I have been working on a model Helio also. The whole thing seems to depend upon the size of wing. I tried working slats on a 42" span model and they only made noise, and gave no noticible effect. The alteration of the flaps made more noticible effect. The L.E. slats opened up about 3/16" and it took a whole week to make each one move. Then the weather changed, the holes swelled up, and that became another wasted effort. Next model was without slats, and it perfomed same as the one without (until the fiddling of the flaps began).

The effort may work on a model, but you need to apply it to a LARGE model, and for S.T.O.L. appearances, it is simplier to overpower the model and acheive the same look.

Wm.