Wing servo installation question

[Richard Onslow]

Build instructions show flap and air brake servos share a single access hatch, per photo. Any ideas on how to secure the servos such that they are removable? I'll be using Kingmax 911 and 612 wing servos for flap and brake respectively and had planned on using standard servo frames but I can't see how to do this (without cutting a second servo hatch). It looks like the ones in the instruction photo are glued in permanently. Model is 5m Airworld ASW20 currently on order, so just planning ahead!
Thanks.

[Trevor]

If you can fit a piece of heat shrink sleeving round the servo before glueing it in (probably with a silicone adhesive) then, should you need to remove it, the sleeving can simply be slit with a knife, releasing the servo.

[Richard Onslow]

If you can fit a piece of heat shrink sleeving round the servo before glueing it in (probably with a silicone adhesive) then, should you need to remove it, the sleeving can simply be slit with a knife, releasing the servo.

Thanks Trevor, yes I've heard of that method but have never tried it. I'd worry about the rigidity of the servo installation on a glider of this size.

[Trevor]

To be honest, I’ve only used it once in over 30 years - and that was on a thermal soarer. However I do know at least one modeller who regularly used the method on 1/4 scale gliders.

[terry white]

Hi guys, I have used this method a number of times in the past.The pros are that one can take out the servo if required in no time at all. Its easy to clean off the silicone ready to replace the servo with new.. The slow cure time allows the centering and positioning of the servo. The silicone readily takes up the difference between the flat surface of the servo and the curved surface of the wing.
However the cons are that the silicon hold is not so good as a thin bond between servo and wing, it has better holding power with some thickness to the material.This is not always possible within the wing situation.I have had the case where a movement of the flying surface has taken the servo out from its silicon bond .Also the flexible movement of the silicon can give rise to double centering.
It is rare that I use this method now as I prefer screwing the servo directly onto a pre-made plywood plate bonded to the inside of the wing with epoxy. However what I find favorable in Richards situation is to heat shrink a band of heat shrink material onto the servo as suggested by Trevor, well scuff this to make a good key and bond the servo into the wing with epoxy resin.This gives all of the pros of silicon with none of the cons.If the servo needs to come out a quick cut through the heat shrink and out it pops. The heat shrink left in the wing is easily torn away from its epoxy bond leaving a good platform to replace the servo back on with epoxy. Hope this helps. Terry.

[Richard Onslow]

Thank you for your advice Terry. It sounds promising, and certainly preferable to cutting new servo hatches in a brand new pair of wings. I'll weigh up the options carefully when the kit arrives.

[Chris Veitch]

My suggestion would be to build a ply box that each servo separately will fit in snugly, but can slide out at one side but held in by a screw/ piece of wood screwed to the box frame. Epoxy the box in place. You can easily build the box around the servo on the bench.

[Phill Tadman]

Hi,

Some of the frames with bearings I’ve used had a slide in socket for the lower tang and screws for the upper tangs.

You can epoxy the frame with the lower retaining bar already attached into the wing, slip the servo in and then secure with the 2 accessible screws.

The picture shows what I mean for frames sold here https://www.t9hobbysport.com/kst-servo-bearing-mount

Perhaps you can find something similar for you preferred servos?

Phill

[Richard Onslow]

Thanks Phill, and ChrisV.
Airworld has since offered to cut extra wing servo hatches at the factory, which should solve this problem completely. I'll find out when the kit eventually arrives.
Cheers, Richard