|Feb 04, 2011, 12:26 AM|
B-25 Mitchell "TONDELAYO": The Tail Feathers.
Wellllll....once again, I had to do some work on the tail feathers to get them to waggle properly!
Early on I noticed the rudders seemed to be a bit stiff, but after flexing them numerous times they seemed to loosen up a bit? After gluing them on to the elevator with epoxy and hooking the control rods on in the correct orientation, I noticed the main control rods were bowing out when fully extended, not to mention the associated servo hum! I could not find any linkage binding anywhere so the only logical reason was the foam rudder hinges. I ended up re-hinging the control surfaces with pin hinges and that cured the problem.
While I was fiddling with all the linkage I noticed they were all installed with the cut ends of the Z-bends facing the foam and a couple were actually rubbing against the foam. Not wanting to run the risk of one of those ends digging into foam during a flight, I decided to re-orientate them in the correct position with the ends on the outside.
Once I was assured everything was operating in a smooth manner I installed the elevator/rudder assembly on the fuse. Once installed I proceeded to run a servo test to once again make sure everything was going to be okay, but once again I was having a binding problem? Upon closer examination I found the rudder linkage was pinched between the fuse and the elevator. The channel that was cut in the fuse section was not wide enough to clearance the control rod. After making a couple small cuts in the channel to clearance the control rod everything was once again operating in a smooth manner.
NOTE: I encountered the same problem I have had on some of the other FMS planes, and that is the rubber glue they use. It seems when they glue those plastic screw retainers in place the glue will sometimes get in the hole. What happens is, when the screw is inserted the rubber glue will wrap around the threads and prevent the screw itself from threading into the plastic anchor. When you try to extract the screw there is so much glue wrapped around it you will end up pulling the screw retainer out. To prevent this I dip a 1/8" bit in some lacquer thinner (alcohol might work as well?) and run in the hole until I am sure all the glue is removed and won't interfere with the screw.
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