Rocket Science, Javascript

Rocket Science

//all units are SI
//INPUT
var v=0;//start velocity
var s=0;//start displacement
var ts=1;//time step per calculation
var md=1000;//dry mass
var mf=100;//fuel mass
var f=1;//fuel flow rate
var Th=20000;//thrust (recommended total mass*10)
var A=3.14;//cross-sectional area of rocket
var Cd=0.25;//drag coeffecient of rocket
var time=300;//how long to run the simulation

//Calculation variables
var a=0;//net acceleration
var t=0;//time
var p=0;//pressure
var T=0;//absolute temp
var L=0;//temperature lapse rate
var h=0;//minimum height of band
var b=0;//current band
var pt=1;//pressure trigger if falling down
var ac=0;//thrust acceleration
var g=0;//gravitational acceleration
var pa=0;//atmospheric drag

for(t=0; t<time; t=t+ts){
    if(0<=s){
    
    
    if(s<11000){//band 0
        b=0;
        T=288.15;
        h=0;
        L=-0.0065;
        p=101325*Math.pow((1-(L*s)/(T+L*s)), (0.0342/L));
    }
    if(11000<=s&&s<20000){//band 1
        b=1;
        T=216.65;
        h=11000;
        L=0;
        p=22632.1*Math.exp(-(0.0342*(s-h))/T);
    }
    if(20000<=s&&s<32000){//band 2
        b=2;
        T=216.65;
        h=20000;
        L=0.001;
        p=5474.89*Math.pow((1-(L*(s-h))/(T+L*(s-h))), (0.0342/L));
    }
    if(32000<=s&&s<47000){//band 3
        b=3;
        T=228.65;
        h=32000;
        L=0.0028;
        p=868.02*Math.pow((1-(L*(s-h))/(T+L*(s-h))), (0.0342/L));
    }
    if(47000<=s&&s<51000){//band 4
        b=4;
        T=270.65;
        h=47000;
        L=0;
        p=110.91*Math.exp(-(0.0342*(s-h))/T);
    }
    if(51000<=s&&s<71000){//band 5
        b=5;
        T=270.65;
        h=51000;
        L=-0.0028;
        p=66.94*Math.pow((1-(L*(s-h))/(T+L*(s-h))), (0.0342/L));
    }
    if(71000<=s&&s<86000){//band 6
        b=6;
        T=214.65;
        h=71000;
        L=-0.002;
        p=3.96*Math.pow((1-(L*(s-h))/(T+L*(s-h))), (0.0342/L));
    }
    if(86000<=s){//band 6
        b=7;
        T=386;
        p=0;
        h=s;
    }
    
    
    if(v<0){
        pt=-1;
    }
    if(v>=0){
        pt=1;
    }
    
    ac=(Th)/(md+mf-f*t);
    g=-3.98E14/(s*s+1.28E8*s+4.096E13);
    pa=-((p*v*v*A*Cd*0.00174)/(T+L*(s-h)))/(md+mf);
    
    if(t<(mf/f)&&s<86000){//If not empty and in atmosphere
        a=ac+g+pt*pa;
        //print("Still going, in atmosphere");
    }
    if(t>=(mf/f)&&s<86000){//If empty and in atmosphere
        a=g+pt*pa;
        //print("free fall");
    }
    if(t<(mf/f)&&s>=86000){//If not empty and out of atmosphere
        a=ac+g;
        //print("burning in space")
    }
    if(t>(mf/f)&&s>=86000){//If empty and out of atmosphere
        a=g;
        //print("free fall in space");
    }
    
    
    
	print(t, a, v, s, p, b, pa*pt);//display
	s=s+0.5*ts*ts*a+ts*v;//s=s0+ut+0.5at^2
	v=ts*a+v;//a=dv/dt
        
    }
    
    else{
        print("Landed!");
    }
}


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