X-Git-Url: https://git.mxchange.org/?a=blobdiff_plain;f=src%2FFDM%2FYASim%2FAtmosphere.cpp;h=92d2fbe56a6e3495762d2c2ffff5c96c42e134e8;hb=c8b8722a14d29e2b4153c39ad4cef0c44a562afd;hp=83c6b974897862d3e0fe7ea485a7e028b14d4624;hpb=0cabedaa4f8ce11bdab4d182937110d111d2590c;p=flightgear.git

diff --git a/src/FDM/YASim/Atmosphere.cpp b/src/FDM/YASim/Atmosphere.cpp
index 83c6b9748..92d2fbe56 100644
--- a/src/FDM/YASim/Atmosphere.cpp
+++ b/src/FDM/YASim/Atmosphere.cpp
@@ -102,6 +102,25 @@ float Atmosphere::calcMach(float spd, float temp)
     return spd / Math::sqrt(GAMMA * R * temp);
 }
 
+float Atmosphere::spdFromMach(float mach, float temp)
+{
+    return mach * Math::sqrt(GAMMA * R * temp);
+}
+
+float Atmosphere::spdFromVCAS(float vcas, float pressure, float temp)
+{
+                                // FIXME: does not account for supersonic
+    float p0 = getStdPressure(0);
+    float rho0 = getStdDensity(0);
+
+    float tmp = (vcas*vcas)/(7*p0/rho0) + 1;
+    float cp = ((Math::pow(tmp,(7/2.))-1)/(pressure/p0)) + 1;
+
+    float m2 = (Math::pow(cp,(1/3.5))-1)/0.2;
+    float vtas= spdFromMach(Math::sqrt(m2), temp);
+    return vtas;
+}
+
 void Atmosphere::calcStaticAir(float p0, float t0, float d0, float v,
                                float* pOut, float* tOut, float* dOut)
 {