Re: speed vs wind
I remember reading about a windmill sort of contraption that used wind power to drive the wheels mechanically. I don't recall the details, but think this moment that its claim to fame was its ability to exceed windspeed directly upwind.
I guess you mean the Blackbird:
It went directly downwind at 2.8 x windspeed
, and direclty upwind at 2.1 x windspeed
(In all cases, the apparent wind is the issue. Dead downwind, you can never exceed windspeed. Upwind, though, the v-squared relationship is beneficial, although aero drag also increases at that same rate.)
A conventional sail craft can neither go directly upwind (at any speed), nor directly downwind faster than wind. Using rotors, like the Blackbird, you can do both.
Last edited by eyytee; 08-02-2012 at 09:21 AM.