/// <summary>
/// Currently this only calculates the change in velocity from 0 to planet radius +* 0.33333.
/// TODO: add gravity drag and atmosphere drag, and tech improvements for such.
/// </summary>
/// <param name="planetEntity"></param>
/// <param name="payload"></param>
/// <returns></returns>
public static double FuelCostToLowOrbit(Entity planetEntity, double payload)
{
var lowOrbit = LowOrbitRadius(planetEntity);
var exaustVelocity = 275;
var sgp = OrbitMath.CalculateStandardGravityParameter(payload, planetEntity.GetDataBlob <MassVolumeDB>().Mass);
Vector3 pos = new Vector3(lowOrbit, 0, 0);
var vel = OrbitMath.ObjectLocalVelocityPolar(sgp, pos, lowOrbit, 0, 0, 0);
var fuelCost = OrbitMath.TsiolkovskyFuelCost(payload, exaustVelocity, vel.speed);
return(fuelCost);
}
/// <summary>
/// PreciseOrbital Velocy in polar coordinates
///
/// </summary>
/// <returns>item1 is speed, item2 angle</returns>
/// <param name="orbit">Orbit.</param>
/// <param name="atDateTime">At date time.</param>
public static (double speed, double heading) InstantaneousOrbitalVelocityPolarCoordinate(OrbitDB orbit, DateTime atDateTime)
{
var position = GetPosition_AU(orbit, atDateTime);
var sma = orbit.SemiMajorAxis_AU;
if (orbit.GravitationalParameter_Km3S2 == 0 || sma == 0)
{
return(0, 0); //so we're not returning NaN;
}
var sgp = orbit.GravitationalParameterAU;
double e = orbit.Eccentricity;
double trueAnomaly = GetTrueAnomaly(orbit, atDateTime);
double aoP = orbit.ArgumentOfPeriapsis;
(double speed, double heading)polar = OrbitMath.ObjectLocalVelocityPolar(sgp, position, sma, e, trueAnomaly, aoP);
return(polar);
}