Wingboat Design

[Doug Carlson]

Profile.

[tspeer]

Yeah, that's crude!-)

I'd shape the bottom more like a single seaplane pontoon, with a steeper run aft of the step than you've shown. After all, a seaplane pontoon is designed for amost exactly what this craft is doing - part flying, part planing; minimizing the shock loading; allowing the craft to rotate forward as it comes up to speed and being able to rotate up to fly off the water in a stable fashion.

The bottom needs to be V'd to reduce the impact loads. The bow looks pretty steep, and it may need some sheer. I think you'd have to picture the craft both at rest, sitting in the water at a modest bow-up attitude, and at speed, in a bow-down attitude. Say, -5 to -10 degrees, with the wing level. The zero lift angle of attack for a cambered airfoil is typically around - 3 degrees, so the wing doesn't need to be at much of an angle of attack when going fast.

I would put the fins up, not down. Drag a fin in the water at speed, and you've got real problems! The fins can be canted out a bit and swept aft.

I'd give the wing a delta planform. Possibly with planing surfaces a the tips, like a Lipisch WIG. Then it would start planing on 3 surfaces until the wing lifted the back end up. The wing should have a fair amount if incidence - maybe something like 10 degrees. I had pictured the trailing edge just touching the water when at rest. If the wing has anhedral, this may mean the planform is more of a cropped diamond.

If you wanted to power it as a boat, I think an interesting idea would be to put a surface piercing prop right behind the step. Possibly have a tunnel in the bottom contour aft of the step to make room for it. That also solves the problem of where to put the engine if the cockpit is aft. The cockpit may have to be moved forward - aft may be a marginally better ride, but this thing is going to be pretty rough no matter what if it's going fast in any kind of waves.

[Doug Carlson]

I'm trying to stay away from fancy surfaces just trying to indicate layout.

[Doug Carlson]

At rest, approximately.

[Doug Carlson]

Head on. Doesn't look like the tips get high enough in this config.

[Doug Carlson]

From the helicopter.

[Doug Carlson]

A little more organized.

[Doug Carlson]

At rest.

[Doug Carlson]

On the step (plane).

[Doug Carlson]

If you had a kevlar scattershield in the tunnel would you sit on a surface prop?

[Doug Carlson]

If the shear is going the right way you could see over the bow.

[Doug Carlson]

New shear at rest.

[Doug Carlson]

Another view.

[tspeer]

You're getting there!

I think I like the straight shear better. I'm still leery of poking the bow into a wave at high speed. I think I'd rather raise the canopy than lower the sheer. The poor pilot has enough problems seeing to the side - being able to look over the wing wouldn't hurt.

The wing could just bend up to form the fins, with a chamfer on the outside to act as a planing surface.

I don't think the tunnel needs to go all the way to the stern. I was thinking the aft part of the hull just behind the step would be lower and slope up to the stern. So you'd need the tunnel near the step, but it would blend out aft. In fact, I think the whole hull could taper toward the stern.

I think you've done a good job capturing the key elements - from here on out it's refinement & styling. This concept is really not all that far from your original sketch - it just carries its tail a lot higher and has the step.

[Doug Carlson]

I have another solution for which I apologize. Its a swath in ground effect or a swig.