Wing Sails

[tspeer]

Originally Posted by ancient kayaker

Now that is very interesting, if the tail can be fixed things get simpler. The arrangement for controlling the boom would have to be able to push the boom out as well as pull it in, but in practice it would not be a problem in a high speed craft as the apparent wind would not be far off the bow at speed. It suggests an offshoot of BMW Oracle's computer control requiring less power to operate the sail, allowing smaller, battery-powered servos. Might bring it within the range of us poor folk!

You might want to consider a belt or chain drive. A large pulley or sprocket on the wing is connected a smaller capstan mounted to a motor. Basically the same way an autopilot is connected to a steering wheel. It's simple, works in both directions, and you can get a wide range of gear ratios between the motor and wing. Wing angle sensors can be driven by the belt/chain, too.

With aerodynamic control balancing the wing, not much power would be required. In fact, a comparatively weak motor would be designed to be overpowered by the tail when the wind was high or gusting. Basically the maximum torque from the motor would correspond to maximum achievable heeling moment from the wing, because the hinge moment about the pivot axis from the wing and tail would correspond to the lift on the wing.

Direct control and tail surface control are not mutually exclusive, either. Rapid changes in wing trim could be done with the direct control. The tail angle would be used as a trim control to alleviate the load on the direct control. The tail would be driven by integral compensation, naturally washing out the direct control. That would preserve the direct control power for transient control, reduce power consumption, and avoid overheating an electromechanical actuator. The tail actuator would not have to operate rapidly, which would reduce its power consumption and weight, too.

In the event of failure of either the direct control or tail control, the other can act as a backup, providing functional redundancy in the system. With some judicious limiting in normal operation vs abnormal situations, and fail-passive design, the surviving control method could be given the ability to overcome the crippled control.

[ancient kayaker]

Originally Posted by tspeer

You might want to consider a belt or chain drive. A large pulley or sprocket on the wing is connected a smaller capstan mounted to a motor ...

Pretty much waht I had in mind for a first experiment in a small boat, but connected to a simple handle wheel or tiller. Worth a try: I'll add it to my list of things to do, but the list is getting awfully long ... so don't nobody go holding yer breath now ...