Has anyone considered putting a hydrofoil on a sea plane? One of the main problems with water landings is that you need a bigger engine to counter the various drags caused by the pontoons. The specific case of "run[ing] across our own wake to be able to get up on the step on glassy water" brings some interesting thoughts.


  [B]asically a floatplane has to break the suction of the water - kind of like pulling your boot out of mud - and if the water isn't moving at all then it has to do that all by itself. If there are some waves, or a wake, or any kind of discontinuity in the water, then that gives the aircraft the momentary break it needs to overcome that initial suction. "The step" in this context refers to the step-up shape you see partway down the float (or hull); when you're "on the step" then you're using the part of the float forward of that step to hydroplane.


It is well known that water's significantly higher density makes high speeds difficult. A solution to that problem is the hydrofoil - a small underwater wing that raises some or all of a boat's hull out of water to reduce friction and increase speed.

So here is my dumb question: would placing a hydrofoil under a pontoon save fuel on takeoff? And how likely would the increased drag during flight cancel that advantage on a typical flight?
Yes. I mean, sort of. Nobody's ever built a production hydrofoilplane.

It's not a bad idea, but seaplanes are a relatively niche product these days and there doesn't seem to be a lot of innovation in the field. Back when there was, there was innovation everywhere so the idea of hydrofoils didn't stick.

The Convair F2Y Sea Dart, a 1950s prototype jet-powered fighter, used two 'hydro-skis' for takeoff and landing. It was more or less awful compared to the crop of land-based aircraft coming along and after a prototype disintegrated they (probably wisely) chose to shut the program down.



There are some other prototype aircraft that used actual hydrofoils that I found after some quick googling. A company called Lisa Airplanes seems to have an LSA - the Akoya - that's under development using tech similar to the Sea Dart.

The 1929 Piaggio P.7 used hydrofoils, and was intended to compete for the Schneider Trophy, but never made it airborne. Interestingly enough it had a screw (marine propeller) at the tail and a proper aviation propeller up front, and the pilot would've had to do some juggling between the two.



It's likely there were others, but I'm running low on sleep.