modified micro wind turbine

[hayfarmer]

Hello,tilted up a small micro turbine today and am pleased with the modifications,
1 ) area in red added a 2 foot piece of 2.5 in pipe over the 2 inch tower to stiffen up the top.
2) raised the top guy anchors 8 inches and welded to top 2 foot piece.
this really helped, now mill doesn't shake till cut in and starts easy in low winds.
sorry about the size but its all I need at the farm.
 

[TomW]

No apology needed for "small".

Seriously.

You are doing so that counts beyond size. The payoff is in the doing and it looks like a nice start. My first were Tape Drives with plastic blades and has led to a 9 foot a 12 foot and a 6.5 foot turbine flying here.

Wind farms ain't built in a day!

Thanks for the share.

Tom

[Rover]

I like it!

I like the fact you raised it quite considerably from the roofline.

  I need to that with my shed one

[Fused]

Small mills count?
 

I knew I stuck around here for some reason.
Its the doers here that gives us something to learn from.

Nice looking mill Hayfarmer, height makes all the difference.

Thanks for sharing.

Fused

[ghurd]

Is that tiny thing big enough?
Oh wait, "its all I need" means it is big enough. 

"now mill doesn't shake till cut in and starts easy in low winds."
Starts easy in low wind is simple enough.

How bad did it 'shake till cut in', before the changes?
All of my little ones (really little) shake between almost close to cut in, to a hair after cut in.  The shaking in the tail seems mostly up&down instead of side to side.
Do you think it is the extra height getting out of the building turbulence a bit more, or could it be a recently higher wind speed since the changes?

Congrats!
Less shaking and starting sooner should mean more power.
G-

[keithturtle]

Gotta start somewhere; he's farther along than me

Turtle, still at it

[hayfarmer]

G, I think the reason for the shaking was the size of the tower top is only 1.5 o.d. when I welded some 2 in  pipe over it and raised the top guy anchor a bit. it doesn't shake at all now,I was worried about metal fatigue ,I know i was pushing it with the small size of the pipe.when I tilt it up it looks like a wet noodle until I get the turnbuckles tight.and yes I think every foot of height makes a big improvement on performance.I am still working on my 35 foot tall mill at my house fighting turbulance with tree topping and may bring it up to 55 feet if the topping doesn't correct it.

[Ungrounded Lightning Rod]

"now mill doesn't shake till cut in and starts easy in low winds."
Starts easy in low wind is simple enough.

Shaking all the time and starting hard, then not shaking except near cutin and starting easy after a blade change, sounds like the old blades were out of static balance.

How bad did it 'shake till cut in', before the changes?
All of my little ones (really little) shake between almost close to cut in, to a hair after cut in.  The shaking in the tail seems mostly up&down instead of side to side.

Shaking only near cutin speed means one (or both) of two things.

Main one is that as you cross cutin the genny starts delivering current (and as a result applying drag torque to its shaft), but only at the waveform peaks.  This causes a vibrating drag, which can be quite severe at first.  As the speed goes up further the current delivery/drag occurs over more of the waveform and eventually the variation of load torque with position in the cycle reduces, reducing (but never quite eliminating) the vibration.  This is the "hum" of a working turbine.  (A turbine that is producing appropriate polyphase waveforms and is driving a resistive load CAN end up with essentially no drag vibration.)

(It's also possible tou have a small amount of imbalance and a tower with a resonance that happens to correspond to an RPM near cutin.  However this is an unlikely coincidence.)

[hayfarmer]

that's why I love this place,it keeps the "MAJIC SMOKE" away.thanks for all the great advise and info. the guro's should get togeather and write a book.I will reserve one in advance. [move][/move]