Control surface gap question
 

Hi, i have a Hobbico Sukhoi su-31 and since it was my true first ARF, i did not know the proper way to install hinges and the control surfaces(Elevators, Alerons, Rudder) and when it was glued, there was a gap in between the surface and where it was glued.(a little smaller than the size of a medium size nail). anyway, the guys at the field said that it is enough to get away with but it will cause "flutter" and i was wondering how you fix a gap in the control surface. any advice is welcome Thanks

RE: Control surface gap question
 

if your concerned with the gap, just fill it in with some balsa. sand to shape and add some covering and just add a couple coats of same colored dope, the wing, to the balsa. won't be able to be it in the air. will give you a start on kit building. dick

RE: Control surface gap question
 

I sorry to say that it is a beyond repair...........just box it up and send it on down South:D:D Well if you don't want to go to that much trouble, maybe another alternative would be to just cut out the old hinges, (are they they fiber type that get CA wick into them after they are slipped into slots?) and possibily use another type of hinge or just use small type in different new slots. Naw too much work just send it on down...

RE: Control surface gap question
 

To fix the gap, just cut strips of covering film and iron it into the gap on the surface edges.

Cheers

RE: Control surface gap question
 

Get some Du-Bro Electric plane hinge tape at the LHS.
Flex each surface all the way one way, and put the tape on both edges to cover over the gap.

RE: Control surface gap question
 

Are they ca hinges? Cut the hinge off and cut them flush. Then recut the slots a hinge with either side of each hinge, this time paying attention to the gap before gluing

RE: Control surface gap question
 

The easiest way to fix the problem is:

1. Disconnect the pushrod from the control horn on the affected/problem surfaces.

2. Make sure the gap and covering surfaces are ABSOLUTELY CLEAN AND FREE OF OIL. Clean the gap and surrounding areas TWICE using rubbing alcohol and a CLEAN cloth/paper towel for each cleaning.

3. Depending on your skill level and if you have the proper tools you can either cut strips of matching covering (Hobbico uses MonoKote on their ARFS ) about 3/4" - 1" wide. Fold the strips in half lengthwise (dull side out ), flex the surface as far as it will go, then insert the strip in the opening (many people just seal the bottom only) and seal it down with a TRIM iron. You can use a regular iron, but for this it is a bit clumsy.

If you don't have an iron (or don't want to do it with monokote strips, disconnect the control rod as mentioned above, flex the surface as far as it will go and use 3M brand "Magic" scotch tape. This tape holds very well and will blend in and be hardly noticeable. While not absolutely necessary, I would tape both sides of the hinge gap.

RE: Control surface gap question
 

HEY, I have that exact plane as well getting ready to build, a guy at my LHS told me just use about 3 t pins on each controll surface next to were the hinges, slide them into the gap after that press the aeileron etc in and you will have a hair thin line gap! its one of the tricks i will take.