Guru
Joined: 10/02/2007
Location: AustraliaPosts: 730
| Posted: 02:43am 10 Jul 2011 |
Hi Trev,
Well looks like the good and bad that you have finally decided to use the blades.
Putting the 2.2m blades on 300mm solid mounts was, "as you said a BIG MISTAKE" , the absolute minium would have been 1/2 the blade length of steel tube and solid inside the tube for 1/2 of the tube . That would have been 1.1m of tube on 500mm solids + what goes into the blade hub . Also there should have been 3 to 4 bolts or 8-10 rivets over that length.
The mounting system I designed to mount the blades is described on the link to the Alu Bades and is load tested to 4~6 Tonns HERE , to run a set of these blade @ 4m+ , I would be thinking along the lines of 6+ Tonns of centrifugal force as a design minium
Where you have cut them back to @3.4m, I think you will find you have more than enough power in light wind and enough power in a blow to burn your AXFX if you are not careful. My Ax @ 3.15 regularly sees over 2Kw in 10m/s and easily make power @ 1.5m/s.
I would not recomend putting up blade sets that are not balanced or checked for tip run out , the alu blades are not exactly the same weight, there can be up to 10g per mtr difference in weights which will tear things apart when it gets going in a good wind.
The other thing to pay special attn to with thes blades is the AOA is set correctly and exactly the same on all all blades , I chased an out of balance wobble for weeks which turned out to be one blade at a 1deg difference causing a differing lift pattern at a certian RPM .
Whether the blades are timber,aluminium,pvc,fiberglass they should be balanced correctly and set to run true at the tip and the Angle of attack set correctly.
PhillM ...Oz Wind Engineering..Wind Turbine Kits 500W - 5000W ~ F&P Dual Kits ~ GOE222Blades- Voltage Control Parts ------- Tower kits