As the induced airflow pushes
up on the wing, it also pushes down on the engine, creating no net gain
in lift. Is my line of thinking correct here?

No.

Consider an engine on each side, pointing upwards. Run the engine, and
the plane lifts off like a helicopter.

Now imagine the engines pointing forward, but with a big flap behind the
engines to deflect the air downwards. (for simplicity's sake, no wing
to speak of) The same thing happens, except that there is also some
forward thrust (tether the plane for demo purposes). Retract the flap
and you'll have no lift, but more forward thrust.

The wing acts like the flap. It turns thurst into lift.

Jose
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