Oscar did the calculations for the FLAPS on my KR with full flaps deployed to 37?, which is likely a little more area than most belly boards, but similar in loads. The load calculation gave me a safe speed for full flaps of 100 mph IAS with a 10% gust load factor. I have had partial flaps out at much higher speeds, but I always keep in mind that the calculation for full deployment was for 100 mph, so marked the ASI and fly the plane accordingly. I don't think the limiting factor was the flap mounts so much as the strength of the flap around where the actuator arm mounts to the flaps. I ended up using the flap actuator sold by Vans for an RV. It is larger and heavier than what I needed, but at the time that I did this installation the cheap Chinese electronics weren't so readily available to us and I was running into a lot of difficulties trying to procure the actuator I wanted.
FWIW, both my ailerons and flaps are mounted with countersunk #8 machine screws into self locking nutplates floxed to the back side of the false spar. One thing that I almost always do with self locking nutplates is to run a tap through them before installation. It reduces the clamping action of the nutplate by rounding the hole a bit, but they will still lock on well enough without stripping the threads if one uses stainless hardware. FWIW, I flew my KR to both AZ and TX for the $50 breakfasts over Christmas break. My KR is over 1100 hrs flight time now. -Jeff Scott Los Alamos, NM? Paul (Visk)- I changed the subject line to be more relevant. You asked about the forces on the deployed belly board at 130MPH. I don't recall what the calculations were, but when Jeff Scott was converting his belly board actuator a few years ago, we ran some numbers on the forces required to push the board out against the oncoming air. Maybe Jeff still remembers-? Maybe he has his board placarded for maximum deployment speed? His installation is not marginal. As I recall, he installed an actuator that has more than adequate power to deploy the board, but what you're asking about are the actual forces and maybe Jeff still has those and will share them. Oscar Zuniga Medford, OR
