HIGH SPEED FLIGHT

#19. What is the purpose of vortex generators in transonic flight?

• ATo energies boundary layer, in order to prevent it spreading outward on swept wing aircraft.
• BTo prevent the formation of shock waves on the upper surface of the wing.
• CTo reduce the effects of shock induced boundary layer separation.
• DTo slow down the boundary layer, to delay the formation of shock waves.

#1. When an aircraft is flying at supersonic speed, in what area will the pressure disturbances caused by its motion be felt?

• AWithin the mach cone.
• BIn front of the normal shock wave.
• CIn front of the oblique shock wave.
• DIn front of the mach cone.

#2. What happens to the location of the centre of pressure as an aerofoil accelerates to M CRIT?

• AIt moves backwards as pitch is reduced to maintain constant lift then moves forward as the first shock wave forms on the upper surface of the wing.
• BIt moves towards the mid chord position due to the effects of the upper surface shock wave.
• CIt moves slowly backwards as pitch angle is reduced to maintain a constant lift force with increasing airspeed, then forwards as the first shock waves form.
• DIt remains stationary due to the balancing effects of changing pitch angle and shock wave formation.