12 / 20

The transonic effect develops...

  • A

    Above MCRIT.

  • B

    Below MCRIT.

  • C

    Above MFS.

  • D

    Above M0.4.

Refer to figure.

Figure shows the flow speed ranges with their approximate Mach number values, where:

  • MFS (Free Stream Mach number) is the Mach number of the flow sufficiently remote from a blade to be unaffected by it.
  • ML (Local Mach number) is the actual speed of the flow over a surface. When a blade flies at a certain MFS the flow over it is accelerated in some places and slowed down in others.
  • The transonic speed region is developed above MCRIT. The blade tips of some high-speed helicopters will be operating in the transonic region. At and above MCRIT a normal shockwave will form over the upper surface of the blade.

Your Notes (not visible to others)



This question has appeared on the real examination, you can find the related countries below.

  • Austro Control