The short answer
Choose the autopilot first, because it sets the connectors, power sensing and firmware that everything else has to match. Then choose GNSS by how precise and repeatable the position must be, telemetry by link budget and the band you may use, and ESCs by current, protocol and firmware. Keep flight-critical work on the autopilot and give a companion computer the rest.
Which Pixhawk flight controller should I choose?
The Pixhawk 6C or 6C Mini for a complete controller with its connectors built in, and the 6X or 6X Pro when you need to choose the baseboard, including ones that carry a Jetson or Raspberry Pi. Then match the power module to it: analog for the 6C family, I2C digital for the 6X, DroneCAN where the controller reads battery data over CAN.
- Pixhawk 6C, 6C Mini, 6X or 6X Pro: which flight controller should you choose?Compare Holybro Pixhawk 6C, 6C Mini, 6X and 6X Pro: integrated versus separate baseboard, case and variant options, and an exact-SKU checklist to order from.
- Analog, digital or DroneCAN: choosing a Pixhawk power moduleMatch a Pixhawk power module to its controller: analog sensing, I2C digital sensing and DroneCAN, plus voltage, current and wiring checks before ordering.
- Building an AI research drone: integrating a companion computer with PixhawkFit a companion computer to a Pixhawk: who does what, serial and Ethernet links, separate power, cooling and a bench-test checklist.
Shop: Holybro autopilot flight controllers · Holybro power modules & PDBs
Standard GPS, RTK or dual-antenna heading?
Standard GPS when a metre or two of error is acceptable, RTK when the vehicle must come back to the same coordinates to within centimetres, and a dual-antenna receiver when you need a heading that doesn't depend on the compass. RTK needs a base station or correction service and a link to carry the corrections.
- Drone GPS, RTK and dual-antenna heading: which do you need?Choose drone GNSS by positioning and heading needs. Compare standard GPS, RTK corrections and dual-antenna yaw, with a Holybro sourcing checklist.
Shop: Holybro GPS systems
How do I choose a telemetry radio?
From a link budget rather than the advertised range, on a band you are allowed to use. 433 MHz and 915 MHz radios are separate part numbers that can't talk to each other, and better antennas and placement usually add more margin than more transmit power.
- How to choose a UAV telemetry radio: data rate, range and ground-station compatibilityChoose a UAV telemetry radio: data rate against range, a worked 915 MHz link budget, antennas and ground-station fit.
Shop: Holybro telemetry radios
Which ESC, and which development kit?
Match an ESC on cell count and current, control protocol, telemetry and firmware family, and use DShot on a new build. If the airframe isn't the project, start from a development kit: the X500 V2 for a first research drone, the X650 for a real payload.
- Choosing a drone ESC: PWM, DShot, telemetry and programming compatibilityChoose a drone ESC by control protocol, telemetry path and firmware family: PWM versus DShot, BLHeli-32 versus AM32, configuration tools and troubleshooting.
- Holybro S500, X500 V2 or X650: choosing a drone development kit for researchCompare Holybro S500 V2, X500 V2 and X650 drone kits: wheelbase, included propulsion and avionics, frame versus ARF versus development format.
Shop: T-Motor ESC · Holybro FPV electronics · Holybro development drone kits
Which sensors does a drone need beyond GPS?
A fixed-wing or VTOL aircraft needs a real airspeed sensor, because GPS measures speed over the ground. To hold position indoors or without GPS, pair a downward range sensor with an optical flow sensor, and add visual odometry only when the mission needs a full pose.
- Choosing an airspeed sensor and pitot tube for a fixed-wing UAVChoose a fixed-wing or VTOL airspeed sensor: airspeed versus GPS speed, I2C versus DroneCAN, pitot installation and the details needed for a quotation.
- Optical flow, lidar or visual odometry: holding position when GPS is unavailableNavigating without GPS: what optical flow, a downward range sensor and visual odometry each measure, where each fails, and what a working indoor stack needs.
Shop: Holybro sensors
What does a complete build look like?
Our build guides put all of this together: a 7-inch autonomous quadcopter, a final-year project drone with its design calculations, and a payload-drop drone for NIDAR and AeroTHON, each with a parts list priced in rupees.
- 7-inch autonomous quadcopter on ArduPilot: parts list and flight-time sumsParts list for a 7-inch ArduPilot quadcopter with GPS waypoints, telemetry and a companion computer, and the sums behind a 15–20 minute flight.
- Drone for a final-year project: parts list and design calculationsA Pixhawk quadcopter for an engineering project: what to buy, and the thrust, flight-time, current and battery sums the project report needs.
- Autonomous payload-drop drone for NIDAR, AeroTHON and similar contestsAn ArduPilot drone that searches for a target with a camera, drops or lowers a payload on it and flies home: parts list, mission set-up and the accuracy sums.
What these parts cost in India: price ranges, cost per kilogram of thrust and bulk-order savings →