Put in some (currently compile-time) tuning for the solver threshold.

A recent change resulted in the Piper Cub oscillating about its
correct solution.

diff --git a/src/FDM/YASim/Airplane.cpp b/src/FDM/YASim/Airplane.cpp
index 04d1b87ef223b8aa1f90a65f7d9ee33101f37b9b..05c64df319e4a9084d60afebb7a938adfa611c85 100644 (file)
--- a/src/FDM/YASim/Airplane.cpp
+++ b/src/FDM/YASim/Airplane.cpp
@@ -929,9 +929,16 @@ void Airplane::solve()
        applyDragFactor(dragFactor);
        applyLiftRatio(liftFactor);
 
+       // Solver threshold.  How close to the solution are we trying
+       // to get?  Trying too hard can result in oscillations about
+       // the correct solution, which is bad.  Stick this in as a
+       // compile time constant for now, and consider making it
+       // settable per-model.
+       float STHRESH = 1.6;
+
        // DON'T do the following until the above are sane
-       if(normFactor(dragFactor) > 1.0001
-          || normFactor(liftFactor) > 1.0001)
+       if(normFactor(dragFactor) > STHRESH*1.0001
+          || normFactor(liftFactor) > STHRESH*1.0001)
        {
            continue;
        }
@@ -943,13 +950,13 @@ void Airplane::solve()
        _cruiseAoA = clamp(_cruiseAoA, -0.175f, 0.175f);
        _tailIncidence = clamp(_tailIncidence, -0.175f, 0.175f);
 
-        if(abs(xforce/_cruiseWeight) < 0.0001 &&
-           abs(alift/_approachWeight) < 0.0001 &&
-           abs(aoaDelta) < .000017 &&
-           abs(tailDelta) < .000017)
+        if(abs(xforce/_cruiseWeight) < STHRESH*0.0001 &&
+           abs(alift/_approachWeight) < STHRESH*0.0001 &&
+           abs(aoaDelta) < STHRESH*.000017 &&
+           abs(tailDelta) < STHRESH*.000017)
         {
             // If this finaly value is OK, then we're all done
-            if(abs(elevDelta) < 0.0001)
+            if(abs(elevDelta) < STHRESH*0.0001)
                 break;
 
             // Otherwise, adjust and do the next iteration