A ground-up helicopter flight model for Arma Reforger. Where the stock game treats a helicopter as a flying car with a spinning prop on top, Rotor Framework actually simulates the rotor — the air flowing through it, the engines and gearbox driving it, the electrical and hydraulic systems that keep it alive, and an autopilot that helps you fly it.
Rotor Framework (RF) is a complete replacement for how helicopters fly in Arma Reforger. Instead of using the game's built-in helicopter handling, it models the aircraft the way a real one works: lift is generated by the rotor blades pushing air, the engines have to actually spool up and produce power, that power runs through a gearbox to the rotor, and the rotor's behaviour is what flies the aircraft.
The result is a helicopter that feels like a machine rather than a vehicle on an invisible rail. It has weight and momentum, it reacts to wind and to your inputs with a bit of lag and follow-through, and it can be flown — or mishandled — in ways the stock helicopters simply can't represent.
It currently powers three aircraft families:
It's built to be cooperative in multiplayer and to play nicely alongside other mods rather than fighting them for control of the aircraft.
New to helicopters? Start with Theory of Operation — A New Pilot's Guide — what the controls actually do, why the aircraft behaves the way it does, and the handful of things that will kill you.
The stock Reforger helicopter model is deliberately simplified — it's an approximation tuned to feel "good enough" and stay predictable. That's a perfectly reasonable design choice, but it means a lot of what makes helicopters interesting (and dangerous) just isn't there. Here's where Rotor Framework diverges:
The rotor is actually simulated. Vanilla applies lift based on your collective input more or less directly. RF calculates the lift each rotor produces from the air actually flowing through it — your speed, your climb or descent rate, air density, blade pitch, and rotor RPM all feed into it. Lift is a result of the rotor's state, not a number read straight off your stick.
Engines and power matter. In vanilla the engine is essentially on or off. In RF the engines spool up, drive the rotor through a gearbox, and have to keep the rotor spinning at the right RPM. Pull too much collective and you can droop the rotor RPM or over-torque the gearbox. There's a real startup sequence rather than an instant-on.
You can break the drivetrain. RF tracks how much torque the gearbox is taking. Yank in more power than the transmission can handle and you accumulate damage; push the rotor past its overspeed limit and it can come apart. None of this exists in the stock model.
Autorotation and settling with power are real. Lose your engine and the rotor keeps turning on the airflow coming up through it — you can autorotate down to a survivable landing if you fly it right. Descend too fast straight down into your own downwash and you can settle with power (vortex ring state), where adding collective makes things worse, just like the real thing. The vanilla model has no equivalent of either.
It handles aircraft vanilla can't. The stock simulation can't properly represent a tandem-rotor aircraft like the Chinook — two main rotors is outside what it was built for. RF models each rotor independently, so tandem, conventional, and other layouts all work.
It's multiplayer-honest and mod-friendly. RF is designed so the pilot and the server both run the same flight model and stay in agreement, which keeps the aircraft smooth for everyone in the server. The server adopts the pilot's flight state while it stays within tolerance and only steps in to correct when it doesn't, and players joining mid-session pick up the aircraft's running state cleanly. Reconciliation is latency- and acceleration-aware and widens its tolerance when the server itself is running behind, so hard manoeuvring and low server FPS don't produce rubber-banding. Controls can be handed between pilot and copilot in flight without the aircraft dropping a beat. It also shares control of the aircraft cooperatively instead of stomping on other physics mods.