Engine and airframe aerodynamic improvements are allowing Gulfstream to claim significant efficiency gains for its GV ultra-long-range business jet. Chief customer engineer Ed Flinn says that the improvements (including a specific-fuel-consumption reduction of "one and a half percentage points") are compensating for the excess weight from which the aircraft still suffers.
The changes to the GV's BMW Rolls-Royce BR710 engines include fully faired bypass ducts, super-polished high-pressure (HP) turbine blades and improved HP turbine cooling. In a bid to reduce the weight of the engines (still some 225kg per shipset heavier than target), the air-cooled oil-cooler has been deleted after it was found to be unnecessary, and the weight of the engine-control mounting tray has been cut. These have saved about 22kg per shipset.
Aerodynamic improvements have centred on a new design for the engine-pylon fairing, new antenna fairings and the deletion of the windscreen wipers in favour of air-jet "pneumatic rain clearance". These improvements will be incorporated on new-build aircraft, and applied retrospectively to the four aircraft already flying.
Source: Flight International