Page 1 of 1

Increasing helicopter speed without altering their aerodynamic properties

Posted: Fri Mar 30, 2018 9:40 am
by CharlotteLabyrinth
After having a conversation with several UA modders (I appreciate your contacts, and meanwhile I apologise about the constantly delayed replies) perhaps it's finally time to write something about this topic...


When modifying helicopter physics in UA, especially when increasing their velocity to make them fly faster, it is quite a common sight to encounter that the helicopters are usually flying very weirdly and awkwardly from the results of speed increase.

There is a small modding trick to bypass this restrictive nature of helicopter aerodynamics, and make helicopters fly faster without severely damaging their intrinsic, unique kinematic properties.

The secret is to only decrease the 'airconst' values of the helicopters, whilst preserving all the other physical properties of the helicopters remain unchanged. It is because in Urban Assault engine, the angle of attack for a helicopter is strictly determined by the mass-force relationships, regardless of airconst values.


The airconst in Urban Assault represents the drag coefficient of the objects at its core. However, since it is also a rather complex parameter that is responsible for implementing the other diverse range of physics elements, changing it will also subtly affect miscellaneous kinematic properties of the units as well. Specifically, it can have a substantial impact on the behaviours and performances of the AI-controlled helicopters.

With less drag force applied, the helicopters will also possess the increased lift coefficient which allows them to gain altitude more quickly as well. But the degrees of downward deflection during the horizontal thrust will remain identical, effectively nullifying the contingent instability caused by the increased lift generation capacity.

But I will not go further into explaining all the unnecessary details about the comprehensive functions of each parameter here in the interest of saving time.


On the contrary, there is an undesirable by-product effect from the decreased airconst. Lower drag coefficient values cause detrimental effects for AI-controlled helicopters when adjusting yaw angles to redirect their headings towards the targets. Which prevent them from performing effective rudder controls while en route to the targets at full speed.

It is because the helicopter AI is designed to be very sensitive at maintaining their adherence to the height levels, which are relative to the elevations of sectors they are currently situated at.

AI helicopters cannot adapt themselves effectively during the course of flight at faster speed, due to their relatively complicated flight mechanics design and AI algorithms, when compared to the AIs for the other types of vehicles present in the game.

This does not apply to the player-controlled helicopters as players are not bound to any height restrictions during the gameplay except the flight ceiling (which is calculated as 1600 * 0.8 = 1280). And most importantly, humans can sufficiently adapt to any dynamic alterations without problems.


This information may not be very useful, but I thought it would be better to share this modding trick. Hopefully it will be helpful for some modders who want to increase the speed of helicopters without sacrificing their original aerodynamic properties greatly.