Plane & Pilot
Monday, July 1, 2013

Badlands Buster

Pictures from an exhibition of LSA STOL like you’ve never seen before

Memories of hang-glider landings flood my brain at the ground rush, which is probably why I'm not white-knuckling the airframe. Then the tailwheel hits, and a couple days later or so, it seems the main gear plops firmly onto the runway. I watch the big oleo gear strut just soak up that sizeable vertical speed bump without a whimper. We don't carom back up into the sky, Woodland works the oversize brakes, and in 30 feet or so, no lie, we've spun around to taxi back. What the hell indeed. Man, what a hoot.

If you have a hankering for fun crazy stuff like landing on the sides of mountain ridges and steep meadows and deep-canyon dinner plates...and jumping back into the won't find an all-around better-performing STOL airplane in the LSA camp.

Lest there be any lingering doubt, I now affirm for all and sundry: The Just Aircraft SuperStol deserves every letter of its name.

Frise, Fowler!

SuperStol designer Troy Woodland knew that the SuperStol's performance would benefit greatly from Fowler flaps, Frise ailerons and leading edge slats. Let's find out why.

Frise ailerons are mounted to rotate at their 25% to 30% chord line. This innovation decreases stick forces. When the aileron moves up into the relative wind to make its wing go down, the leading edge of the aileron drops down into the airflow underneath the wing. That air force against the aileron's leading edge aids in rotating the aileron, reducing required stick force.

That deflecting air flows over the top of the aileron to add lifting force, which helps lift the entire wing and also reduces the ultimate required deflection angle of the aileron.

Fowler flaps drop down from the trailing edge of the wing but also slide back, too. (Think jet airliner on takeoff and landing.) This little trick increases the effective chord—or leading-to-trailing-edge distance—of the wing, creates an air gap and increases camber, which transform the inner portion of SuperStol's wing into a larger lifting surface.

Leading edge slats, like Fowler flaps, also increase the chord and camber of the wing. Some airplanes, like the Zenith CH750, have fixed L.E. slats. SuperStol's automatically deploy in and out, pulled forward by the increased angle of attack of the relative wind, to create a gap between themselves and the main wing. The slat develops some lift on its own as air flows around it and the air continues on, some over the wing, which stays attached to the upper surface at higher angles of attack than normal.

Altogether, slats and Fowler flaps deliver a larger wing surface that keeps flying at higher angles of attack and slower speeds for very short field landings and takeoffs—the prime directive for all STOL airplanes—yet they can retract to reduce drag at cruise speeds.

Labels: LSAs


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