/* Flywheel energy, version 2.0
Copyright 2008 by Dale A. Heatherington (coded March 30, 2008) */

function flywheel2(dataform,material,od,id,thick,rpm)
{
	var density;
	
	
	
	/* Compute volume of ring.  Vol of cylinder = V = pi*r*r*h  */
	
	var ro = (od/2) * 0.0254;  //outside radius, meters
	var ri = (id/2) * 0.0254;  //Inside radius, meters
	var th = thick * 0.0254; //Thickness, meters
	var Vro = Math.PI * ro * ro * th ; //Cubic meters
	var Vri = Math.PI * ri * ri * th ;
	 
	density = 0;
	if(material[0].checked){ density = 7850 ; }  //Steel,  7850 kg/cu.m
	if(material[1].checked){  density = 8580 ; }  //Brass   8580 kg/cu.m
	
     var mass_od = Vro * density;   //Mass in Kilograms of flywheel disk  (OD)
	 var mass_id = Vri * density;   //Mass in Kilograms of flywheel disk  (ID)
	 var mass = mass_od - mass_id ;			//Mass of ring flywheel

		
	
	var V = (rpm/60) * 2 * 3.142;				/* convert RPM to radians per second */
	var Inertia = .5 * mass_id * (ri * ri);		/* Moment of inertia for inside dia disk */
	var KE_id = 0.5 * Inertia * (V * V);		 /* Kinetic energy for inside dia disk */
	
	
	V = (rpm/60) * 2 * 3.142;				/* convert RPM to radians per second */	
	Inertia = .5 * mass_od * (ro * ro);		/* Moment of inertia for outside dia disk */
	var KE_od = 0.5 * Inertia * (V * V);		 /* Kinetic energy for outside dia disk */
	
	var KE = KE_od - KE_id ;  /* Ring KE is the difference between disk diameter OD and disk diameter ID KEs. */
	
	var Vsurface = (rpm/60) * 3.142 * 2 * ro;  /* Surface speed of OD */
	
	var gforce = ((Vsurface * Vsurface) / ro) / 9.80665 ;

        dataform.ke.value = KE; 
             
        dataform.surface_speed.value = Vsurface;
        dataform.surface_speed_fps.value = Vsurface * 3.2808 ;
	
        dataform.gforce.value = gforce;
		dataform.mass_lb.value = mass * 2.204 ;
		dataform.mass_kg.value = mass;



 }