From bf2ad1f49dbf0c5f656a7ce0aa3cc9d1b2ef7cd3 Mon Sep 17 00:00:00 2001
From: Peter Barker <pbarker@barker.dropbear.id.au>
Date: Fri, 12 Jun 2026 14:25:44 +1000
Subject: [PATCH] Tools: add heli-quad SITL frame information and default
 parameters

The default parameters use a symmetric collective range so the
zero-thrust point lands on mid-PWM, matching the SITL heli-quad
model's flat-pitch point.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---
 Tools/autotest/arducopter.py                  |  1 +
 .../default_params/copter-heliquad.parm       | 11 ++++
 Tools/autotest/models/heliquad.json           | 64 +++++++++++++++++++
 Tools/autotest/pysim/vehicleinfo.json         | 16 +++++
 4 files changed, 92 insertions(+)
 create mode 100644 Tools/autotest/default_params/copter-heliquad.parm
 create mode 100644 Tools/autotest/models/heliquad.json

diff --git a/Tools/autotest/arducopter.py b/Tools/autotest/arducopter.py
index ef5ff3fbb6f..2e30dc50d30 100644
--- a/Tools/autotest/arducopter.py
+++ b/Tools/autotest/arducopter.py
@@ -12864,6 +12864,7 @@ class AutoTestCopter(vehicle_test_suite.TestSuite):
             'heli-blade360': "wrong binary, different takeoff regime",
             'heli-ddvptail': "wrong binary, different takeoff regime",
             'heli-ddfptail': "wrong binary, different takeoff regime",
+            'heli-quad': "wrong binary, different takeoff regime",
             "quad-can" : "needs CAN periph",
         }
         for frame in sorted(copter_vinfo_options["frames"].keys()):
diff --git a/Tools/autotest/default_params/copter-heliquad.parm b/Tools/autotest/default_params/copter-heliquad.parm
new file mode 100644
index 00000000000..70eef345914
--- /dev/null
+++ b/Tools/autotest/default_params/copter-heliquad.parm
@@ -0,0 +1,11 @@
+FRAME_CLASS 13
+# symmetric collective so the zero-thrust point lands on mid-PWM
+# (1500), matching the SITL heli-quad model's flat-pitch point
+H_COL_MIN 1000
+H_COL_MAX 2000
+H_COL_ANG_MIN -10
+H_COL_ANG_MAX 10
+H_COL_ZERO_THRST 0
+H_COL_LAND_MIN -2
+# no tail rotor, so no roll trim required in hover
+ATC_HOVR_ROL_TRM 0
diff --git a/Tools/autotest/models/heliquad.json b/Tools/autotest/models/heliquad.json
new file mode 100644
index 00000000000..c04e19371cf
--- /dev/null
+++ b/Tools/autotest/models/heliquad.json
@@ -0,0 +1,64 @@
+# collective pitch quadcopter (heliquad)
+#
+# only the upper half of the collective range gives positive thrust,
+# so hoverThrOut is lower than for a fixed-pitch quad
+
+{
+    # total vehicle mass in kg
+    "mass" : 3.0,
+
+    # vehicle diameter
+    "diagonal_size" : 0.35,
+
+    # the ref parameters should be taken from a test
+    # with the copter flying at constant speed in zero wind. This is used
+    # to estimate the drag coefficient
+    "refSpd" : 15.08,    # m/s
+    "refAngle" : 45.0,   # degrees
+    "refVoltage" : 12.09, # volts
+    "refCurrent" : 15.0, # Amps
+    "refAlt" : 593,      # meters AMSL
+    "refTempC" : 25,     # degrees C
+    "refBatRes" : 0.01,  # BAT.Res from log
+
+    # full battery voltage
+    "maxVoltage" : 12.6,
+
+    # full battery capacity, Ah
+    # 0 means unlimited
+    "battCapacityAh" : 0,
+
+    # thrust is roughly linear in blade pitch
+    "propExpo" : 0.3,
+
+    # approximate maximum yaw rate in deg/sec
+    "refRotRate" : 120,
+
+    # hover throttle from 0 to 1
+    "hoverThrOut" : 0.2,
+
+    # MOT_PWM_MIN
+    "pwmMin" : 1000,
+
+    # MOT_PWM_MAX
+    "pwmMax" : 2000,
+
+    # MOT_SPIN_MIN
+    "spin_min" : 0.15,
+
+    # MOT_SPIN_MAX
+    "spin_max" : 0.95,
+
+    # maximum motor slew rate, or zero to disable
+    "slew_max" : 150,
+
+    # total effective disc area in sq m for 4 x 0.35m diameter rotors
+    "disc_area" : 0.385,
+
+    # momentum drag coefficient
+    # ratio of momentum drag relative to a ducted rotor of the same effective disc area
+    "mdrag_coef" : 0.2,
+
+    # number of motors
+    "num_motors" : 4
+}
diff --git a/Tools/autotest/pysim/vehicleinfo.json b/Tools/autotest/pysim/vehicleinfo.json
index 926006dfefe..853d6bdd97b 100644
--- a/Tools/autotest/pysim/vehicleinfo.json
+++ b/Tools/autotest/pysim/vehicleinfo.json
@@ -242,6 +242,14 @@
                     "default_params/copter-heli.parm"
                 ]
             },
+            "heli-quad": {
+                "model": "heli-quad:@ROMFS/models/heliquad.json",
+                "waf_target": "bin/arducopter-heli",
+                "default_params_filename": [
+                    "default_params/copter-heli.parm",
+                    "default_params/copter-heliquad.parm"
+                ]
+            },
             "singlecopter": {
                 "waf_target": "bin/arducopter",
                 "default_params_filename": "default_params/copter-single.parm"
@@ -348,6 +356,14 @@
                 "default_params_filename": [
                     "default_params/copter-heli.parm"
                 ]
+            },
+            "heli-quad": {
+                "model": "heli-quad:@ROMFS/models/heliquad.json",
+                "waf_target": "bin/arducopter-heli",
+                "default_params_filename": [
+                    "default_params/copter-heli.parm",
+                    "default_params/copter-heliquad.parm"
+                ]
             }
         }
     },