From 9df753551e0ed2fbf50af2151f81fd991d669f94 Mon Sep 17 00:00:00 2001
From: Peter Hall <iampete@hotmail.co.uk>
Date: Wed, 10 Nov 2021 02:16:51 +0000
Subject: [PATCH] Plane: quadplane: tailsitter: always relax pitch after
 transtion

---
 ArduPlane/quadplane.cpp  | 2 +-
 ArduPlane/tailsitter.cpp | 8 ++++++++
 ArduPlane/tailsitter.h   | 8 +++++---
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/ArduPlane/quadplane.cpp b/ArduPlane/quadplane.cpp
index 7b5152e16d..749f58e491 100644
--- a/ArduPlane/quadplane.cpp
+++ b/ArduPlane/quadplane.cpp
@@ -906,7 +906,7 @@ void QuadPlane::relax_attitude_control()
 {
     // disable roll and yaw control for vectored tailsitters
     // if not a vectored tailsitter completely disable attitude control
-    attitude_control->relax_attitude_controllers(tailsitter._is_vectored);
+    attitude_control->relax_attitude_controllers(!tailsitter.relax_pitch());
 }
 
 /*
diff --git a/ArduPlane/tailsitter.cpp b/ArduPlane/tailsitter.cpp
index f2bde63eec..fbe195e490 100644
--- a/ArduPlane/tailsitter.cpp
+++ b/ArduPlane/tailsitter.cpp
@@ -685,6 +685,14 @@ void Tailsitter::speed_scaling(void)
     }
 }
 
+// return true if pitch control should be relaxed
+// on vectored belly sitters the pitch control is not relaxed in order to keep motors pointing and avoid risk of props hitting the ground
+// always relax after a transition
+bool Tailsitter::relax_pitch()
+{
+    return !enabled() || !_is_vectored || (transition->vtol_limit_start_ms != 0);
+}
+
 /*
   update for transition from quadplane to fixed wing mode
  */
diff --git a/ArduPlane/tailsitter.h b/ArduPlane/tailsitter.h
index 2b24744206..ef7579728b 100644
--- a/ArduPlane/tailsitter.h
+++ b/ArduPlane/tailsitter.h
@@ -62,9 +62,8 @@ public:
     // return the transition_angle_vtol value
     int8_t get_transition_angle_vtol() const;
 
-
-    // true when flying a tilt-vectored tailsitter
-    bool _is_vectored;
+    // return true if pitch control should be relaxed
+    bool relax_pitch();
 
     // tailsitter speed scaler
     float last_spd_scaler = 1.0f; // used to slew rate limiting with TAILSITTER_GSCL_ATT_THR option
@@ -111,6 +110,9 @@ private:
 
     bool setup_complete;
 
+    // true when flying a tilt-vectored tailsitter
+    bool _is_vectored;
+
     // refences for convenience
     QuadPlane& quadplane;
     AP_MotorsMulticopter*& motors;