“We are building new sets of the 4200 turbines. As you know we modified a bit the design of the frame, to suit our needs and expertise. Since we are making quite a few of them and we wish to maintain same parts for easy production and maintenance we had chosen the attached design.
“We maintain the same offset and other dimensions dimension. The only difference from your design is the tail hinge direction it is 45 deg instead of 55. We found no real difference. We just need to compensate with tail weight, and the making is simpler.
Attached are images of the parts before welding and the perspective drawings. I’m producing now a detailed production file that I can mail you once the last drawing is prepared. Some of the dimensions like yaw bearing and tail hinge are a bit different, but the design is very robust and judging from the last days it sustained some 25 avg and gusts of >35 m/s wind without a problem. The main idea behind this design is that once you drill the holes accurately, everything falls into place without any complicated alignment and tough welding. (welding is not really part of my expertise so I wanted to rely on a design that is more tolerant….)”