Downwind lift possible with a non-rotating freestanding mast?

[folotp]

Hi,

I am wondering if it is possible for the sails to generate lift when going downwind on a non-rotating freestanding mast. Like on a Freedom rig for example. Would the boom have to go too far forward?

Thanks.

Pierre-André

[messabout]

Pierre; When you say lift, are you referring to vertical lift? If so you will need to introduce a vertical component to the force of the sail. That implies that the mast is raked, as on a windsurfer. More rake means more vertical lift and diminished forward drive. Vector sums at work.

[Perm Stress]

Windsurfer style freedom rigs with wrap-around sails, certainly.
If dead downwind, booms have to be about 30 or so degrees forward from abeam.
The side effect is force component to "windward" -opposite side from the boom.

[tspeer]

Originally Posted by folotp

Hi,

I am wondering if it is possible for the sails to generate lift when going downwind on a non-rotating freestanding mast. Like on a Freedom rig for example. Would the boom have to go too far forward?

Thanks.

Pierre-André

You need to reduce the angle of attack below the stall angle. The boom has to go well forward to accomplish this. It can't do that when there are shrouds, and the gooseneck is probably not going to have enough freedom of motion on a fixed mast.

A fixed, cantilevered round mast could do it, with the sail and gooseneck rotating around the mast.