Re: Need a Sparrow Strainer alternative


--- In Q-LIST@..., dan@... wrote:

Wait. . . I just looked up "gurney flap" in wikepedia. . .wouldn't a
"gurney flap" push the trailing edge of the elevator UP and the nose
DOWN? That seems to be the opposite of what the sparrow strainer is
trying to accomplish. Just FYI.

The TE of the LS1 elevator is curved
down. . . the sparrow strainer causes a DOWN force on the TE to reduce
AFT stick forces. Perhaps you would need to install "Gurney Spoilers"
but that might cause even more problems. :-)

Also not sure how you
"increase lift or downforce." What does that even mean?

Dan Yager
Editor [1]
I wrote "lift or downforce" because which one the flap produces depends on whether it's placed on the upper or lower surface of the trailing ege: upper-surface placement promotes downforce which would make the Gurney a functional equivalent of the sparrow-strainer. I expect to do some experimenting to find the optimum Gurney span to duplicate the trim effect of the original winglet but high-speed runway tests should indicate whether the trim force is in the ballpark and a flight may be attempted. As for the sudden change in trim force when a sparrow strainer departs, that's exactly the reason to use a Gurney flap instead: it's just a little lip glued onto the elevator, sturdy and difficult to dislodge. Could be made from carbon-fiber BID and glued on with a structural adhesive such as Hysol, adding less weight behind the elevator's hinge line than a winglet. As I said, well worth trying...

Rick Nordgarden

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