SME
Flight Mechanics, Stability & Control · Problem type
Stable or not from the Cₘ–α line
Use this for “An airplane has Cₘ₀ = 0.05 and Cmα = −0.01 per degree. Is it stable, and does it trim at positive lift?”
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Is the airplane stable, and where does it trim?
Tap a card, then tap its group.
Read the sign of the slope Cmα first, then the sign of Cₘ₀.
Assumptions
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α is measured from the zero-lift line, so positive α means positive lift.
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The airplane trims where Cₘ = 0, at α = −Cₘ₀ ÷ Cmα.
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Static stability needs Cmα < 0, the same as the CG ahead of the neutral point.
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