What is "Initial Stability"?

[Dougal 165]

I've seen it written in some aircraft specs that, due to the high mounted wing, there is good initial stability.Can some please explain what might be meant by this... How might a high wing aircraft be more stable that a low wing?Thanks

[Murmur 3,941]

>I've seen it written in some aircraft specs that, due to the>high mounted wing, there is good initial stability.>>Can some please explain what might be meant by this... How>might a high wing aircraft be more stable that a low wing?>>Thanks"Initial stability" is not the correct term since it's used for boats, the correct term is "lateral stability", that is the tendency of the aircraft to return from rolling to level flight.When the aircraft has a slip angle, the air flowing around the fuselage is deflected. If the a/c has high wings, the windward wing has an increased angle of attack near the root (due to the upward flow of air meeting the fuselage), while the leeward wing has a decreased angle of attack (due to the downward flow trailing the fuselage). This produces a net rolling moment analogous to the one due to dihedral effect, and therefore increases lateral stability.The opposite happens for a low wing aircraft.Marco

[Tom Allensworth 1,532]

"Initial Stability" is the period of time from the moment I crawl into the cockpit, crank up the engine(s), and start to taxi. From there onward, kiss stability goodbye. :)

[Cessnaflyer 56]

What also helps is that the CG is below the aircraft and it acts as a pendulum keeping the fuselage on the bottom side of the airplane.

[LAdamson 240]

>What also helps is that the CG is below the aircraft and it>acts as a pendulum keeping the fuselage on the bottom side of>the airplane.Yes, I still go for the pendulum/parasol effect; even though many tend to offer numerous and more complicated explanations.Anyway, for those that haven't done it; jump into a Cessna 172 and rock the wing quickly with the yoke and release. It will quickly roll in the direction you swung the yoke, and then swing back to level, or slightly past, then back to level. That's the stability.Now do it in our Van's RV's, and it just stays the bank angle you released the stick. Same with many other aerobatic type airplanes. The Piper Warrior/Archer/Arrow airplanes have quite a noticeable amount of dihedral in their wings to create stability. I just haven't rocked one lately.L.Adamson

[Dougal 165]

Thank you kindly gents.Tom, is that con o sans alcohol?