Makes no difference, other that it would be very difficult for a helicopter to fly in that small an enclosure.
You can easily analyze this with centers of gravity. If you have a closed box (no effects with the outside world other than through the scale it sits on), then anything that does not actively accelerate the center of gravity (CG) makes no difference to the scale. In other words, a helicopter sitting on the bottom, or flying near the top, or moving at a steady speed registers the same to the scale.
When the CG is accelerating there must be a net force on the box, so the scale will read a change. For example when the helicopter takes off and moves to the top of the box the CG of the total box + helicopter accelerates up. This requires an upward force from the scale, so the scale will read heavier than normal while it accelerates up, go back to normal while it moves at a steady speed, go lower than normal while it decelerates to a stop near the top, and finally return to normal while it hovers near the top.