How can an vehicle move faster than the wind that is powering it?

Thread starter Topher925
Start date Oct 20, 2008
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Vehicle Wind

In summary, the conversation discusses the concept of a wind-powered vehicle, such as an iceboat or sailboat, being able to travel faster than the wind speed that is powering it. It is debated whether this is possible and how it could work. Some suggest that it is a hoax, while others provide explanations based on physics and mechanics. It is also mentioned that iceboats can achieve high speeds by sailing at an angle to the wind, rather than directly downwind. The conversation ends with a discussion about the diagrams in an article about iceboat sailing, and whether they accurately represent the angles and speeds involved.

Oct 22, 2008

#176

spork

Trond said:

let me know when you are ready to discuss the cart

I'll let you know.

Jeff Reid said:

Does anyone have an actual table of heading versus Vmg?

I presume you mean measured heading vs. VMG? I don't have that. Certainly given the measured L/D of the sail and skates I can give you that data.

Another issue is lift versus drag as it applies to sails. When heading downwind, aerodyamicd and ground lift are zero while aerodyanmic drag = ground drag.

I'm not sure what you mean. Can you give me more detail?

Also unlike wings, sails aren't designed to divert the air flow by 90 degrees.

I don't understand what you mean here either. I don't think I've ever seen a wing that diverts airflow by 90 degrees. If you compare a windsurf sail to a hang glider wing, they're practically indistinguishable. And before you all tell me how ludicrous that statement is, I've owned plenty of hang gliders and windsurf rigs over that last couple of decades.