Vs: Stall speed or minimum steady flight speed for which the aircraft is still controllable

Vs0: Stall speed or minimum flight speed in landing configuration.

Vs1: Stall speed or minimum steady flight speed for which the aircraft is still controllable in a specific configuration]1

How is Vs different from Vso or Vs1? Is it safe to assume Vs is a generic term involving both Vso and Vs1?


VS is the generic term. However, since stall speed varies depending upon how the aircraft is configured (in particular the flaps), we break that down into VS0 for landing config and VS1 for cruise config. In theory, we should list the stall speed for every possible configuration, but it's generally sufficient to list just those two because all others should be somewhere in between.

  • $\begingroup$ This is a good answer. If you get a moment, could you refine a little why "in a specific configuration" maps to "cruise config"? Is this canonically always the case, or does this vary from designer to designer? $\endgroup$ Jul 8 '21 at 14:19
  • $\begingroup$ @KennSebesta I’m not aware of any variance, and nobody has corrected me in 2.5 years. Few pilots will care about exact stall speeds for any configuration other than minimum drag, aka “clean”, since that’s where we spend most of our flight time, and landing, since that’s where we are flying slowest and thus at greatest risk of stall. $\endgroup$
    – StephenS
    Jul 8 '21 at 20:37
  • $\begingroup$ There's one more scenario where some of us care: studying for the FAA written. :D $\endgroup$ Jul 9 '21 at 0:04

VS0 and VS1 definition from Cessna 172 POH

VS0 and VS1 per Cessna 172 S POH

VS1 is most front C.G, flaps up with max weight (2550 lbs)

  • $\begingroup$ To help users that can't read/visualize the image, would you mind describing the content in words? $\endgroup$
    – Federico
    Jul 29 '21 at 21:05

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