This is the profile flat winged stunt trainer I built for my son showing the general layout of the controls from the bellcrank to the flap horn then back to the elevator. I tend to over-engineer a bit but it gives the general idea. I've used a balljoint at the bellcrank because that allows the rear end of the bellcrank to go underneath the flap pushrod without any interference. The little bumps on the fuselage side (thin plywood) are to limit bellcrank movement so any violent (panic
) control input doesn't overload the control horns. The balljoint runs in a slot to increase/decrease sensitivity but that's just an added bonus and isn't really necessary, I did it because I could
. Another photo shows the connections at the flap horn using large clevises with the safety lock that stop them springing open and a similar clevis/horn is used at the elevator. If you use a wire elevator pushrod then you'll need a guide halfway along to stop it from flexing under compression (push) loads but CF rods are rigid enough not to need this.