What does flight assist do? Is there any reason to disable it?
Flight assist allows you to fly your ship in a way that makes playing the game enjoyable, without having to try to press 27 buttons at the same time.
Basically Flight assist allows you to fly your spaceship as though you were in an athmosphere, e.g. if you stop accellerating it will slow your ship down, rather than continue on forever as would happen with a rocket.
Many players turn off flight assist for short periods of time during combat, or to gain stealthy entry to a space station. When flight assist is off you can accelerate away from something and shut off your engine, you will then continue to float in that direction,but with very little heat etc. With flight assist on, once you stop accelerating in that direction, you stop.
There are loads of videos showing players using flight assist off to great effect
AocJJones comparing Flight Assist (FA) On to atmospheric flight gets part of the basic idea, but doesn't quite get it for me...
Flight Assist Off doesn't necessarily require a HOTAS setup, but it really does require that you have easy access to controls for all six degrees of motion. A dual-stick config would probably be ideal.
Flight Assist Off is partially a "hard mode", but it also enables some useful things. Mostly it's something that it's handy to be able to use now and then, but you'll mostly want to leave it off.
In Elite: Dangerous, your ship follows a basic Newtonian physics model, with the exceptions of an upper speed limit (based on your ship/engine and power distribution settings) and an upper rotation (pitch/yaw/roll) rate limit. Your speed and rotation limits are different in different directions.
Flight Assist On automatically keeps your ship and your direction of travel aligned, cancels out any rotation to match the current stick setting, automatically cancels your velocity to match your current throttle setting and puts a lower speed limit on thrust in directions other than forward.
Another way to put it is that with Flight Assist On, all of your controls are controlling the speed, but with Flight Assist Off, all of your controls directly control thrust.
With flight assist off, once you start a particular movement with a thrust (whether forward/backward, vertical, lateral or one of your rotational axes), to stop it you have to counter with an equal and opposite thrust.
With Flight Assist On, when you want to pitch up, you pull back on the stick (or move the mouse or push a button) until you've pitched as far as you want, then you let go and your ship stops pitching. With Flight Assist Off, when you want to pitch up, you pull back on the stick, let go, wait until you've nearly pitched how much you want, then push forward on the stick the same distance and time as you originally pushed forward. If you're moving at the time, Flight Assist On will always leave you moving in the direction you're pointed. With Flight Assist Off, you have to do some further work to change your direction of travel to match the direction you're pointed.
Basically, with Flight Assist off, your ship slips and slides around, and you have to be careful not to get into an uncontrollable tumble.
Here's a few useful things you can do with flight assist off:
- Boost, flip over, and fly backwards away from an opponent at full speed. You can fly backwards with FA on, but you won't be able to travel in a straight line, you'll have to stop entirely at some point, and you won't be able to travel backwards as fast.
- Strafe (vertical or lateral thrust) faster. You can still fly sideways or vertically with FA on, but not as fast as with FA off, and not with quite as much control.
- Get an intentional persistent roll/yaw/thrust combo that puts you into a corkscrew. This makes it difficult for an enemy to target you while you flee, and gives you a chance to look at one of your panels to do something else for a second, without taking too much fire.
- Drift into a station with all your systems off. Very tricky, but possible with FA off. Handy for smuggling.
Here's a useful video series for better understanding how to use Flight Assist Off:
And here's a single video from one of the recognized Flight Assist Off masters, about how to use FA Off:
And here's a more entertaining video, from an earlier beta, of using FA Off to help with sneaking past station authorities (smuggling):