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BD-4 Amphibian

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Riggerrob

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It was probably limited to carry only two people. That large hull probably weighed as much as two people.
... the same way that Cessna 172 on floats is really only a two-seater.

We wonder what they used for lateral stability on water ?????? wing tip floats or Dornier-style sponsons/water wings ??????
 

edwisch

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The BD-4 has the wrong wing -- area and airfoil -- to be a good candidate for an amphibian. Reminiscent of the Seawind amphibian that you never saw at the Oshkosh seaplane base, only on the grass...
 

BJC

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The BD-4 has the wrong wing -- area and airfoil -- to be a good candidate for an amphibian. Reminiscent of the Seawind amphibian that you never saw at the Oshkosh seaplane base, only on the grass...
I’m curious: What are the differences between the BD-4 airfoil and the D H Beaver airfoil?

What makes the Beaver’s airfoil good for land and floats?

Thanks,


BJC
 

edwisch

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High lift at low speeds is the key. Land vs floats is not really the right question... Also, a land plane can have more deck angle on the surface than can a float plane, hence higher angle of attack, so that's another consideration in airfoil selection.
 

Dan Thomas

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Sep 17, 2008
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I’m curious: What are the differences between the BD-4 airfoil and the D H Beaver airfoil?

What makes the Beaver’s airfoil good for land and floats?

Thanks,


BJC
It's not that good. A friend developed at STC for a droop leading edge for the Beaver, and it worked well. Some pilots said that they used to use a bit of flap in cruise to get better lift without mushing. With the droop that wasn't necessary, though I understood droop was to improve low-speed handling, not cruise.
 

Riggerrob

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DHC-2 Beaver drooped leading edge STC also helped tame stall characteristics. Apparently stock Beaver wings had an annoying habit of stalling all at ounce, while later drooped modifications tended to stall progressively from root to tip, still providing some aileron control on the edge of the stall.
 
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