March 25, 2013
Gulfstream is turning up the heat in the large-cabin business aircraft competition with its new G650 flagship, the largest, fastest, farthest-ranging—and at $64.5-million per copy—most expensive executive jet in the company's history. The aircraft cruises at nearly 30 kt. faster than the current generation of large-cabin business jets and its 7,000-nm range exceeds that of the G550, the previous distance leader, by 250 nm.
Moreover, the G650's cross-section is wider and taller than that of any rival, save for converted jetliners, its cabin is touted as 5-6 dB quieter than that of hush-quiet G550, and its pressurization system delivers a less-than-5,000-ft. cabin altitude at flight level (FL) 510—all welcome attributes on intercontinental missions that can exceed 14 hr. aloft.
The aircraft features several new systems including Gulfstream's first three-axis digital flight control system and a more redundant electrical system with a new power distribution architecture.
Gulfstream customers dictated the terms of the all-new G650's design, overwhelmingly favoring time-proven aluminum versus new-technology composites for the primary airframe. However, composites are used in the horizontal stabilizer, elevators and rudder, plus floorboards, rear pressure bulkhead, engine nacelles and winglets. Fuselage frames are evenly spaced at 17.5-in. intervals, wider than that on previous Gulfstreams, which makes room for longer-spaced, and larger cabin windows. That also increases legroom in the cabin because seat placement is based on window spacing.
As with all large-cabin Gulfstreams, the G650 is powered by twin Rolls-Royce turbofans. The 16,900-lb.-thrust BR725 is a growth version of the 15,385-lb.-thrust BR710 that powers the G550. And as with previous models, Gulfstream eschewed leading edge slats.
Instead, they fitted the aircraft with a 1,283-sq.-ft. wing that results in the lowest wing loading of any ultra-long-range business aircraft. This results in acceptably low takeoff and landing speeds.
The wing also has 33 deg. of sweep at quarter chord to reduce Mach-induced drag. The large, outwardly canted, highly swept winglets help reduce wingtip vortices, an important design feature considering the wing's modest 7.73:1 aspect ratio. The airfoil thus is optimized for Mach 0.855 cruise. The G650 is the first large-cabin Gulfstream to have an area ruled aft fuselage to reduce high-speed interference drag between the engine nacelles and fuselage.