Blades stalling

[TurboMiles]

We are having a Damn good long front come through and I can't run the wood blades, neighbors will murder me.  So I reinstalled the G5 blades, they work OK if I remove a phase.  The wind is blowing 15-20, gusts to 25. It was mentioned that the noise could be the alt, no chance it's the alt.  I do hear a groan from the alt, but the high pitch whistle is all the blades.  I need to figure out how to remove the whistle and everything will be great.  I've had the wood blades in a 20mph wind and the inverters I have is able to control it, haven't had them up for higher winds.  The wood blades are so powerful, I want to run them so bad.  I believe I may have carved them wrong, but not sure where I went wrong.  Can I see pictures of your wood blades?

[niall]

if the blades are working that well .....you mustn't be to far off   

heres a 1.2m blade ....the wood is cedar with an ash leading edge

its a standard blade with a tsr of 5 ( if i rembember right ) ....
the drop angle at the tip is about 2mm and extends out to whatever the wood thickness allows at the root , the airfoil is standard ( the belt sander variety )

these were done of a blade calculator but there basically close to Hughs 2,4m prop

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this is the 3.6m mill .....the blades are the same format and are basic hardware store pine laminate ...just bigger , as you can see the mast is short at 10m

the cut in rpm is about 140rpm ....so its a " fairly "  quiet machine , cut in for the 2.4m would be 210 rpm so the 3.6 is kind of a quieter machine ...ish , the neibhours were never to bothered about it and at 10m even if it fell it would stay on my side of the ditch  ( things that go bump in the night )



as its going up the tail falls into its furled position , this drops back as the mast goes vertical

the only time it made a whistling noise ( similar to your vid and what Ross described ) was when i tried adding winglets to the blade tips....i had to knock them off 

[TurboMiles]

The lack of a sharp trailing edge was the source of the whistle, all I get is a whooosh sound now, happy

[TurboMiles]

[rossw]

The lack of a sharp trailing edge was the source of the whistle, all I get is a whooosh sound now, happy

Errr... that's what I meant to demonstrate with my pics.

[TurboMiles]

The lack of a sharp trailing edge was the source of the whistle, all I get is a whooosh sound now, happy

Errr... that's what I meant to demonstrate with my pics.

I'm sorry, I thought you were showing me the tip and how you rounded it off.  My apologies.

[rossw]

I'm sorry, I thought you were showering me the top and how you rounded it off.

Nah, it's all good mate. The original pull-truded blades were cut off hard at the end, and along the trailing edge.
Certainly, I rounded the sharp ends off, but the main difference came from re-shaping the trailing edge to take it back to a nice, fine, smooth edge.

[TurboMiles]

How long are the Chinese blades and what kind of alt do you have them on?  Do they make good power for you?

[rossw]

How long are the Chinese blades and what kind of alt do you have them on?  Do they make good power for you?

I've had, and got, a variety.
The original (junk) ones were just under 10' diameter, junky hard fibreglass with hard edges and not much profile. I ground them, painted them, balanced them, and got reasonable performance from them but lousy start-up.


After they were destroyed by a tree going through it during a storm:



I rebuilt the head, and bought some new blades and hub (which needed some machining to fit the old generator head)



These started up much better, were far quieter and produced more watt-hours per typical day, but were down a little in top-end power for some reason I'm at a loss to explain. Perhaps in all the rebuilding, the alternator lost some output.
This old mill makes around 1KW peak in strong winds.

I have another one I still have not put up yet. It's 2.5KW and I have little doubt it'd make that easily in a decent wind.
Its prop is just over 14' diameter. I have a picture from when I was balancing it, but it's pretty awkward to manage inside and impossible to do outside except when it's dead calm (almost never!)


I've got another 7.5KW of PV to put up, so I honestly don't see this new mill ever flying.

[TurboMiles]

Impressive!  Does the 14' prop use an s809 airfoil?  Would these be going on an axial?

[rossw]

Does the 14' prop use an s809 airfoil?  Would these be going on an axial?

I'm not sure. Bought it about 8 years ago and can't remember the details.
The machine that came with it is radial, not axial. Looks to be a modified but hefty 3 phase induction motor




Weighs about 60kg (130 lbs) by itself if I recall correctly...

[TurboMiles]

That looks serious.  You should put it up lol. It would be a monster.  The sun doesn't shine 24/7.

[rossw]

That looks serious.  You should put it up lol. It would be a monster.  The sun doesn't shine 24/7.

Despite living on the top of a decent hill, we get very poor quality winds here. Turbulent, unpredictable and unreliable.
Back when PV was $7-$10/watt wind made sense. Nowdays, it simply doesn't. Over-panel so even on overcast days I still get useful power has less maintenance, less complaints from idiot townsfolk, is silent and just works. In winter when we have super thick fog, PV doesn't make much, but a turbine sits there doing nothing either. I just have too much other work to do to mess about with it to be honest.

[DJ]

Reading about turbines I was lead to wonder why people still use them unless they are in an area where it snows most of the year?  If that's the case, you don't need a turbine, you just need to move somewhere decent!  :0)

I have been playing with some panels for the last couple of months and I'm impressed by what they put out under cloud. it's 7:45 Pm here and the heat has given way to clouds that look like a storm is on the way and I'm still getting 20% of what I did at todays peak in full sun which was  damn near 100% output.

Brand new decent panels can be had  here for .64c/ W. That's probably under .50C in the US.  I have bought and see used panels all the time for $50 for 250W units.
Are panels hugely more expensive in other parts of the world?

Seems to me Turbines are terribly expensive for their output and can take a lot of setting up and getting right as well then you have to maintain the things which does not seem a light job in a lot of cases.
I think I'd much rather have PV and a disel generator for the wet stretches of a fortnight or so a year when it rains non stop.

At my next house, I want to cover the thing with all the panels I can fit and do a ground array as well if need be. That might be in the form of a verandah or pergola using panels AS the roof rather than on the roof. I want to have every modern power sucking luxury and rather than cut back to save, I'll invest initially so I'm able to run it all for next to nothing in the long term.  :0)

Many people I know are paying over $1000 a quarter here.
On a years payback, that for grand would buy 20Kw of used panels.  I think that would cover most peoples household needs even on cloudy days.  Add another $1K for some used inverters and another for used fittings and wiring also readily available and you are not going to be needing much power from the grid. If you have the old style whirly meter and backfeed, you are probably going to have to keep an eye out you don't end up generating more than you use.   :0)

[TurboMiles]

Thank you for spamming this thread about my wind turbine in the wind/hydro section with your unrelated solar advice.