One dream: the weightless sailboat

L'aile d'eau (1998)

Luc Armant

Ingo Voegler

Kitefoil

Le voilier des airs

Burgess/Costes/Feldzer/Hulot/Rousson

1939 ->1992-2014

Hapa/C-Glider

Hagedoorn/Costes/Rousson/Claudel

1960 -> 2007-2011

Hydrokite

TU Delft / 2008

flying pod + hydrogenerator

Syroco

Alex Caizergues and team

500m World Sailing speed records

Syroco speed craft

Design

Tools used

• Expert advices (Luc Armant, F-one, ...)
• Analytic models
• CFD
• Multibody Velocity Prediction Program

Forces aligned: no  ballast/float to balance

Tension only in kite: large power/finesse to weight ratio

Aerodynamic lift: potential for reduced cockpit+shaft drag

Fully submerged foil: reduced ventilation/wave drag

Super ventilating or supercavitating ?

https://foils.org/wp-content/uploads/2018/10/Parker-Entry-1ST-PRIZE-MIT.pdf

Gondola

Impact protection

Designed to crash on the surface at 80kt without breaking

Reduced drag

Streamlined in air+water

Free weathervaning water then air (+damping)

Water protection

Buoyancy

Minimal stability

For electronic

But control challenge

Electronic foil control system ?

Build

Test

Workshop

• Max load tests
• Endurance test (battery + thermal)
• Software logic check
• Speed/latency test
• Sensors test and calibration

• Electronics (batteries, poor connector, ...) might start fire...
• NMEA 2000/CAN can be a nightmare
• Electromagnetism is sometimes like black magic

Foil only

• Wire rudder control ❌
• Hydraulic rudder control ❌
• Manual RC electronic rudder control ✅
• Automatic rudder control (Roll PID control with IMU in foil) ✅

• Drag of cylinder is reduced with ventilation
• Foil can jump very high and come back toward anchoring point
• Density/weight distribution must be right for initial positioning

Kite only

• Manual RC electronic differential steering control
• Manual RC electronic trim control
• -> Static flight, dynamic flight, take off

Gondola only

• Buoyancy
• Watertightness
• Radio link robustness (up and capsized)
• Internal elements fixation
• Undisturbed roll/pitch/yaw

Lot of efforts only to get to this state !

Foil + Gondola

• Hull roll/pitch/yaw stability with foil in water
• Take off
• Stability/damping in air
• Ultrasonic/GPS RTK check
• Load sensor check

• Skeg is good for low yaw/roll coupling
• Chase boat wave is not helping-> need to go out of wake

Kite + gondola (+catamaran)

• 1 person onboard kiteboat steering the catamaran
• Kite motors inside gondola controlled remotely from chaseboat

• Elastics are good to get rid of slack in control lines
• Apparent wind reduces turbulence level and make things easier

Archimedian navigation

• Small kite
• Deploy kite and lines
• Ability to capsize and redress by steering kite to zenith
• Ability to relaunch kite
• Ability to accelerate
• Ability to slow down
• Ability to jibe
• (no real ability to choose course)
• Ability to control larger kites

Kite + gondola + foil

• Capsizing is not an issue
• Kite release system must be robust

Flight

• Selection of kite size to be able to take off
• Ability to take off gondola
• Ability to fly low
• "Ability" to jump
• Selection of foil size to be able to choose angle to the wind.

Kite + gondola + foil

• Low Speed Stabilisation System for pitch/yaw stability
• Rudder->yaw->roll control not very fast for altitude control at low speed

Future: run ?

Plane

Train

Wind turbine

Airborne Wind Energy

Boat

Offshore wind turbine

Sailboat

Foiling boat

Aile d'eau

Dual Aircraft Platform

Dynamic soaring

Energy

production

Energy

consumption

Ground

Air

Air

Water

Dynamic simulation