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Forum Index : Windmills : Safety first
| Author | Message | ||||
| turnymf Regular Member  Joined: 04/10/2008 Location: AustraliaPosts: 84 |
I had a thought Would it be a bad idea to have some sort of wire that held onto a loose blade if hub to blade connection failure occured? |
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SparWeb Senior Member  Joined: 17/04/2008 Location: CanadaPosts: 196 |
I don't think so. Where would the blade go if it did break loose? Smash into the tower or flail about until it hit the other blades? The remaining blades would be turning with such a drastic imbalance that the shaft bearings could fail anyway. What makes the tether so strong that it won't break either? Why not invest the time and effort into making sure the blades are properly and rigidly mounted to the hub? The most courageous members of these forums are the ones who post pictures even after accidents and damage has broken the blades. Learn from those postings, because every one has a story to tell about how the wind can get the upper hand over machines built by man. Steven T. Fahey |
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| turnymf Regular Member Joined: 04/10/2008 Location: AustraliaPosts: 84 |
Hi SparWeb Yes but "Where would the blade go if it did break loose?" Hopefully still on the tower and not sticking out of someone elses property/head "Smash into the tower or flail about until it hit the other blades?" So be it "The remaining blades would be turning with such a drastic imbalance that the shaft bearings could fail anyway." They will be unbalanced anyway with only two blades. If I had one blade fail, I wouldn't be to sure about the other two "What makes the tether so strong that it won't break either?" I would think that blade failure would be from twisting fatigue rather than rotational force, so a large wire may not be needed "Why not invest the time and effort into making sure the blades are properly and rigidly mounted to the hub?" 100% agree "The most courageous members of these forums are the ones who post pictures even after accidents and damage has broken the blades. Learn from those postings, because every one has a story to tell about how the wind can get the upper hand over machines built by man" OK I am firmly in the vawt camp so high rpm is not a huge problem for me but I do learn a lot from postings here and elsewhere I made a little prop mill and appreciate the rpms involved, it can get bloody scary when you are holding one Because of this I appreciate that more power can be genertated form most any prop design over vawts, but I live with neighbours all around and have little chean air so I'm into vawts If I was making hawts in town, saftey would be a big concern for me |
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| Janne Senior Member Joined: 20/06/2008 Location: FinlandPosts: 121 |
I agree with Steven, it's propably not a good idea. If it fail at high speed, the cable would have to be really sturdy to hold the blade, and even then it would propably shatter itself onto the tower. Though there is this old photo, in here the blade is hanging on with it's pitch control linkage. What propably had happened, is that the wet snow that rained that that night sticked on unevenly, and the resulting imbalance running first loosened some of the bolts holding it on, and then sheared the rest. But had it broken with more than a "just turning" speed it would have flown cleanly off for sure. Sorry for the poor image quality. 
If at first you don't succeed, try again. My projects |
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| turnymf Regular Member Joined: 04/10/2008 Location: AustraliaPosts: 84 |
F1 cars now use two tethers to pevent wheels from flying off, there has got to be some gs in that Great picture Janne If I was living around the base of that mill I would be very happy the blade to stayed at the hub, regardless of any damage to the rest of the blades |
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