ORIGINAL: F.Imbriaco
ORIGINAL: Jetstream
Read in another thread of yet another wing failure. Is this something of a problem with design or manufacturer? I was seriously interested in this plane.....
What other thread or forum ? Checked R/C groups and saw nothing there.
I have a Griffin that it is approaching flight ready. On day one, I went over the every inch of it with a fine tooth comb and high intensity mini- flashlight. I inspected the internal structure of the wing panels, wingtube socket in the fuse and in the wing. Looking through the wing servo opening, I got a decent view of the rib that anchors the wingtube socket . All looks OK.
The only thing that I saw in wing internal was a fracture of the first half rib -it is made of 1/8'' foam . That didn't appear to be structural, rather just a support rib for the composite skin during the manufacturing process. Nevertheless, I cut out an identical half rib out of 3/16 '' depron and glued it alongside with some RC 56 canopy glue. Gave me a warm and fuzzy feeling(lol)
Unless the ''another wing failure '' posted by Jetstream indicated a failure at the end of the wingtube as mentioned as a possibility by MTK, do we know for sure ?
OK- Which brings us all back to BUILDING 101. A carbon wingtube has a CUTTING EDGE device at either end. The wingtube in this design, like many similar ships of the day, does not require the use of 4-40 retaining screws, so it will rotate minutely in the socket , but just enough to allow the ''cutting edge'' of the opposite ends of the carbon wingtube to become dastardly and wear away at the wingtube socket rib mount/ joint.
The fix is simple and takes a couple of minutes. Trace the i.d. of the carbon wingtube on a piece of VERY SOFT 3/16'' or 1/4'' BALSA, not hardwood, and you'll have a nice balsa mini- doughnut. Drill a 1/8'' hole in the center so that it'll relieve air when inserted. LIGHTLY Scuff the inside ends of the wingtube, clean with alcohol, and then insert the balsa doughnuts into either end with some slow cure CA( no kicker so you can position) or epoxy. You want roughly 3/32'' or 1/8'' is sticking out. Make sure it isn't cocked. Now perform a slight radius of the exposed balsa edge and you should be set to go.
The wingtube will continue to rotate minutely, but the sharp edge of the carbon is buffered , so no cutting will take place.
This practice has been shared over the years. I certainly didn't come up with it, but it may have been forgotten.