X-Git-Url: https://git.mxchange.org/?a=blobdiff_plain;f=src%2FSystems%2Fpitot.cxx;h=4f18431cd46631eefbf26669aa9d4b77fe690708;hb=81cd33e2fa9b5930784d3aed920eea0e3038e7f7;hp=5cfc6188b20ad514bbe96d5fba8ff99d946c78f2;hpb=4d146352d702ebfdb53a390eb4b406a30fc17cc8;p=flightgear.git

diff --git a/src/Systems/pitot.cxx b/src/Systems/pitot.cxx
index 5cfc6188b..4f18431cd 100644
--- a/src/Systems/pitot.cxx
+++ b/src/Systems/pitot.cxx
@@ -1,14 +1,25 @@
 // pitot.cxx - the pitot air system.
 // Written by David Megginson, started 2002.
 //
+// Last modified by Eric van den Berg, 24 Nov 2012
 // This file is in the Public Domain and comes with no warranty.
 
-#include "pitot.hxx"
+#ifdef HAVE_CONFIG_H
+#  include <config.h>
+#endif
+
+#include <simgear/constants.h>
+
 #include <Main/fg_props.hxx>
 #include <Main/util.hxx>
 
+#include "pitot.hxx"
+
 
-PitotSystem::PitotSystem ()
+PitotSystem::PitotSystem ( SGPropertyNode *node )
+    :
+    _name(node->getStringValue("name", "pitot")),
+    _num(node->getIntValue("number", 0))
 {
 }
 
@@ -19,12 +30,15 @@ PitotSystem::~PitotSystem ()
 void
 PitotSystem::init ()
 {
-    _serviceable_node = fgGetNode("/systems/pitot[0]/serviceable", true);
+    string branch;
+    branch = "/systems/" + _name;
+
+    SGPropertyNode *node = fgGetNode(branch.c_str(), _num, true );
+    _serviceable_node = node->getChild("serviceable", 0, true);
     _pressure_node = fgGetNode("/environment/pressure-inhg", true);
-    _density_node = fgGetNode("/environment/density-slugft3", true);
-    _velocity_node = fgGetNode("/velocities/airspeed-kt", true);
-    _total_pressure_node =
-        fgGetNode("/systems/pitot[0]/total-pressure-inhg", true);
+    _mach_node = fgGetNode("/velocities/mach", true);
+    _total_pressure_node = node->getChild("total-pressure-inhg", 0, true);
+    _measured_total_pressure_node = node->getChild("measured-total-pressure-inhg", 0, true);
 }
 
 void
@@ -37,30 +51,20 @@ PitotSystem::unbind ()
 {
 }
 
-#ifndef INHGTOPSF
-# define INHGTOPSF (2116.217/29.9212)
-#endif
-
-#ifndef PSFTOINHG
-# define PSFTOINHG (1/INHGTOPSF)
-#endif
-
-#ifndef KTTOFPS
-# define KTTOFPS 1.68781
-#endif
-
-
 void
 PitotSystem::update (double dt)
 {
     if (_serviceable_node->getBoolValue()) {
-                                // The pitot tube sees the forward
-                                // velocity in the body axis.
-        double p = _pressure_node->getDoubleValue() * INHGTOPSF;
-        double r = _density_node->getDoubleValue();
-        double v = _velocity_node->getDoubleValue() * KTTOFPS;
-        double q = 0.5 * r * v * v; // dynamic
-        _total_pressure_node->setDoubleValue((p + q) * PSFTOINHG);
+        double p = _pressure_node->getDoubleValue();
+        double mach = _mach_node->getDoubleValue();
+        mach = std::max( mach , 0.0 );
+        double p_t = p * pow(1 + 0.2 * mach*mach, 3.5 );    // true total pressure around aircraft
+        _total_pressure_node->setDoubleValue(p_t);
+        double p_t_meas = p_t;
+        if (mach > 1) {    
+          p_t_meas = p * pow( 1.2 * mach*mach, 3.5 ) * pow( 2.8/2.4*mach*mach - 0.4 / 2.4 , -2.5 );    // measured total pressure by pitot tube (Rayleigh formula, at Mach>1, normal shockwave in front of pitot tube)     
+        }
+        _measured_total_pressure_node->setDoubleValue(p_t_meas);
     }
 }