/////////////////////////////////////////////////////////////////////////////
//
// javascript source code for the Futura calculator at:
// http://www.natew.com/frames.cgi/heli/calc/html.FuturaGearing
//
// Nate Waddoups, 8 May 2001
//
/////////////////////////////////////////////////////////////////////////////

var rPi = 3.1415926535;

var g_rClutchPulley = 21;
var g_rSecondPulley = 42;

var g_rBelting = 1;
var g_rGearing = 1;

var g_rTotal = 1;

function InitializeRatios ()
{
  g_rClutchPulley = 22;
  g_rSecondPulley = 42;
  g_rGearing = 73 / 15;

  Solve (null);
  RPM ();
}

function Solve (button)
{
  if (button)
  {
    with (button.form)
    {
      if (button.form.id == "ClutchForm")
      {
        g_rClutchPulley = eval(button.teeth);
      }

      if (button.form.id == "SecondForm")
      {
        g_rSecondPulley = eval(button.teeth);
      }

      if (button.form.id == "GearingForm")
      {
        var strRevision = button.rev;

        if (strRevision == "old")
        {
          g_rGearing = 50 / 10;
        }
        else
        {
          g_rGearing = 73 / 15;
        }
      }
    }
  }

  g_rBelting = g_rSecondPulley / g_rClutchPulley;
  var rTotal = g_rBelting * g_rGearing;

  var rDisplayBelting = Math.round (g_rBelting * 100) / 100;
  var rDisplayGearing = Math.round (g_rGearing * 100) / 100;
  g_rTotal = Math.round (rTotal * 100) / 100;

  document.all["Belt"].innerHTML = rDisplayBelting + " : 1";
  document.all["Gear"].innerHTML = rDisplayGearing + " : 1";
  document.all["Total"].innerHTML = g_rTotal + " : 1";

  RPM ();
  Length ();
}

function RPM ()
{
  document.all["OutputRotorSpeed"].innerHTML = Math.round
	(document.all["InputMotorSpeed"].value / g_rTotal);

  document.all["OutputMotorSpeed"].innerHTML = Math.round
	(document.all["InputRotorSpeed"].value * g_rTotal);
}

function Length ()
{
  var rFudge = 375 - ((22 * 5 / 2) + (42 * 5 / 2));

  var rHalf1 = g_rClutchPulley * 5 / 2;
  var rHalf2 = g_rSecondPulley * 5 / 2;
  var rTotal = rHalf1 + rHalf2 + rFudge;
  
  document.all["Length"].innerHTML = Math.round (rTotal * 100) / 100;
}

/////////////////////////////////////////////////////////////////////////////
// EOF.  Stop reading here ->