SITL: added ignition control for gas heli

libraries/SITL/SIM_Helicopter.cpp

@@ -48,6 +48,7 @@ Helicopter::Helicopter(const char *home_str, const char *frame_str) :
     } else {
         frame_type = HELI_FRAME_CONVENTIONAL;
     }
+    gas_heli = (strstr(frame_str, "-gas") != NULL);
 }
 
 /*
@@ -60,6 +61,8 @@ void Helicopter::update(const struct sitl_input &input)
 
     float rsc = (input.servos[7]-1000) / 1000.0f;
     float rsc_scale = rsc/rsc_setpoint;
+    // ignition only for gas helis
+    bool ignition_enabled = gas_heli?(input.servos[6] > 1500):true;
 
     float thrust = 0;
     float roll_rate = 0;
@@ -73,6 +76,10 @@ void Helicopter::update(const struct sitl_input &input)
     float swash2 = (input.servos[1]-1000) / 1000.0f;
     float swash3 = (input.servos[2]-1000) / 1000.0f;
 
+    if (!ignition_enabled) {
+        rsc = 0;
+    }
+
     switch (frame_type) {
     case HELI_FRAME_CONVENTIONAL: {
         // simulate a traditional helicopter

libraries/SITL/SIM_Helicopter.h

@@ -56,6 +56,7 @@ private:
         HELI_FRAME_DUAL,
         HELI_FRAME_COMPOUND
     } frame_type = HELI_FRAME_CONVENTIONAL;
+    bool gas_heli = false;
 };