Yeah, you can maximally lift the weight of the air you're displacing, right? That plane can carry 124000kg. Air is about 1kg/m3 at sea level, so that requires a

Yeah, you can maximally lift the weight of the air you're displacing, right? That plane can carry 124000kg. Air is about 1kg/m3 at sea level, so that requires a balloon of 124000m3 (assuming the balloon and gas weigh nothing). That's a cube of 50x50x50 meters under optimal assumptions.