Change engine sound, while on air, to a less squeeky one (1.4 -> 0.9).

git-svn-id: svn+ssh://svn.code.sf.net/p/supertuxkart/code/main/trunk@5515 178a84e3-b1eb-0310-8ba1-8eac791a3b58

src/karts/kart.cpp

@@ -1244,8 +1244,9 @@ void Kart::updatePhysics(float dt)
         }
         else
         {
-            // When flying, fixed and fast engine noise to make it more scary
-            m_engine_sound->speed(1.4f);
+            // When flying, fixed value but not too high pitch
+            // This gives some variation (vs previous "on wheels" one)
+            m_engine_sound->speed(0.9f);
         }
         m_engine_sound->position(getXYZ());
     }