Gulfstream fixed those problems for the G280 starting with a clean-sheet wing derived from the G550 airfoil with a slightly different twist distribution and new large, wide radius winglets. It has more sweep and 495 sq. ft. of area, 34% more than the G200 wing. While it has less than half of the G550's wing, the G280 has nearly identical wing loading because of its lower weight. Similar to the G550, design cruise speed is Mach 0.80, up from Mach 0.75 for the G200. That yields up to 29 KTAS more speed, enough to shave half an hour or more off the flight time between London and New York.
The larger wing, along with the wing center section tank and feeders, also holds 20% more fuel than the G200's wing and center tanks. The increased fuel capacity in the wing tanks enabled Gulfstream to shrink the size of the forward belly tank and eliminate the 5,515-lb. capacity, 67-cu.-ft. fuselage tank, replacing it with a 1,130-lb. capacity aft belly tank.
Overall fuel capacity actually was reduced by 390 lb. from the G200, but the more-efficient wing and new engines more than made up the difference. Range with four passengers is boosted nearly 300 nm even though long-range cruise is 29 KTAS faster. Gulfstream selected second-generation 7,624-lb.-thrust Honeywell AS907-2-1G turbofans, marketed as HTF7250G engines, to replace the P&WC powerplants on the G200. The Honeywell engines give the G280 the best thrust-to-weight ratio of any Gulfstream in current production.
Similar to Savannah-built Gulfstreams, the G280 also gets a new T-tail empennage that replaces the G200's cruciform tail. The vertical and horizontal stabilizers have more area to handle the aircraft's nearly two-ton weight increase. The horizontal stab also has more sweep.
The new aircraft retains fuselage outer loft contours, but the G200's all metal, semi-monocoque structure was modified to handle increased pressurization, the new wing, additional windows and aft internal baggage bay access door. In addition, the external baggage door was changed to a plug design that opens inward. The main entry door is virtually the same as the one on the G200, but it's now hydraulically retracted rather than using air springs.
The increase in pressurization to 9.2 psi from 8.9 psi results in a 1,000-ft. reduction in maximum cabin altitude. Passengers, however, will on average experience slightly higher cabin altitudes because the aircraft can climb directly to FL 430 or higher, resulting in a 6,500-ft. cabin altitude. The G200 could barely reach FL 390 at MTOW, where cabin altitude is 6,000 ft.
The flight control system of the new aircraft has little in common with that of the G200 other than similar pitch control mechanisms and the stall protection system. The roll control system, for example, uses manually actuated ailerons with servo tabs that provide a high fidelity aerodynamic feel. Computer controlled multifunction spoilers provide most of the muscle needed for roll control. The result is natural feel, abundant roll control authority and well-harmonized pitch and roll forces at the yoke.
The G280 is fitted with a fly-wire-wire (FBW) rudder in place of the manually actuated, boost-assisted system installed on the G200. The rudder pedals have no mechanical connection to the rudder. Instead, the pedals have movement transducers that send electrical signals to two, dual-channel digital FBW computers. Each computer then commands a separate FBW electrohydraulic rudder servo actuator, powered by the left or right hydraulic system.
The avionics system also sends signals to the FBW computer for rudder bias in the event of asymmetric thrust, yaw damping and turn coordination. In the event of an engine failure, the rudder bias system is so effective that it virtually eliminates any sideslip. Since the rudder pedals aren't connected to rudder linkages, they wouldn't provide pilots tactile feedback of an engine-out condition without an add-on system. The G280 is fitted with a rudder feel servo system that mildly deflects the rudder pedals in proportion to thrust asymmetry, thus providing artificial feel that “talks to your toes” during an engine-out condition.
In keeping with long-standing Gulfstream design practices, the G280 has no leading-edge high-lift devices. The trailing-edge flaps are electrically controlled and hydraulically actuated. The G200's relatively small wing, in contrast, needs flaps and leading-edge slats and Krueger flaps to boost lift for takeoff and landing.