McDonnell Douglas F/A-18 Hornet

During flight testing, the snag on the leading edge of the stabilators was filled in, and the gap between the Leading edge extensions (LEX) and the fuselage mostly filled in. The gaps, called the boundary layer air discharge (BLAD) slots, controlled the vortices generated by the LEX and presented clean air to the vertical stabilizers at high angles of attack, but they also generated a great deal of parasitic drag, worsening the problem of the F/A-18's inadequate range. McDonnell filled in 80% of the gap, leaving a small slot to bleed air from the engine intake. This may have contributed to early problems with fatigue cracks appearing on the vertical stabilizers due to extreme aerodynamic loads, resulting in a short grounding in 1984 until the stabilizers were strengthened. Starting in May 1988, a small vertical fence was added to the top of each LEX to broaden the vortices and direct them away from the vertical stabilizers. This also provided a minor increase in controllability as a side effect. F/A-18s of early versions had a problem with insufficient rate of roll, exacerbated by the insufficient wing stiffness, especially with heavy underwing ordnance loads.
The first production F/A-18A flew on 12 April 1980. After a production run of 380 F/A-18As (including the nine assigned to flight systems development), manufacture shifted to the F/A-18C in September 1987.
• Improvements and design changes
In the 1990s, the US Navy faced the need to replace its aging A-6 Intruders, and A-7 Corsair IIs with no replacement in development. To answer this deficiency, the Navy had the F/A-18E/F Super Hornet developed. Despite its designation, it is not an upgrade of the F/A-18 Hornet, but rather, a new, larger airframe using the design concepts of the Hornet. Hornets and Super Hornets will serve complementary roles in the US Navy carrier fleet until the Hornet A-D models are completely replaced by the F-35C Lightning II.