Barrows has designed a system of u-shaped sheet metal stiffeners between the ribs at about 15% MAC on the top surface only. This will prevent oil canning of the surface in flight in the vicinity of the strut. This has been seen on one plane only, but its easy and cheap to put a stiffener in so I will do it. I spent the day cutting 020 sheet into strips and bending them into u-channel. I intend to bond them to the inside of the wing with 3M 5200 polyurethane. I glued a few in and also made sacrificial test pieces for test purposes. They seem to hold very well. Someone on the Bearhawk forum recommended VHB tape (very high bond?) but I couldn't find it locally. I need to get this done and move on, so 5200 it is. I just used a piece of coreplast as a 4“ spacer to place the goopy channel ahead of the spar, and then pieces of coreplast jammed between the channel and the bottom skin to hold light clamping pressure. The 5200 takes at least a week to harden.