hughs design to try and improve the low wind performance. its heavily stalled at the moment, but thats fine given the stator burnouts i have had in the past in gales. interesting stuff thanks for sharing.

bob golding

youmanskids · « **Reply #17 on:** March 31, 2010, 06:33:54 PM »

thanks for the reply chris, I looked at your pics and videos (nice shop BTW), looks like you could use a 1 1/2 inch pipe for the cylinder and make it fairly simply with scrap steel. why the differnt size springs and what "force-length" are they? is it for increased tension as it compresses sequential spring sizes?

Dust wouldn't seem to me to be a problem for a mechanical cylinder like yours (this is not a piston type setup). ice, however, inside could shut you down, but would seem to be unlikely.

I like the concept alot, simple, and adjustable... just want to see it work on a big one (17-20 footer if possible)

keep the ideas coming, and thanks for the help. Roger

ChrisOlson · « **Reply #18 on:** March 31, 2010, 08:30:12 PM »

I experimented with different springs and found if you use one long spring it's too progressive. In other words, it's too easy to compress it at first, then it reaches the right pressure towards the end. I wanted a more constant rate outfit that matches what an angled hinge does.

So, using a spring scale to measure the furling force on a machine that that had been flown and successfully furled with the angled hinge, I arrived at what I needed for spring pressure to mimic that. Using a stack of shorter springs is what did the trick.

All that cylinder is is a piece of 1" black pipe with springs in it and a rod pushing on the springs. There's nothing complicated about it. I pressed a 1/2" brass bushing into the pipe cap on the end of it to give the rod something to slide on. I used a dry graphite lubricant on the rod and inside the bore. Then when I assembled it I packed some grease in the cap before I screwed it on. Every time the rod retracts and extends the grease keeps the rod a little "wet" with grease.

As the final test I laid the thing on the shop floor and pressure washed it. Then with the rod wet I compressed and released the cylinder several times. I took it apart to see if water got in it - not a single drop in there - and there's no seal on the shaft. That's when I was satisfied that it was going to work.

I put that first one on the machine and it flew for two or three weeks before we even got enough wind to furl it. I adjusted it that day to what I wanted for output and haven't touched it since. Since then I've built three more of them for my other machines. If you buy everything new you end up with around $17 in building one.

--

Chris

ChrisOlson · « **Reply #19 on:** March 31, 2010, 08:35:06 PM »

Take a 10 foot machine with a 108" tail, 7.2 square feet of fin. How much can the tail weigh and still get this thing to furl? There's your built-in limitation on tail length with a gravity/angled hinge system.

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Chris

ChrisOlson · « **Reply #20 on:** March 31, 2010, 08:48:14 PM »

Yes, I have 8.5" - 7% of the rotor diameter for offset. To my way of thinking, 4.5" would make for a pretty squirrelly machine.

Dust will not affect this cylinder. You could sand blast it and it will still work unless the shaft got pitted by the sand blaster and wouldn't slide anymore. I pressure washed the thing for about 3-4 minutes at 1,500 psi, then actuated it several times to see if water got in it. It didn't.

With the combination of grease being packed in the cap of the cylinder, and using a brass bushing for the rod to slide on in the end cap, it wipes all the water off when it actuates. There's nothing precision in it to wear out, short of the brass bushing on the shaft, and even that's a loose fit.

Some people are afraid of using springs to control furling because they might fail, but those people shouldn't be driving a car then. The average automobile has scores of springs in it used for everything from the suspension to closing the valves in the engine. How many times do those springs fail? Not very often. And if a spring did fail in this cylinder all it will do is furl early.

--

Chris

TomW · « **Reply #21 on:** April 01, 2010, 06:41:28 AM »

Chris;

And if a spring did fail in this cylinder all it will do is furl early.

Appears to "fail safe" which is good it seems compared to springs holding something in tension that fails?

I like that bit and the multiple springs approach for a way to get the compression curve you want.

Thanks again for explaining.

Tom

Ungrounded Lightning Rod · « **Reply #22 on:** April 01, 2010, 07:31:51 PM »

How far out can you get it to furl? If it weren't for the increasing weight of the boom you could extend it until the curvature of the earth took it out of the lower atmosphere. Curve the boom and you could go a quarter of the way around the Earth.

The longer lever means a given weight pulls down harder and thus torques the pivot harder. But it also means that a given side force torques the pivot harder in the other direction, exactly in proportion.

Another way to look at it is to notice that the tail fin is climbing an inclined plane - the plane of its rotation - on an essentially frictionless surface (due to the low friction of the hinge pivot). The angle of the surface is set solely by the angles of the pivot tilt and the current angle of the hinge, and the force fighting its climb is solely its weight multiplied by the slope. None of these factors is affected by the length of the boom. So a given weight of tail vane (neglecting the weight of the supporting rod), with the center of effort and center of gravity closely matched (as is typical of a sheet of anything flat), will climb just as well a foot or ten yards from the pivot.

Ungrounded Lightning Rod · « **Reply #23 on:** April 01, 2010, 07:34:27 PM »

(Well, actually if you went out far enough that you had to bend the boom to stay in the atmosphere the changing direction of "down" would start to affect the forces - making it EASIER to furl.)

OffGridGuy · « **Reply #24 on:** April 01, 2010, 11:26:56 PM »

Here a video of my 8' doing a bit of furling.

It is pretty smooth. I'll have to look for a storm furl in my collection.

http://www.youtube.com/watch?v=Ae5Vs41USLs

Could we start a furling video archive ?

It's great to see everyone's handy work.

Ungrounded Lightning Rod · « **Reply #25 on:** April 02, 2010, 01:39:42 PM »

Hear hear.

Hint to people taking videos of windmills: That wind noise (along with breath noise from people talking directly AT, rather than past, the microphone) is what those big foam covers for microphones exist to prevent. Try to find one to fit the microphone on your camera.

ChrisOlson · « **Reply #26 on:** April 02, 2010, 05:25:53 PM »

Curve the boom and you could go a quarter of the way around the Earth.

Well, yes, I realize that in theory there is no limit to the boom length. I'm saying that in practice the length of the boom is limited by how light you can build the tail. If you can build the tail infinitely light, then you can build the boom infinitely long. However, when you start using the word "infinitely" it many times doesn't apply to practical situations.

--

Chris

Ungrounded Lightning Rod · « **Reply #27 on:** April 05, 2010, 01:47:18 PM »

What I'm saying is that the length is limited by how light you can build the BOOM. The weight of the tail vane is not an issue at all.

ChrisOlson · « **Reply #28 on:** April 06, 2010, 08:12:55 AM »

I think it is somewhat of an issue because the weight at the center of the tail (boom and fin) mass is what determines when it furls, along with the hinge angle, offset and load on the generator.

So I think it's equally important to consider the weight of materials in both the boom and fin if you want to build a long tail for a gravity-based furling system.

What I have liked about using a vertical hinge is that the weight of the tail assembly (boom and fin) is irrelevant, within limits. And changing springs or adjusting the "power screw" on the cylinder is very easy to do compared to remodeling an entire tail assembly, or re-weighting it, to change where it furls.

Again, for the guys following the published plans, the gravity hinge will work with great success in most cases. When you depart from a known working design, as I do in most of my turbine designs, having it more easily adjustable is a plus. This system has worked very well for me.

--

Chris

ChrisOlson · « **Reply #29 on:** April 06, 2010, 08:23:52 AM »

And I'd like to note that this is all about trading ideas. If you're not an experimenter then I wouldn't recommend trying something new - stick to the plans. If you have a working angled hinge furling system, and it works, why change it?

But if somebody wants to try this at some point - feel free to email me and I'll do my best to explain how I build it, how it works and outline the improvements I've made to it on my later machines so it works better. It's an alternative to the angled hinge system, and there's always more than one way to skin a cat.

In the homebrew wind business, if people weren't interested in alternatives then everybody would just buy power from the utility company. So that's why I posted it - it's an alternative idea that has proven it works - on three of my turbines - and it works well.

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Chris

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Author Topic: Furling Video (Read 5235 times)