Fa2004 16.3334-4 Axes But first we need to be a little more specific about which Body Frame we are going use. Several standards 1. Body Axes-X aligned with fuselage nose. Z perpendicular to X in plane of symmetry(down). Y perpendicular to XZ plane, to le rig 2. Wind Axes-X aligned with vc. Z perpendicular to X(pointed down). Y perpendicular to XZ plane, off to the right 3. Stability Axes-X aligned with projection of vc into the fuselage plane of symmetry. Z perpendicular to X(pointed down). Same S(BODY) X-AXIS (STABILITY) BODY X-AXIS Z-AXIS (WIND Advantages to each, but typically use the stability axes In different flight equilibrium conditions, the axes will be oriented differently with respect to the a/c principal axes = need to trans form (rotate) the principal inertia components between the frames When vehicle undergoes motion with respect to the equilibrium Stability Axes remain fixed to airplane as if painted on.Fall 2004 16.333 4–4 Axes • But first we need to be a little more specific about which Body Frame we are going use. Several standards: 1. Body Axes ­ X aligned with fuselage nose. Z perpendicular to X in plane of symmetry (down). Y perpendicular to XZ plane, to the right. 2. Wind Axes ­ X aligned with �vc. Z perpendicular to X (pointed down). Y perpendicular to XZ plane, off to the right. 3. Stability Axes ­ X aligned with projection of �vc into the fuselage plane of symmetry. Z perpendicular to X (pointed down). Y same. R E LATIV E WIND ( ) ( ) ( ) � � B ODY Z-AXIS B ODY Y -AXIS X-AXIS WIND X-AXIS S T AB ILIT Y X-AXIS B ODY • Advantages to each, but typically use the stability axes. – In different flight equilibrium conditions, the axes will be oriented differently with respect to the A/C principal axes ⇒ need to trans￾form (rotate) the principal inertia components between the frames. – When vehicle undergoes motion with respect to the equilibrium, Stability Axes remain fixed to airplane as if painted on