Lakota "900W" turbine mounting

9 Posts
Apr 9, 2006 06:25 pm
Lakota "900W" turbine mounting

I wonder if anyone can tell me what pipe size is required to mount one of the subject turbines on.  It looks like I should be able to use a simple, cheap, tilt-up Air-X type tower to safely erect one of these units (I think that the Whisper towers are way over-engineered -- and I'd like to avoid have to deal with ANY concrete.  Anyhow, I haven't been able to find that pipe diameter requirement in any of the great amount of product research I've been doing.  Also, I am interested in hearing any personal experiences with Lakota "501-1kW" turbines... and maybe how it was mounted and worked!

That's the basic question -- "what's the pipe size?".  Anyone who wants to hear additional ranting about alternative energy may keep reading.

I'm designing a wind-generator/ battery/ invertor/ grid-tied system for my house.  I'd go off-grid completely, but I intend to install, at first, just a sufficiently robust back-up power system.  Then, I will start adding wind generators as they become economically pheasible, until I can actually generate the, say, 2000 kW-h/mo that I would ever use (worst case).

IMHO, the subject turbines offer the best of all possible worlds, in terms of unit weight, power output vs. wind speed curves, cost/kW-h -- you name it.  Also, I like the idea of using (not tiny) but multiple small wind generators (like the subject class), rather than a single big one.  There's two reason for this, mainly -- 1) the small ones are very light-weight, comparatively, and therefore require less stringent mounting requirements per each, and 2) if my (hypothetically) one big Genny fails, I'm stuck with no generation cpacity!  But, if one of a few smaller models fails, I still have something left working for me while I repair/replace the broken one.  

I should be fair.  There's a big difference (as I understand it thus far) between the Lakota's (which output DC voltage) and the bigger, heavier units, which output AC voltage, is that, given the DC power-transmition problem, the generators I like will basically cause me to have to build a "battery shed" where I'd keep my batteries and invertor, and finally, from there, send 240 VAC to the house, something on the order of 500 feet away.  So... anyone reading this probably knows how challenging it is (if you've tried) to design a suitably-sized and cost-effective alternative-energy system for your home;  I'm an electrical engineer and can autoritatively say that it's a significantly challenging overall optimization process.  

Back to being fair, other brands and larger gennies have their merits and may likely be best for a given situation.  Thanks in advance for any comments or suggestions.

 
351 Posts
Apr 10, 2006 09:59 pm
Re: Lakota "900W" turbine mounting

The air-x towers are engineered for 14lb turbine with 45 inch blades.  You want to put a 34 pound turbine with 82 inch blades on it. Right Huh?

You obviously do not understand the forces involved.

Either use the Areomax tower that is designed for your the Lakota turbines. Or contact Southwest Windpower saying that you want one of their towers for use with a Lakota. I'll guarantee that it will be a whisper tower, not an air X.

By the way, I you are in the US and your county does any type of building permits, you will usually need one.  

If you do not have manufacture documentation saying that your tower is approved with a given turbine, no building permit.

 
9 Posts
Apr 11, 2006 03:12 am
Re: Lakota "900W" turbine mounting

Thanks, oso, for the input above.  You help me see another calculation to make.

You're right, the Lakota 900W, 48 VDC nom. is 34 lbf.  It DOES NOT have 82" blades, however -- the swept area diameter is 82".  Big difference.
This turbine has a swept area of 36.9 feet.

Now, comparing the Whisper 200 900W 12-48 VDC nom. unit: weight is 65 lbf (you're right there).  And the swept area is 40 ft sq.. -- not much, but a little more area than the Lakota.

So, the Lakota here is a bit over half the weight of the Whisper 200 and has (92%) the swept
swept air of the Whisper 200.  Swept areas and weights roughly taken into account, the big difference in between the two is in the respective weights.  Weight is a vertical load... not nearly as important, at least here, as the horizontal force hitting a 40 sq.ft. stop sign.... at whatever unsupported height and wind speed we want to assume.

That said, back to my pipe size (which I would like to have as small as possible in my design -- (for cost and convenience sakes), the heavier Whisper requires a 2.5 in. Sch. 40 pipe (appropriately supported, however that may be done).

So... you really didn't answer my specific question, but you helped me reach an important conclusion.  I'm convinced now that a 2.5 in. sch. 40 pipe should be sufficient to support operation of the Lakota... and when I find out the actual dia. pipe I need for the Lakota base, I'll make or buy a suitable adapter for the top end.  

Now, off to see what looks good, as far as simple towers go that are designed around a 2.5" pole.

Please comment... I'm never mad to be shown that I've made an error, and always glad to learn something new or gain a new perspective on projects.

 
351 Posts
Apr 11, 2006 03:04 pm
Re: Lakota "900W" turbine mounting

I was "rushed in my previous response and meant to say 82 inch diameter blades, but somehow missed on "diameter".

I have never installed a Lakota 900w, but the tower instructions talk about using a 4 foot rizer of 2 inch pipe (ID 2 1/8 OD 2 3/8) They caution about being care to ream out the ID after making the cut and having not threads on the upper end.  I am not sure how tubine base/adapter sits on this.

2 and 1/2 inch (or larger)schedule 40 pipe is often used on the bigger towers. 2 inch and under they usually use either SS20 or SS40 tubing.  I believe the thread couplings are weak spots on the smaller sizes of water pipe. So, I would attempt to minimize the number of threaded couplers in your tower.  20 foot lengths of pipe would be better than 8 foot lengths.

How much do you know about guy and anchor sizing ?

Oso


 
9 Posts
Apr 11, 2006 04:22 pm
Re: Lakota "900W" turbine mounting

oso, Heh... I replied quickly, too, and might have missed something, but I did, not too long after, find in an Aeromax tower kit manual that they do indeed have various height kits that fit the Lakta 900W model bases -- like you said, nominal 2" sch. 40 pipe (2-3/8" O.D.)

I agree: any coupling would seem to be a weak point, but the towers are probably designed (via the guy-wire set-ups) to minimize that effect.  Personally, I'm no expert on guy-wire design spec's.  My strengths are more along the line of solid, building principles and electronics.  I *could* design and optimize a tower from first-priciples, but that's like re-inventing the wheel.

Cut threads at the genny base would reduce the pipe strength there a bit, certainly, and I would not allow that.  Of course, for any genny install, one should watch out for sharps inside the pipe, because that's where the wiring is going to come down throgh, regardless of how it comes out the bottom.

Earlier, you mentioned building codes.  I have no problem getting odd projects approved -- as this one (most of mine) are / will be.  As a physical engineer, believe me, I'm sensitive to undersizing things.  I ALWAYS overbuild.  In this particular situation, I needed to find the Lakota base requirement: done now.

The actual system I emply probably won't involve using a tower at all.  Right now, my brain is circulating the idea of pushing pipes up through the roof of my barn and strongly fastening them to 8" dia. (wood) poles in the sturcture.  I note that in the Lakota towers (above), there is a 5-foot free-standing section, above all guy-wire support.  I also note that the ability of pipe to withstand horizontal loading goes up dramatically, from sch. 40 to sch. 80.  So... blow me up again!  But, I think that I can safely use 2" sch _80_ pipe to put those Lakota's up at least 10 feet (at hub level) above my barn roof peak (which will top me out at 50 or so feet above ground level).... with no guy wires -- just solid support of the pipe below the roof -- oh, and yeah, I'll have to reduce the top diameter back to 2-3/8", one way or another... no big deal.

This saves the cost of any kind of tower kit and the labor involved in putting it up.  I just LOVE these Lakota gennies.  I can pull their 3-ph AC down through the barn, to their chargers, very close to my battery bank, charge the bank, invert DC/AC, and send the power to the house on existing wire.  Multiple charger units can be linked in parallel, on the DC side, so I can mod-up as much as I need to meet my ultimate demand.

Now...  I'm in search of a no-frills solution to the invertor section.  To make that story short, 2 stacked SW4048's would do the job, but I don't want to pay for the utility-connection relays, internal chargers, etc., as I can already easily switch between what I want to be completely separate grid or wind-based power-source (that hardware was installed for running the house, alternatively, on a 10 kW diesel generator.  I don't need or want all that redundancy and extra cost... but, I have yet to find *simple* invertors that will give me enough and pure sine wave AC power at 220 VAC/60Hz.  The right thing has got to be out there, and from what I've found that's *close*, the cost difference will be well worth it -- and less "do-dads" means less things to break down the road, too.

What do you know about inverters?

 
351 Posts
Apr 12, 2006 12:05 pm
Re: Lakota "900W" turbine mounting

"I have yet to find *simple* invertors that will give me enough and pure sine wave AC power at 220 VAC/60Hz."

I think that your requirement for "Pure sine wave" power at 220V 60 hz is going to mandate the more expensive inverters.

I have seen advertisements for MSW inverters that are simple 220V 60hz inverters.  If you could use one of those to supply 80-90 percent of your power needs, and then use smaller SW inverters where the cleaner power is really needed, you might save some bucks.

Oso

 
29 Posts
Apr 13, 2006 09:22 pm
Re: Lakota "900W" turbine mounting

Your mentioned "pushing pipes up through the roof of my barn ..... 10 feet (at hub level) above my barn roof peak ".
Please consider that 10ft above the roof you will have a lot of turbulences as the wind hits your 40ft high barn like a wall and output will be lower. Recommendation for towers location from the windturbine producers are more free standing away from any obstruction.

For my windturbine tower we pushed smaller pipes into bigger pipes and welded the whole thing together e.g. 1.5" pipe into 2" pipe into 2.5"  pipe. Then keep the pipe for flange connection a little longer sticking out and welded the flange on it. I am no expert in plumbeling and here in Philippines they are using substandard materials and sizes -- no idea if the really US standard sizes fit so neatly together...

 

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