Turbines on the African Savanna, easy assembly

Two men, one flat bed truck, 5 windmills in one day. Well maybe ignoring the generator. The key here is that the support for the central spindle is relatively simple - just a plate on the solid ground, with spikes banged through. The windmills/turbines are erected as a large marquee tent would be - guy ropes, pulleys, strong arms and hopefully no wind.

What differentiates this from standard horizontal axis windmills is the construction.

With horizontal axis wind turbines (HAWT) on hillsides, and the flat, you need a decent foundation (concrete), and potentially a concrete tower to support the weight of the generator with most likely has to be bought in by helicopter. That's costly by anyone's standards.

Don't even mention the the maintenance cost of the HAWT. With this design of VAWT, you could just lower it to the ground with the ropes/cables again. It weight perhaps 1000 times less that the HAWT.

The likelihood is that the VAWT with sail cloth will be less fatal to birds. Potentially less interfering with radio signals too. Both of those are 'in theory'.

Lastly, the HAWT design requires a support more than half the length of the blades to stop them biting the ground. The VAWT design, being guy-roped can go much higher in the same square-footage on the ground.

Next up pictures of the Meccano model from 1991 that actually worked. If I can find the negatives.

Image thanks to Stargirl from flickr and drawingcoach

VAWT on hillside

The wind is coming over the hill towards us/the camera. Two sails are shown. The left one is coming towards us, and the right one is going away. The left adding to rotation, the right momentarily resisting it.

The sails shown in this design are solid.  If they were cloth and between two bars, then the sails could adopt a modest aerofoil shape and add to rotational force in multiple positions. Most notably, positions 4 & 6 in the previous blog entry.  As is with this solid sail design, positions 4, 5, and 6 are effectively drag.

Also, the gearing is shown as a chain and cogs here. That would be impractical due to chain sag. The real one that I built was used bevel gears that are also inefficient.

This illustration shows something that is a couple of hundred yards tall. It will keep going in low wind conditions and still perform in higher winds.

Next up, horizontal vs vertical axis wind turbines. 

My Windmill

I had the idea in 1984 or thereabouts, but did not attempt to patent until 1991.  Its a design for a vertical axis windmill.  The patent failed, because of prior art. Some that art goes back to the 1850's.  I used to have the failed patent application, with 1" of stapled relevant patents. I think I left it at a client site a couple of years ago.

A guy from 'the west country' of the England had been granted a patent on it some years before me.  He's still above and hoping to make some business from it with under-water turbines, but I think the best use is for wind.

How it works - view from above

So this diagram describes one sail and its rotation around a central axis under the influence of wind.  Eight freeze-frame images give a single rotation of the sail around a central axis.

Each sail has to run in two directions - the red dot shows that the sail after one revolution around the axis, would be facing in the other direction.  Meaning there is a 2:1 gear ratio between the (fixed) central spindle and the rotation of the sail around its own axis.

Directions of force are shown via small arrows. It's pretty obvious that all angles to the wind are helping the general rotation apart from frame 5.

You could make each sail as a sheet of sail-cloth between two vertical rods. In the case of my prototype, I made them out of cardboard.  With a sail-cloth form, you could get some aerofoil effect. 

Points of Sailing

Anyone familiar with yachting or dingy sailing will note that sailing positions to the wind guide the design for this turbine.  The novelty (and the thing I tried to patent) was the 2:1 gear ratio.

More in a follow up.