As Goop sets up, it shrinks ~2-4%. If you leave Goop around the parimeter of the servo case it will set up and distort the flying surface. Creating a fillet is the worst thing to do. No Goop present in this area...no distortion.
Another thing to ensure the ultimate rigidity of the servo versus the wing/control surface, when installing the covers also apply a small dap of Goop between it and the servo case. I have yet to discover another means of securing servos in a composite wings, that either exceeds this rigidity, has lighter mass, and is still removable.
In fact I run a thin bead on the servo covers to secure them to the wing surface, gets rid of the ugly tape normally used (ughhhh). Earlier this spring this exact setup exceeded 420KmH.
Tip: you can seal a foam servo well with epoxy, and then use Goop to secure your favorite servos without fear of melting the foam...
John Hayes wrote:
I'm sure this has been covered before but.... I've been having fits trying to come up with the best method for securing servos in a Phil Barnes foam core wing. I have used a glue known as PFM, I think it also is known as shoe goo. This adhesive, although strong and secure, dimples the top surface of the wing. Not sure if its attacking the foam, but it certainly distorts the top surface.
Most recently on my new ship I have used silicone, this at first seemed to work well, but it didn't hold up and my flap servos are now floating around. Makes for an interesting launch when the flaps are both in different positions!
On my last Mantis I used the PFM and the servos been secure, I've just lived with the depressions in the top surface. I haven't blocked in around the servo, perhaps that will be my first next move. If any of you have had good repeatable success, or good adhesive suggestions I would appreciate hearing about it. I know there's a lot of servos installed out there and there must be a better way.
Thanks,
John Hayes
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