I was just re-reading Design & Application: Hingeless Aileron, a discussion about designing and testing the "hingeless aileron" on the Zenith Zodiac.
The results of a very specific calculation are shown here. A sheet of 0.016" thick 6061-T6 is being flexed repeatedly at the same point. The deflection is ±15° from flat, applied to form an arc with 0.8" length. This is a radius of curvature of 3.06"; call it 3".
To quote Chris Heintz's conclusion: "It is some 120,000 hours, which, reduced by the safety factor of 8 (usual when analysis is performed), amounts to 15,000 hours flying time."
Now, there's one huge number missing here, which is the number of deflections (and amount of deflection, if not maximal) per hour of flight.
Can someone teach me how to do this calculation, to find acceptable number of cycles for a given aluminum alloy, at given thickness, at given radius of curvature / deflection? To make it an interesting exercise, finding the answer to this will let us reverse Chris Heintz's calculations and figure out what he assumed as "typical" aileron usage.
(I'm considering using a flex hinge for a later revision of my design, although it would be of a thicker material, but with a much lower deflection and radius of curvature.)
The results of a very specific calculation are shown here. A sheet of 0.016" thick 6061-T6 is being flexed repeatedly at the same point. The deflection is ±15° from flat, applied to form an arc with 0.8" length. This is a radius of curvature of 3.06"; call it 3".
To quote Chris Heintz's conclusion: "It is some 120,000 hours, which, reduced by the safety factor of 8 (usual when analysis is performed), amounts to 15,000 hours flying time."
Now, there's one huge number missing here, which is the number of deflections (and amount of deflection, if not maximal) per hour of flight.
Can someone teach me how to do this calculation, to find acceptable number of cycles for a given aluminum alloy, at given thickness, at given radius of curvature / deflection? To make it an interesting exercise, finding the answer to this will let us reverse Chris Heintz's calculations and figure out what he assumed as "typical" aileron usage.
(I'm considering using a flex hinge for a later revision of my design, although it would be of a thicker material, but with a much lower deflection and radius of curvature.)
