Excellent laboratory.

Cuts the frustum and the auxiliary power unit system. 4-16 4. ORBITER SYSTEMS 4. ORBITER SYSTEMS Propulsion ORBITAL MANEUVERING SYSTEM TRUSS BEAM GRAPHITE/EPOXY FRAMES INTEGRALLY CROSS BRACE — REMOVABLE MACHINED ALUMINUM SKIN-STRINGER PANELS * WELDED CONSTRUCTION * RIVETED SKIN/STRINGER/FRAME STRUCTURE UPPER WINDOW FRAMES HAT SECTION STIFFENED SKINS MACHINED WINDOW PANELS NOSE LANDING GEAR AND NOSE LANDING GEAR AND ACTUATOR NOSE.