The Gulfstream IV is a significantly improved, larger, longer ranging and advanced development of the earlier II and III.
The most significant improvement with the G-IV over the earlier Gulfstream models are the Rolls-Royce Tay turbofans, which bring significant fuel burn and noise emission improvements despite their higher thrust output than the II and III's Speys (the IV continues a Gulfstream and Rolls-Royce association that dates back to the original Dart powered Gulfstream I). Other changes include a stretched fuselage and aerodynamically and structurally improved wing with 30% fewer parts, greater fuel capacity and range, increased span tailplane and an advanced EFIS avionics suite with six colour CRT displays.
Design work on the IV began in early 1983, with the first of four production prototypes making the type's first flight on September 19 1985. FAA certification was awarded on April 22 1987. The improved Gulfstream IV-SP (SP = Special Performance), with higher payload and landing weights and improved payload range performance, replaced the IV from September 1992.
A third development is the special mission SRA-4. Designed primarily for military roles (such as maritime patrol and electronic surveillance, depending on equipment fit) it is also offered as a freighter for priority cargo transport (the US Navy has ordered four and the Marines one as C-20G operations support aircraft capable of accommodating 26 passengers or three freight pallets).