next generation maple blade

[rotornuts]

Well here's the first

This one didn't balance well for I think a few different reasons but I never expected to nail it on the first try.

In reply to a few questions from the other post. For ed, it did do about 80 - 100 rpm in 5-7 mph winds and about 300 in 15-ish so that puts it in the tsr 7.5 range. After that it crashed.

nothing to lose, the white counter balances are indeed just stubby blades for three reasons, one - to provide additional lift and hopefully offset some of the one sided torque of the main blade, two - the 120 offset is to give the dynamic balance of a three blade, three - to reduce drag and turbulence by having the counterweights profiled rather than round or square etc.

ted, I'm abandoning the 120 offset counterbalance for now because it has proven to be harder to do than I expected I'll revisit it after I learn how to balance this in a two blade format and I'll likely try to bring them in closer to the hub. see the next generation plan.

truman, I'm about 100% confident that at some point in the future I'll build a three blade rotor with blades like this thing has, It has alot of torque in low wind due to the blade area. It would offend anyone who is worried about high wind performance but not me and I think it would look really cool, lol.

For the next generation I'm going to mimic the maple seed even more and use the single counterweight just like it does till I learn more about this.

Here's a photoshop mutation of the above to give you an idea what it will look like and below is the original 2" norm turbine.

this is what started it all

me blowing on it during photo

Having fun if not success.

nuts

[monte350c]

You might be able to cut the counterweight size down by drilling and inserting lead plugs.

I think you're on to something here and it will be great to see where this ends up!

Ted.

[RP]

Don't forget that the center of mass on the big blade may not be on a line through the center of the blade.  Maybe your counterweights should be at 117 and 237 degrees for example.

[rotornuts]

that's true rp, when I went to lay out the counterweight locations I realized that I needed a reference point on the main blade and it should be the center of mass so I hung the main blade off the hub and used a 4' carpenters level to locate center down the length. If you closely examine the picture with the balance blades you'll see the centerline of the main blade falls slightly behind the apex of the tip.

Ted, I was just today looking at lead downrigger weights and wondering if they would be good to melt down to do what you were thinking. I have no experience doing this though.

[iFred]

Not sure if this helps but...

Enigma Ceiling Fans -single blade units...

http://www.farreys.com/ceiling_fans/fanimation/enigma_fan.html

The balance point and counter balance right what you have suggested. Not sure about what the blade angle does, maybe that is dynamic balance.

[iFred]

close up - if the image is not large, right click on it and view image

[electrondady1]

on the original model the axis is offset more than your wooden enlargement the section with parallel sides is much longer

[electrondady1]

[PHinker]

Rotornuts,

   Nice!  You've got some serious blade carving skills.  The scaled up maple leaf blade is gorgeous.  I think a full 3-blader (w/o the counterweights) would really be eye-catching.  Please keep updating the diary as you make progress as this is very interesting.

[ghurd]

Wheel weights!

Free.  Not free at the tire shop unless you know somebody.

Go to a parking lot and look where the curbs stick out into traffic a little too close.

When I cast my own fishing jigs, I could pick up 5 or 10 pounds in an hour at the mall.  There were maybe 5 drive-up ATMs with tight turn clearances, and Sunday morning each was good for a pound or 2.

Maybe the Taco Bell, etc, drive through?  (I have become used to getting strange looks)

People who hit curbs tend to do it often, I think. The more they do it, the bigger the weight they need next time to get the wheel balanced.  3" long weights are not uncommon.

Not as soft as pure lead, but good for most things. Still melts easy.  I think it could be poured into a hole in the wood.

G-

[ghurd]

Serious pretty-ness.  Furniture grade looks.

G-

[windstuffnow]

  I'm assuming the rotor speeds were taken as an unloaded speed?  It would be interesting to test it with different loads to see where the best power/rpm falls.  I would bet they would run the best in the TSR range of around 4.  Just a visual guess.   If you added more blades instead of balancing the single I think alot of the speed performance will go away and your back to basic fat blades again.  I'd stick with the single.

  Looks nice, can't wait to see the next generation blade!

Have Fun

Windstuff Ed

[electrondady1]

 i really like what youve done. sorry about my lack of posting skill. i just noticed on the real seed pod the pin is offset farther than the x you drew on the photo i'll try it again

[wooferhound]

I just feel like this kinda blade can never be balanced. Sure you can balance it on a nail of hanging from a string, but as soon as it starts to spin the centrifugal forces start taking over making it unbalanced again. You could balance it for a specific RPM but will become unbalanced as RPM becomes faster or slower.

The center of gravity is changing in relation to the RPMs.

As RPM increase, the long part of the blade becomes more affected and pulls harder from the center than the short counterbalance. The Maple seed compensates for this action by changing it's center balance point depending on the speed of the spin.

It may work if you get the counterbalance extended the correct distance from the center.

That being said, I don't understand about the ceiling fans that iFred posted. I checked the link and the have 3 speeds (Not Reversable). I would assume that the 3 speeds aren't very different. I'm also seeing that the blade on the fan is super thin at the end.

[rotornuts]

woof,

If the mass on both sides is the same it should rotate free of vibration at any speed. I'm going to do some more research on centrifugal and centripedal forces before I do the next one.

nuts

[monte350c]

Too bad you don't know someone at Discount Tire. You could just take the whole thing down there, chuck it into the FMC tire balancer and start tacking on weights where the FMC said they were needed.

Luckily though there's lots of info about correcting dynamic imbalance. In fact most cars would be pretty unpleasant to drive at highway speeds unless this problem

 was solved.

You may find this article interesting:

http://www.engr.colostate.edu/~dga/me324/Labs/Lab%2011/ME324%20-%20Lab%2011.htm

Have fun and keep us posted!

I'd love to try one of these things - as soon as I get the motor conversion bug out of my system. One thing at a time...

Ted.

[monte350c]

Oops - almost forgot, if you're doing anything with melting lead, it's not too difficult.

It can be melted easily with a propane torch. But you should take some personal health type precautions. Good idea to do the melting outdoors. Better if you have some kind of mask. No, it's not plutonium or anything - but better not breathing lead fumes if you can help it!

Ted.

[wooferhound]

I have tried to balance ceiling fan blades before. (worked at a cieling fan store)

If the weight is near the hub it has almost NO effect

if you put the same weight on the end of the blade the effect is MUCH stronger

 In fact you can keep mounting the weight at different positions along the length of the blade until it balances out, but then when you change the speed of the fan it will be outta balance again.

 The best position I found for mounting the weight was in the center of the blade between the hub hole and the end, I think this is the best idea for your blade too. Where your counterbalance is half the distance from the hub compaired to the length of the blade.

[ghurd]

Can't say if it will help,

How to balance a ceiling fan...

http://www.taunton.com/finehomebuilding/pages/hvt002.asp

G-

[truman]

easy counter weights would be to drill a whole slightly smaller than a common bolt screw it in and cut it flush with the wood repeat until balanced

[nitish]

Hello folks,

I am interested in designing wind turbine blades (I have a particular idea in mind).  I am new to this (I quit my job in fiber optics and am trying to get involved in the wind energy field).  I need some direction:

• Where should I educate myself about wind turbine blade design?
  
• What software is used to analyze performance of wind turbine blades?
  
  

Rotornuts: Your maple seed pod blade design looks good.  How far have you progressed?

Regards,

[rotornuts]

It's on hold for now. Dynamic balance is a problem. Balance wouldn't be as much of an issue if not for the unbalance force on the axis. I still believe in the idea but I've been sidetracked by the vertical axis machines for now. I find that with some time comes solutionjs so it's on the shelf so to speak.

As for education: short of going into something that deals with fluid dynamics and aerodynamics then carrying the knowledge over to the secretive world of wind turbine design I suggest hundreds of hours of googling the net(no joke).

Mike

[nitish]

Hello Mike,

Thanks for the comments and advice....really appreciated.

I am glad to hear you mention that I should start with studying fluid dynamics....I was thinking along the same lines.

We are blessed to have the net....it is certainly a great resource.

Take care,

Nitish