The empennage is of metal and composite construction, with twin aluminium/composite material honeycomb structure vertical stabilizers with boron-composite skin, resulting in an exceptionally thin tailplane and rudders. Composite horizontal all-moving tails outboard of the vertical stabilizers move independently to provide roll control in some flight maneuvers. The F-15 has a spine-mounted air brake and retractable tricycle landing gear. It is powered by two Pratt & Whitney F100 axial compressor turbofan engines with afterburners, mounted side-by-side in the fuselage and fed by rectangular inlets with variable intake ramps. The cockpit is mounted high in the forward fuselage with a one-piece windscreen and large canopy for increased visibility and a 360° field of view for the pilot. The airframe began to incorporate advanced superplastically formed titanium components in the 1980s.