The turbulent drag is ____ to the laminar drag.
A. 2 to 4 times
B. 3 to 5 times
C. 4 to 6 times
D. 5 to 7 times
查看答案
Which of the following is wrong about the vortex generator? ____.
A. Its shape looks like a small triangular wing panel.
B. Can suppress the airflow separation and reduce the drag.
Can enhance the lift of the wing.
D. Placed on engine nacelles and can suppress the airflow separation of nacelle.
The vortex lift generated by the leading-edge vortex can reach ____ of the total lift.
A. More than 10%
B. More than 20%
C. More than 30%
D. More than 40%
Which of following belongs to passive control in the noise control of aircraft? ____.
Adopting fairings
Blowing control
C. Aspirating control
D. Plasma micro jet.
The engine suitable for hypersonic vehicles is ____.
A. Turbojet
B. Fanjet
C. Propjet
D. Ramjet
微信支付 
支付宝支付