Control surface end fill

[Bob Axsom]

In the new 3" wingtips I built I installed 0.016 2024 T3 stiffener plates at the aft end to close the opening outboard of the ailerons with the mounting flanges turned outboard (into the wingtip) and mounted them with pop rivets. Thus, the tip side wall is flush with the opening instead of recessed. This has worked well and would appear to reduce drag. Using other methods and materials I plan to "flush up" the end recesses in all of the control surface end openings. I'm sure this has been done. Any observations or experience comments?

Bob Axsom

[szicree]

Bob,

I think most folks cut a block of foam to fit in there and then glass over it. I'm still on the fence about whether to bother or not, but if I do I think I'll use some of this stuff instead of carving a block of foam:

http://www.hobbypeople.net/gallery/864206.asp

I've used it for other stuff and it's really cool. You mix equal parts, stir for about 20 seconds and pour in place. It dries very fast and could then be trimmed flush with a hacksaw blade. I think the advantages over shoving a block of foam in there are:

1) Quicker
2) Perfect fit
3) You could rig up some type of bolt to hang on to the foam, as done with the pour-in-place elevator counterweights.