wandb/index.js

Weight and balance calculation for airplane flying

// Weight and balance calculation
// Public domain

"use strict";
const leftpad=(x,y)=>(" ".repeat(y)+x).slice(-y);
const rightpad=(x,y)=>(x+" ".repeat(y)).slice(0,y);
const fs=require("fs");
if(process.argv.length<3) {
  console.error("ERROR: Aircraft type missing");
  process.exit(1);
}
const ac_file=fs.readFileSync(process.argv[2].includes("/")?process.argv[2]:__dirname+"/typedata/"+process.argv[2].toLowerCase()+".typ","ascii");
const numeric={};
const ac={sfront:0,fuelld:0};
["emwt","emcg","seatrow1arm","seatrow2arm","seatrows","bag1max","bag2max","bag1arm",
 "bag2arm","fuelmax","fuelarm","iminweight","imaxweight","imincg","imaxcg",
 "sfront","srear","cargo1","cargo2","fuelto","fuelld","plot"].forEach(x=>(numeric[x]=true));
ac_file.trim().split("\n").map(x=>x.trim().split("=")).forEach(x=>x.length>1&&(ac[x[0]]=numeric[x[0]]?parseFloat(x[1]):x[1]));
process.argv.slice(3).map(x=>x.trim().split("=")).forEach(x=>(ac[x[0]]=numeric[x[0]]?parseFloat(x[1]):x[1]));
if(!ac.bag1max) ac.bag1max=ac.cargo1=0;
if(!ac.bag2max) ac.bag2max=ac.cargo2=0;
if(ac.seatrows<2) ac.srear=ac.seatrow2arm=0;
const calc=()=>{
  if(ac.fuelto>ac.fuelmax) return "Maximum fuel load exceeded";
  if(ac.cargo1>ac.bag1max) return "Cargo area 1 maximum exceeded";
  if(ac.cargo2>ac.bag2max) return "Cargo area 2 maximum exceeded";
  let empty_moment=ac.emwt*ac.emcg;
  let front_seat_moment=ac.sfront*ac.seatrow1arm;
  let rear_seat_moment=ac.srear*ac.seatrow2arm;
  let cargo1_moment=ac.cargo1*ac.bag1arm;
  let cargo2_moment=ac.cargo2*ac.bag2arm;
  let total_empty_moment=empty_moment+front_seat_moment+rear_seat_moment+cargo1_moment+cargo2_moment;
  let total_empty_weight=ac.emwt+ac.sfront+ac.srear+ac.cargo1+ac.cargo2;
  let total_empty_cg=total_empty_moment/total_empty_weight;
  let fuel_moment=ac.fuelto*ac.fuelarm;
  let total_to_moment=total_empty_moment+fuel_moment;
  let total_to_weight=total_empty_weight+ac.fuelto;
  let total_to_cg=total_to_moment/total_to_weight;
  let fuel_moment_ld=ac.fuelld*ac.fuelarm;
  let total_ld_moment=total_empty_moment+fuel_moment_ld;
  let total_ld_weight=total_empty_weight+ac.fuelld;
  let total_ld_cg=total_ld_moment/total_ld_weight;
  return [
    /*                       WEIGHT                  ARM                        MOMENT                MAXIMUM                    */
    [ "Empty Weight",        ac.emwt,                ac.emcg,                   empty_moment,         Infinity,                   ],
    [ "Front Seats",         ac.sfront,              ac.seatrow1arm,            front_seat_moment,    Infinity,                   ],
    [ "Rear Seats",          ac.srear,               ac.seatrow2arm,            rear_seat_moment,     ac.seatrows>1?Infinity:0,   ],
    [ "Cargo Area 1",        ac.cargo1,              ac.bag1arm,                cargo1_moment,        ac.bag1max,                 ],
    [ "Cargo Area 2",        ac.cargo2,              ac.bag2arm,                cargo2_moment,        ac.bag2max,                 ],
    [ "Zero Fuel Totals",    total_empty_weight,     total_empty_cg,            total_empty_moment,   Infinity,                   ],
    [ "Fuel at Takeoff",     ac.fuelto,              ac.fuelarm,                fuel_moment,          ac.fuelmax,                 ],
    [ "Takeoff Totals",      total_to_weight,        total_to_cg,               total_to_moment,      Infinity,                   ],
    [ "Fuel at Landing",     ac.fuelld,              ac.fuelarm,                fuel_moment_ld,       ac.fuelmax,                 ],
    [ "Landing Totals",      total_ld_weight,        total_ld_cg,               total_ld_moment,      Infinity,                   ],
  ];
};
console.log("Aircraft type: %s",ac.typename);
console.log("                   | WEIGHT  | MAXIMUM | ARM     | MOMENT  |");
console.log("------------------------------------------------------------");
const res=calc();
if(typeof res==="string") {
  console.error("ERROR: %s",res);
  process.exit(1);
}
res.forEach(x=>x[4]&&console.log(
  rightpad(x[0],19)+"|"+leftpad(x[1].toFixed(0),8)+" |"+leftpad(x[4]==Infinity?"":x[4].toFixed(0),8)+" |"+leftpad(x[2].toFixed(1),8)+" |"+leftpad(x[3].toFixed(0),8)+" |"
));