/// <summary>
/// These are just a few different attempts to figure drag for various blunt bodies
/// </summary>
private void DragModel(Vector3d local_velocity, double M, double rho)
{
// Has the same x/y/z as the vertices in PartMaxBoundaries etc
Vector3d model_velocity = to_model_rotation * local_velocity;
double viscousLift, potentialLift, newtonianLift;
viscousLift = potentialLift = newtonianLift = 0;
double CdAdd = 0;
//float AxialProportion = Vector3.Dot(localUpVector, local_velocity);
double AxialProportion = model_velocity.y;
float AxialProportion_flt = (float)model_velocity.y;
double AxialProportion_2 = AxialProportion * AxialProportion;
double OneMinusAxial_2 = Math.Abs(1 - AxialProportion_2);
double M_2 = M * M;
double M_2_recip = 1 / M_2;
double maxPressureCoeff;
if (FARDebugValues.useSplinesForSupersonicMath)
{
maxPressureCoeff = FARAeroUtil.MaxPressureCoefficient.Evaluate((float)M);
}
else
{
maxPressureCoeff = FARAeroUtil.MaxPressureCoefficientCalc(M);
}
double sepFlowCd = SeparatedFlowDrag(M, M_2, M_2_recip);
//This handles elliptical and other non-circular cross sections
//float crossflowParameter = Vector3.Dot(localForwardVector, Vector3.Exclude(localUpVector, local_velocity).normalized);
//crossflowParameter *= crossflowParameter;
double crossflowParameter = model_velocity.z * model_velocity.z;
double crossflow = model_velocity.x * model_velocity.x + crossflowParameter;
if (crossflow != 0)
{
crossflowParameter /= crossflow;
}
crossflowParameter = crossflowParameter * majorMinorAxisRatio + (1 - crossflowParameter) / majorMinorAxisRatio;
if (AxialProportion_2 > 0.98)
{
crossflowParameter *= 50 * OneMinusAxial_2;
}
Cd += CdCurve.Evaluate(AxialProportion_flt);
viscousLift = ClViscousCurve.Evaluate(AxialProportion_flt);
double axialDirectionFactor = cosAngleCutoff * AxialProportion;
if (axialDirectionFactor > 0)
{
Cd = Math.Min(Cd, sepFlowCd * taperCrossSectionAreaRatio) * AxialProportion_2 + Cd * OneMinusAxial_2;
}
else
{
Cd = Math.Min(Cd, maxPressureCoeff * taperCrossSectionAreaRatio) * AxialProportion_2 + Cd * OneMinusAxial_2;
}
if (M_2 > 1)
{
potentialLift = ClPotentialCurve.Evaluate(AxialProportion_flt) * M_2_recip;
}
else
{
potentialLift = ClPotentialCurve.Evaluate(AxialProportion_flt);
}
Cm = CmCurve.Evaluate(AxialProportion_flt) * 0.1;
CoDshift = CenterOfDrag;
double MachMultiplier = MachDragEffect(M);
Cd *= MachMultiplier;
if (HighLogic.LoadedSceneIsFlight)
{
Cd += FARAeroUtil.SkinFrictionDrag(rho, lengthScale, local_velocity.magnitude, M, FlightGlobals.getExternalTemperature(part.transform.position) + FARAeroUtil.currentBodyTemp); //Skin friction drag
}
else
{
Cd += 0.005;
}
for (int i = 0; i < attachNodeDragList.Count; i++)
{
attachNodeData node = attachNodeDragList[i];
double dotProd = Vector3d.Dot(node.location.normalized, local_velocity);
double tmp = 0;
double Cltmp = 0;
if (dotProd < 0)
{
dotProd *= dotProd;
tmp = sepFlowCd;
// Cltmp = tmp * (dotProd - 1);
// Cltmp *= pair.Value;
tmp *= node.areaValue * dotProd;
// Vector3 CoDshiftOffset = -Vector3.Exclude(pair.Key, part.transform.worldToLocalMatrix.MultiplyVector(velocity.normalized)).normalized;
// CoDshiftOffset *= Mathf.Sqrt(Mathf.Clamp01(1 - dotProd));
// CoDshiftOffset *= Mathf.Sqrt(1.5f * pair.Value);
CoDshift += node.location * (tmp / (tmp + Cd));
}
else
{
Vector3d worldPairVec = part_transform.TransformDirection(node.location.normalized);
double dotProd_2 = dotProd * dotProd;
double liftProd_2 = 1 - dotProd_2;
double liftProd = Vector3d.Dot(worldPairVec, liftDir);
double forceCoefficient = dotProd_2 * bluntBodyCosForceParameter;
forceCoefficient += liftProd_2 * bluntBodySinForceParameter;
forceCoefficient *= maxPressureCoeff * node.areaValue; //force applied perependicular to the flat end of the node
tmp = forceCoefficient * dotProd;
Cltmp = -forceCoefficient * liftProd; //negative because lift is in opposite direction of projection of velocity vector onto node direction
double Cmtmp = dotProd * liftProd * bluntBodyMomentParameter;
Cmtmp *= node.areaValue * node.recipDiameter;
if (!node.pitchesAwayFromUpVec)
{
Cmtmp *= -1;
}
Cm += Cmtmp;
double tmpCdCl = Math.Sqrt(tmp * tmp + Cltmp * Cltmp);
CoDshift += node.location * (tmpCdCl / (tmpCdCl + Math.Sqrt(Cd * Cd + Cl * Cl)));
/*double liftProd = Vector3d.Dot(worldPairVec, liftDir);
*
* tmp = maxPressureCoeff * dotProd_2 * dotProd;
* tmp *= node.areaValue;
*
* Cltmp = maxPressureCoeff * dotProd_2 * liftProd;
* Cltmp *= -node.areaValue;
*
* double radius = Math.Sqrt(node.areaValue / Math.PI);
* Vector3 CoDshiftOffset = Vector3.Exclude(node.location, local_velocity).normalized;
* CoDshiftOffset *= (float)(Math.Abs(liftProd) * radius * 0.4);
*
* double Cmtmp;
* if (node.pitchesAwayFromUpVec)
* Cmtmp = -0.325 * radius * node.areaValue / S * Math.Abs(liftProd);
* else
* Cmtmp = 0.325 * radius * node.areaValue / S * Math.Abs(liftProd);
*
* double tmpCdCl = Math.Sqrt(tmp * tmp + Cltmp * Cltmp);
*
* CoDshift += node.location * (tmpCdCl / (tmpCdCl + Math.Sqrt(Cd * Cd + Cl * Cl))) + CoDshiftOffset;
*
* Cm += Cmtmp;*/
}
CdAdd += tmp;
newtonianLift += Cltmp;
}
viscousLift *= MachMultiplier;
Cd += CdAdd;
Cl = viscousLift + potentialLift;
Cl *= crossflowParameter;
Cm *= crossflowParameter;
Cl += newtonianLift;
// Debug.Log("Cd = " + Cd + " Cl = " + Cl + " Cm = " + Cm + "\nPot Lift = " + potentialLift + " Visc Lift = " + viscousLift + " Newt Lift = " + newtonianLift + "\nCdAdd = " + CdAdd + " sepFlowCd = " + sepFlowCd + " maxPressureCoeff = " + maxPressureCoeff + "\ntaperCrossSectionAreaRatio = " + taperCrossSectionAreaRatio + " crossflowParameter = " + crossflowParameter);
}
/// <summary>
/// These are just a few different attempts to figure drag for various blunt bodies
/// </summary>
private void DragModel(Vector3d local_velocity, double M)
{
// Has the same x/y/z as the vertices in PartMaxBoundaries etc
Vector3d model_velocity = to_model_rotation * local_velocity;
double viscousLift, potentialLift, newtonianLift;
viscousLift = potentialLift = newtonianLift = 0;
double CdAdd = 0;
//float AxialProportion = Vector3.Dot(localUpVector, local_velocity);
double AxialProportion = model_velocity.y;
float AxialProportion_flt = (float)model_velocity.y;
double AxialProportion_2 = AxialProportion * AxialProportion;
double OneMinusAxial_2 = Math.Abs(1 - AxialProportion_2);
double M_2 = M * M;
double M_2_recip = 1 / M_2;
double maxPressureCoeff;
if (FARDebugValues.useSplinesForSupersonicMath)
{
maxPressureCoeff = FARAeroUtil.MaxPressureCoefficient.Evaluate((float)M);
}
else
{
maxPressureCoeff = FARAeroUtil.MaxPressureCoefficientCalc(M);
}
double sepFlowCd = SeparatedFlowDrag(M, M_2, M_2_recip);
//This handles elliptical and other non-circular cross sections
//float crossflowParameter = Vector3.Dot(localForwardVector, Vector3.Exclude(localUpVector, local_velocity).normalized);
//crossflowParameter *= crossflowParameter;
double crossflowParameter = model_velocity.z * model_velocity.z;
double crossflow = model_velocity.x * model_velocity.x + crossflowParameter;
if (crossflow != 0)
{
crossflowParameter /= crossflow;
}
crossflowParameter = crossflowParameter * majorMinorAxisRatio + (1 - crossflowParameter) / majorMinorAxisRatio;
if (AxialProportion_2 > 0.98)
{
crossflowParameter *= 50 * OneMinusAxial_2;
}
Cd += CdCurve.Evaluate(AxialProportion_flt);
viscousLift = ClViscousCurve.Evaluate(AxialProportion_flt);
double axialDirectionFactor = cosAngleCutoff * AxialProportion;
if (axialDirectionFactor > 0)
{
Cd = Math.Min(Cd, sepFlowCd * taperCrossSectionAreaRatio) * AxialProportion_2 + Cd * OneMinusAxial_2;
}
else
{
Cd = Math.Min(Cd, maxPressureCoeff * taperCrossSectionAreaRatio) * AxialProportion_2 + Cd * OneMinusAxial_2;
}
if (M_2 > 1)
{
potentialLift = ClPotentialCurve.Evaluate(AxialProportion_flt) * M_2_recip;
}
else
{
potentialLift = ClPotentialCurve.Evaluate(AxialProportion_flt);
}
Cm = CmCurve.Evaluate(AxialProportion_flt) * 0.1;
CoDshift = CenterOfDrag;
double MachMultiplier = MachDragEffect(M);
Cd += 0.003; //Skin friction drag
Cd *= MachMultiplier;
foreach (KeyValuePair <Vector3d, attachNodeData> pair in attachNodeDragDict)
{
double dotProd = Vector3d.Dot(pair.Key.normalized, local_velocity);
double tmp = 0;
double Cltmp = 0;
if (dotProd < 0)
{
dotProd *= dotProd;
tmp = sepFlowCd;
// Cltmp = tmp * (dotProd - 1);
// Cltmp *= pair.Value;
tmp *= pair.Value.areaValue * dotProd;
// Vector3 CoDshiftOffset = -Vector3.Exclude(pair.Key, part.transform.worldToLocalMatrix.MultiplyVector(velocity.normalized)).normalized;
// CoDshiftOffset *= Mathf.Sqrt(Mathf.Clamp01(1 - dotProd));
// CoDshiftOffset *= Mathf.Sqrt(1.5f * pair.Value);
CoDshift += pair.Key * (tmp / (tmp + Cd));
}
else
{
Vector3d worldPairVec = part_transform.TransformDirection(pair.Key.normalized);
double dotProd_2 = dotProd * dotProd;
double liftProd = Vector3d.Dot(worldPairVec, liftDir);
tmp = maxPressureCoeff * dotProd_2 * dotProd;
tmp *= pair.Value.areaValue;
Cltmp = maxPressureCoeff * dotProd_2 * liftProd;
Cltmp *= -pair.Value.areaValue;
double radius = Math.Sqrt(pair.Value.areaValue / Math.PI);
Vector3 CoDshiftOffset = Vector3.Exclude(pair.Key, local_velocity).normalized;
CoDshiftOffset *= (float)(Math.Abs(liftProd) * radius);
double tmpCdCl = tmp + Math.Abs(Cltmp);
CoDshift += pair.Key * ((tmpCdCl) / (tmpCdCl + Cd)) + CoDshiftOffset;
if (pair.Value.pitchesAwayFromUpVec)
{
Cm -= 0.25 * radius * pair.Value.areaValue / S * Math.Abs(liftProd);
}
else
{
Cm += 0.25 * radius * pair.Value.areaValue / S * Math.Abs(liftProd);
}
}
CdAdd += tmp;
newtonianLift += Cltmp;
}
viscousLift *= MachMultiplier;
Cd += CdAdd;
Cl = viscousLift + potentialLift;
Cl *= crossflowParameter;
Cm *= crossflowParameter;
Cl += newtonianLift;
// Debug.Log("Cd = " + Cd + " Cl = " + Cl + " Cm = " + Cm + "\nPot Lift = " + potentialLift + " Visc Lift = " + viscousLift + " Newt Lift = " + newtonianLift + "\nCdAdd = " + CdAdd + " sepFlowCd = " + sepFlowCd + " maxPressureCoeff = " + maxPressureCoeff + "\ntaperCrossSectionAreaRatio = " + taperCrossSectionAreaRatio + " crossflowParameter = " + crossflowParameter);
}
