A single-seater glider of mass 250kg has a total wing area of 16m2. During take-off, the speed of the air relative to the lower surface of the wing is 10ms−1. Assume the density of air is 1.2kgm−3 and g=9.8ms−2.
(i) Write the condition that must be satisfied by the aerodynamic force on the wings for the glider to just lift off the ground.
(ii) Calculate the minimum speed of the airstream over the upper surface of the wing that will enable the glider to take off.
(iii) Comment briefly on how a head-wind of 5ms−1 blowing opposite to the glider’s motion would affect the numerical value obtained in part (ii).