Welcome to our Terms and Definitions Feedback Form!

Just as with every other publisher of rapidly evolving, complex content, occasionally there are things that we can improve upon. Sometimes the reasons for this are technical and sometimes they're not. What makes our materials and system unique is that, thanks to this direct link to our editorial team which you are now using, we can rapidly consider and incorporate your feedback. We hope that you can appreciate that we have this system in place not because our stuff is shoddy, but, rather, because it is good.

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Here is the current term: If below it different substantially compared to how it appears in your app/software, be sure to update your software/app's content prior to using this form.

Stall Speed

Stalls depend only on angle of attack, not airspeed. However, the slower an airplane goes, the more angle of attack it needs to produce lift equal to the aircraft's weight. As the speed slows further, at some point this angle will be equal to the critical (stall) angle of attack. This speed is called the "stall speed". An aircraft flying at its stall speed cannot climb, and an aircraft flying below its stall speed cannot stop descending. Any attempt to do so by increasing angle of attack, without first increasing airspeed, will result in a stall.

The actual stall speed will vary depending on the airplane's weight, altitude, configuration, and vertical and lateral acceleration. Guidelines for the case of zero acceleration are provided by the following V speeds:

V_S: The computed stalling speed with flaps retracted at design speed. Often has the same value as _S1.
V_S0: The stall speed in landing configuration (full flaps, landing gear down, spoilers retracted).
V_S1: The stall speed in a "clean" configuration (flaps, landing gear and spoilers all retracted as far as possible).
V_SR: Reference stall speed.
V_SR0: Reference stall speed in the landing configuration.
V_SR1: Reference stall speed in the clean configuration.
V_SW: Speed at which onset of natural or artificial stall warning occurs.

On an airspeed indicator, the bottom of the white arc indicates v_S0 at maximum weight, while the bottom of the green arc indicates V_S1 at maximum weight. While an aircraft's v_S speed is computed by design, its v_S0 and v_S1 speeds must be demonstrated empirically by flight testing.

source: Wikitionary / Wikipedia and Related Sources (Edited)

Please do not use this form to tell us that the definition you saw doesn't necessarily match the context where you saw it. We use an automated keyword-based system to match the tens of thousands of definitions in our glossaries with our material. Sometimes, when a term has more than one meaning or use or when an abbreviation might stand for more than one thing or resemble a 'normal' word, this results in a definition for a term being shown that doesn't necessarily match the context. Please do not report such issues here. Rather, please use your best judgment to evaluate whether such definitions apply to what you're reading. If the answer is 'no' but nevertheless you feel the term doen't have a good definition in our system but should, please go back and find the 'suggest a term' link in the app. Thanks!

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