Live Telemetry
The Live Telemetry page (https://rotorlab.app/fc, also reachable at /live) reads real telemetry from a flight controller directly in your browser, with nothing to install. It speaks both ArduPilot (MAVLink v1 and v2) and Betaflight or INAV (MSP), decodes heartbeat, attitude, battery, GPS, and VFR data, and shows arm state, flight mode, and link health as they change.
Reach for it when you want to watch an aircraft live on the bench or in the field, record a flight for later replay, or compare a real flight against what RotorLab predicted for one of your builds.
Paid add-on
The live flight-controller link is a gated feature. If your plan does not include it, the page shows a "Live features not enabled" overlay with a Go to add-ons button that takes you to the Add-ons section of your Account page. See Plans and billing.
Connect a flight controller#
At the top of the page, pick the Firmware (ArduPilot (MAVLink) or Betaflight / INAV (MSP)) and the Connection, then press Connect. There are three live connection paths, plus a replay option:
| Connection | How it works | Requirements |
|---|---|---|
| USB (Web Serial) | Plug the board in, pick the serial port and Baud (115200, 57600, 921600, or 230400). | Chrome or Edge on desktop. |
| Network (WebSocket) | Point the WebSocket URL field at a raw-MAVLink WebSocket bridge on your LAN, for example wss://drone.local:5760. | When the page is served over HTTPS the browser blocks insecure ws://, so the bridge must use wss://. |
| RotorLab Cloud relay | Read a drone anywhere over the internet through a small agent that dials out to the RotorLab server. Pick the Channel and watch the Drone agent pill show whether the agent is online. | An API key and the relay agent, covered in Cloud relay and the agent. |
| Replay a recording | Load a .rlog recording file and play it back through the same cockpit. | A recording made on this page. |
If no serial device is selected, or the WebSocket bridge cannot be reached, the page explains what went wrong in a message box under the connection row. Press Disconnect to end the session. If the device is unplugged or the stream ends, the page reports "Connection lost" and you can press Connect to reconnect.
Privacy#
Nothing from the USB or LAN paths leaves your machine: the browser decodes the byte stream locally. The cloud relay path necessarily passes the raw stream through the RotorLab server, keyed to your account.
What the cockpit shows#
Once connected, the instrument panel appears:
- Attitude & heading: an artificial horizon with a pitch ladder and roll scale, a heading rose with a numeric heading readout, a battery gauge (voltage and remaining percentage, estimated from cell count when the firmware does not report it), a throttle gauge, and small tiles for altitude (m) and groundspeed (m/s). A status tag on the horizon shows No link, Armed, or Disarmed, with the current flight mode.
- Link: firmware, vehicle or version, armed state, flight mode, and link age (seconds since the last message).
- Power: battery voltage (V), current draw (A), remaining (%), and throttle (%).
- Attitude & flight: roll, pitch, and yaw (degrees), airspeed and groundspeed (m/s), and altitude (m).
- GPS: fix type (from No GPS through 2D, 3D, DGPS, RTK float, and RTK fixed) and satellite count.
A counter at the top right shows how many messages and kilobytes have arrived, so you can confirm data is flowing.
Record and replay#
Press Record while connected to capture the incoming byte stream exactly as it arrives. A recording is held in memory and auto-stops at a 20-minute or 48 MB limit, whichever comes first, with the running time and size shown next to the button. When you stop, two buttons appear:
- Download saves the recording to a
.rlogfile on your machine. - Save to my account stores it in your RotorLab account. Saved recordings appear in the My recordings card with their duration, size, and date, along with your storage usage and retention period. Each row has Replay, Download, and Delete buttons.
To replay, switch Connection to Replay a recording and choose a file (up to 128 MB), or press Replay on a saved recording. Playback controls include play and pause, stop, 10-second skips in either direction, a seek bar, and 0.5x, 1x, 2x, and 4x speeds. Seeking rebuilds the cockpit state from the start of the recording, so the instruments always show the aircraft exactly as it was at that moment.
Flight summary and build comparison#
While data flows (live, recorded, or replayed), the Flight summary card accumulates averages: flight time, average and peak current, average and minimum voltage, estimated mAh used, average throttle, average groundspeed, and maximum altitude.
Use Compare against a build to pick a saved build from your library. The page runs the model for that build and shows a table of predicted versus measured values with differences: hover current draw, endurance versus flight time, nominal pack voltage, and pack energy versus energy used. Large differences show where the model and the aircraft diverge, which is exactly what Live Calibration corrects.