diff --git a/libraries/SITL/SIM_Buzzer.h b/libraries/SITL/SIM_Buzzer.h
index 74c2309472..1af1635b77 100644
--- a/libraries/SITL/SIM_Buzzer.h
+++ b/libraries/SITL/SIM_Buzzer.h
@@ -40,11 +40,6 @@ public:
 
     AP_Int8  _enable;  // enable buzzer sim
     AP_Int8  _pin;
-    bool was_on;
-
-    uint32_t on_time;
-
-    bool prep_done;
 };
 
 }
diff --git a/libraries/SITL/SIM_EFI_MegaSquirt.h b/libraries/SITL/SIM_EFI_MegaSquirt.h
index d32707874d..f957a296c7 100644
--- a/libraries/SITL/SIM_EFI_MegaSquirt.h
+++ b/libraries/SITL/SIM_EFI_MegaSquirt.h
@@ -44,8 +44,6 @@ public:
 private:
     void send_table();
 
-    uint32_t time_send_ms;
-
     struct PACKED {
         uint16_t size;
         uint8_t command;
diff --git a/libraries/SITL/SIM_Helicopter.h b/libraries/SITL/SIM_Helicopter.h
index a2d757385e..5845ae2770 100644
--- a/libraries/SITL/SIM_Helicopter.h
+++ b/libraries/SITL/SIM_Helicopter.h
@@ -62,7 +62,6 @@ private:
     float hover_throttle = 0.5f;
     float terminal_velocity = 80;
     float hover_lean = 3.2f;
-    float yaw_zero = 0.1f;
     float rotor_rot_accel = radians(20);
     float roll_rate_max = radians(1400);
     float pitch_rate_max = radians(1400);
@@ -70,10 +69,8 @@ private:
     float rsc_setpoint = 0.8f;
     float izz = 0.2f;
     float tr_dist = 0.85f;
-    float tr_accel_max = 50.0f; //rad/s/s
     float cyclic_scalar = 7.2; // converts swashplate servo ouputs to cyclic blade pitch
     float thrust_scale;
-    float tail_thrust_scale;
     Vector2f _tpp_angle;
     float torque_scale;
     float torque_mpog;
diff --git a/libraries/SITL/SIM_MS5XXX.h b/libraries/SITL/SIM_MS5XXX.h
index 345722b2ba..532fcdc119 100644
--- a/libraries/SITL/SIM_MS5XXX.h
+++ b/libraries/SITL/SIM_MS5XXX.h
@@ -23,10 +23,6 @@ private:
     // float pressure;
     // float temperature;
 
-    // time we last updated the measurements (simulated internal
-    // workings of sensor)
-    uint32_t last_update_ms;
-
     void reset();
 
     enum class Command : uint8_t {
diff --git a/libraries/SITL/SIM_RichenPower.h b/libraries/SITL/SIM_RichenPower.h
index 962eb3a609..8b5eba90a4 100644
--- a/libraries/SITL/SIM_RichenPower.h
+++ b/libraries/SITL/SIM_RichenPower.h
@@ -71,8 +71,6 @@ private:
 // So we set batt fs high 46s
 // Gennie keeps batts charged to 49v + typically
 
-    class SIM *_sitl;
-
     uint32_t last_sent_ms;
 
     void update_control_pin(const struct sitl_input &input);
@@ -122,7 +120,7 @@ private:
         uint8_t footermagic1;
         uint8_t footermagic2;
     };
-    assert_storage_size<RichenPacket, 70> _assert_storage_size_RichenPacket;
+    assert_storage_size<RichenPacket, 70> _assert_storage_size_RichenPacket UNUSED_PRIVATE_MEMBER;
 
     union RichenUnion {
         uint8_t parse_buffer[70];
diff --git a/libraries/SITL/SIM_Scrimmage.cpp b/libraries/SITL/SIM_Scrimmage.cpp
index 64b623094f..e4d91548ac 100644
--- a/libraries/SITL/SIM_Scrimmage.cpp
+++ b/libraries/SITL/SIM_Scrimmage.cpp
@@ -35,8 +35,7 @@ Scrimmage::Scrimmage(const char *_frame_str) :
     Aircraft(_frame_str),
     prev_timestamp_us(0),
     recv_sock(true),
-    send_sock(true),
-    frame_str(_frame_str)
+    send_sock(true)
 {
 }
 
diff --git a/libraries/SITL/SIM_Scrimmage.h b/libraries/SITL/SIM_Scrimmage.h
index 5887d3368f..e6228cb281 100644
--- a/libraries/SITL/SIM_Scrimmage.h
+++ b/libraries/SITL/SIM_Scrimmage.h
@@ -86,8 +86,6 @@ private:
     uint64_t prev_timestamp_us;
     SocketAPM recv_sock;
     SocketAPM send_sock;
-
-    const char *frame_str;
 };
 
 } // namespace SITL
diff --git a/libraries/SITL/SIM_Temperature_MCP9600.h b/libraries/SITL/SIM_Temperature_MCP9600.h
index 29b60a3d6e..d8109cbaed 100644
--- a/libraries/SITL/SIM_Temperature_MCP9600.h
+++ b/libraries/SITL/SIM_Temperature_MCP9600.h
@@ -30,7 +30,6 @@ private:
 
     // should be a call on aircraft:
     float some_temperature = 26.5;
-    float last_temperature = -1000.0f;
 
     uint32_t last_temperature_update_ms;
 };
diff --git a/libraries/SITL/SIM_VectorNav.h b/libraries/SITL/SIM_VectorNav.h
index c072807da5..4e73f69478 100644
--- a/libraries/SITL/SIM_VectorNav.h
+++ b/libraries/SITL/SIM_VectorNav.h
@@ -41,10 +41,6 @@ public:
     void update(void);
 
 private:
-    // TODO: make these parameters:
-    const uint8_t system_id = 17;
-    const uint8_t component_id = 18;
-
     uint32_t last_pkt1_us;
     uint32_t last_pkt2_us;