Do you tape the bottom or top or does it matter?
This has been discussed before on this forum so I am sure that I will get some BOO TO YOU replies. However while RC may be taboo here, RC modelers have developed many items that really assist in keeping good control of a model. Sealing hinge lines is one of the best.
1. Using any tape you wish or "money-kote" (or like material)-- everything I have used has to be replaced now and then - tape all hinge lines on the bottom. Most flying is topside up, so bottom saves some oil from creeping into the seal. Crease the material into the hinge line along with the hinges as well as you can. Keep some play there for keeping slack when the surface is moved opposite the bottom.
2. When an airplane is maneuvering in a loaded maneuver, air can escape from one side to the other. This changes the airflow for maybe just a microsecond which can cause a jolt to the maneuver. You don't see Pattern or IMAC or even most Pylon Racers fail to seal surfaces.
3. When I was rather new in RC (early '70s I did not worry about this) but I learned. One person that I came to know was one Mr. DON LOWE. When on the AMA EC we seldom agreed on anything, however IMO, Don was the MASTER on any form of RC or any other aerodynamics. You could well take his advice to the model airplane BANK!
4. Don's main item was to SEAL the control surfaces. Once I started doing so, my airplanes
learned to fly much better. I wish I had had such knowledge when I was a CL stunt competitor. George Aldrich said to keep the flaps snug. Back then we used cloth hinges and that certainly helped, especially if properly done. Still sealing the hinge line will stop air drifting through and save many a "bubble" from being there.
Any bubble, even elevator, can create a bubble that will cause a change even if just a short back and forth shift of the longitudinal axis and possibly an accident, much less just a poor maneuver.
Of course YOUR CHOICE and there will be the usual NO-NOs with their inputs. However as a kid and I was told by my Mom when I did not want to take my coat to school, "It's better to HAVE it, and NOT NEED it, than to NEED it and NOT HAVE it.
SEAL the HINGE LINES.