axial generator with lamination core

[Bruce S]

A good question, I think.

But we also maybe need to understand motivation: would such a project be for satisfaction in its own right, or to save money or carbon?

For a typical urban site the latter seem unlikely given your criteria.

Rgds

Damon

Damon;
I'm now at the point where the unit I'm desperately trying to get approval from our city's building commission is one that kinda fills at least two of those.
I like building things and I think if I keep stuff from going to the landfill and will charge some LEDs on my umbrellas then I'm happier.

I think Rinus' ideas may be far more farther and larger than I could even get close to doing at this point.

Cheers
Bruce S 

[mbouwer]

One of the options for a small and light diy mast is the segmented modular steel tower.
Then tack welding the segments and afterwards covering it with a layer of polyester.

[mbouwer]

Modvion uses wooden prefabricated segments.
Diy we could also use wooden slats and then cover them.

[MattM]

How tall are you proposing, and to hold how big of device?

[mbouwer]

A windmill friend collected scrapped stevedore binding material ( thickness 1 mm ) to shape a 5 meter conical tilting mast.

[Mary B]

The tower or other support structure is all that stands between you and a lawsuit f someone is injured or property is damaged when it comes down. Unless you know how to calculate the engineering specs I do not recommend home made towers... you have the payload wind loading, each tower section has wind loading... it is complicated math that gets worse the taller you go

[mbouwer]

The mast will be heavily overdimensioned and based on the different cross-sections it is possible to do calculations on it.
There is also not such a nasty load on the mast when there is a quietly running turbine on it with safe blade adjustment.

[Mary B]

The mast will be heavily overdimensioned and based on the different cross-sections it is possible to do calculations on it.
There is also not such a nasty load on the mast when there is a quietly running turbine on it with safe blade adjustment.

(Attachment Link)

Things fail, wind load climbs... not planning for it is not good practice. I always spec my towers for worst case conditions, 1 inch of ice and 60mph winds in winter, 100mph winds in summer

[mbouwer]

Agreed and that's also why it's so nice that we can share experiences on the forum.

Bottom view of the ring for the mast. Diameter 260 mm and 24 holes for bolts M 8

[mbouwer]

The intention is a movable foundation. The steel discs weigh 10.4 kg each and the shafts are 40 mm in diameter.
Now I have to shape a frame where the discs are spaced far enough apart.

[Adriaan Kragten]

Today a friend gave me this Sparta bicycle motor and the intention is to turn it into a windmill generator.

(Attachment Link)

If you count the number of magnets you get 20, so there are ten north poles and ten south poles. If you count the number of coils you get twentyfour. So the ratio is 24/20 = 6/5. These different numbers are chosen to prevent a high peak in the cogging torque but I doubt if this is effective enough to use this motor as a generator for a wind turbine. The angle in between the magnet poles of the armature is 360/20 = 18°. The angle in between the stator poles is 360/24 = 15°. So the difference is 3°. This means that you will get 360/3 = 120 preference positions per revolution. This isn't a high number and therefore the preference positions will be rather strong. These rather strong preference positions won't be a problem for a bicycle motor but it may give your wind turbine a rather high starting wind speed.

Today I have bought a similar motor (for only 20 euro) to see if it is possible to use it as a generator for a wind turbine with a rotor diameter of about 1.8 m. The first thing which I checked is the peak on the cogging torque. I measured a peak of about 0.6 Nm which is rather high. I found that the generator has 20 prefererence positions per revolution in stead of 120 which I don't understand if the armature has 20 poles and if the stator has 24 poles. I will open the housing and see if the internal construction is the same as that of the photo given by mbouwer. I will measure at least the open DC voltage for a certain rotational speed after making three new wires directly to the three phases and using a 3-phase rectifier. If possible on my existing test rig, I will also measure the torque and so the Pmech-n and the Pel-n curves for a 12 V battery load. My investigations will be published in a new KD-report if it appears that the generator is usefull for a certain rotor. The results will be mentioned in a separate post.

[mbouwer]

It strikes me that several windmill friends are getting excited about converting a bicycle engine to a windmill generator.
Perhaps someone knows an example where this has been achieved.

[mbouwer]

The bicycle motor has an outside rotating drum with magnets.

If you want to start from a existing construction with magnets and coils, wouldn't it be easier to use a DC motor with an inside rotating rotor as a starting point?

[mbouwer]

For a windmillfriend who wants to get started with a bicycle motor:
I still have one lying around and you can get it for free.

[Adriaan Kragten]

For a windmillfriend who wants to get started with a bicycle motor:
I still have one lying around and you can get it for free.

(Attachment Link)

If that is the one from which you have removed the winding, it is useless. But anyone who will try this can better wait untill my experiments are finished. It is not only the generator which counts but one also has to design a rotor which can be connected to one of the generator flanges and it must have a sufficiently large starting torque coefficient.

[Adriaan Kragten]

The bicycle motor has an outside rotating drum with magnets.

If you want to start from a existing construction with magnets and coils, wouldn't it be easier to use a DC motor with an inside rotating rotor as a starting point?

(Attachment Link)

This isn't a DC motor but a permanent magnet 3-phase AC motor. One can use DC current to drive this motor if one uses a 3-phase inverter with variable frequency. What is the origin of this motor?

[mbouwer]

This motor is completely intact.

[mbouwer]

The motor shown in Reply # 671 was part of a 36 volt battery powered electric wheelbarrow.

[mbouwer]

When later on the windmill head is on this top part of the mast I can roll the assembly to a place with undisturbed wind for a test.

[mbouwer]

This is a nice way to make the mast I think. Conical lattice with polyester covering.
It can be scaled up to the desired strength and dimensions.

[mbouwer]

The blade suspension is light and strong and when I also cover it with polyester it is part of the blade.
I'm going to make 3 of them now.

[mbouwer]

As far as the blade control is concerned, I think it would be best to build on the Midwoud design.

[MattM]

Search for midwoud1 on this website and youtube if you do not understand mbouwer'sreference.
https://www.fieldlines.com/index.php?topic=148775.0

[mbouwer]

https://www.fieldlines.com/index.php/topic,145925.0.html

Reply #92  on page 4 of this topic shows a nice rotorhead test.

[MattM]

How much force is on those central gears?  I wonder if 3D printing could make mass production affordable.  If you could get by with plastic gears it becomes much more practical.

[mbouwer]

But the question is whether you really need those gears.

[DamonHD]

This topic was split into "Re: axial generator with lamination core" -
2-axis solar tracker

[mbouwer]

Nice test set-up: Vestas equipped with guyed blades. 

[mbouwer]

The guying of blades opens up possibilities to make the blade suspension so much lighter.

[Mary B]

Nice test set-up: Vestas equipped with guyed blades. 

(Attachment Link)

Wonder if that is a construction jig to keep the blades form rotating and bringing the turbine live? Don't want fingers in high voltage by accident... or in moving parts!

[mbouwer]

Guying makes it possible to shape the blades longer and longer I think and to build turbines with more megawatts.

[DamonHD]

Do you know how new and/or how many MW that turbine is?

Rgds

Damon

[mbouwer]

It is a standard V136 - 4.2 MW
But they now have their 15 MW and they may want even larger and bigger