Flying-Boat V0.2

thingiverse

A small experiment with foils to evaluate the feasibility of a flying boat with U shaped hydrofoils. This is a pure Fablab creation we started to have the idea to test this with Ricardo at 20h00 one evening @ the Artilect Fablab in Toulouse and at midnight all the part where designed & cut ready for assembly. The end idea could be to modify a hobbiecat or similar boat. But for now it is to have fun with the understanding of hydrofoils. Concept to demonstrate: U shaped foil which have to following interesting advantages: Reduced induced drag due to the presence of sidewalls No stress concentration a the root of the wing requiring costly carbon fibers Connected to the bot by a pivot axis allowing easy angle of attack control and to put the foil out of water for ditching. Things not included in this design: A decent hull lateral control & stability Pitch & altitude control & stability Hydrofoil polar calculation Hydrofoil design: Chord widith 74mm Speed 5kph -> 1.4m/s Water kinematic viscosity @ 10degC = 1.267E-6m^2/s Reynolds (in water) Re = 8.0X10^4 Lifting surface 0.03m^2 Initial idea was to use an Eppler 818 profile it is good at those low Reynolds numbers. More details can be found there http://airfoiltools.com/airfoil/details?airfoil=e818-il However making such a small profile with styrofoam was an issue. Since at those very low reynolds a flat plate works well. a 1 mm plastic plate was used with some camber. First test: Very crude just pulled by a truing at the end of a stick on the local river She managed to take off at fast walking pace even loaded up to 3.5kg The hull shape is extremely crude & the bow create an incidence effect to the front foil requiring a bit more incidence to take off. What is next: Upgrade the prototype to have a better hull shape Integrate lateral and vertical control integrate a propulsion system making similar effort as sails. generate a polar for the foils. Pictures Courtesy of Ricardo. Made in Fablab Artilect: https://artilect.fr/ Instructions Very simple build with laser cut 3mm plywood Assembly with a lot of hot glue. Pitch adjustment through an adjusting screw guided by a long nut fixed to the hull with more hot glue. The wing part of the foil in in 1mm plastic foil. initial idea for the wing was a profile cut in stirofoam with hot wire but it was not practical for such a small shape. and we found out that at these extremely low Reynolds just a curved flat plate was perfect.