User:TomPN

Hi! I'm TomPN, and I'm an avid fan of Kerbal Space Program. I'd like to upload my program for calculating whether you should use a Hohmann transfer or a Bi-elliptical transfer, but it's an exe so I can't. I can post the source code, however, so here goes:

#include <math.h>
#include <iostream>
#include <cstdlib>

using namespace std;

double delta_v (double mass, double radius_1, double radius_2, double radius_3)
{
  double gravity_constant = 0.0000000000667;
  double mu = gravity_constant*mass;
  double a_1 = (radius_1 + radius_2)/2;
  double a_2 = (radius_2 + radius_3)/2;
  double delta_v = sqrt(((2*mu)/radius_1)-(mu/a_1))-sqrt(mu/radius_1)+sqrt(((2*mu)/radius_2)-(mu/a_2))-sqrt(((2*mu)/radius_2)-(mu/a_1))+sqrt(((2*mu)/radius_3)-(mu/a_2))-sqrt(mu/radius_3);
  return delta_v;
}

int main ()
{
  cout << "Orbital transfer calculator v1.1\nWritten by TomPN\n15/12/2015\n" << endl;
  double planet_mass;
  cout << "Please enter the mass of the body you are in orbit around (in kilograms x10^20): ";
  cin >> planet_mass;
  double mass_multiplier = 100000000000000000000.0;
  planet_mass *= mass_multiplier;
  double current_orbit;
  cout << "Please enter your current orbital radius (in metres): ";
  cin >> current_orbit;
  double final_orbit;
  cout << "Please enter your desired orbital radius (in metres): ";
  cin >> final_orbit;
  double sphere_of_influence;
  cout << "Please enter the radius of the sphere of influence of the body that you are\n currently in orbit around (in metres): ";
  cin >> sphere_of_influence;
  double percentage = 0.9;
  double bi_elliptical_apoapsis = percentage*sphere_of_influence;
  double hohmann_delta_v;
  double bi_elliptical_delta_v;
  if (current_orbit < final_orbit)
  {
    hohmann_delta_v = delta_v (planet_mass, current_orbit, final_orbit, final_orbit);
    bi_elliptical_delta_v = delta_v (planet_mass, current_orbit, bi_elliptical_apoapsis, final_orbit);
  }
  else
  {
    hohmann_delta_v = delta_v (planet_mass, final_orbit, current_orbit, current_orbit);
    bi_elliptical_delta_v = delta_v (planet_mass, final_orbit, bi_elliptical_apoapsis, current_orbit);
  }
  if (hohmann_delta_v > bi_elliptical_delta_v)
  {
    cout << "Perform a bi-elliptical transfer with an apoapsis between " << bi_elliptical_apoapsis << " and " << sphere_of_influence << " metres." << endl;
  }
  else
  {
    cout << "Perform a Hohmann transfer." << endl;
  }
  system ("PAUSE");
  return 0;
}

You'll need a C++ emulator (can be found online) or compiler (can be downloaded) to run the code.