The receiver

At a glance

• Flies any model with a flight controller that takes CRSF, SBUS, IBUS or PPM. The set-up pages are for Rotorflight helicopters.
• Works with both our transmitters, Version 1 and Version 2.
• One, two or three radios. If one loses the signal, the next takes over.
• Set up from your phone: iPhone, iPad or Android, over Bluetooth. Or any web browser over WiFi.
• Updates itself over the air. Your settings stay.
• Also a USB joystick for RealFlight, neXt and other simulators.
• About £35 of parts (approximate).

The radio link

It speaks the same language as our Version 1 receiver, so Version 1 and Version 2 transmitters both fly it.

• Fast: about 500 packets a second, 16 channels each.
• Copes with a busy band: it hops about 100 times a second across 83 channels of the 2.4 GHz band. The receiver picks the next channel and tells the transmitter.
• Up to three radios. If the radio in charge loses the link, the next one takes over at once.
• You can see it working. The transmitter's Telemetry page shows lost packets, the longest gap, how often the radios swapped and how long each one was in charge.
• The right model loads by itself. The receiver sends its own ID, so the transmitter picks the right model memory (Automatic Model Selection).
• Each radio is checked at switch-on. The app shows which ones the receiver found.
• Bind as on Version 1. Clear bind puts the old pairing aside. Cancel puts it back, so nothing is lost by trying.

To the flight controller

One lead does the flying. Your sticks go to the flight controller; its telemetry comes back. Plug it into the flight controller's receiver port (on a Nexus-X, Port A).

Choose what it sends

• CRSF: the default. 250 frames a second, with telemetry back. Rotorflight's own choice. (Drop it to 100 or 50 for fussy CRSF-to-PWM converters.)
• SBUS: about 71 frames a second, 16 channels.
• IBUS: about 140 frames a second, 14 channels.
• PPM: 8 channels on one wire.

No PWM servo outputs. To drive servos without a flight controller, use the Version 1 receiver or a CRSF-to-PWM converter.

Add a short USB-C cable for everything else

A short USB-C cable from the receiver to the flight controller's own USB socket opens Rotorflight's full set-up channel. With the lead and the cable, the app does almost everything Rotorflight's Configurator does. Only flashing Rotorflight itself needs a computer.

• The receiver finds the cable by itself. Nothing to set.
• It costs nothing in the air. Once the radio link is live, the receiver stops asking questions over USB.
• Leave it in. Tie it down.

Telemetry on your transmitter

• From Rotorflight: flight-pack volts, current, capacity used (mAh), head speed and ESC temperature.
• No Rotorflight? Add a small voltage divider and the receiver measures the pack itself.
• The receiver only listens to the telemetry. It takes nothing from the flying link.
• A guard stops a fault in Rotorflight 2.3 (firmware 4.6) that can switch telemetry off without telling you. The receiver repairs it from a good copy.
• Not on Version 2: GPS, altitude and vario. The Version 1 receiver has those.

Safety built in

The receiver looks after itself, so you can concentrate on flying.

• Switch the transmitter on first. The receiver then keeps its WiFi off. Bluetooth stays open for 30 seconds, in case you want the app.
• Arm, and the radios go quiet. About a second after you arm, WiFi and Bluetooth switch off. On a Rotorflight model this always happens. Disarm, and Bluetooth comes back.
• Nothing can change while the model is armed. The app refuses, and updates wait.
• Every change is checked. The app reads each setting back and says "Saved & verified" only when it matches.
• Signal lost? The receiver holds the last good positions for 1.5 seconds, then goes to failsafe. On CRSF, Rotorflight's own failsafe takes charge. For SBUS, IBUS and PPM you set the failsafe positions from your sticks.
• No transmitter at all? The receiver keeps the throttle at motor-off and the controls centred. The swash does not jump during an update.
• A forgotten model is not left to run its battery flat. With the voltage divider fitted, the receiver saves the flight and goes to sleep at 3.30 V a cell.

The phone app

Free, for iPhone, iPad and Android. No adverts, no accounts, no tracking. It talks to the receiver by Bluetooth, so it works at the field with no network.

Needs iOS 16 or later, or Android 8 or later. On your phone the app is called RXV2. Both versions update themselves.

• Help on every page: tap ?. Press and hold any underlined word to see what it means.
• Find a setting: type a word, in your words or Rotorflight's. Tap a result and the page opens with that setting lit up.
• See your sticks: 16 live channel bars and a 3-D helicopter that moves with your sticks.
• Something wrong? Open the Event log and tap Send debug data to Malcolm. No passwords go with it.
• One phone at a time. A receiver talks to one phone (or one transmitter screen) at once.
• On a computer: join the receiver's WiFi and the same pages open in any web browser.

Pictures from the app's demo mode, with made-up numbers.

Rotorflight, made easy

Rotorflight is an excellent flight controller for helicopters, but setting it up is hard. The app makes it plain: no laptop, and no need to learn Rotorflight's words.

• Wizards take a new helicopter from wiring to the blades-on check, then through tuning. Each step is ticked off. Before it flies, do the failsafe and range tests on Build one.
• Sliders where the numbers used to be: "How hard should it start?", "How agile?", softer or sharper.
• All six banks (Rotorflight's profiles). Copy one bank to another, scaled for head speed.
• Back up the tune and set-up, every bank, to your phone, and share a tune with a friend: their tune, not your servos. Ports, LED, GPS and ESC settings are not included.
• Read the black box at the field Not found elsewhere for Rotorflight The receiver reads the flight recorder over the USB cable, shows the vibration, and suggests one filter change. For Rotorflight, we know of no other tool that does this without a computer.
• On an iPhone Not found elsewhere We know of no other iPhone or iPad app for Rotorflight.

All the Rotorflight tools

From the transmitter too

• Version 2 transmitter: its own Rotorflight pages (PIDs, rates, governor, rescue, servos, filters, switches, backups and more). It reaches the flight controller through this receiver, over Bluetooth, with the model disarmed.
• Version 1 transmitter: rates, PIDs and the governor, over the radio link.

Rotorflight on the transmitter

Flight records

The receiver keeps a record of every flight. You read it on your phone.

• Receiver log: pack volts per cell with a charge estimate, current, head speed and ESC temperature, live.
• Flight analysis: ESC temperature, head speed, volts and amps on one graph. With the link's frame rate, gaps and radio swaps.
• The last 20 flights are kept, each with its date and time.
• Clocks that set themselves. The receiver learns the time from your phone or your transmitter. Nobody sets a clock.
• Event log: one line for every notable moment since switch-on.

Demo mode: the numbers are made up.

Updates

New receiver software is published on this website. Install it in one of three ways:

1. From the phone. The app offers it. Tap Install. It goes over Bluetooth, using the phone's internet, so it works at the field.
2. Over WiFi at home. The receiver fetches it itself, in about a minute.
3. Through a Version 2 transmitter. No app needed. Model setup → Receiver updates → Install, with the model on and connected, with the safety on (with no safety switch: the motor off). The receiver fetches the update over the WiFi it already knows. The transmitter goes quiet for about a minute while the receiver updates. Keep the model switched on until the result shows, in green or red.

• Settings, binding, flight records and backups are kept.
• A failed install leaves the old software in place. The next start says how far it got.
• Changed your mind? Roll back to any older version in the list.
• Never while armed. The receiver refuses.
• A new board? Put the first software on in your browser: Flash a chip (Chrome, Edge or Opera, on a computer).

Flight simulators

The same receiver flies your simulator. Unplug it from the flight controller first: the computer then powers it. Plug it into the computer by USB and switch it to simulator mode in the app. The computer sees a joystick and a keyboard. You fly RealFlight or neXt with your own transmitter, on Windows or Mac.

• Any channel to any simulator input, reversed if you like, with live bars.
• RealFlight's menu buttons from the phone, or from switches on your transmitter (channels 10 to 14).
• Camera views for RealFlight and neXt, from the phone. Every key can be changed.
• A governor-like start in neXt. The receiver holds the motor back, instead of an instant start.

The dongle: the receiver without radios

Fly another make of radio? Keep it. The dongle is the same board with no radio modules. Wire it to a spare port on a Rotorflight flight controller and you get the whole app, whatever receiver flies the model.

• It knows it is a dongle because it finds no radios when it starts.
• It goes quiet while the model is armed.
• It can also be a simulator interface: it turns almost any receiver (CRSF, SBUS, IBUS or PPM) into a USB joystick.
• You need one Seeed XIAO ESP32-S3 and four wires. Under an hour.

Warning

Build the dongle with four wires. Do not order the dongle circuit board in the repository: its first batch was wired wrongly and can destroy the chip.

Build a dongle The one-page guide

How it compares

What the receiver does that commercial systems do not, as far as we know.

And it can change when a need appears. Its author often adds a feature within a day of a pilot asking, and the code and the board are open, so you can change it yourself. Commercial systems are almost always take it or leave it.

"Not found" means not in the makers' own documents that we read, in October 2026. Tell us if we have missed something.

The Version 1 receiver

Still flying, and still supported. Choose it for a model with servos and no flight controller, or for GPS and vario.

• Teensy 4.0 with one or two radio modules.
• Up to 11 PWM servo outputs (9 on single-radio boards), each with its own frame rate and centre.
• SBUS out, and Rotorflight over a direct link, with telemetry and rates, PIDs and governor from a Version 1 transmitter.
• Optional sensors: volts, barometer (altitude and vario) and GPS.
• Circuit board files and case in the Version 1 repository.

Build one

The receiver is a XIAO ESP32-S3, two radio modules, a regulator and a few capacitors on a small two-sided board.

Questions? Write to Malcolm at mmessiter@gmail.com. He is happy to help.