{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

lecture_2

# lecture_2 - 16.333 Lecture#2 Static Stability Aircraft...

This preview shows pages 1–5. Sign up to view the full content.

16.333: Lecture #2 Static Stability Aircraft Static Stability (longitudinal) Wing/Tail contributions 0

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Fall 2004 16.333 2–1 Static Stability Static stability is all about the initial tendency of a body to return to its equilibrium state after being disturbed To have a statically stable equilibrium point, the vehicle must develop a restoring force/moment to bring it back to the eq. condition Later on we will also deal with dynamic stability , which is concerned with the time history of the motion after the disturbance Can be SS but not DS, but to be DS, must be SS SS is a necessary, but not suﬃcient condition for DS To investigate the static stability of an aircraft, can analyze response to a disturbance in the angle of attack At eq. pt., expect moment about c.g. to be zero C M cg = 0 If then perturb α up, need a restoring moment that pushes nose back down (negative)
Fall 2004 16.333 2–2 Classic analysis: Eq at point B A/C 1 is statically stable Conditions for static stability ∂C M C M = 0; < 0 ∂α C M α note that this requires C M | α 0 > 0 Since C L = C L α ( α α 0 ) with C L α > 0 , then an equivalent condition for SS is that ∂C M < 0 ∂C L

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Fall 2004 16.333 2–3 Basic Aerodynamics i w X cg X ac L w Z cg M ac w D w c.g. FRL w Fuselage Reference Line (FRL) Wing mean chord Take reference point for the wing to be the aerodynamic center (roughly the 1/4 chord point) 1 Consider wing contribution to the pitching moment about the c.g. Assume that wing incidence is i w so that, if α w = α F RL + i w , then α F RL = α w i w With x k measured from the leading edge, the moment is: M cg = ( L w cos α F RL + D w sin α F RL )( x cg x ac ) +( L w sin α F RL D w cos α F RL )( z cg ) + M ac w Assuming that α F RL 1 , M cg ( L w + D w α AF RL )( x cg x ac ) +( L w α F RL D w )( z cg ) + M ac w But the second term contributes very little (drop) 1 The aerodynamic center (AC) is the
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern