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Well-Known Member
Oct 20, 2003
Northern NSW Australia
I am working on a hinge/horn (hinged 10mm below the lower surface) assembly to be mounted on the underside of the wing TE attached beneath the LE of the aileron. These I may trade off weight for strength and get them done from billett. The assembly will include the control linkages, connecting to a bellcrank on the wing mounted attachment which transmits force from the aileron bellcrank in the wing to the actuating pushrod to the control mounted pivot/linkage assembly.
I'll have some drawings later, but my initial sketches in the configuration I envisaged, only gives me a very small amount of travel on the control horn. 20/15° deflection (Friese ailerons) controlled for equal distance throws of only 6mm by the horn.
This will mean at times there will be a pretty large moment in effect at this point, and I was wondering if since the connecting rod is going to be short, if these forces can be sufficiently dealt with by a conventional linkage system? I can see the ailerons being pretty heavy.:confused:


Mar 2, 2003
Western Washington
I think having pictures will help however, in general I think you'll find that the reaction forces on a Frise aileron are somewhat lower than those you might see on a plain aileron. The moment per deflection is consistant but since the hinge point is some distance away (below the lower skin line) this allows for a longer arm for the control rod attachment point, and thus the axial forces on the control should be relatively low.

However, to get the magnitude of those forces, see if you can get a hold of a copy of the JAR specifications. In parts, these are virtually a copy of the FAA's FARs, including the loading diagrams located in the Appendix of Part 23. The diagrams spell out pretty well the loading magnitude and configuration for any flap and control surface.