Flying-Boat V0.2 by kolergy

Last crawled date: 3 years ago

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/