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Merge pull request #2119 from JoePfeiffer/fix-base-drag-take-2

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Fix base drag
This commit is contained in:
Joe Pfeiffer 2023-03-23 20:57:56 -06:00 committed by GitHub
commit f26d0cbfaf
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 91 additions and 29 deletions
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49
core/src/net/sf/openrocket/aerodynamics/BarrowmanCalculator.java
View File

@ -755,11 +755,17 @@ public class BarrowmanCalculator extends AbstractAerodynamicCalculator {
final InstanceMap imap = configuration.getActiveInstances();
for(Map.Entry<RocketComponent, ArrayList<InstanceContext>> entry: imap.entrySet() ) {
final RocketComponent c = entry.getKey();
if (!(c instanceof SymmetricComponent)) {
continue;
}
if (c.isCDOverridden() ||
c.isCDOverriddenByAncestor()) {
continue;
}
SymmetricComponent s = (SymmetricComponent) c;
double foreRadius = s.getForeRadius();
double aftRadius = s.getAftRadius();
@ -770,35 +776,20 @@ public class BarrowmanCalculator extends AbstractAerodynamicCalculator {
}
int instanceCount = entry.getValue().size();
if (c.isCDOverridden() ||
c.isCDOverriddenByAncestor()) {
continue;
// get forward radius of next component
final SymmetricComponent nextComponent = s.getNextSymmetricComponent();
double nextRadius;
if ((nextComponent != null) && configuration.isComponentActive(nextComponent)) {
nextRadius = nextComponent.getForeRadius();
} else {
nextRadius = 0.0;
}
// if aft radius of previous component is greater than my forward radius, set
// its aft CD
double radius = 0;
final SymmetricComponent prevComponent = s.getPreviousSymmetricComponent();
if (prevComponent != null && configuration.isComponentActive(prevComponent)) {
radius = prevComponent.getAftRadius();
}
if (radius > foreRadius) {
double area = Math.PI * (pow2(radius) - pow2(foreRadius));
double cd = base * area / conditions.getRefArea();
total += instanceCount * cd;
if ((forceMap != null) && (prevComponent != null)) {
forceMap.get(prevComponent).setBaseCD(cd);
}
}
// if I'm the last component, set my base CD
// note: the iterator *should* serve up the next component.... buuuut ....
// this code is tested, and there's no compelling reason to change.
final SymmetricComponent n = s.getNextSymmetricComponent();
if ((n == null) || !configuration.isStageActive(n.getStageNumber())) {
double area = Math.PI * pow2(aftRadius);
// if fore radius of next component is less than my aft radius, set my
// base CD
if (nextRadius < aftRadius) {
double area = Math.PI * (pow2(aftRadius) - pow2(nextRadius));
double cd = base * area / conditions.getRefArea();
total += instanceCount * cd;
if (forceMap != null) {

71
core/test/net/sf/openrocket/aerodynamics/BarrowmanCalculatorTest.java
View File

@ -499,6 +499,77 @@ public class BarrowmanCalculatorTest {
assertEquals("should be warning from podset airframe overlap", 1, warnings.size());
}
@Test
public void testBaseDragWithOverride() {
final WarningSet warnings = new WarningSet();
final BarrowmanCalculator calc = new BarrowmanCalculator();
// get base drag of minimal rocket consisting of just a tube.
final Rocket tubeRocket = new Rocket();
final AxialStage tubeStage = new AxialStage();
tubeRocket.addChild(tubeStage);
final BodyTube tubeBodyTube = new BodyTube();
tubeStage.addChild(tubeBodyTube);
final FlightConfiguration tubeConfig = new FlightConfiguration(tubeRocket);
final FlightConditions tubeConditions = new FlightConditions(tubeConfig);
final AerodynamicForces tubeForces = calc.getAerodynamicForces(tubeConfig, tubeConditions, warnings);
final double tubeBaseCD = tubeForces.getBaseCD();
// get base CD of minimal rocket consisting of just a cone
final Rocket coneRocket = new Rocket();
final AxialStage coneStage = new AxialStage();
coneRocket.addChild(coneStage);
NoseCone coneCone = new NoseCone();
coneCone.setAftRadius(tubeBodyTube.getOuterRadius());
coneStage.addChild(coneCone);
final FlightConfiguration coneConfig = new FlightConfiguration(coneRocket);
final FlightConditions coneConditions = new FlightConditions(coneConfig);
final AerodynamicForces coneForces = calc.getAerodynamicForces(coneConfig, coneConditions, warnings);
final double coneBaseCD = coneForces.getBaseCD();
// now our test rocket, with a tube and a cone
final Rocket testRocket = new Rocket();
final AxialStage testStage = new AxialStage();
testRocket.addChild(testStage);
final BodyTube testTube = new BodyTube();
testTube.setOuterRadius(tubeBodyTube.getOuterRadius());
testStage.addChild(testTube);
final NoseCone testCone = new NoseCone();
testCone.setAftRadius(coneCone.getAftRadius());
testStage.addChild(testCone);
FlightConfiguration testConfig = new FlightConfiguration(testRocket);
FlightConditions testConditions = new FlightConditions(testConfig);
// no overrides
AerodynamicForces testForces = calc.getAerodynamicForces(testConfig, testConditions, warnings);
assertEquals("base CD should be base CD of tube plus base CD of cone", tubeBaseCD + coneBaseCD, testForces.getBaseCD(), EPSILON);
// override tube CD
testTube.setCDOverridden(true);
testTube.setOverrideCD(0);
testForces = calc.getAerodynamicForces(testConfig, testConditions, warnings);
assertEquals("base CD should be base CD of cone", coneBaseCD, testForces.getBaseCD(), EPSILON);
// override cone CD
testCone.setCDOverridden(true);
testCone.setOverrideCD(0);
testForces = calc.getAerodynamicForces(testConfig, testConditions, warnings);
assertEquals("base CD should be 0", 0.0, testForces.getBaseCD(), EPSILON);
// and turn off tube override
testTube.setCDOverridden(false);
testForces = calc.getAerodynamicForces(testConfig, testConditions, warnings);
assertEquals("base CD should be base CD of tube", tubeBaseCD, testForces.getBaseCD(), EPSILON);
}
/**
* Tests railbutton drag. Really is testing instancing more than actual drag calculations, and making
* sure we don't divide by 0 when not moving