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Re: [Phys-L] (we suggest not performing science experiments when you’re the driver) Was; Re: Impossible vehicles.




Bernard Cleyet wrote, in part: > Sailing craft don’t require turbines, gearing, etc. to move faster than the wind.  I think I’ve done it, as shown by the direction of my boat’s tell-tail. 

While it is true that a racing catamaran particularly one with a lifting water-foil may sail at three times the prevailing airspeed, it does not reach this speed directly down wind but rather at a downwind 'tack'. However, a series of tacks at high speed downwind CAN result in faster than  downwind progress at  a faster rate than the windspeed. On Wednesday, June 2, 2021, 11:43:55 PM CDT, bernard cleyet <bernard@cleyet.org> wrote:



Not having read completely the impossible vehicle conversation, perhaps shouldn’t be posting. 


BUT:  Sailing craft don’t require turbines, gearing, etc. to move faster than the wind.  I think I’ve done it, as shown by the direction of my boat’s tell-tail. 


https://www.kqed.org/science/8503/how-do-these-boats-sail-faster-than-the-wind <https://www.kqed.org/science/8503/how-do-these-boats-sail-faster-than-the-wind>


bc … thinks maybe is bad

Quickie quiz:  What are a group of giraffes called? 

On 2021/Jun/02, at 18:59, John Denker via Phys-l <phys-l@mail.phys-l.org> wrote:

The physics of sailing upwind is the same as sailing downwind faster than the wind.
This is discussed in some detail, using a couple of different approaches, at
  https://www.av8n.com/physics/sailing-upwind-downwind.htm

Some useful diagrams are included.
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