The Gulfstream G-III is the third generation of a very successful family line of private jets. Gulfstream Aerospace Corp designed the Gulfstream G-III to be similar to the GII (of which more than 250 models were sold), but better. The G-III can fly 4,600 miles (4,000 nautical miles) at a speed of .84 Mach while carrying eight passengers. Alternately, it can fly 4,140 miles (3,600 nautical miles) at the same speed with twice the amount of passengers.
The cabin of the G-III usually holds fourteen to nineteen passengers, but it can be configured to hold up to nineteen in a high-density layout. The cabin has sufficiently spacious dimensions: 41.3 feet long, 6.1 feet high, and 7.3 feet wide, totaling a cabin volume of 1,345 cubic feet. Standard amenities include a full-sized galley with a refrigerator, coffee, maker, and the usual food preparation equipment.
The choice to use two Rolls-Royce Spey Mark 511-8 engines, the exact engines used on the GII, was not a choice by default. Before deciding on the two-engine configuration, Gulfstream Aerospace Corp tested three and four-engine configurations. In the end, they decided that two engines would provide the performance capabilities for the jet while keeping costs low.
Each engine is able to produce 11,400 pounds of thrust each on takeoff, but the two are flat-rated to 9,000 pounds in order to meet FAR part 36 noise requirements. In the case of an engine failure, however, the remaining engine will automatically jump to full power.
At sea level and at standard conditions, the G-III can take off in 5,100 feet. At an altitude of 5,000 feet and a temperature of 77°F, it can take off in 7,175 feet. After takeoff, the G-III can climb directly to 43,000 feet. Its maximum certified flight ceiling is 45,000 feet (which it can reach even when loaded to its maximum takeoff weight of 68,900 pounds). Long-range cruise speeds of 442 knots (.84 Mach) can be reached at 45,000 feet, and a high-speed cruise of 488 knots (.88 Mach) can be reached at 39,000 feet.
With maximum fuel and reserves, the G-III has a maximum range of 5,070 miles (4,410 nautical miles). When flying at its top cruise speed, it can fly 3,330 miles (2,900 nautical miles) nonstop. Its cabin is rated to 9.5 psi, which means it can maintain a seal level cabin to an altitude of 22,100 feet.
In addition to having great performance capabilities, the G-III is a very reliable jet. All vital functions have at least one backup system, and sometimes more. For example, the jet is equipped with four boost pumps for the fuel system, even though only one is needed when flying at the highest certified altitude.
Some of the G-III’s performance capabilities can be attributed to its new wing design. The wing has a 10% greater span than the wings used on the GIIs, and achieves significantly better range. Whitcomb winglets were added to reduce fuel burn.
A completely new nose design resulted in a redesigned cockpit as well. It is three feet longer, providing enough space for a third pilot to come along for extended trips (as much as eight hours).
In addition to the much roomier cockpit, pilots should appreciate the new avionics system. A Dual Sperry ED-800 electronic flight instrumentation system coupled with a Sperry Primus 800 multifunctional display and a four-screen EFIS dominate the flight deck. Standard equipment includes three Honeywell laser gyros (which are lighter and more reliable than mechanical gyros), a Sperry SPZ800 flight director system, Global GNS 1000 FMS, a Sperry Primus 800 color weather radar, as well as all necessary communication and situation awareness equipment.
In short, the G-III is a reliable, long-range private jet that still offers a very large (1,345 cubic foot) cabin and the high performance standards needed to compete in today’s private jet market. The Gulfstream series keeps getting better with time, as the G-III demonstrates.