While taking off, the net external force acting on an airplane during the ground roll segment can be assumed to be constant. The airplane starts from rest. S_LO and V_LO are the ground roll distance and the lift-off speed, respectively. αV_LO (α>0) denotes the airplane speed at 0.5 S_LO. Neglecting changes in the airplane mass during the ground roll segment, the value of α is ______ (rounded off to two decimal places).