Bearhawk STOL mods

[Battson]

My thoughts exactly.

[Battson]

I wonder how much difference lowering the flap hinge point below the wing will help, like a Husky or Maule. I suspect a bit, but then we would have to figure out if the wing is strong enough to handle the change in forces.

The wing has been modelled by the guys at Javron, it was found to be strong enough to hang double slotted AA flaps on it. I am sure a lower hinge point would not be a lot different. Maybe cause to be more careful with flap speeds.

This is my personal favourite to improve Bearhawk performance, in terms of bang for buck.

[Bcone1381]

I'll expand on curiosity of flap effectiveness.....

What about Cessna Style flap tracks. You get a true "fowler" flap action and miss out on bumping your head on the hinge that hangs down.

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[zkelley2]

Has anyone tried flap seals? I know the gap is small but air is smaller. Gap seal on my elevator and rudder worked quite well. Tape along the bottom like my elevator and rudder would be easy to do.

With the plain flap on the bearhawk you're not really counting on any air up and over to re-energize the boundary layer. I don't think it'd do anything.

[schu]

Has anyone tried flap seals? I know the gap is small but air is smaller. Gap seal on my elevator and rudder worked quite well. Tape along the bottom like my elevator and rudder would be easy to do.

It for sure couldn't hurt, but I'm not flying yet, so I don't know.

I wonder how much difference lowering the flap hinge point below the wing will help, like a Husky or Maule. I suspect a bit, but then we would have to figure out if the wing is strong enough to handle the change in forces.

I also wonder how well your drooping ailerons work. Would you do it again? Any details you can share?

schu

[rodsmith]

I have also wondered if this would be beneficial. You could try it and let us know.

[Helidesigner]

Has anyone tried flap seals? I know the gap is small but air is smaller. Gap seal on my elevator and rudder worked quite well. Tape along the bottom like my elevator and rudder would be easy to do.

[Battson]

Yes that is the Maule flap idea discussed on previous pages, but no that is not a fowler flap - that is a slotted flap.

[Hewko]

So would it be possible during the build to make the standard Bearhawk flap into a fowler flap by attaching a second lower flap pivot point, about 2 inches lower similar to a Maule? And then moving the flap actuating rod attach point correspondingly lower on the flap? The roughly hand drawn in extension point on the attached image shows it better than I can explain it. Is this worth trying or will it introduce problems?

[Battson]

It would certainly make a difference (not necessarily better) - but it depends, what are you trying to achieve? If you only care about slow flight, adding camber and increasing angle of incidence are no-brainers. If you also care about cruise speed, maybe not such good ideas...

[whee]

In essence I agree with Rod.

Both the A and B wings were designed with slow flight in mind, the Cessna was not designed for that specifically. While I think the Cessna wing is pretty good on it’s own the Sportsman cuff offers better slow flight for the guys that want it.

[rodsmith]

Would a sportsman style LE cuff make any difference on the Ribblet airfoil? Does anyone know if this has been tried on a Bearhawk?

Having read Harry Ribblet's book I would say no. The sportsmans cuff is a bandaid on a poor airfoil. Harry Ribblets airfoils corrected the design deficiencies of the NACA series like the 24012 used on a lot of Cessnas. The sportsmans cuff is adding leading edge droop to the 24012 airfoil. This is already designed into the Ribblet 30 series airfoils. Adding additional droop on a Ribblet airfoil would have unpredictable results, might improve one end of the speed envelope with major detriment on the other end. So how about the 4412 airfoil on the A model? Bob modified the 4412 adding leading edge droop. There are two methods of calculating this change. According to Harry, Bob did it the correct way.

[jaredyates]

Would a sportsman style LE cuff make any difference on the Ribblet airfoil? Does anyone know if this has been tried on a Bearhawk?

When I put on my science hat, my answer is I don't know, and I don't know of anyone who has tried it. When I put on my intuition hat, I have to wonder of it's like putting ketchup on a high dollar steak. As with any proposed mod, the key question is what is the shortcoming that the cuff would be addressing?

[Hewko]

Would a sportsman style LE cuff make any difference on the Ribblet airfoil? Does anyone know if this has been tried on a Bearhawk?

[svyolo]

Yeah, I might be. But I think I will keep it simple.