[mc607]

Are there any pros or cons to filling in the small triangular void at the te of the wingtip rib?

 

[RV6_flyer]

Cons:

More / extra work.
More time spent getting airplane ready to fly.
More weight.
Water / condensate does not have an exit path.

JMHO.

 

[BruceW]

+1 on Gary's last point.

 

[Carl Froehlich]

I fill in the complete end rib on the wingtips and all control surfaces. This is strictly cosmetic and does take time. I drill a 3/16” hole through the glass fill on the trailing edge to have a water drain path.

I like the “finished” look, but build yours as you want.

Carl

 

[mc607]

Thanks all.

 

[calpilot]

Filling in the butt ribs on control surfaces will reduce some drag, however be cautioned that there must be a drain hole for water to exit, or there could be corrosion and or imbalance.

DAR Gary

 

[bjdecker]

Some data...

+1 for Carl's and Gary's comments.

I recall reading a Bob Axom post from long ago, so I decided to tinker a bit with my -7.

Experiment:

I covered all of the rib ends with HVAC aluminum tape to create a smooth surface and overlapped pieces such that they wouldn't bind the flight controls if they came loose.

Aesthetics aside, I found that covering the inboard elevator ribs (E-705, E-709) yielded the greatest speed gain of ~2Ktas @ 6500ft. (1.75Ktas, 3Ktas, 2Ktas, 1Ktas, etc.)

All of the other counterweight "horns" and rib end coves didn't yield anything measurable. I suspect this is due to the angle that the elevator ribs are relative to the airstream causing a low pressure "suck" at that location.

...Steve Smith please opine...

Finish Technique:

I used 1/2" Owens Corning foam board for the filler material. I created a 3/16" radius around the edges of the foam so the rib would nestle inside the rib curve and provide a lip of sorts for the epoxy + filler to hold the rib into place. Glued the foam into rib "cove" with West Systems epoxy on the inside and West Systems Epoxy + milled fibers (fiberglass, not cotton flox) on the outside. Finish sanded flush with the skin edge. Drilled a small (#27 drill) hole into the trailing edges and bottom rib/flange holes to allow for water egress.