I need help on Battlefield 3 jets multiplayer!?

Afterburner... does not make your turns sharper.. the rule is...

Lower airspeed = lower turn radius... *TO A POINT.* Slowing down WILL help you make sharp turns, but only down to a certain airspeed, where below that will make it sluggish....

I find that 300 knots and around is best for F35s and probably most other aircraft. Just remember don't go below that speed and you'll find your turning radius decreases (you turn faster...) give yourself time to play around with it, maybe on an empty serv. And you do NOT want to use afterburner -NO NO NO- on turns, only in straight flight.

TL;DR / WTF version: Don't use afterburner with turns, when turning good to slow down, but don't go below 300. That'll help with turns faster

The Afterburner makes turning harder. All it does is make your jet move faster and makes sharp turning harder. There are some pretty beastly jet fliers out there though so be mind full of that. Make sure you have your afterburner off and don't go to 3rd person when tailing someone. When people do sharp turns it's usually when they're in 1st person and just turn like a madman if you know what I'm saying. Just give it more and more practice and soon you will figure out ways of countering this.