I'm thinking that for F1D testing an airfoil that isn't close to a catenary curve would be hard to do without adding weight and defeating the purpose. What is the airfoil of an FiD anywhere that it isn't next to a rib? An F1D wing is basically a cloud of covering constrained at the edges. The spars put a tension on the covering, and the covering assumes a catenary curve depending on that tension. The ribs keep the structure from collapsing under that tension. When they are arc shaped, they conform to the curve the covering would take anyway, and give the builder a target as to how much covering to use to get a suitable curve. They also keep the tension from the tips from affecting the curve too much. How far away from the rib made with any other shape would it be that the covering would be following a catenary curve anyway.
To test these new airfoils in F1D, you could add spars where the airfoil flattens out or you could add more ribs, both likely to add more weight.
I think Mr. Holtzmann made fine wings with this airfoil in the A-6 size where the structure/ covering ratio is a lot higher than for F1D.
I've put 6% Simplex ribs in my Science Olympiad plane with an 8 cm wing chord. I'm sure I haven't put so many ribs in that I've got anything but a catenary covering anyway. The subtleties of adjusting the incidence, decalage and down thrust have given me the most improvements in duration. That new airfoil would need to be tested over a precisely measured range of those factors to see its advantages, after getting a wing that actually maintains that shape in flight.
Enjoy the challenge
Joe
Received on Sun Feb 08 2015 - 07:00:18 CET
This archive was generated by Yannick on Sat Dec 14 2019 - 19:13:48 CET