--calc to determine prop shaft/prop blade tips rpm--

  the first part of the calc, is about finding the force being applied to each blade of the prop, that is facing the wind...

  first stage--

steps)

   1)  the weight of one cubic foot of air, in pounds =  0.0807, ( i looked that up on the internet)... i utilized this value in my "mph to foot-pounds" post as well--

   2)  then divided by 36( to get the weight of 1 cubic inch of air, in pounds) = 0.00224

   3)  then, crunch numbers with "mph to foot-pounds per-second" calc...

    mph to foot-pounds per-second calc--

   ( 1 cubic inch of air)  - ( feet per-sec)   =    ( foot-pounds per-sec)
         (weight)   -               ( distance)      =      ( force per sq-inch, per-sec)
        0.00224   -               (1.46 x mph)   =             -1.45776
                                           1.46 x 1      

as we see, the "foot-pounds per-sec" value above, is a negative number( in foot-pounds), so we must "putt"...and we shall--

  1.45776(foot-pounds) x 1.3558( modifier) = 1.97643( newton meters)

    a single putt( for eagle)--

   ( foot-pounds)   =   ( newton meters)
      .145776                  .197643

here we are back in whole numbers...happy-time...( as the number is not too many decimals small, i am going to go with "foot-pounds" again)--   :o)

  4) then plug .145776 "foot-pounds per-sec", into the prop calc--

 (  foot-pounds of )     (sq inches)        (prop)
 (force per sq-inch)     (per blade)        (pitch)   (prop)           (# of   )    (degrees of) (divided)
 (       per sec       )  x (facing wind) +(angle)+ (radius) x 2 x (blades) x(  rotation  )(by)(sec)
 (     .145776        ) x (  33 +               45    +  12 x     2 x      3 x            360      % 60)= rpm
        

   .145776 x  (33+45+12 x 2 x 3 x 360 % 60) = 3240.00(  rpm at the shaft)


  5) then multiply the prop shaft rpm x 0.021 to calc prop tip rpm( 68.04)--

    prop shaft rpm-to prop tip rpm calc--

     (shaft rpms)        ( modifier)         ( prop-tip rpms)
      3240.00     x        0.021       =          68.04

  i believe this calc can be utilized to derive the proper size of prop to install on a windmill for the conditions( expected wind), it will encounter while in service...also, this math may prove useful if a "hydraulic variable-pitch prop" is in service on the mill...a computer, programmed to change prop pitch, to keep the blades "spinning within the mean", and generating peak power, even if wind is low, may be needed--

 best wishes, john kruschke--