20 Foot Page 3 - Metal Work

finiished chassis

There is all the metal work completed for the main chassis of the machine. The alternator is offset 10" from the center of the yaw bearing (that part that slips over the tower). The pipe between the alternator and the yaw bearing is 4" diameter sched 40. The yaw bearing pipe is 30" long and made from 5" diameter sched 40 pipe. The tail pivot is attached to it with a sort of triangular 'box' that we welded together made from 3/8" steel. It tips back about 18 deg and it's 45 deg off to the opposite side of the yaw bearing as the alternator is. The tail pivot is 24 inches long, made from 2" sched 40 pipe. At this point it makes sense to build a stand so you can put the machine on it and work on it - or paint it etc... So building the stand is another project that we had to do around this time.

finished chassis again!

This shows another angle. Also notice the alternator itself is tipped back about 5 deg or so to give extra clearance between the blades and the tower. The blades get a lot of force pushing on them (or pulling on them sometimes when the machine yaws quickly) and good blade clearance is important. I learned this the hard way on the 17' machine so now I make sure there's more than enough.

fabricating the tail

It's just like the smaller machines we make, just bigger. In fact, many of the dimensions I simply doubled the 10' machines we make. Where use 3" pipe on the 10' machine I used 6" pipe here etc. The tail bearing is 24 inches long just like the pivot, and it's made from 2.5 inch sched 40 pipe that slips nicely over the 2 inch stuff we made the pivot from. The tail boom is 10' long made from sched 40 1.5 inch pipe. The tail bracket is made from 1.5" x 1/4" bar stock and it's 48 inches long. The gusset under the tail boom is made from 2" x 1/4" steel bar stock. The whole thing weighs about 60 pounds if I recall.

wooden tail

The wooden tail is made from 1/4" thick baltic birch plywood. Its 5' tall and 3' wide at the widest point. I'll probably remake this out of thicker wood. It seems a bit floppy up there and it furls really earlier. A heavier tail would be more rigid and the extra weight would cause the machine to furl in higher winds. I think it could safely be made from 3/8" plywood or even half inch stuff.

cleaning up the steel

Nobody will notice once its up on a 75' tower, but we like to grind our welds down and sand the steel so the paint goes down nicely and it looks decent. The orbital sander does a nice job of removing scale and weld BB's.

painted magnet rotor

We painted the magnet rotors red.

painted chassis

We painted the machine black. We use pretty common acrylic enamel automotive paint with a self etching primer - it seems to hold up well and it looks nice.

assembly in the shop

Now, except for the blades the machine is pretty much finished. We'll assemble it on the stand in the shop so we can test it - look at it - play with it etc.. until the blades and tower are finished. Pictured above Rich and George fit the stator.

all finished up

There is the machine pretty much all together. It weighs about 400 pounds now so we can't move it. We'll disassemble it all again in order to move it and then reassemble it when the blades and the tower are finished.