You do not have mouse aim, you have mouse joystick. That’s what FRC does. But you can use a mouse to simulate having a flight stick to allow poor eastern european village people like me with questionable desks to play sim.
Videos of me using mouse joystick - it shows on screen (not in replays alas):
The carrier one is before I figured out the rudder pedal analogue, or got comfortable trimming while landing
https://www.youtube.com/watch?v=PoGJPpd6_To
https://www.youtube.com/watch?v=lQxtIcBpwoI
https://www.youtube.com/watch?v=LXl0wUUGqbA
For rudder controls, I have Q & E set up as “Relative controls.” I press Q once, it deflects rudder by ~3% (nonlinearity makes it non-exact) and it stays that way. I press it once again and ~6%. I hold it down hard for full deflection (as demonstrated in the forward slip demonstration). Pressing 2 “Lifts the foot” from the rudder pedal to reset to 0% without “having to step on the other pedal”.
The mouse is basically an approximation of a flight stick (whose main difference is that letting go of it doesn’t make it go back to neutral, I need to press a button to represent letting go of it, and that it’s super flat and different to hold). Keyboard gives me approximation of rudder pedals (QE) and ADWS allows me to keep controlling my plane with rough inputs when holding down C to look around and track my enemies (rather than using a hat control on a flight stick or head tracking). Normally i use C by pulling stick back a little, pressing C and looking around while rolling with A/D to maneuver. It’s very janky and took me a good bit to learn and not just kill myself repeatedly doing it.
I also use the keyboard for flaps, trim and MEC. Occasionally the A/D input also comes in handy for “yanking the stick” hard when I don’t have space to move my mouse as much as it’d be needed if it were a proper stick.
Here’s my control layout:
Now, I’m pretty sure this control set up is a handicap rather than an advantage. I’d love to have real rudder pedals and a proper, stable flightstick and a desk to support it. Even with practice, the rudder controls I set up still feel clunky and imprecise/delayed compared to actual pedals. Like the forward slip landing: my F4U-4 jerked pretty badly as I released the rudder “pedal” while a real one would’ve allowed me to gently lift my foot instead and still get it neutral in a faster timeframe.