• "Wing Drop" describes an uncommanded rapid wing drop, or change in roll angle, that occurs in the heart of the maneuvering flight envelope. During Integrated Test Team flight testing, wing drop was found to occur between 7-12 degrees angle of attack and .7-.95 mach. It was repeatable because it could be expected to occur when flying within this regime; however, it was not "predictable" because of the conditions that caused onset of wing drop and the resulting direction and severity of roll varied. Sometimes the pilot could easily correct the roll with a small bank-angle change; other times, full lateral stick was not enough to "lift" the wing. When this occurred the pilot had to release the stick to allow the aircraft to recover nose low and build airspeed before flying again. Other times the wing drop did not occur.

• In support of program office efforts, a Blue Ribbon Panel including both NASA-Ames and NASA-Langley members conducted an independent review in September 1997. As more flight-testing revealed no easy solutions, in December 1997, a second Blue Ribbon Panel was formed, consisting of many industry and government members. The panels made numerous recommendations. To better understand the flow mechanisms of wing drop, the panel recommended a flight test approach with supporting wind tunnel and Computational Fluid Dynamics solutions. Specifically for the F/A-18 E/F program they advised to "continue the systematic approach of flight-testing to optimize their design so as to minimize buffet and other impacts." The program complied with this recommendation, analyzing and flight testing a variety of potential solutions. Another panel recommendation was that the DoD "initiate a national effort to thoroughly and systematically study the wing drop phenomena" so that future programs could benefit. DOT&E championed this national effort to study wing drop. Accordingly, AIR 4.0, the Assistant Commander for Research and has taken the lead in coordinating efforts both within the services and industry. The F/A-18E/F program office is cooperating fully with the effort.

• A porous wing fold fairing was determined to be the most promising fix for wing drop, and multiple versions were tested to determine the optimum design. A Developmental Test phase included a limited number of test flights with operational test pilot on a chosen configuration to access the acceptability of the solution. Wing drop was found to be greatly reduced but two forms of buffet were manifested. The first was experienced in 1G transonic flight and is analogous to driving on a gravel road. The other occurred at a variety of altitudes and configurations and was associated with varying angle of attack in a turn. Neither was qualitatively assessed to interfere with task accomplishment. Testing of various engineering configurations to alleviate buffet continues to include flight test of a thickened trailing edge flap and improved flight control software.
  

• A dynamic operational test of the aircraft, OT II B, was conducted in two phases. In the first phase, eighteen sorties were flown emphasizing weapons delivery accuracy and limited low-level flights. During this test phase, the single aircraft was equipped with a developmental version of the porous wing fairing. These flights, as well as concurrent developmental test events, suggested that wing drop was controlled to the point that it was called "residual lateral activity." Residual lateral activity involves small, uncommanded changes in wing bank angle that are moderate, correctable and assessed to have little mission impact and no task abandonment.
  
• Phase 2 of OT-IIB comprised 41 flights conducted with two aircraft and focused on tactics employment in the conduct of representative mission profiles. These missions included Dissimilar Air Combat Maneuvering, Fighter Escort, Interdiction, and Close Air Support. Both aircraft flew with the production-design of the porous wing farings and with the most recent flight control software. An expanded envelope afforded the pilots the opportunity to evaluate the aircraft in a wider arena than previously experienced. Preliminary results over a wide, aerodynamic spectrum representative of the tactical environment point to a further decrease in residual lateral activity. Some activity remains but has been termed as more analogous to a wing tremble. Buffet was still present and remains identical to what was experienced in the developmental test phase flights. Again, it did not interfere with task accomplishment but, in some long duration missions, could easily become tiring and distracting. The Integrated Test Team continues to test and has not yet flown all of the recommended fixes and combinations to further reducing buffet.
  
• Along with continued data collection in the air and wind tunnel, solution options will be assessed using a systems engineering approach to determine their impact on key performance parameters such as range, acceleration, and radar cross section. The goal is to maximize the improvements in flying qualities while minimizing the impact on other performance parameters. Any solution will involve tradeoffs.

• Acceleration of the F/A-18E/F is comparable to the F/A-18C aircraft with either the basic F404 or the Enhanced Performance Engine F404 in subsonic and negative-G regimes. However, the F/A-18E/F is slower to accelerate to supersonic speeds in one G flight compared to the F/A-18C. Closely tied to this is the aircraft climb performance. Above 30000 ft, this performance is substandard. A tiger team is still investigating ways to improve aerodynamic performance. The tactical implications will be assessed during OPEVAL.

• Reliability of the F/A-18E/F has been excellent and has received high praise from the test crews. In addition, controls and displays as well as night lighting have received favorable comment.

The F/A-18E/F TEMP, approved by DOT&E in April 1996, is current and being executed. Additionally, the program office completed a Live Fire Alternative Plan that was submitted to Congress by DOT&E.

The F/A-18E/F Live Fire Test program, based on vulnerability analysis, threat analysis, and ballistic testing of components and major subassemblies, is thorough and aggressive. Live Fire testing of the F414 engine indicated that if a blade became separated from a turbine wheel, the blade could penetrate the engine casing and cause damage to other components of the aircraft. The engine casing was redesigned and subsequent tests indicate separated blades will be contained. Fuel ingestion and ballistic tolerance testing have also been conducted on the F-414 with encouraging results in comparison to similar tests of the F-404. Redesign and testing are continuing for the dry bay and engine fire suppression systems. Included among the recommended design improvements: redundant paths in the gas generator ignition circuitry, intervention techniques to protect the gas generator ignition controller from electrical overloads, and revised casing components.

The FA18E/F program is Y2K compliant with the exception of two areas. The first area is the Tactical Mission Planning System (TAMPS). This system supports various phases of mission planning and employment of the Super Hornet as well as other aircraft. It is currently not Y2K compliant but an updated version is planned for release in December 1998. The second area of Y2K noncompliance is the Enhanced Comprehensive Asset Management System (ECAMS) used to track maintenance on the aircraft. It is planned to be replaced by Automated Maintenance Environment (AME) which will be Y2K compliant and in concert with the NALCOMIS Optimized System. AME will be fielded in early CY99.

adequacy of supporting modeling and simulation has been mixed. A challenge to the OT program will be to design a test and evaluation strategy that will be able to determine if the F/A-18E/F is more survivable than the F/A-18C/D-a key requirement of the program. Due to the similarity between the two aircraft, any digital model that attempts to predict comparative survivability in a missile fly-out scenario must be a high-fidelity model that can account for the very dynamic environment (maneuver, IDECM, towed decoy, RCS reduction, etc.). Efforts to improve these predictive models using JMASS architecture will likely not be mature in time to support this program.

T&E Program Management has been superb. The Integrated Test Team conducting the EMD flight program at NAS Patuxent River, MD, consists of test pilots from the prime contractor, Navy system command and Navy OT communities. Maintenance and test support is also provided by a combination of government and contractor personnel. This unique management arrangement provides a very rapid, cooperative systems-approach to problem solving, using all available assets and knowledge while providing great insight with early OT involvement in developmental testing.