By speed control( needed upward force) of fans the drone could be take off or take down as weight of drone all ways acting downward. Though negative force (downward) could be obtained by changing direction of rotation of motors as would forced air upward ………
If the motor is inverted but the propeller is not inverted, it still forces the drone upwards through downward air forces acting from the propeller when the motor drives.
If the motor is inverted but the propeller is not inverted, it still forces the drone upwards through downward air forces acting from the propeller when the motor drives.
If the motor is inverted but the propeller is not inverted, it still forces the drone upwards through downward air forces acting from the propeller when the motor drives.