If I was in an elevator in a sky-scraper and the cable broke, I would free fall and feel weightless until hitting the ground. When I cause a stall on an airplane (power-ff) and the wings stop producing lift, why doesn't the same effect occur?
If the cables break on an elevator (and the safety brakes fail), you won't be in true freefall. You'll still have friction from wind resistance, from the guide rollers on the rails, etc. The same is true in an airplane. Even if you're falling straight down, you'll still have wind resistance.
In addition, lift doesn't just drop straight to zero when the wing stalls (no matter what it might feel like to the pilot). Here's the lift-to-angle diagram for a typical wing:
This wing stalls at about 16° AoA. But notice that the coefficient of lift doesn't simply drop to zero, it just starts descending at that point. So even in a stall, the wings are still generating some lift, just not enough to overcome the weight of the plane.
Is a “stalled” aircraft free-falling?
If I was in an elevator in a sky-scraper, and the cable broke, I would free fall and feel weightless (until hitting the ground of course). When I stall an airplane(power-off) and the wings stop producing lift, why doesn't the same effect occur?
Because in a stall, the aerodynamic force component acting against the direction of the weight vector is not actually zero. In fact, after a very short time it becomes equal to the weight vector, thus yielding a steady-state situation in the vertical plane. Lift and drag, as conventionally defined, both contribute to this aerodynamic force component; lift is by no means zero even in stalled flight. In a stall, you are definitely not free-falling. You are just flying along a very poor glide ratio or descent ratio. After the first few seconds, you are no longer accelerating. An aerodynamic force exists that not only limits the rate of downward acceleration, but also yields a specific downward terminal velocity, as well as as a specific forward speed.
A stall is not a free-fall. It is a loss of laminar airflow over the wing, resulting in a loss of lift. The response to a stall is to stop the (usual) roll induced by one wing stalling before the other. Then drop the nose - most aircraft will do this by design - until you achieve a flyable speed with proper airflow over the wing. The problem here is that you may not have enough altitude to reach that speed >> crash. I once stalled and dropped from over 25000 (not looking at altimeter) to under 12000 before I had enough airspeed to pull up. With the resulting pucker factor I bottomed out at around 7000 ft.
Speaking as a commercial pilot, pilot instructor and skydiver I think I can answer this.
An aircraft has a centre of pressure, which is the lift vector that comes out of the wing and opposes the weight. As you increase the angle of attack of the wing, up to around 16 degrees angle of attack, the centre of pressure (lift) moves slowly forward. When you stall, the boundary layer which is the area of low pressure air sucking the wing upwards, rips off and the centre of pressure moves rearwards, behind the centre of gravity. This drops the nose of the aircraft. The drop of the nose reduces the angle of attack and the wings start to fly again.
Even if you hold the aircraft in a stall at the buffet, the wing will still drop and attempt to fly again repeatedly. So, you're never in freefall, which would assume terminal velocity, you're just pitching up and down as you move forwards in the stall.
Freefall, as a skydiver, implies no forward movement and no lift, even though many skydiving diciplines do involve both such as tracking, wingsuiting and even formation, where you de-arch to slow yourself down and rise relative to others.