reported by Ondřej Kužel on December 8, 2014

UNIT: Ondřej Kužel, QA Specialist, QA Dept.
TO: Arma 3 Dev-Branch Users
OPSUM: We wish you a pleasant flight: Arma 3's new advanced helicopter flight dynamics.


It's been about four months since our Advanced Flight Model took off. After some initial resonance - and lifted by the upstream of your feedback - we've reached a stable level flight. Pilots have survived, adapted and now it's time to... well, adapt again (I'll explain why later on)! With the release of some significant new features with update 1.36, we'd thought it was high time to share some more information.

First of all, though - to the newbies in our ranks - welcome! Be sure to check out OPREP: Rotorlib Integration in the pocket of the seat in front of you. It introduces the key features of the new Flight Model (FM) and will bring you up to speed quite quickly. With that in mind, we'd like to share what's great about the new FM, explain a little about the journey to full release, and outline just a few of the improvements made over the last few months - thanks in no small part to the splendid feedback of our community.


So, Standard or Advanced? Does it offer anything more than ground collisions, blade strikes, instability, and an even greater chance of rotor-based disaster? I bet my buttons it does. After some initial sniffing and swearing, you'll quickly get the grasp. Constant anticipation, adjustments, one control axis having an impact on others - it will all get under your skin. As a reward, the Advanced Flight Model offers you a completely different level of agility and response. Rapid insertions, tricky maneuvers, aerobatics, autorotations - all of that is now waiting to be mastered.

Moreover, it's a new level of helicopter gameplay. You'll have to think strategically. Manage your load carefully. Different rotor configurations behave differently; each crew member, each rocket in the pod, each liter of jet fuel now plays a role. Wanna haul some extra fuel and ammo? Being greedy won't help if you don't have enough power to lift off (or after you've picked up your comrades in an evac)! But that's just a taster or the new gameplay - the best thing to do is to get in game... and play! However, if you're interested in discovering a bit more about our development, read on.


Behind our Advanced Helicopter FM dwells something called RotorLib: a 3rd-party simulation library from our partners at Real Time Dynamics. This implements a generic mathematical model, which takes care of all the precise simulation of a helicopter (rotors, fuselage, wing surfaces, weight, etc). This FM has a variety of detailed parameters to simulate specific types of helicopters. Together with a professional aircraft designer, Etienne Vandame, these properties were configured by our team (even simulating aerodynamic forces for those helicopters with no real-life equivalent, using aircraft design software).

But simulated data alone isn't enough. We pushed hard to offer up our helicopters for your feedback as soon as they were able to fly, and you've given us a terrific response! Some of you were able to take us into great detail and even gave us professional insights. Admittedly, we were not always able to keep up. Still, we're enormously grateful for your feedback, and we hope the changes we were able to introduce indicate how valuable our cooperation has been. With that in mind, let's take a look at some of the improvements!


First of all, RotorLib itself. During the dev-branching phase - and alongside numerous smaller ones - we received two major updates of the libraries from our partners. Minor tweaks enabled us to, for example, create a savegame with a RLib simulated helicopter. The first major update was about general fidelity and performance. The second brought a simulation retouch to incorporate Vortex Ring State (VRS). Of course, many of us have been pushing for it since back in Take On Helicopters; so, let's take a look at where we're at now.

VRS simulation required a re-adjustment of our helicopters' configuration. We had to proceed carefully and enabled the technology in the Dev-Branch only. That gave as a chance to tune VRS from being quite literally a 'killer feature' into a more realistic and playable piece of the flight model jigsaw. Now it's unleashed for all! At first - despite of what we've said about the FM offering a more 'natural' sense of handling - VRS may be a condition that doesn't come across so intuitively! Watch out for your descent rates, keep calm, and go easy on your collective. Ultimately, enjoy & Adapt!™


Our resident rotorhead, producer Lukáš Miláček, has been closely watching and moderating our Advanced Helicopter FDM Feedback forums thread, turning it all into real action. In cooperation with Etienne, we've been constantly tweaking the helicopters' configuration. The Blackfoot was tamed and doesn't go runaway in higher speeds. The xH-9 family helicopters have turned into great fun machines. The list of tweaks goes on and on, while other elements were added as completely new features.

Rotors, for example, can now be destroyed by a collision or by Felix Baumgarten-sized G-force stresses. We've also added / tuned visual feedback for ground effect, VRS and for reaching / exceeding the limits of the airframe. Our Audio department, too, went rotor-loco, improving helicopter sounds with fresh field recordings and some new sound features (which they seem eager to share more details about it in a future OPREP). Vehicle UI now has improved clarity and helmet mounted displays received some TLC, too. Many of these features can also be enjoyed with Standard FM.


We recognise that everything isn't quite as splendid as it could be. One of the most noted issues - helicopters' tendency to explode when rolled over to a side - is still a valid problem. It's not a deliberate design decision. Just like you, we despair when a skillful autorotation turns into a mass murder just by a tiny mistake. Different concurrent simulations have posed a limitation in collision detections. We are trying to tackle it and our programmers have already gone a couple of extra (air) miles. We don't yet know quite how far there is to go.

Ongoing issues aside, we hope you've enjoyed the cooperation as much as we did. And we hope you like the results! Keep the feedback flowing on our forums and Feedback Tracker. Of course, we'd like to thank you for supporting our continued development by buying the game and the DLCs. But now let's not wait anymore. Get to the choppa! Spin up the blades. Have you already tried the helicopter Support MP game mode? Give it a whirl on one of our 4 dedicated official servers. See how all the new platform updates transform into a pure gameplay. Or hone and prove your mad skillz by chasing the super rare Golden Rotorhead achievement. IAC. We wish you a pleasant flight!

Here are a couple of additional recommendations for fearless AFM pilots:

  • A newcomer? Try the AFM with the new helicopter VR courses under the Learn section and get the Advanced Virtual Pilot achievement.
  • Game helpers allow players to fly the advanced FM with mouse and keyboard (although we would recommend using a joystick for a better experience).
  • The auto-hover helper will still work with the advanced FM, but it will be not as precise as when using the standard FM.
  • Controls in AFM become more sensitive and are set linear. You can modify the sensitivity curves in the controller settings under Configure/Controls.
  • For those who don't own pedals there is the so called "auto-trim" helper, that can assist with pedals and countering torque. You can switch it on under Configure/Game.
  • If the stress damage option is enabled in the difficulty settings, the helicopters' components will have limited durability. If the forces calculated by the FM exceed limits, they may break the rotors and transmission.
  • Even with stress limits disabled, the FM calculations can result in main rotor RPM drop. When main rotor looses RPM it makes aircraft stall and may lead to a crash. There is no helper automation in game that will assist in such situations. Players should watch warning lights and reduce collective input to get the helicopter back to normal flight safe conditions.
  • Did you know that AFM will allow you to easily outmaneuver a pilot flying with the SFM?
  • If you want to keep the conditions equal for everyone on the server you can enforce the AFM using the forceRotorLibSimulation property in the server.cfg (0 - options, 1 - forced on, 2 - forced off)