So, I'm back from my trip, and back in the shop !
First order of battle was to figure out what happened when the machine oversped and started to vibrate like crazy. It turned out that it had spit out one of the blade shaft support bearings.
The bearing was covered with snow, so we got another one, disassembled the governor (after testing if we could get the shaft to 'bind' by pushing at the blade tip, and we found that was not it).
We drilled a hole in the end of each shaft, tapped it for a 5/16" bolt to hold the bearing on with a lockwasher.
We also changed the weights so the bolts that hold the governor on the main shaft can be reomoved with the shafts & weights in place. This makes it much easier to work on the machine, just loosen up six bolts and the central support and you can pop the governor + blades right off.
After that we put it all back together again, but with a big change to the way the blades are mounted.
Originally the blades were mounted in the 'thickest' point of the blade profile. Now we have flipped the blade supports around, and the blades are supported about 1/3rd from the trailing edge of the profile at the root of the blade. This causes the air 'scooped' by the front of the blade to help the blade to try to feather.
We also painted the blades, one red, one white and one blue. No nationalistic signicificance there, we'd already red tipped one blade, so that one became red and the rest of the machine was white & blue. This hopefully will help us with analyzing balancing issues while looking at the machine from the ground.
So, after reassembling the whole works and roughly balancing it we put it back up.
We ran it unloaded for a bit to see if we could get the feathering to work or not and within 10 seconds of spooling up there was this 'clack' and the whole machine lurched forward !
I thought something had gone horribly wrong and quickly hit the kill switch.
After a minute or two of talking to Johannes about maybe having missed something we suddenly realised that nothing had gone wrong, the machine had feathered for the first time, just as we intended. The 'feed forward' that you get from those blades trying to scoop is tremendous though, and it causes the feathering sequence to go tremendously fast once started. This causes the whole machine to temporarily function like an airplane propellor driven by the momentum stored in the rotating mass, which causes it to screw itself into the wind.
It looks like we'll need to dampen that and tighten up the spring a bit to get it to work a bit more smoothly, but it does seems to work !
No pictures today, it's just way too dark...