In case a plane stalls, what should stall first, the tip or the root of the Wing?
Why?

Question

Satya · Accepted Answer

It is preferable for the wing root to stall first. If the wingtip stalls before the root,
the disrupted airflow near the wingtip can reduce aileron effectiveness to such a
extent that it may be impossible to control the airplane about its longitudinal axis.
When an aircraft stalls at the root first, it means there’s enough airflow over the
tips of your wings to prevent any rapid rolling motion during a stall, which makes
the airplane more stable. It also makes your plane more resistant to entering a
spin.

Phil Sweet · Answer

It depends on wing geometry. You need to look at the aerodynamic center of the wing, which is the center of effort for perturbation forces. The center of lift (unstalled) will usually be well forward of the aerodynamic center. As Cl increases, it is desirable to have the center of lift shift aft. This produces speed stability by lowering the nose, thus gaining speed and restoring the original Cl. This is a static stability condition - it says nothing about how the pertubation gets damped.
At local incipient stall, the local drag goes up and the local lift drops precipitously. That lost lift will have to be picked up by the rest of the wing.
In a swept back wing, if the root stalls first, the lift lost is forward of the lift that replaces it, shifting the center of lift aft.
In a swept forward wing, if the tip stalls first, the lift lost is forward of the lift that replaces it, shifting the center of lift aft.
Here's a doc on the stall characteristics of a flat swept-forward wing which naturally begins to stall at the root. - naca-tn-1797 A Study of Stall Phenomena on a 45° Sweot Forward Wing.pdf {I can spell swept, but whoever scanned and converted it couldn't ;)}

In case a plane stalls, what should stall first, the tip or the root of the Wing? Why?

2 Answers

Add your own answers!

Ask a Question