Hull shapes for Water Plane

Apparently not. Piaggio P.7 hadn't one Piaggio P.7 - Wikipedia https://en.wikipedia.org/wiki/Piaggio_P.7
regards
krzys

 

My proposal for seaplanes includes cambered steps, low wings and asymmetrical hulls.
JS

 

A seaplane must be calculated as a planing boat with varying weight as aerodynamic lift takes over. This requires knowledge of how both a planing boat and an airplane are calculated. Calculate, don't guess.
JS

 

Why did you choose low wings? They can be easily hit by waves .
Besides, I don't understand this cambered steps . Trapezoidal wings shape also.

 

As my professors always told me...start with a free body diagram showing all the forces. Do that and you will answer all the above questions. FWIW, this is basic engineering design 101.

 

This is a very neat design, my first approach was similar. Wing close to the surface, yet safely above it. The center hull is well above the water and a propeller can be mounted diectly. Separation of functions: payload hull and floating hulls, makes optimizing each easier. Reverse V-Tail is more stabilizing than convetional V-tail.

Despite being a good design, there are a few issues:

The separate floats create a lot of aerodyamic drag, and it is better to integrate the fuctions in one hull. I.e. the cargo hull offers boyant volume for "free".

The elevator needs to be substantially higher than the wing for stability when transitioning in and out of ground effect. Therefore T-tails and high H-tails are preferable. Also this will need a lot of trim variations, where V-tails perform poorly.

The pusher propeller has more losses due to uneven inflow compared to a tractor propeller. You loose 8-12% efficiency just from that. Furthermore, rear mountrd engines are more elaborate to cool, which costs another 3-6% efficiency. (Why are there no boats with tractor propellers?). Having the engine in the rear often creates headaches when it comes to CG location with and without payload.

There is too much taper on the wing planform. For safety reasons mildly tapered wings with the twist distribution creating an elliptical lift distribution is better. This ensures that the wing tips and ailerons don't stall first.

 

With hydrofoils this becomes even more complicated. There is a boyant hull, a planning hull, a lifting hydofoil, and a lifting wing. Each effect overlapping.

The last two I can handle. The first seems trivial (I hope). But I know little about planing hulls. Would you kindly share references to books or papers that explain the calculations for planing hulls? Are there methods involving hand calculations that have been calibrated with tests?

Furthermore, do you know how I can evaluate wave loads?

 

Wings close to the water are better for ground effect, which can create a massive performance boost. But of course the wings need to be high enough to not plow in the water

 

FlyingMo: Furthermore, do you know how I can evaluate wave loads?

Start with Savitsky which can also include resistance in waves. I also use J.Koelbel and others.
JS

 

Can be calculated according to Koelbel & Clement, Dynaplane.
JS

 

Thank you!

 

Do you guys have experience with and an opinion about the tool "powerhull" by nautcad:
powerHull – nautcad https://nautcad.com/?page_id=149

 

Your long floats seem to allow for the increase of angle of attack by about 3deg only. You will need very efficient flaps to take off.
Compare with the old Savoia-Marchetti S.65 with somewhat similar layout, that allowed for about 6deg of positive pitch while planing.
regards
krzys

 

At present I do not knew the wake aft of the camberad step.
I don't see the similarity to the aircraft you refer to.
Today I would choose to work with adjustable interceptors both at the step and the wing between the hulls.
JS