4 forces act on the aircraft relative to the earth. Lets call them weight, lift, drag and thrust. When one of the opposing forces exceeds the other an acceleration is produced. The engines are normally thought to provide thrust to equal or overcome drag, but they may (or may not) also provide an element of lift. The wings provide lift and various forms of drag. Weight can contribute to drag or to thrust. And so it goes on. The greatest lift would be produced when the product of mass and vertical acceleration is greatest (probably on rotation in a normal airliner flight).
Simples!
Except that these forces are usually referred to relative to aircraft datums, so lift is at its maximum during a max-g avoiding action turn shortly after acceleration after take-off?
