Day at the Beach!

[taylorp035]

I finally figured it's time to make a wind thread for my revamped windmill.  Some of you have been following my diary, but since I went to Presque Isle to test it out today, I felt it deserved a wind thread.
Basic specs include:

49.5" diameter
6 blades made from 21" x 3" x 1" ash
new hub made from mahogany with perfectly drilled holes
treadmill motor good for 33 rpm/volt
portable design for easy transportation and assembly

Purpose:  The idea was that 6 fast blades would preform better than 3 average blades.


The first step was to cut the curve on the back side so the blade would be narrower at the tips than the root.  The first 6" are 1.5" wide, then it goes to 1.75" @ 9" from the tip, 2.25" @ 12", and 3" @ 15" - 21".  This was done with a saw-sall.
The next step was to cut the flat face ( the wind side ).  The curve that I drew for it was an inversely proportional to where it was from the tip and proportional to how wide the blade was at that point.




The grain really popped out when I sanded them.




A shot looking down the length.  Unfortunately, cameras don't have two eyes, so taking pictures of a twisted blade don't come out that well.  The tip was 4 degrees.




The hub required 16 holes.  12 for the blades, 3 for bolting it to the flywheel, and one in the center.  The 6 holes in the center were counter sunk so it would lay flat on the flywheel.




All bolted together




5 of the 6 blades completed.








Hub is assembled and ready for testing.  Balancing was easy, as I only had to swap two blades to even it out.  Then I hooked some power up to the motor to test it, which I took it up to 1000 rpm.





So, today I got really ambitious and took it out to Presque Isle State Park.  After about an hours worth of driving, I found a spot between beach 8 and 9.  My goal was to set it up where no one would complain, so beach 11 was not a good option.  I walked out there and it was really good wind, but the sand was kicking up and eating at my skin.  

After 3 trips back to the Jeep, my brother and I managed to haul it out to the sandy point where the light house was.  We then dug a hole for my 6 1/2' long 4" diameter PVC pipe and set up shop.  At first we decided to stay behind a sand dune since it was so windy.  The forecast called for 10-20 knot winds from the West and 3-5 ft waves.




You can see the light house in the background.







Here we moved the windmill about 15 feet closer to the water, where the wind was much better.  Voltages went up from 10-14 to 14-18 volts.




The guy in the background was painting the light house.  I thought he did pretty good





And a picture of me.




In my opinion, I thought the performance was good, but not great.  I wanted to take off three blades and see what would happen, but I was too tired and the 7/16" wrench was in the Jeep.  Start up was excellent, but it was quite windy.  I wish I had brought my 12v drill instead of my 18v so I could some performance tests

Here are some videos:

http://www.youtube.com/watch?v=G2cdGwOZ0MU

http://www.youtube.com/watch?v=Whbjm91sYPs


Any questions, please ask

[taylorp035]

Also here is another video:

http://www.youtube.com/watch?v=3PyovXE-oDg


One last thought was that the blades were very quite.  I could not here them over the leaves on the trees, which I was pleasantly surprised, especially since there are 6 blades.

[ghurd]

"Any questions, please ask"
How many times did you change T-shirts?
What's your famous brother look like?  

Pretty sure 3 of them will do better.

Really, all that 'wind shadow' stuff counts both in front and behind the blades.
Video 1869 looks like you/him were standing directly behind the blades with the meter.
Standing off to the side would make a big difference.

I was test flying some of Ed's 1M white experimenters plastic blades, just about like your test.
About 1M behind, my open hand dropped the charging amps by maybe 25~33%?  (it was a long time ago)

BWT- next time maybe do the same video except walking from behind to the side, and back, a few times.
It would be a classic.

You guys are doing a great job.
G-

[taylorp035]

We are twins, so we never changed shirts    Notice the red and black shoes.

I agree with the wind shadow, but I didn't really care since I didn't bring a 12v battery.

[ghurd]

Hey- pretty sure I will be at beach 1/2/3/? Sept 19 for the time trials.
Will have about 35.5 minutes of down time between when she starts and finishes, which is usually at some way-too-early time of day.
Plenty of extra room in the car for an ECM.
G-

[taylorp035]

While you are at the park, check out beach 2 --> windmill + Stull Center.  If it is open, they have the power meter inside on your left.


What's an E.C.M. ?

I couldn't decide which one it was...

From Wikipedia, the free encyclopedia
Jump to: navigation, search

ECM may refer to:

    * Every Child Matters, a UK government initiative for children
    * Electret microphone, a type of condenser microphone
    * Engine Control Module, Car parts related
    * Entitlement Control Message, a message carrying conditional access information in a digital broadcast conditional access system
    * Error correction mode, a fax protocol
    * ECM verb or "Exceptional case marking verb", a linguistic term

Organizations:

    * Every Child Ministries, a Christian charity for African children
    * European Common Market, the common market of the European Community
    * European Congress of Mathematics

In science and mathematics:

    * Extracellular matrix, any material part of a tissue that is not part of a cell
    * Electrochemical machining, a method of working hard materials
    * Electron Cloud Model, an atomic model
    * Electronically commutated motor (brushless DC (BLDC) motor), an electric motor which uses electronic switching to control the motor rotation
    * Electronic countermeasures, a part of electronic warfare
    * Electronic control module, a unit to control electrical systems
    * Elliptic curve method, an algorithm for integer factorization
    * Error correction model
    * Erythema chronicum migrans a skin rash associated with Lyme disease

In business:

    * Electronic Contract Manufacturing, a term related to the outsourcing of electronic assembly
    * Engineering change management, process to control changes in product design
    * Enterprise content management, a strategy in the information technology industry
    * Equity capital markets, a financial term
    * Error Correction Mechanism, a type of econometric model, closely linked with the concept of cointegration
    * Explora Capital Management, an investment company

In software:

    * Enterprise content management, the capture, management and communication of processes within an organization
    * Error Code Modeler, OpenSource software for processing CD images, made by Neil Corlett

In music:

    * ECM (record label), a record label
    * Ensemble contemporain de Montréal, a Canadian contemporary music ensemble

[Flux]

Nice work.

You may not have had as much wind as you think at that low height and with obstructions at the back.

I have no doubt that it would have been faster with 3 blades. It certainly was not that fast if you were running it open circuit and you were not much above cut in.

For a fast 4ft prop on no load in a good wind I would have expected it to be screaming and possibly fluttering and if your cut in speed was right I would have expected something over 40v.

When you get a chance try it again but this time with a battery connected and see how it performs with 3 blades and with 6. I am sure 3 blades will get you much more speed but it depends on how well you are matched to the blades whether you do better in the end with 6.

You will need to get it higher to really give it a fair test but it is unusual to have blades running quietly on no load and it may indicate that you had much less wind than you thought.

Flux

[ghurd]

What's an E.C.M. ?

I couldn't decide which one it was...

From Wikipedia, the free encyclopedia
 
In science and mathematics:

    * Electronically commutated motor (brushless DC (BLDC) motor), an electric motor which uses electronic switching to control the motor rotation
  

It is a 3 phase motor that already has the magnets in it.
And the coils are (usually) easy to get to for a bit of "patient reconfiguration".  6 coils per phase make for a lot of options.
Can spin an unmodified one, shaft between your palms, past 100V easy.

A few pics.  Check out the video too.
http://s701.photobucket.com/albums/ww20/ghurd1/ECM%20Conversion/

AdamL posted a fairly complete start to finish diary.
http://fieldlines.com/board/index.php/topic,130036.0.html

Others have posted quite a few stories.  Some get pretty over-complicated.
G-

[zap]

Nice work!  Great pictures and video too!

The mill seemed to be hunting a tad too much?  You might want to almost double up the size of that tail?

Next time head down the shore and pick up Norm... have him bring his coffee can mill

[willib]

The blades look nice , and seem to preform well .

In the video you were getting over 17 Volts. so thats over 561 RPM , and they seemed to handle it well.

My opinion on the six blades over the three is , they should preform better in a low wind situation under load , than the three blades, just because they will produce more torque than the three blades.

i am not saying that the larger windmills should have six blades , its just that your Permanent Magnet DC motor needs the speed to get above cut in , and the torque to produce the amps , so a six blade windmill seems the right choice for your situation.

 nice job!

[Flux]

You need more tests, on load and a better idea of wind speed before you can really come to much of a conclusion. Normally high speed generators work with less torque so unless the bearing and brush loss is unusually high the faster prop will be better.

A given tsr prop need the correct pitch and solidity. For your pitch I suspect the solidity is high. Just looking at it I have a feeling it may be best with 4 blades but that would need re drilling the hub. try it to see if three is better than 6. if it is then you may find it worth trying 4.

I don't find that blade number makes a lot of difference for a given tsr as long as you stay within reasonable limits as long as pitch and solidity match but even so the very fastest props use 1 blade, normal fast ones use 2 and most practical things use 3. Machines with poor start up sometimes need more blades to get moving and in many cases small machines use more blades than really necessary to hold them back in high winds.

Cut in at 400 rpm is well within reasonable limits for a fast 2 blade 6ft prop, it should be easy for 3 blades at 4ft. In the end you will have to find out whether you lack speed or torque. Only reaching 17v in a fair wind suggests that you are speed limited with the thing open circuit, as soon as it goes on load it will drop to cut in speed even with the possible better torque of the 6 blades.

Let us know how it turns out.

Flux

[taylorp035]

I definitely want to re-do the test, especially with some physical numbers.  The wind was so perfect because there was zero turbulence once I got out from behind the sand dune.  I would love to try out a 2 blade, maybe with a really wide root and a very thin tip, about 5-6 ft sounds good.  Hopefully beach 10 or 11 will be available b/c they are better exposed to the west winds. 

I can try out 3 blades in my back yard, but the winds are not nearly as consistent, at least not until winter.

[taylorp035]

In the end you will have to find out whether you lack speed or torque.

It was quite obvious that my last version with my 50" 3 blade lacked torque, as it never spun much more than ~500-600 rpm under load, even in 20 mph winds.  It did spin up to maybe 1000 rpm when I broke my record at 173 watts , but it was obvious  that the blades were stalling.  My small 30" CNC 2 blade windmill would take off like a rocket at about 8-12 mph ( a good 1000-1500 rpm ).  I guess I could duplicate those blades to a 60-72" diameter.
I guess I just need some more time testing, unfortunately someone has to register and serve food to 4,000 people tomorrow.....

I was wondering if anyone had a link to a page where it describes how to design a blade based on torque or speed?  I was wondering if the wind facing side causes the torque, or is it the angled airfoil?  My CNC blades were very flat and had very small pitch, but they would "kick" in at ~8 mph.

EDIT:  After reading some more stuff on Hugh's web site, it looks like when you double the speed, the blade should be 1/4 the width, far from what mine are.  Plus, my blades are way too thick, especially for 6 blades, so I think going down to 3 or even 2 blades for a test would be worthwhile (6 bolt locations provides a lot of different configurations )