wind tower question

[trentman]

i have a 8ft hugh piggott type turbine on 36ft 2 inch tower at present

i would like to upgrade to his 10ft diamter turbine ,all is the same except tail is 5ft long instead of 4ft long

will my tower be ok

[luv2weld]

You didn't give us enough info to help you. How many guys? Where are they? What

is the diameter of the guy wires? Tell us about your guy anchors.

Is the 2 inch black pipe or electrical conduit?? Is it welded together or did you

use pipe couplings???

You also need to tell us about the generator itself, (rotor diameter, number of

magnets, number of coils, wire size and wraps.) Just saying Piggott type is not

much information.

Finally, the blades. Yeah, I know you gave the length. But what about the chord,

the thickness, the TSR.

It's better to give too much info than not enough. We can't help you until we

know what we're dealing with.

Ralph

[trentman]

hi ralph

thanks for the input

the tower consists of 60.3mm od pipe with wall thickness 2.5mm

there are two pieces 6 metres long that are welded together, a bigger tube

on the outside about 1.5metres long

it is guyed at 1.4metres from the top 4 ways and again at the mid point using

4mm guy wire

the base is 1 cubic metre of concrete and the 4 anchors consist of a quarter

of a cubic metre of concrete

the turbine has two dual rotors with 12 magnets on each rotor

stator 9 coils of 1.18mm wire wound two in hand 75 turns

the blade will be 3 metres with a tsr of around 7

i hope this is enough information, the rest of the details are in hugh piggotts book

regards mark

[luv2weld]

Mark,

I don't understand what this means

a bigger tube on the outside about 1.5

metres long

Is this the yaw tube or is this a sleeve over the joint where the two pipes are

welded together for strength or reinforcement??

Also I'm going to assume you have 2 rotors

the turbine has two dual rotors with 12 magnets on each rotor

There are 3 things that bother me with what you have described.

1. The wall thickness of your tower scares me. That's really thin for the force

that will be placed on it. I would feel much better if the wall thickness was

about 6.5mm.

2. Your upper guys are 1.4 metres from the top of the tower. Aren't they in danger

of being struck by the 3 metre blades??? If you are running a 2.4 metre blade now,

you have a little clearance. But I would measure carefully before I put longer

blades on.

3. I don't know what type of soil your anchors are in. If the soil gets soggy,

will the anchor pull sideways or even pull out??? Are you even subject to such

things as soggy ground??

Maybe we do overkill, but our 10 foot turbine is on 4 inch black pipe, 1/4 inch

wall thickness, up 46 feet. Our guys are 1/4 inch and the anchors are deadmen,

made of pieces of I beam buried 36 inches deep. I'd rather be safe than sorry.

Hope this is helping.

Ralph

 

[wpowokal]

Mark, IMHO as is no. But then you seem to have a gardian angle so who knows, but 3M over 2.4M is a 50% increase in swept area. One can only asume you are in a low wind area.

Less concrete under the tower and place the rest at the guy anchors is a better plan next time.

Even now you should install one more set of guys midway in the top section, and be very careful of buckeling on raising and lowering.

allan down under

[Mary B]

Black iron pipe was never designed as structural pipe. It was designed to hold pressure. Steel tubing of the proper wall thickness would be much safer in the long run. 4130 is commonly used on large antenna arrays where the wind loads can be quite high.

[SparWeb]

Too thin.

You need another tower.

[Flux]

If that turbine was built for 8ft and you put 10ft blades on it without changing the alternator offset then it will furl late if at all and the tower loading will be even higher than the theoretical increase from swept area alone.

Flux

[DanB]

Basically - no matter what (even with an 8' machine) I think 2" sched. 40 steel pipe is too small.  In truck testing I've bent 2" pipe right over with 10' machines on it.  I think 2.5" is OK - it's not failed up here yet but I think there is very little safety factor and to do things over again I'd use stronger stuff.  Seems like with towers - a very little bit more spent on material can add a lot of safety factor.  

[luv2weld]

MaryAlana,

I know that black iron is not structural, but I have never found 4130 tubing in

a salvage yard (unless it was mangled so bad you couldn't use it.) Since I didn't win

the lottery yet, I have to find my parts and pieces as cheaply as I can. But black

pipe is certainly stronger than electrical conduit of the same OD. Mark said his

current tower has a wall thickness of 2.5mm. That sounds like it is either conduit

or a tower for a small radio antenna.

Just trying to help a friend in the right direction without bankrupting him.

Some of us cannot afford to buy all new steel to put up a large antenna array.

[Mary B]

This web page http://www.math.niu.edu/KARC/mast/ has an antenna mast calculator. Treat the blades as a solid disc and input that for the antenna sq ft area. It will give you a rough idea of how safe your installation may be.

[winston]

I had an Air 403 with a little over a meter in blade diameter

it was on 1 1/2" schedule 40 pipe

after 3 years the pipe cracked at the pipe union --it was welded too (although I am not a top notch welder)

this tower sounds way too weak for a 10' wind generator

[trentman]

thanks for all your response

so far i think i have been lucky with my 2" pipe it has been

up for three years now and have seen winds up to 60 miles per hour with

no problem.

i think i will leave this tower as it is and use 3" pipe with 6mm wall thickness

for my 10 foot turbine

will this be ok or is it overkill ?

regards Mark

[DanB]

It sounds very good - it's overkill but itll be there for a long time and you have a good safety factor.  Overkill is good where towers are concerned I think.  You would also be OK probably to put a slightly larger machine on that in the future should you want to.