Hi David,

Always appreciate your input. I will have a look at the issue of Canard Pusher and get refresh my memory. Thanks for the tip.

Cheers,

Jay

Jay,

I concur: Eliminate the sparrow strainers (they’re a hack anyway) and, instead, design an elevator that has a small amount of reflex on its trailing edge. That is exactly what John Roncz did on his Long-EZ canard replacement airfoil in the 1980s that is now the standard airfoil for those planes. The elevator “floating angle” should give the needed elevator deflection to make the canard give just the right amount of lift for a slow cruise speed, around 1.3 to 1.4 times stall speed. Rutan spells out this requirement in his Canard Pusher issue … 59(?) … where he discusses all the design requirements for pitch trim stability of canard airplanes. This “fix” could also be applied to the GU canard….

I can’t wait to see your results!

David J. Gall

Good point Mike. That was Charlie’s suggestion also, based on his experience from his dragonfly.   I have a redesigned elevator on the drawing board that I have discussed before on this forum that is neutral in trail, so would not require the strainer. Sometime when I get the motivation, I will build a new set of elevators using this design and flight test them.

The LS-1 airfoil was never designed to have an articulated control surface.  I think the use on the Q200 was a bit of a hack, so required the sparrow strainer to correct the unintended consequences. The LS-1 is still the primary airfoil used on wind turbines, since it is very resistant to degraded performance caused by surface contamination, but those blades are one piece, so it is the perfect choice.

Cheers,

Jay