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Clamp beta factor in transonic region

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This commit is contained in:
SiboVG 2024-10-08 19:03:06 +02:00
parent 4f80d28bec
commit e51790e69d
1 changed files with 19 additions and 5 deletions
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24
core/src/main/java/info/openrocket/core/aerodynamics/FlightConditions.java
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@ -55,7 +55,7 @@ public class FlightConditions implements Cloneable, ChangeSource, Monitorable {
* Sqrt(1 - M^2) for M<1
* Sqrt(M^2 - 1) for M>1
*/
private double beta = MathUtil.safeSqrt(1 - mach * mach);
private double beta = calculateBeta(mach);
/** Current roll rate. */
private double rollRate = 0;
@ -243,10 +243,7 @@ public class FlightConditions implements Cloneable, ChangeSource, Monitorable {
return;
this.mach = mach;
if (mach < 1)
this.beta = MathUtil.safeSqrt(1 - mach * mach);
else
this.beta = MathUtil.safeSqrt(mach * mach - 1);
this.beta = calculateBeta(mach);
fireChangeEvent();
}
@ -288,6 +285,23 @@ public class FlightConditions implements Cloneable, ChangeSource, Monitorable {
return beta;
}
/**
* Calculate the beta value (compressibility factor/Prandtl-Glauert correction factor) for the given Mach number.
* Source: "Active Guidance and Dynamic Flight Mechanics for Model Rockets", David Ketchledge (1993)
* @param mach the Mach number.
* @return the beta value.
*/
private static double calculateBeta(double mach) {
if (mach < 0.8) {
return MathUtil.safeSqrt(1 - mach * mach);
} else if (mach < 1.1)
// Because beta reaches infinity for M=1, we clamp the factor to 0.6 in the transonic region (Mach 0.8-1.1)
return 0.6; // sqrt(1 - 0.8^2)
else {
return MathUtil.safeSqrt(mach * mach - 1);
}
}
/**
* @return the current roll rate.
*/