This is a fairly standard type of wind machine and is drawn into the wind by a tail fin. The propellor is of quite a solid, welded construction, and it has a twist in each blade although it is not an aerofoil. The main reason for building this particular model was to find out if a small wind machine (1.2m span) could survive all the storms and gales without any active mechanism to spill-off the wind when things got bad. (The wind machine was allowed to free-wheel without a generator.) The propellor shaft bearings were standard motor industry wheel bearings for a Mini. I am happy to say the wind machine survived 5 years without any mantenance, and was in excellent condition when I dismantled it to use the parts for something else. (Click on picture to enlarge)
This was an early attempt at a cheap way to increase the shaft speed to drive a car dynamo (like an alternator but without the electronic controller). The span was around 1.8m, which in my opinion is too big as the suseptability to storm damage is too great. It did work well but the dynamo was not powerful enough to slow the propellor down during times of high wind-speed. Although I could have tried a larger dynamo, the price and weight would have been a problem so I started on an alternative idea, also the chain was very noisy. I chose a chain in the first place because it is more efficient than a v-belt, the ratio was about 3:1. (Click on picture to enlarge)
Because this wind machine was installed on an old television tower on top of a very high hill, there were rarely times when it was not turning. In fact, as its job was only to charge a battery for an electric fence, there was very little slowing of the propellor by the alternator (car alternator), and the risk of self-destruction due to the stresses of over-speed were very real. Unsurprising then that during a particularly violent storm the propellor made contact with the tower and that was that! Price is a tough master where wind machine are concerned, you have to build them cheap. It would be easy if we could use top quality components. The tyre of the bike wheel was in contact with a rotor on the alternator, making a cheap but effectivestep-up gearbox, and the propellor blades were deliberately made to be inefficient because of the strong winds. Bike wheels are not stron enough, I doubt I shall use one again. (Click on picture to enlarge)
Installed after the bicycle machine at the same location, this time much stronger and with a v-belt drive (v-belt losses were not an issue for this application). Still not strong enough though, it did not survive what was considered to be the worst storm for many years. Often luck is against you when installing a wind machine, either the wind drops and the machine can't be tested for weeks, or there's a ridiculous storm that nobody predicted. I know it isn't really true but sometimes that's how it makes you feel. 1.2m propellor. (Click on picture to enlarge)
Not one of my machines this time. I have included the photo because it is a good example of a low speed high torque design often used for pumping. Because the rotor presents a large cross-section (or swept area) to the wind, the machine can pump effectively even at very low wind speeds. This type of machine is highly suceptable to storm damage and usually has a brake, or quite often a release mechanism that turns the tail fin causing the edge of the rotor to face the wind, thus offering very little resistance and massively reducing the chance of damage. It is possible to generate electricity with this machine but it is not ideally suited to the job. (Click on picture to enlarge)
This machine is really a wind version of a water wheel. The wheel itself had four 'paddles' and was about 6 inches in diameter. It was quite long though, about six feet, and was supported by a bearing at the top and a car alterator at the bottom. It was another in a long line of experiments to try and achieve a high shaft speed without using a gearbox or pulleys etc. It worked well in high wind but produced nothing if the wind was less than 20mph. Very noisy and not practical at this size, although I do understand that scaled-up versions that are enclosed in a housing are very effective. In case you were wondering, my objective in my experiments was to find a design of machine that was cheap, could produce at least a charging current for batteries at low wind speed, and significant power at high voltage during storms. Most of these photos show only one part being tested at a time, in my later machines I attempt to bring all the ideas together. (Click on picture to enlarge)
Now we come to a completely different idea. This machine produces compressed air to drive an air turbine at ground level. Although producing compressed air is not very efficient, it was a cheap machine to build. With wind machines price really is king, or more specifically, the cost per Watt of power produced. The compressor is a modified four-stroke engine from a lawn mower. As hundreds of thousands of these were made it was an attractive idea to keep the price down because they are readilly available from scrap yards. Another big attraction was that power taken from the propellor could be varied by altering the reservoir pressure, this means that the machine could always work at maximum possible output (good matching) which is more of a problem to achieve when making electricity, particularly at high wind speeds. (Click on picture to enlarge)
A close-up view of the compressed air machine. Testing was with a crude low-speed 1.2m propellor with no twist along its length. (Click on picture to enlarge)
Now we come to one of my more recent machines. This is half of what will become a dual output machine. Once again, costs rule the design, so the rotating base is a car front wheel mounting (you can see the disk brake in the close-up). The generator is a standard 2kW three phase motor sealed to IPW55 (Ingress Protection Water), and produces power using a method known as asynchronous generation. This is a very simple form of generation and does not require any special electronics so it is cheap, reliable, and can easily match the input power to the propellor during storms. The propellor is of a welded construction, and taper-mounted with accurate twists to allow high speed rotation. The diameter is once again 1.2m. I'll publish some better pictures when the final version is ready. (Click on picture to enlarge)
Close-up of the previous machine. Note that there is no tail-fin to bring the machine into wind. This was one economy too far and although it moved into the wind, it was never in quite the correct alignment to get the best out of the wind. I believe this is caused by the angle of the blade presented to the wind being different at the top than the bottom, combined with moving slightly with the wind and against it in each case. The wire at the bottom right is an earth cable for lightening conduction. (Click on picture to enlarge)
Here we have a novelty machine used as a bird scarer. It actually worked well for its purpose and demonstrates a simple type of vertical axis machine. As it rotates a hinged flap is caught by the wind and drops down causing the machine to keep on rotating. Just a bit of fun really. (Click on picture to enlarge)
Another test trying to eliminate a gearbox. This time a direct drive to a car alternator. Only intended to work at very high wind speeds, it is more like a turbine or a small version of the large diameter wind pump above. Very small 0.3m diameter blade. The reason for trying to eliminate any gearing is partly cost and efficiency but mainly because under storm conditions on a larger machine the power throughput means the gearbox must be quite large and heavy. There is also the problem of shock pulses when the wind suddenly changes direction, this sort of effect is not good for gearboxes. Gearboxes are one of the main reasons why very large wind machines are so hidiously expensive, their reliability record is not good either, so if it is possible to avoid them altogether we will have a much better machine. (Click on picture to enlarge)
This was a seesaw type machine that could capture much of the available power at most wind speeds. It was not coupled to a generator in this photo but the idea was to allow a board at one end of the seesaw to partialy rotate one way and then the other in time with the seesaw's motion up and down. Difficult to describe but actually quite a simple idiea. Definitely warrants further investigation and particularly useful in light winds. (Click on picture to enlarge)
Propellers. Please click on picture for details
