The Return of Commercial Sail â€“ UT Wind Challenger & Retracting Rigid Wing Sails
Early airplane wings were built of canvasÂ stretchedÂ over a wooden frame, held together with wire rigging. Â Modern airplane wings are built of aluminum and other metals. Â The comparison to sails, masts and rigging on ships may not apply directly. Â Nevertheless, the last America’s Cup winner, the US-17, formerly known as the BMW Oracle Racing 90,Â screamed to victory in 2010, sailing on a 223 feet rigid wing sail, more than 80 percent larger than the wing of a Boeing 747 airplane. Now a Japanese group, includingÂ engineersÂ from theÂ UniversityÂ of Tokyo, are developing the design of aÂ merchantÂ ship with retracting rigid wing sails, the UT Wind Challenger.
We recently posted about the efforts of B9 Shipping andÂ FairtransportÂ toÂ develop commercialÂ sailing ships using an automated “Dynaship/Dyna-Rig,” similar to that used on theÂ sailingÂ yachtÂ MalteseÂ Falcon. Â The Dyna-Rig approximates theÂ aerodynamicÂ efficiencyÂ of a wing sail while still using cloth sails.
The UT Wind Challenger usesÂ aluminumÂ and reinforced plastic hollow wing sails. Â The UT Wind Challenger team has addressedÂ a majorÂ problemÂ with wing sails – thatÂ theyÂ are difficult to manage in port, by using what they refer to as “vertical reefing,” the wing sails retract into themselves. Â It appears that the UT wing sail design could be applied to considerably larger ships than is currently beingÂ planned forÂ thoseÂ ships using the Dyna-Rig. Â TheÂ developersÂ estimate a 30% savings in fuel consumption using the wings sails, which sounds like a rather conservative estimate given the sail area involved. There are plans to build a reduced scale prototype to test the concept by around 2016.