From: rdsaam@att.net   
      
   On 8/16/17 1:55 AM, Sylvia Else wrote:   
   >>>   
   >> Basic momentum transfer indicates faster than wind is not possible   
   >> assuming uniform wind gradient from surface to sail or propeller height.\   
   >   
   > This is not correct, at least, it's not unless you require that the   
   > sails not move relative to the boat.   
   >   
   > A sailboat will accelerate until the forces on its parts are in   
   > equilibrium. If you have moving sails (as in a propellor or via some   
   > other mechanism) you have to analyse the actual forces involved to see   
   > where this equilibrium occurs.   
   >   
   > Sylvia.   
   >   
   >   
   Force on the vehicle = vehicle mass(M)*acceleration   
                         = d(air momentum)/dtime - vehicle drag   
      
   Without drag, the vehicle approaches the wind velocity at t= infinity.   
   With drag, the vehicle never approaches wind velocity.   
      
   The Velocity of vehicle (with any vehicle drag)   
   is always less than the intersected velocity of the wind   
   no matter what internal vehicle angular or rotational mechanisms   
   are introduced.   
      
   The captured air heat capacity by the vehicle provides the energy   
   to move the vehicle faster than the wind.   
   It is a heat engine.   
      
   air heat capacity availability   
   for a 1 degree temperature change (thermal gradient)   
   across the vehicle ~ (1E7 erg/g/K * 1K) = 1E7 (g/g)cm^2/sec^2.   
      
   This air heat energy availability compares   
   to wind component energy availability at 30 mph   
   as (mass/mass)(30 mph)^2  or .18E7 (g/g)cm^2/sec^2.   
      
   It is apparent that air thermal effects can predominate.   
      
   Vehicle curvature is engineered   
   to capture the thermal gradient for vehicle movement.   
      
   Why are none of these vehicular competitions performed at night   
   all though these thermal effects   
   could still be present to a lesser degree?   
      
   Richard   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)