|Dave Bran||17/11/2015 09:21:31|
1898 forum posts
Last was a power modded 1970's glider with a polyester Fus (Firecrest).
I'd struggled to find a decent glue to hold the components in, but thought I'd managed it after a couple of failed tests.
Several flight sessions later, it suddenly went out of trim while in a loop, badly so. Fighting it quite a bit I got it around and back down towards a landing though it was extremely loose on the controls, when it suddenly uncontrollably veered starboard into the leafy lower branches of an Oak.
Quite a soft "landing" and the only damage was a dented LE to one wing.
On inspection it became I think clear what had happened, the two servo rails (wood) had parted from the Fus.
When I'd pulled elevator up to lift the all flying tail up for the loop it'd obviously created so much load that the bond had failed, leaving the two servos screwed to rails no longer fixed in position and now almost dangling on their snakes.
The tree had taken the motor off the Fus , too, a clean separation of the motor mount bond leaving the Fus intact.
Having tried and failed with Polyester Resin (keyed and reinforced), Epoxy, Hot Glue, etc, if I'm bothered to fly it again (and I'm not sure I am!) I'm going to screw through the Fus into the bearers!!
11639 forum posts
I am a little surprised that polyester resin did not work. Generally if you abrade the surface, clean the dust off with some acetone, then either mix up some filler and polyester resin and use as a paste. Talc is ok with most gliders as weight up front t is not critical.
Another approach is to wet out with polyester and then use cloth to bond the rails to the body.
Perhaps one major difference that I have normally adopted with gliders is to make a ply tray with which to bond in place.
An alternative adhesive that sticks to polyester and epoxy is Stablit Express by Henkel. Pretty expensive though. I have normally used on tail booms.
Crashes are inevitable, particularly when the model is rock solid in handling and you have flown it hundreds of time. It could be you or model/radio related. It seems to eventually come with the territory.
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