Here is pictures of my Extended blades I made from ben`s blades design....I have made them slightly longer and to the exact size of a purchased turbines blade length.
It`s pushing the design to the Extreme using PVC guttering.I have to say they work excellent in low winds.......Fast wind we will have to see how much they bend????
View the compressed pictures and video showing the better start up.......
Interesting. I was just discussing the possibility of blade extension with a friend and came up with the following idea. A small run of flat steel bolted on the front of the blades to another piece on the rear and the supporting hub. This would stop flex and centrifugal force from ripping the blades apart and should allow you to go considerably bigger. Even if you get to the point where the blades have some flex under force at high RPM their mass will pull them straight. As the bending force in this case will be high wind speed it is also the point when centrifugal force will be pulling them straight as they will be spinning their fastest.
Hi Mike, No Problem. I just use mini nuts and bolts.They are put through the holes that are already on the dynohud and are rather small and I got them at maplins.
Basically I have used thin board that might not last the test of time,but I painted and varnished the wood so It will hold for a year easy.
To apply the dynohub to the wood I just made wooden square and diagonlly marked across the board to find the dead centre.From there I used a Protractor that allows you to draw a circle and I slowly drilled out the shape slowly.This also allowed me a good fit and made a decent blanced wooden fitting to fit the blades onto.
One note about the blades.
I installed them by having already drilling two holes per blade into the wooden square....This then allows you to push your blades as far as possible near the dynohub.Then i mark the blades holes to drill by getting a pen and pushing it through the drill holes so they are a perfect match.
I find this way easier and less hassles if you have little tools.
I also got the wood free from a window that was smashed and the board was lying doing nothing.
In the future maybe a White plastic square would be ideal.I know you canaslo get plastic roofing nuts and bolts,but I`d stick to the metal ones.....
All in all I think I have managed to cut a lot of weight off the finished model and thats needed when using a Dynohub as your turning a lot of weight round not like the treadmill motors etc....
Last night I managed to get over 20 volts and 0.67 Amps from the dynohub....Usually you will expect to get under half an amp current....
They are still worth building!!! I`m going to save up and build a hugh piggot Turbine in the near future!!
Ben`s Blade plans (Extended)
Posted - 10/08/2007 : 21:28:04
