TYPE: Supersonic business jet
PROGRAMME: Gulfstream Aerospace and Lockheed Martin revealed at Farnborough on 7 September 1998 that they were jointly conducting an 18 to 24 month feasibility study into an SBJ. As then envisaged, the aircraft, similar in size to the Gulfstream II, would have featured a stand-up-headroom cabin accommodating eight passengers, and would cruise at M1.6 to M2.0 over a range of more than 4,000 n miles (7,408 km; 4,603 miles). Key design goals were the ability to operate out of existing business aviation airfields; take-off noise compatible with anticipated future emissions regulations; fuel-efficient operation at subsonic speeds; and an initial cruising altitude above that of subsonic traffic.
The feasibility phase of the project, completed in mid-2000, was followed by a further two years of wind-tunnel testing and project definition; studies carried out by the company confirmed that there is a market, but sonic boom suppression, engine emissions and noise present technological challenges. Gulfstream and Lockheed Martin, through its Advanced Development Projects division, defined the SBJ, and lobbied the US government for support via the Defense Advanced Research Projects Agency which received US$15 million for its quiet supersonic aircraft technology (QSAT) budget. However Lockheed Martin has since withdrawn from the programme. In 2000, patents were filed with different layouts including tailplane mounted at tail fintip and drooping to attach to engine nacelles; further patents included one with large delta wing shape plus nose canard; in October Gulfstream displayed, at NBAA, the Quiet Supersonic Jet (QSJ) which had swept wing and wingtip-mounted swept tail.
By late 2003, the QSJ had evolved into a variable-geometry wing, T-tail aircraft with two pod-mounted engines on the rear fuselage, each side of the fin. Design goals include maximum take-off weight of 45,359 kg (100,000 lb), cruising speed of Mach 1.8, take-off field length of 1,981m (6,500 ft), range of 4,800 n miles (8,889 km; 5,523 miles) and airport noise level 10 EPNdB quieter than Stage 4 requirements.
Estimated unit cost is in the region of US$70 million to US$80 million (2002), based on 200 produced. The proposed aircraft is not related to the abortive Gulfstream-Sukhoi SSBJ project from which Gulfstream withdrew in 1992. Executive Jet Aviation, which operates the NetJets fractional ownership programme, is reportedly interested in the concept of supersonic business jets.