hotrod180 wrote:EZFlap wrote:....Battson, making your Bearhawk into a (true) Fowler flapped airplane looks like a moderate amount of effort. You would need to offset the flap hinge quite a ways down from the wing lower surface (like an airliner flap hinge), but by doing it that way you could achieve the Fowler action with only a "plain" pinned hinge and no complicated tracks and rollers. ....
That part sound easy, why is the redesign of the flap cove necessary? Dropping the hinge points would configure it like a Cessna barndoor flap, rotating down and back when deployed, and that sure works good on a Cessna. Not exactly sure what a true "fowler flap" is, because I've heard those Cessna flaps referred to as a fowler or a semi-fowler design.
Based on what I've read, Cessna 100 series (and many 200 series) have a semi-fowler flap, but the rearward movement is very limited and they are probably closer to a slotted design (like you see on a Husky) than a full fowler design (like you see on the SuperSTOL, Sherpa) in terms of the extra lift generation.
As I understand it, a true fowler flap has a much larger range of motion, and a different hinge design which by necessity hangs down outside the aerofoil. So a true fowler is characterised either by quite large exposed slotted guides, a complex hinge mechanism, or same hidden inside fairings like you see on a PC12 or similar.
By way of an update on our investigations for the Bearhawk, we determined the torque created by a full fowler flap system would require significant structural changes to the wing to support the flap guides. The location of the fuel tank doesn't lend itself well to making such changes, either. The exposed guide design is a problem because it obstructs the rear doors from opening. So until we can solve those issues, we've parked that idea.
We've looked at slotted flaps too, these would be a much easier install. But because the potential performance increase on offer is about half of what a full fowler option could deliver, we're less enthusiastic about that option. One possible aggravation is, the added weight of doing the mod to a completed aircraft will also reduce the benefit in terms of STOL performance. But the main issue is it's summer, and we're too busy flying to worry about mods right now!
