diff --git a/ArduCopter/ArduCopter.pde b/ArduCopter/ArduCopter.pde
index 0e49aa3b94..c8e37ed791 100644
--- a/ArduCopter/ArduCopter.pde
+++ b/ArduCopter/ArduCopter.pde
@@ -1,6 +1,6 @@
 /// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
 
-#define THISFIRMWARE "ArduCopter V2.9-dev"
+#define THISFIRMWARE "ArduCopter V2.9.1-dev"
 /*
  *  ArduCopter Version 2.9
  *  Lead author:	Jason Short
diff --git a/ArduCopter/ReleaseNotes.txt b/ArduCopter/ReleaseNotes.txt
index 36bc5d0f48..45f37199f0 100644
--- a/ArduCopter/ReleaseNotes.txt
+++ b/ArduCopter/ReleaseNotes.txt
@@ -1,6 +1,14 @@
 ArduCopter Release Notes:
 ------------------------------------------------------------------
-ArduCopter 2.9-rc5 14-Jan-2013
+ArduCopter 2.9.1-rc1 31-Jan-2013
+Improvements over 2.9:
+1) THR_MID parameter added to allow users to adjust the manual throttle so that vehicle hovers at about mid stick
+2) bug fix for autotrim - roll axis was backwards
+3) bug fix to set sonar_alt_health to zero when sonar is disabled
+4) capture level roll and pitch trims as part of accel calibration
+5) bug fix to ppm encoder false positives
+------------------------------------------------------------------
+ArduCopter 2.9 & 2.9-rc5 14-Jan-2013
 Improvements over 2.9-rc4:
 1) add constraint to loiter commanded roll and pitch angles
 2) relax altitude requirement for take-off command to complete