Plane & Pilot
Tuesday, October 2, 2012

Way Ready For Prime Time

Amphibian dreams vs. reality: here’s a classy amphib in full production

Duck Feet Vs. Flying Boats
Pilots avidly defend the merits of the particular aircraft they fly. Some seaplane (floats-only) pilots, hoping to graft the same land-anywhere chops to their birds as amphibians like the SeaMax come by naturally, don't always realize at first they're also increasing risk.

Seaplane-seasoned pilots can and often do forget to retract wheels on water landings after converting to wheeled floats. Wheels-down water landings aren't casual miscues: They often lead to fatalities because such rigs frequently capsize immediately and passengers get trapped underwater. That nasty tendency also drives insurance rates dramatically higher—you can even get coverage. Hulled amphibs like the SeaMax have main wheels behind the CG, which makes them less likely to capsize.

Amphib floats can be more challenging to land and handle on the ground, too. And brakes fail more frequently since they're immersed in water for long periods of time, which calls for increased maintenance (lubrication of gear-well doors and brakes, etc.).

Crosswinds present problems, too. On water, pilots can almost always set down into the wind. On land, amphib float planes give away some crosswind capability to land-only planes. Poorly executed crosswind landings more readily cause gear-collapsing side loads, too.

Floats also reduce roll response, since all that mass acts like a pendulum. Likewise, the higher center of gravity makes for more vulnerability to wind during ground handling.

Finally, many amphib float systems don't have shock absorption built in. Hard landings can send a strong jolt through the airframe. Amphib wheels are usually smaller than those on landplanes, too, providing less shock absorption even if just from the tires, along with more wear and tear on brakes.

Does that make amphibs like the SeaMax inherently safer? Boat-hulled planes have their own set of challenges, such as more easily shipping water into the cockpit in rough seas and lower ground clearance on land. The bottom line is, know the risks you're taking on before you succumb to "Gotta have it all!" fever, whatever type of airplane you fly, because in aviation, there are always trade-offs.

Labels: LSAs


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