Proposed outcome
Build a 230-250 mm wheelbase development quadcopter that can be flown manually, hold position, execute a short geofenced waypoint mission, return or land on fault, and record enough data to explain every test.
All project proposals
Aerial robotics project
Autonomous 9-Inch Development Quadcopter
Build a roughly 9-inch (230-250 mm) motor-to-motor quadcopter with 5-inch propellers, PX4 flight control, telemetry, and a logged autonomous mission.
IntermediateRobotics Core
Recommended platform
Use a carbon-fiber 5-inch-prop frame with an approximately 9-10 inch motor-to-motor diagonal. A compact PX4-supported autopilot such as a Pixhawk 6C Mini, a matched 4S propulsion system, GPS/compass, telemetry radio, and independent RC link make the aircraft large enough to assemble and instrument without moving into heavy-lift territory.
Readiness checklist
Review the skills, goals, acceptance tests, and safety limits before committing to the build.
Prerequisites
- Comfort soldering high-current power connections and checking continuity with a multimeter.
- Basic understanding of LiPo battery safety, voltage, current, polarity, and motor/ESC ratings.
- Basic Python and Linux command-line skills for simulation, logs, and ROS 2.
- Access to a legal outdoor flying area and a second person who can act as a spotter.
Learning goals
- Match frame, motors, ESCs, propellers, battery, and power distribution as one propulsion system.
- Configure and validate an autopilot, receiver, GPS, telemetry link, and flight failsafes.
- Use flight logs to evaluate vibration, estimator health, battery sag, and control response.
- Build autonomy in simulation before progressively bounded outdoor flight tests.
- Integrate vehicle state, commands, mission status, and safety state through ROS 2.
Success criteria
- Document an all-up-weight estimate, current budget, connector map, center-of-gravity target, and expected flight time before assembly.
- Pass continuity, smoke-stopper, sensor, motor-order, motor-direction, RC-loss, low-battery, and manual-kill tests with propellers removed.
- Hover manually for 60 seconds and land safely on five consecutive flights.
- Produce logs showing acceptable vibration, healthy state estimation, battery behavior, and no critical failsafe events.
- Complete at least four of five bounded waypoint missions while retaining manual override and return-or-land behavior.
- Publish source, configuration, wiring, parts record, raw logs, plots, demo media, and a failure postmortem.
Safety and scope constraints
- Five-inch propellers can cause serious injury; every bench test is propeller-off unless the airframe is in a purpose-built restraint operated by an experienced builder.
- A physical RC transmitter, deliberate arm/disarm control, and tested radio-loss failsafe remain available during every autonomous flight.
- Powered flight happens outdoors in a clear legal test area with a spotter, never inside a home or near uninvolved people.
- Manual stabilized flight must be reliable before position modes or autonomous missions are enabled.
- LiPo batteries are inspected before use, charged with a chemistry-matched balance charger, and never charged unattended.
Build phases
Parts are cumulative. Pass the exit gate before buying for or starting the next phase.
Phase 1: Simulation and safety envelope
Learn PX4 flight modes, mission planning, geofencing, return behavior, and command-loss handling before selecting or powering hardware.
Parts for this phase
- Linux computer capable of running PX4 SITL and Gazebo
- QGroundControl ground-station software
- Optional USB gamepad for manual simulation
- Written limits for altitude, distance, speed, battery, weather, and abort behavior
Exit gate
Complete ten simulated takeoff-hover-land cycles plus radio-loss, low-battery, geofence, and return-or-land scenarios.
Phase 2: Airframe and propulsion design
Choose components as a matched system and document weight, voltage, current, mounting, connectors, and propeller clearance before ordering.
Parts for this phase
- 230-250 mm carbon-fiber frame sized for 5-inch propellers
- Four matched 2207-class motors appropriate for the selected 4S battery and 5-inch props
- Four individual ESCs or a 4-in-1 ESC with current headroom
- Several matched clockwise and counter-clockwise 5-inch propeller sets
- 4S LiPo battery, XT60 lead, balance charger, LiPo bag, and cell checker
Exit gate
The proposal includes an all-up-weight estimate, thrust margin, peak-current budget, wiring diagram, connector list, and verified propeller clearance.
Phase 3: Mechanical and power assembly
Build a serviceable frame, solder the high-current path, and verify power integrity without installing propellers.
Parts for this phase
- Selected frame, motors, ESCs, power module, and battery connector
- Low-ESR capacitor sized for the propulsion voltage
- Silicone wire, heat shrink, cable ties, thread locker, and mounting hardware
- Temperature-controlled soldering iron, flux, multimeter, and smoke stopper
Exit gate
Pass polarity, continuity, short-circuit, fastener, wire-clearance, strain-relief, center-of-gravity, and smoke-stopper inspections.
Phase 4: Autopilot and avionics bring-up
Install PX4, mount sensors away from vibration and magnetic interference, and establish independent command and telemetry links.
Parts for this phase
- PX4-supported compact autopilot such as a Pixhawk 6C Mini
- Compatible power module with voltage and current sensing
- GPS and compass module on a raised mount
- RC transmitter and receiver with a deliberate arm/disarm control
- Telemetry radio, safety switch, buzzer, and status LED
Exit gate
QGroundControl reports healthy sensors, calibrated controls, correct orientation, valid power readings, GPS lock outdoors, and a stable telemetry link.
Phase 5: Propeller-off motor and failsafe validation
Prove motor mapping, direction, actuator response, arming rules, and every automatic stop or recovery path before generating thrust.
Parts for this phase
- Completed aircraft with propellers removed
- Motor-direction software or safe two-wire phase swap access
- Bench checklist and test log
- No new flight hardware required
Exit gate
Pass motor order/direction, arm/disarm, manual kill, RC loss, telemetry loss, low battery, estimator fault, and reboot-to-disarmed tests.
Phase 6: Controlled manual flight
Perform conservative line-of-sight hover tests, confirm trim and stability, and inspect logs between every configuration change.
Parts for this phase
- Matched and correctly oriented propeller set plus multiple spares
- Clear outdoor test field, landing pad, safety glasses, and spotter
- Fire-resistant battery transport and isolation container
- Wind meter optional but useful for documenting conditions
Exit gate
Complete five consecutive 60-second hovers and safe landings with healthy vibration, estimator, link, and battery logs.
Phase 7: Position control and bounded missions
Validate altitude and position hold, then progress from one waypoint to a short geofenced mission with return-or-land behavior.
Parts for this phase
- Existing GPS/compass, telemetry link, and ground station
- Optional downward rangefinder for more consistent low-altitude landing
- Measured outdoor mission box with conservative altitude and distance limits
Exit gate
Complete position hold, one-waypoint, multi-waypoint, geofence, and return-or-land tests without removing manual override.
Phase 8: ROS 2 capstone integration
Bridge vehicle state and bounded mission commands into ROS 2, record a rosbag, and run the same mission interface in simulation and hardware.
Parts for this phase
- Linux laptop with ROS 2 and a MAVLink bridge
- Existing telemetry radio and aircraft
- Phone or camera for demo media
- No onboard companion computer required for the first version
Exit gate
Complete at least four of five geofenced missions and publish the architecture, configuration, code, logs, plots, demo, and postmortem.
Kits and references
Use these established platforms, guides, and repositories to validate component choices and implementation details.
Holybro QAV250 development kit
A 250 mm reference airframe in the same size class, available with Pixhawk 6C Mini, 2207 motors, 5-inch props, GPS, and telemetry options.
Pixhawk 6C Mini
PX4's maintained documentation for the compact autopilot used as the proposal reference.
PX4 Autopilot
The open flight-control, estimation, mission, and failsafe software stack.
MAVROS
A MAVLink bridge commonly used to connect PX4 vehicles with ROS 2.
FAA recreational flyer guidance
Current U.S. recreational flight, TRUST, airspace, registration, and operating guidance.
Links and recommendations reviewed July 10, 2026.
The other current proposal
Compare the ground and aerial platforms before choosing where to invest your build time.