Difference Vsr <-> Vs

[Ischicopter]

Hi folks,

can anyone explain the difference between Vsr (reference stall speed) and Vs?

I understand Vsr is used for CS-25 aircraft and Vs is used for CS-23 aircraft. Still, I wonder why? They are both referring to the CAS at CLmax so there must be another definition for it.

Any help will be appreciated. Thanks!

Cheers.

[Dofi27]

I think you are wrong about Vs. All the speed in any poh or checklist are TAS speeds.

[Genghis the Engineer]

Originally Posted by Dofi27

I think you are wrong about Vs. All the speed in any poh or checklist are TAS speeds.

Nonsense.

Some of the older Cessnas and a few other aeroplanes of the same vintage give speeds in CAS.

All others, and certainly anything build post about 1970 gives all speeds in IAS.

Operating speeds are never given in TAS.

Ischicopter, there are numerous reference and actual stall speeds, which may have various abbreviations depending upon aeroplane weight, configuration and class. Vs is usually the stall speed in the current configuration, other abbreviations may be used to define the stall speeds at particular flap/gear settings, often for reference at MTOW, etc. Don't go looking for universal rules about these abbreviations, you won't find them.

A reference stall speed may be used in some aeroplanes - particularly but not only part 25 aeroplanes - to provide a reference for determination of 1.2Vs on climb-out, 1.3Vs on approach, etc. How it's defined will depend upon the aeroplane.

G

[keith williams]

Vs is approximately 94% of what most people would consider to be the "common sense definition" of stall speed.

Vsr is essentially the 1g stall speed.

The above comments probably sound like nonsense, but hopefully the following link may help.

http://www.captainpilot.com/files/B7...%20Warning.pdf