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Fixed wing flight model improvement considerations
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*I will explain the problem, how it should work, and the solution.


The main problem is that Fixed-Wing Aircraft do not produce enough lift to fly like a normal aircraft. For example, say the aircraft has ~ 33.8 kN of mass (The L-39). That means when at equilibrium, this aircraft will produce ~ 33.8 kN of lift. This is currently simulated to a short extent. How I think this is currently simulated is that the speed of the aircraft (When parallel to the ground) determines the vertical speed of the aircraft. This is the main problem. An aircraft produces lift upwards in respect to the aircraft's center of gravity, not to the ground. Yet in Arma lift is produced in respect to the ground, not the aircraft. This is quite annoying when attempting to preform normally easy maneuvers as the aircraft will not change direction when rolled. When the wings are at a 45° degree angle in relation to the ground (for the L-39) the aircraft should rotate, say, 15° per second? Keep in mind that the aircraft will lose some altitude due to the Knife's Edge Effect.

How it should work:

• Amount of lift produced is linked to the airspeed of the aircraft. To find exactly how much, find the Lift Coefficient. This is accomplished by a little algebra. It isn't as complicated as you may think, just get a calculator and some paper.
• Lift is produced vertically in respect to the aircraft's center of gravity. Yes, if you roll an aircraft sideways it will change direction (though it will decrease altitude)
• Aircraft fuselage will be affected by airflow (Like a throwing dart or an arrow, or an aircraft)
• All ailerons, elevators, and rudders will affect the moment, both vertically and horizontally, of the aircraft around its center of gravity. (Unless they get blown off, of course >:D)
• Aircraft will produce no lift in relation to the ground when aircraft is rolled to an angle of 90° in relation to the ground. Also known as the Knife's Edge Effect. It will still produce lift, but not upwards.
• Flaps / Airbrakes will increase drag and lift, while decreasing speed, allowing for slower flight speeds.
• Aircraft will be in equilibrium at its takeoff speed.


Ok, so how can we do this? Well, I'm not so keen on the PhysX programming or config files,
but this should work pretty well.

•Lift: Make the aircraft produce exactly enough lift to fly (Neither rising nor falling) at its cruising speed, or "takeoff speed" (As stated above, use algebra to find it). Then just go up the ladder. Use the same formula, and replace the takeoff speed with the new speed (maybe make a graph to visualize it better). Then when you lower / raise flaps, just increase the lift produced at the different speeds, thus lowering the takeoff speed of the aircraft (Plus you'll have a damn good start at improving the flight model). The amount of drag that is increased via flaps really won't matter, but air brakes will.

•Roll, Pitch, & Yaw: No need to simulate tail fin lift or anything (you still have to use the formula to find the forces produced when in use). Calculate the amount of lift the Elevator/Aileron/Rudder produces when used, and convert that into the speed of the moment affecting the fuselage (In other words how fast the plane is rotated up/down & left/right). Then when you pull the stick back, the plane will rotate upwards at that speed. Or when you push the stick left, the plane will roll left at that speed, and the plane will turn left due to the lift produced by the wings. It will also lose altitude due to the Knife's Edge Effect.

Hopefully now we would have a much improved, realistic flight model! {F23468}


Legacy ID
Steps To Reproduce

Yeah. Just fly some fixed-wing aircraft in Arma and then play some DCS. Maybe get a flight lesson, I don't know.

Event Timeline

gutsnav edited Steps To Reproduce. (Show Details)Mar 16 2014, 4:39 AM
gutsnav edited Additional Information. (Show Details)
gutsnav set Category to Engine.
gutsnav set Reproducibility to Always.
gutsnav set Severity to None.
gutsnav set Resolution to Open.
gutsnav set Legacy ID to 2949100779.May 7 2016, 6:11 PM
izaiak added a subscriber: izaiak.May 7 2016, 6:11 PM

This is a known issue, but one I would definitely would like to see fixed. And well written for the people that don't know what's going on.

Upvoted, would be better when some more/bigger planes would be added to Arma 3 in the future.

hladas added a subscriber: hladas.May 7 2016, 6:11 PM