Someone asked me a while ago how aeroplanes can fly upside down. After all, the wings normally ‘suck’ the plane upwards. So if you fly upside down then surely they suck the plane down to the ground?
The trick is that you don’t just flip the plane over and try to fly horizontally – if you did that, you would get sucked down. Instead, you also point the nose a little bit up towards the sky so that your wings are passing through the air at the same angle as they would do in normal flight (somewhere between zero and fifteen degrees).
Of course, that’s all just theoryschmeery until you see someone actually doing it for real. Awesome.