public static float BrakeDistancePrecise(float V0, VesselWrapper VSL, out float ttb)
{
ttb = 0f;
var dist = 0f;
var mass = VSL.Physics.M;
var throttle = ThrottleControl.NextThrottle(V0, 1, mass, VSL.Engines.MaxThrustM, VSL.Engines.DecelerationTime10);
float next_mass;
float ttb_cur;
while (V0 > 0.1)
{
throttle = ThrottleControl.NextThrottle(V0, throttle, mass, VSL.Engines.MaxThrustM, VSL.Engines.DecelerationTime10);
ttb_cur = EnginesProps.TTB(V0 / 2, VSL.Engines.MaxThrustM, mass, VSL.Engines.MaxMassFlow, throttle, out next_mass);
dist += BrakeDistance(V0, ttb_cur, VSL.Engines.MaxThrustM, mass, VSL.Engines.MaxMassFlow, throttle);
ttb += ttb_cur;
mass = next_mass;
V0 /= 2;
}
throttle = ThrottleControl.NextThrottle(V0, throttle, mass, VSL.Engines.MaxThrustM, VSL.Engines.DecelerationTime10);
ttb_cur = EnginesProps.TTB(V0, VSL.Engines.MaxThrustM, mass, VSL.Engines.MaxMassFlow, throttle, out next_mass);
dist += BrakeDistance(V0, ttb_cur, VSL.Engines.MaxThrustM, mass, VSL.Engines.MaxMassFlow, throttle);
ttb += ttb_cur;
return(dist);
}
public LandingPath(VesselWrapper vsl, Orbit orb, double target_altitude, double startUT, double dt,
double start_mass, double fuel = 0, double brake_vel = 0)
{
VSL = vsl;
Orbit = orb;
TargetAltitude = target_altitude;
StartUT = startUT;
UT0 = VSL.Physics.UT;
EndMass = start_mass;
FuelUsed = 0;
FuelLeft = fuel;
BrakeDeltaV = brake_vel;
if (Orbit.referenceBody.atmosphere || brake_vel > 0 && fuel > 0)
{
EndUT = startUT + orb.timeToPe;
HavePoints = brake_vel > 0 && fuel > 0;
var p = newP(StartUT);
var m = start_mass;
var s = Math.Max(VSL.Geometry.MinArea, VSL.Geometry.AreaWithBrakes);
var ascending = p.Ascending;
var orig_dt = dt;
p.Duration = dt;
while ((ascending || p.Altitude > TargetAltitude) && p.UT < EndUT)
{
var dAlt = p.Altitude - TargetAltitude;
var linear_time = dAlt / p.SrfSpeed;
if (!ascending && dt > 0.01 && linear_time / 2 < dt)
{
p.Duration = dt = linear_time / 2;
}
var drag_accel = p.SpecificDrag * s / m;
var prev_alt = p.Altitude;
Atmosphere |= drag_accel > 0;
HavePoints |= Atmosphere;
if (HavePoints)
{
if (Points.Count == 0)
{
FirstPointUT = p.UT;
if (Atmosphere)
{
AtmoStartUT = p.UT;
}
}
Points.Add(p);
// VSL.Log("drag dV {}, m {}, fm {}, brake_vel {}, p {}",
// drag_dv, m, fuel, brake_vel, p);//debug
var r = p.pos.magnitude;
if (p.HorSrfSpeed > 1 && brake_vel > 0 && fuel > 0)
{
//adjust dt to capture most of the thrust
float mflow;
var thrust = VSL.Engines.ThrustAtAlt((float)p.SrfSpeed, (float)p.Altitude, out mflow);
var dV_cm = thrust / m * dt;
if (dt > 0.01 && dV_cm > p.SrfSpeed / 10)
{
dt = p.SrfSpeed / 10 * m / thrust * 0.9;
}
//compute thrust direction
var vV = Utils.ClampL(Vector3d.Dot(p.vel, p.pos / r), 1e-5);
var b_dir = LandingTrajectoryAutopilot.CorrectedBrakeVelocity(VSL, p.vel, p.pos,
p.DynamicPressure / 1000 / LandingTrajectoryAutopilot.C.MinDPressure,
(p.Altitude - TargetAltitude) / vV).normalized;
//compute change in velocity and mass
var Ve = thrust / mflow;
var dm = mflow * dt;
if (dm > fuel)
{
dm = fuel;
}
var bV = (double)VSL.Engines.DeltaV(Ve, (float)dm);
if (bV > brake_vel)
{
bV = brake_vel;
dm = EnginesProps.FuelNeeded((float)bV, Ve, (float)m);
}
p.vel -= b_dir * bV;
brake_vel -= bV;
// VSL.Log("vV {}, vB {}, thrust {}, mflow {}, Ve {}, dm {}\nb_dir {}\nvel {}\npos {}",
// vV, bV, thrust, mflow, Ve, dm, b_dir, p.vel, p.pos);//debug
//spend fuel
fuel -= dm;
m -= dm;
}
//adjust dt if its too small
else if (!ascending && dt < orig_dt && linear_time / 50 > dt)
{
dt = Math.Min(linear_time / 50, orig_dt);
}
if (Atmosphere)
{
p.vel -= p.srf_vel / p.SrfSpeed * Math.Min(drag_accel * dt, p.SrfSpeed);
}
p.vel -= p.pos * p.Body.gMagnitudeAtCenter / r / r / r * dt;
p.pos += p.vel * dt;
p.UT += dt;
p.Update();
if (Atmosphere && AtmoStopUT < 0 && p.SrfSpeed < 10)
{
AtmoStopUT = p.UT;
}
}
else
{
p.Update(p.UT + dt);
}
ascending &= p.Altitude > prev_alt;
}
if (HavePoints)
{
Points.Add(p);
if (Atmosphere && AtmoStopUT < 0)
{
AtmoStopUT = p.UT;
}
}
EndUT = p.UT;
LastPoint = p;
EndMass = m;
FuelUsed = start_mass - m;
FuelLeft = Math.Max(fuel, 0);
if (brake_vel > 0)
{
BrakeDeltaV -= brake_vel;
}
}
else
{
EndUT = TrajectoryCalculator.NearestRadiusUT(Orbit, Orbit.referenceBody.Radius + TargetAltitude, StartUT);
LastPoint = newP(EndUT);
}
}