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Fuselage 73
αe = αfus − αzl, where αzl is the angle of zero lift; in reverse flow (|αe| > 90), αe ← αe − 180 signαe. Let
αmax be the angle-of-attack increment (above or below zero lift angle) for maximum lift. If |αe| ≤αmax
and otherwise
CL = CLααe
CM = CM0 + CMααe
π/2 −|αe|
CL = CLααmaxsignαe
π/2 −|αmax|
π/2 −|αe|
CM =(CM0 + CMααmaxsignαe)
π/2 −|αmax|
for zero lift and moment at 90 degree angle-of-attack. In sideward flight, these coefficients are zero.
Then L = qSwetCL and M = qSwetℓfusCM are the lift and pitch moment.
9-3.3 Side Force and Yaw Moment
The fuselage side force and yaw moment are defined in fixed form (Y/q and N/q), or scaled form
(CY and CN, based on the fuselage wetted area and fuselage length). The effective sideslip angle is
βe = βfus −βzy, where βzy is the angle of zero side force; in reverse flow (|βe| > 90), βe ← βe −180 signβe.
Let βmax be the sideslip-angle increment (above or below zero side-force angle) for maximum side force.
If |βe| ≤βmax
and otherwise
CY = CNββe
CN = CN0 + CNββe
π/2 −|βe|
CY = CYββmaxsignβe
π/2 −|βmax|
π/2 −|βe|
CN =(CN0 + CNββmaxsignβe)
π/2 −|βmax|
for zero side force and yaw moment at 90 degree sideslip angle. Then Y = qSwetCY and N = qSwetℓfusCN
are the side force and yaw moment. The roll moment is zero.
9–4 Weights
The fuselage group consists of the basic structure; wing and rotor fold/retraction; tail fold/tilt; and
marinization, pressurization, and crashworthiness structure.