hongshaorou/openrocket
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Clamp beta factor in transonic region

Browse Source
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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
core/src/main/java/info/openrocket/core/aerodynamics/FlightConditions.java
View File

@ -55,7 +55,7 @@ public class FlightConditions implements Cloneable, ChangeSource, Monitorable {
* Sqrt(1 - M^2) for M<1 * Sqrt(1 - M^2) for M<1
* Sqrt(M^2 - 1) 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. */ /** Current roll rate. */
private double rollRate = 0; private double rollRate = 0;
@ -243,10 +243,7 @@ public class FlightConditions implements Cloneable, ChangeSource, Monitorable {
return; return;
this.mach = mach; this.mach = mach;
if (mach < 1) this.beta = calculateBeta(mach);
this.beta = MathUtil.safeSqrt(1 - mach * mach);
else
this.beta = MathUtil.safeSqrt(mach * mach - 1);
fireChangeEvent(); fireChangeEvent();
} }
@ -288,6 +285,23 @@ public class FlightConditions implements Cloneable, ChangeSource, Monitorable {
return beta; 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. * @return the current roll rate.
*/ */