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Aviation History
1993
1993 - 0030.PDF
approach angle (3.5° instead of 3.75°), while still maintaining adequate "hook to ramp" clearance, it also gives students a slightly larger margin for error in their approach. The Lexington was unable to accommo date most of the Navy's larger aircraft because of the limited capabilities of its deck, jet-blast deflectors, catapults and ar resting gear. Since the Forrestal does not have these restrictions, it can perform a greatly expanded training role for the Navy, including night carrier-landing qualification and practice and recurrency qualification for pilots whose fleet carriers have been in port for long periods. The Forrestal may even be developed into a kind of "at-sea classroom", offering nu merous disciplines and the opportunity to train new personnel at sea before setting off on an actual combat cruise. Although the ship had all its weapons systems removed when it left the active-fleet duty in Decem ber 1990, some of its sensitive communica tions gear was left intact. The aircraft carrier is undergoing a $144 million overhaul from September 1992 to November 1993, so it will be early 1994 before many of the vessels expanded capabilities can be tested. If the most recent T-45 schedule setbacks are the last, how ever, the Forrestal's return to duty will coincide almost perfectly with the introduc tion of the T-45. The main advantage of the Goshawk from the Forrestal's perspective is that it utilises a nose-tow catapult hook-up rather than the more complex and outdated bridle used by the Rockwell T-2 and MDC TA-4. Bridles require a different catapult set-up (meaning that train ing and operational aircraft cannot be launched at the same time) as well as spe cial arrester and re trieval equipment, which the Forrestal only has on one of its two active catapults. They take much longer to hook up and present more of a safety hazard for the catapult crew. "With the bridles, we have a minimum of five people underne ath the aircraft at full power, with the shuttle is now not expected to enter service until the third quarter of 1993. Even before the accident, however, the programme was almost two years behind schedule. "The T-45 is a new product and it has been a painful process getting it into the system," a naval officer acknowledges. The initial flight tests of the T-45 in 1988-9 revealed a variety of unacceptable characteristics, especially in the approach- to-landing phase of flight. A series of modifications followed, including the addi tion of full-span leading-edge slats, a ventral fin and a larger vertical tail surface, a powered rudder, an elevator/speedbrake interconnect and the replacement of the The T-45 Goshawk has been designed specificaUy for its role aft," a catapult officer explains. "The T-45 will only require one or two," he adds. THE T-45A GOSHAWK The introduction of the T-45A, the most significant of the new training changes, was scheduled for late 1992 until one of the three prototype aircraft crashed during a test flight in early June. The first Goshawk original Rolls-Royce/Turbomeca Adour Mk.861-49 powerplant with an uprated Adour Mk.871 engine. While the changes seemed to resolve the major deficiencies in the aircraft, some nagging problems continued, such as an intermittent yaw oscillation after landing. After an analogue dual-gain nosewheel steering system proved unreliable, the air craft was modified with digitally controlled dual-gain nosewheel steering, which seems to be working well. Continued flight testing revealed the need for a number of other modifications, which are being incorporated into the aircraft. The rear fuselage has been rein forced after a severe "tailhook slap" dam aged the tailcone and engine tailpipe of a test aircraft and forced the postponement of the final carrier-suitability tests in late 1991. The angle-of-attack light is also being relo cated after tests showed it was not visible to landing signal officers during the entire approach sequence. The location and operation of the cockpit flap control mechanism have been changed. The switch is being moved from the for ward panel to the left side panel and changed to a handle that actually moves, and, therefore, can be monitored and/or overridden by the instructor in the back seat. A viscous damper has been added to reduce the stick force per g, and the Goshawk's re-usable catapult holdback fit ting has been strengthened. The emergency gear-extension system has also been modi fied so that the nose-gear doors close again after the gear comes down. Although the gear doors close in normal operations, the initial emergency system left the doors open, creating a high amount of drag. Fixes are still being developed for the Goshawk's stiff throttle, which has received many pilot complaints, and for the logic in its digital yaw-damper controller, which still has a problem in speed ranges around 220kt (400km/h). There is still some debate about who will pay for the initial changes, but the Navy says that it expects McDonnell Douglas to pick up the tab for most of the latest modifications, except the estimated $1 mil lion it will cost to change the flap handle. The numerous delays in the programme have caused a significant increase in the total cost of the T-45 training system, however, which the Navy will have to pay. 211 FLIGHT INTERNATIONAL 6 - 12 January, 1993
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