commit the work-in-progress drag calculations, including creating TubeCalc for calculations common to LaunchLugs and TubeFinSets
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JoePfeiffer
parent
2c4ebabaa1
commit
4477d9226e
@ -1756,6 +1756,9 @@ Warning.TUMBLE_UNDER_THRUST = Stage began to tumble under thrust.
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Warning.EVENT_AFTER_LANDING = Flight Event occurred after landing:
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Warning.ZERO_LENGTH_BODY = Zero length bodies may not result in accurate simulations.
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Warning.ZERO_RADIUS_BODY = Zero length bodies may not result in accurate simulations.
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Warning.TUBE_STABILITY = Tube fin stability calculations may not be accurate.
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Warning.TUBE_SEPARATION = Space between tube fins may not result in accurate simulations.
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Warning.TUBE_OVERLAP = Overlapping tube fins may not result in accurate simulations.
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! Scale dialog
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ScaleDialog.lbl.scaleRocket = Entire rocket
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@ -392,4 +392,7 @@ public abstract class Warning {
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public static final Warning ZERO_LENGTH_BODY = new Other(trans.get("Warning.ZERO_LENGTH_BODY"));
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public static final Warning ZERO_RADIUS_BODY = new Other(trans.get("Warning.ZERO_RADIUS_BODY"));
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public static final Warning TUBE_STABILITY = new Other(trans.get("Warning.TUBE_STABILITY"));
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public static final Warning TUBE_SEPARATION = new Other(trans.get("Warning.TUBE_SEPARATION"));
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public static final Warning TUBE_OVERLAP = new Other(trans.get("Warning.TUBE_OVERLAP"));
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}
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@ -8,7 +8,7 @@ import net.sf.openrocket.rocketcomponent.RocketComponent;
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import net.sf.openrocket.util.MathUtil;
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import net.sf.openrocket.util.Transformation;
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public class LaunchLugCalc extends RocketComponentCalc {
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public class LaunchLugCalc extends TubeCalc {
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private final double CDmul;
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private final double refArea;
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@ -0,0 +1,27 @@
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package net.sf.openrocket.aerodynamics.barrowman;
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import net.sf.openrocket.aerodynamics.AerodynamicForces;
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import net.sf.openrocket.aerodynamics.FlightConditions;
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import net.sf.openrocket.aerodynamics.WarningSet;
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import net.sf.openrocket.rocketcomponent.LaunchLug;
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import net.sf.openrocket.rocketcomponent.RocketComponent;
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import net.sf.openrocket.util.MathUtil;
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import net.sf.openrocket.util.Transformation;
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public abstract class TubeCalc extends RocketComponentCalc {
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private final double CDmul;
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protected final double refArea;
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public TubeCalc(RocketComponent component) {
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super(component);
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LaunchLug lug = (LaunchLug)component;
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double ld = lug.getLength() / (2*lug.getOuterRadius());
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CDmul = Math.max(1.3 - ld, 1);
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refArea = Math.PI * MathUtil.pow2(lug.getOuterRadius()) -
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Math.PI * MathUtil.pow2(lug.getInnerRadius()) * Math.max(1 - ld, 0);
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}
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}
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@ -10,6 +10,7 @@ import net.sf.openrocket.aerodynamics.FlightConditions;
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import net.sf.openrocket.aerodynamics.Warning;
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import net.sf.openrocket.aerodynamics.Warning.Other;
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import net.sf.openrocket.aerodynamics.WarningSet;
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import net.sf.openrocket.rocketcomponent.BodyTube;
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import net.sf.openrocket.rocketcomponent.FinSet;
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import net.sf.openrocket.rocketcomponent.RocketComponent;
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import net.sf.openrocket.rocketcomponent.TubeFinSet;
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@ -33,9 +34,9 @@ import org.slf4j.LoggerFactory;
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* @author kruland
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*
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*/
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public class TubeFinSetCalc extends RocketComponentCalc {
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public class TubeFinSetCalc extends TubeCalc {
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private final static Logger logger = LoggerFactory.getLogger(FinSetCalc.class);
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private final static Logger log = LoggerFactory.getLogger(FinSetCalc.class);
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private static final double STALL_ANGLE = (20 * Math.PI / 180);
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@ -56,8 +57,13 @@ public class TubeFinSetCalc extends RocketComponentCalc {
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protected double[] chordLead = new double[DIVISIONS];
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protected double[] chordTrail = new double[DIVISIONS];
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protected double[] chordLength = new double[DIVISIONS];
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protected final WarningSet geometryWarnings = new WarningSet();
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private final double[] poly = new double[6];
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private final double wettedArea;
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private final double frontalArea;
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private final double thickness;
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private final double bodyRadius;
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@ -73,9 +79,52 @@ public class TubeFinSetCalc extends RocketComponentCalc {
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throw new IllegalArgumentException("Illegal component type " + component);
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}
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TubeFinSet fin = (TubeFinSet) component;
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final TubeFinSet tubes = (TubeFinSet) component;
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final TubeFinSet fin = tubes; // keep this around while we're still leveraging FinSet
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geometryWarnings.add(Warning.TUBE_STABILITY);
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if (tubes.getTubeSeparation() > MathUtil.EPSILON) {
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geometryWarnings.add(Warning.TUBE_SEPARATION);
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} else if (tubes.getTubeSeparation() < -MathUtil.EPSILON) {
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geometryWarnings.add(Warning.TUBE_OVERLAP);
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}
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// precompute geometry
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bodyRadius = tubes.getBodyRadius();
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// wetted area for friction drag calculation
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// Area of inner surface of tubes.
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final double innerArea = tubes.getFinCount() * tubes.getLength() * 2.0 * Math.PI * tubes.getInnerRadius();
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// Area of the outer surface of tubes. Since roughly half
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// of the area is "masked" by the interstices between the tubes and the
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// body tube, only consider half the area
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final double outerArea = tubes.getFinCount() * tubes.getLength() * Math.PI * tubes.getOuterRadius();
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// Area of the portion of the body tube masked by the tube fins
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final BodyTube parent = (BodyTube) tubes.getParent();
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final double maskedArea = tubes.getLength() * 2.0 * Math.PI * parent.getOuterRadius();
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wettedArea = innerArea + outerArea - maskedArea;
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log.debug("wetted area of tube fins " + wettedArea);
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// effective frontal area for pressure drag calculation
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// model interstices between tube fins and body tube as closed blunt area
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// area of disk passing through tube fin centers
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final double tubeDiskArea = Math.PI * MathUtil.pow2(bodyRadius + tubes.getOuterRadius());
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// half of combined area of tube fin interiors.
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final double tubeInnerArea = tubes.getFinCount() * Math.PI * MathUtil.pow2(tubes.getInnerRadius()) / 2.0;
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// body tube area
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final double bodyTubeArea = Math.PI * MathUtil.pow2(bodyRadius);
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// refArea is effective frontal area of a tube, from LaunchLugCalc
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frontalArea = tubes.getFinCount() * refArea + tubeDiskArea - tubeInnerArea - bodyTubeArea;
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log.debug("effective frontal area " + frontalArea);
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thickness = fin.getThickness();
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bodyRadius = fin.getBodyRadius();
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finCount = 3 * fin.getFinCount();
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baseRotation = fin.getBaseRotation();
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cantAngle = 0;
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@ -94,7 +143,7 @@ public class TubeFinSetCalc extends RocketComponentCalc {
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*/
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@Override
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public void calculateNonaxialForces(FlightConditions conditions, Transformation transform,
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AerodynamicForces forces, WarningSet warnings) {
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AerodynamicForces forces, WarningSet warnings) {
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if (span < 0.001) {
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forces.setCm(0);
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@ -113,14 +162,13 @@ public class TubeFinSetCalc extends RocketComponentCalc {
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if( (0 < bodyRadius) && (thickness > bodyRadius / 2)){
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warnings.add(Warning.THICK_FIN);
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}
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warnings.add(new Other("Tube fin support is experimental"));
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//////// Calculate CNa. /////////
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// One fin without interference (both sub- and supersonic):
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double cna1 = calculateFinCNa1(conditions);
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// logger.debug("Component cna1 = {}", cna1);
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// log.debug("Component cna1 = {}", cna1);
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// Multiple fins with fin-fin interference
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double cna;
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@ -141,7 +189,7 @@ public class TubeFinSetCalc extends RocketComponentCalc {
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cna = cna1 * finCount / 2.0;
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}
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// logger.debug("Component cna = {}", cna);
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// log.debug("Component cna = {}", cna);
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// Take into account fin-fin interference effects
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switch (interferenceFinCount) {
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@ -182,7 +230,7 @@ public class TubeFinSetCalc extends RocketComponentCalc {
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tau = 0;
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cna *= 1 + tau; // Classical Barrowman
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// cna *= pow2(1 + tau); // Barrowman thesis (too optimistic??)
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// logger.debug("Component cna = {}", cna);
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// log.debug("Component cna = {}", cna);
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// TODO: LOW: check for fin tip mach cone interference
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// (Barrowman thesis pdf-page 40)
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@ -191,9 +239,9 @@ public class TubeFinSetCalc extends RocketComponentCalc {
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// Calculate CP position
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double x = macLead + calculateCPPos(conditions) * macLength;
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// logger.debug("Component macLead = {}", macLead);
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// logger.debug("Component macLength = {}", macLength);
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// logger.debug("Component x = {}", x);
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// log.debug("Component macLead = {}", macLead);
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// log.debug("Component macLength = {}", macLength);
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// log.debug("Component x = {}", x);
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// Calculate roll forces, reduce forcing above stall angle
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@ -352,7 +400,7 @@ public class TubeFinSetCalc extends RocketComponentCalc {
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double y = i * dy;
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macLength += length * length;
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logger.debug("macLength = {}, length = {}, i = {}", macLength, length, i);
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log.debug("macLength = {}, length = {}, i = {}", macLength, length, i);
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macSpan += y * length;
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macLead += chordLead[i] * length;
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area += length;
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@ -368,7 +416,7 @@ public class TubeFinSetCalc extends RocketComponentCalc {
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}
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macLength *= dy;
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logger.debug("macLength = {}", macLength);
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log.debug("macLength = {}", macLength);
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macSpan *= dy;
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macLead *= dy;
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area *= dy;
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@ -537,7 +585,7 @@ public class TubeFinSetCalc extends RocketComponentCalc {
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*/
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private double calculateCPPos(FlightConditions cond) {
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double m = cond.getMach();
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// logger.debug("m = {} ", m);
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// log.debug("m = {} ", m);
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if (m <= 0.5) {
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// At subsonic speeds CP at quarter chord
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return 0.25;
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@ -556,7 +604,7 @@ public class TubeFinSetCalc extends RocketComponentCalc {
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val += poly[i] * x;
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x *= m;
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}
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// logger.debug("val = {}", val);
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// log.debug("val = {}", val);
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return val;
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}
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@ -586,82 +634,26 @@ public class TubeFinSetCalc extends RocketComponentCalc {
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poly[1] = (-31.6049 * (-0.705375 + ar) * (-0.198476 + ar)) / denom;
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poly[0] = (9.16049 * (-0.588838 + ar) * (-0.20624 + ar)) / denom;
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}
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// @SuppressWarnings("null")
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// public static void main(String arg[]) {
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// Rocket rocket = TestRocket.makeRocket();
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// FinSet finset = null;
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//
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// Iterator<RocketComponent> iter = rocket.deepIterator();
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// while (iter.hasNext()) {
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// RocketComponent c = iter.next();
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// if (c instanceof FinSet) {
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// finset = (FinSet)c;
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// break;
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// }
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// }
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//
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// ((TrapezoidFinSet)finset).setHeight(0.10);
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// ((TrapezoidFinSet)finset).setRootChord(0.10);
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// ((TrapezoidFinSet)finset).setTipChord(0.10);
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// ((TrapezoidFinSet)finset).setSweep(0.0);
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//
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//
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// FinSetCalc calc = new FinSetCalc(finset);
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//
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// calc.calculateFinGeometry();
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// FlightConditions cond = new FlightConditions(new Configuration(rocket));
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// for (double m=0; m < 3; m+=0.05) {
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// cond.setMach(m);
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// cond.setAOA(0.0*Math.PI/180);
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// double cna = calc.calculateFinCNa1(cond);
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// System.out.printf("%5.2f "+cna+"\n", m);
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// }
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//
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// }
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@Override
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public double calculateFrictionCD(FlightConditions conditions, double componentCf, WarningSet warnings) {
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warnings.addAll(geometryWarnings);
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final double frictionCD = componentCf * wettedArea / conditions.getRefArea();
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log.debug("frictionCD " + frictionCD);
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return frictionCD;
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}
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@Override
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public double calculatePressureCD(FlightConditions conditions,
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double stagnationCD, double baseCD, WarningSet warnings) {
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double stagnationCD, double baseCD, WarningSet warnings) {
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double mach = conditions.getMach();
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double cd = 0;
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// Pressure fore-drag
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if (crossSection == FinSet.CrossSection.AIRFOIL ||
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crossSection == FinSet.CrossSection.ROUNDED) {
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// Round leading edge
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if (mach < 0.9) {
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cd = Math.pow(1 - pow2(mach), -0.417) - 1;
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} else if (mach < 1) {
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cd = 1 - 1.785 * (mach - 0.9);
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} else {
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cd = 1.214 - 0.502 / pow2(mach) + 0.1095 / pow2(pow2(mach));
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}
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} else if (crossSection == FinSet.CrossSection.SQUARE) {
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cd = stagnationCD;
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} else {
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throw new UnsupportedOperationException("Unsupported fin profile: " + crossSection);
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}
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// Slanted leading edge
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cd *= pow2(cosGammaLead);
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// Trailing edge drag
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if (crossSection == FinSet.CrossSection.SQUARE) {
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cd += baseCD;
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} else if (crossSection == FinSet.CrossSection.ROUNDED) {
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cd += baseCD / 2;
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}
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// Airfoil assumed to have zero base drag
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// Scale to correct reference area
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cd *= finCount * span * thickness / conditions.getRefArea();
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return cd;
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warnings.addAll(geometryWarnings);
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final double cd = (stagnationCD + baseCD) * frontalArea / conditions.getRefArea();
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log.debug("pressure CD " + cd);
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return cd;
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}
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private static int calculateInterferenceFinCount(TubeFinSet component) {
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@ -672,11 +664,4 @@ public class TubeFinSetCalc extends RocketComponentCalc {
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return 3 * component.getFinCount();
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}
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@Override
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public double calculateFrictionCD(FlightConditions conditions, double componentCf, WarningSet warnings) {
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// launch lug doesn't add enough area to worry about
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return 0;
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}
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}
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