Plane & Pilot
Tuesday, May 24, 2011

Searey LSX: SkyBoat Extraordinaire

Wings, webbed feet and wheels add up to the ultimate hybrid bird

A Short Course In Duck-Feet Flying
"Amphibious" airplanes are equally at home on water or land, since their floaty parts have retractable wheels. Floatplanes by contrast can only fly off water, but are common in remote areas such as Alaska, where commerce is made possible largely because bush aircraft can operate exclusively from lake and ocean seaplane bases located near towns.

One advantage float-only plane pilots trumpet is the ease of hopping out on the float for better control as you glide up to the dock. But, as Kerry Richter notes, "Floatplanes and amphibious floatplanes will never match a hull aircraft for maneuverability on the water, or for coming up on soft-sand beaches. Even floatplanes with amphib wheels need firmer surfaces than an amphibious airplane."

An amphibian's hull is designed from the start to optimize water handling. They can be nimbly driven around on the water because, unlike a floatplane, there's just one floatation surface...and it's shaped like a boat.

Both types of seaplanes, however, must pay attention to wave-height limitations. "It has a lot to do," says Kerry, "with how steep the 'V' is in the float or hull." Generally, the deeper the V, the softer it will behave in bigger waves because it can plow through them easier.

"But bush planes, which need to get up in short distances, have a shallower V to minimize water drag. The flip side is, in rough water, they take more of a beating because there's more horizontal surface for the water to smack against.

"With the SeaRey, we tried to hit the middle with a hull that could handle decent wave height, but still get off quick," Kerry explains about the aircraft's design. "We advise new water pilots to restrict themselves to waves of one foot or less until they know what they're doing."

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