A small drone has two identical rectangular wings, each of area 0.80m2. When it moves forward, the average speed of the airstream just above each wing is 25ms−1, while that below the wing is 15ms−1. Take the density of air to be 1.2kgm−3 and g=9.8ms−2.
(i) Calculate the magnitude of the pressure difference between the lower and upper surfaces of a wing.
(ii) Hence find the total upward force acting on the drone due to both wings.
(iii) The mass of the drone (including its payload) is 12kg. State, with reason, whether the drone will rise, fall or stay in level flight under the above conditions.