transformable seaplane/sailboat

[Squidly-Diddly]

http://seaeagle.org/

Interesting idea, but I can't see it sailing well enough to make the sail feature worthwhile.

[tspeer]

I think this would be a good application for a freewing. The spars would need to fold up, but the wings would pivot about the spars under the control of the wing-mounted tails in both flight and sailing modes. When sailing, the freewing woujld be much like the Harborwing wing rig.

To fold the spars, I would pivot them about a longitudinal axis at the top of the struts. The ends of the spars would be restrained at the center fuselage in flight and at the floats when sailing. Sailplanes do something like this now to make the wings removable. Each wing has a stub spar that goes to the opposite side of the fuselage, and when pinned together the two stub spars are capable of carrying the bending loads of the wing. Controlling the folding from the inboard ends of the spars would significantly reduce the loads on the folding actuators.

As for its sailing qualities, it would have a lot of windage. You're certainly not going to see 20 kt from this catamaran! Like so many airplane/surface vehicle hybrids, the point is not that it performs well in both modes but rather that it can do it at all.

The simple act of folding the wings up and feathering them into the wind would make docking the plane much easier and there would be far fewer restrictions as to where it could go to load and unload. Being able to actually sail would be a plus.

The principal thing sailing adds is long endurance. There's no point in sailing long distance - flying is much the better way to get between widely separated points. But if the craft had to spend a long time on station or make a lot of stops in the local area, then sailing would save a lot of fuel.