Posted for "Rick Lafford" <gliderguy89@earthlink.net>:

 Charlie,
 
 I suspect that the flow back that far on the airfoil is turbulent enought
 that additional smoothing doesn't help reduce drag. Leakage from bottom to
 top at speed is also probably minimal. Where gap seals typically help is in
 improving low-speed control response on airfoils that were not designed to
 work with a slot. Aileron and rudder effectiveness are typically improved by
 sealing. The most effective seals I've seen are the internal rolling type.
 
 Good luck on your search for speed and thanks for sharing your experiments
 with the group.
 
 Rick Lafford (HS)