EAA Airventure, Oshkosh, WI — After working at airports most of his life, legendary aviation innovator and designer Burt #Rutan wanted an airplane that could go many places, but not be limited by the need for a runway.
The SkiGull is a trimaran-hulled, amphibious airplane designed to land on water, snow, ice, and other unimproved surfaces–without having to bring the craft into a shop and physically change its configuration.
Rutan believes there are four significant shortcomings to common seaplanes: shock absorption, the major configuration changes required to operate off of various kinds of surfaces, the fact that seaplanes are noisy, slow, short-ranged, and inefficient, and the fact that the corrosive effects of salt water limit where the planes can go.
First, and foremost, the #design includes two skis that retract and extend from the tri-hull’s outboard sponsons. In the water the skis allow the craft to take off with substantially less effort than is required for a traditional seaplane. A pneumatic extension and retraction system also provides shock absorption on the water, a feature Rutan says is missing from all current seaplane designs, and is necessary for safe and smooth operations on calm-wind glassy water, and on very choppy water.
Range and efficiency are addressed with Rutan’s experience designing craft like the Voyager and the GlobalFlyer, both of which flew around the world unrefueled and nonstop. The SkiGull’s wing bears a strong resemblance to both long-duration designs and Rutan envisions trips from California to Hawaii in the craft.
A modern, composite airframe, which is assembled without the use of metal fasteners, solves the salt water corrosion problem. All the metal parts of the plane are easily replaced should corrosion become an issue.
However, he found hydrodynamics much more difficult and discovered that the sort of numerical processing that works for airplanes, starts to break down in the water.
Rutan’s solution, and the solution for many boat designers, is to build a test article, run it through the water, collect data and see how it performs. Results of those tests showed that the takeoff ski-extension speed he calculated was way off; the calculated takeoff distance was actually longer than what testing demonstrated.
The #aircraft is substantially complete and Rutan had a goal of bringing it to AirVenture 2015. But addressing some of the typical challenges associated with a new design, and the need for a structured flight test program, just would not allow the trip to happen.