The Gulfstream G150 is out to steal a larger slice of the lucrative mid-sized business jet cake, but it faces tough competition

After years of relative stability, the mid-size business jet market is getting a shake-up. Long dominated by Bombardier's Learjet 60 and Raytheon's Hawker 800, this workhorse sector of the market is making room for two new entrants: Cessna's all-new Citation Sovereign, now entering service, and Gulfstream's G150, which was rolled out last month by manufacturing partner Israel Aircraft Industries (IAI).

The traditional mid-size segment of the market had been largely ignored by manufacturers as they explored the new super mid-size sector. But as this niche is now filled with competing aircraft, attention has returned to a category that has accounted for steady and substantial sales over the years. Cessna chose to develop an all-new mid-size aircraft, the Sovereign, while Gulfstream decided to answer customer criticisms of its slow-selling G100 by developing a larger-cabin derivative.

High performer

Compared with other mid-size business jets, the G100 is a high performer, but its narrow fuselage is cramped and uncompetitive. Design goals for the G150 were to keep performance comparable to the G100's while increasing cabin volume, improving aircraft aesthetics and updating avionics and systems, says Stan Dixon, programme director.

The solution was a "lateral stretch" that increases cabin width by 300mm (12in), to 1.75m (5.75ft), and height by 50mm, also to 1.75m, says Dixon. The result is an unusual, almost square, cabin cross-section, which Gulfstream claims offers more head and foot room than the competition. The cabin is 300mm wider at head level than either the Hawker or Sovereign, and at floor level is 100mm and 400mm wider, respectively, the company says. Gulfstream offers six-, seven- and eight-seat cabin layouts. Compared with the G100, the roomier cabin allows 50mm wider seats, a 100mm broader aisle and an addition of 50mm-wide arm ledges along the cabin walls. Long-lived LED lighting is introduced internally, as well as externally.

With the wider cabin comes a broader cockpit, which improves accessibility, and a reshaped nose for better aesthetics, aerodynamics and visibility, says Dixon. A 400mm plug aft of the wing tapers the wider fuselage into the existing G100 tail section and houses a new fuel tank.

Other than moving outboard 150mm because of the lateral stretch, the wing is unchanged from the G100. IAI windtunnel-tested different winglet shapes, but the aerodynamic improvement did not outweigh the commonality benefit of staying with the design used on both the G100 and G200. G200-style oval cabin windows, a new wing/body fairing to reduce drag, and increased elevator trim tab area to reduce rotation forces complete the external changes.

The G150 is designed to carry four passengers 5,000km (2,700nm) at Mach 0.75. Maximum operating Mach number is 0.85 and the aircraft will fly coast-to-coast across the USA at M0.8, says Dixon. Gulfstream calculates the G150 will fly from New York to Los Angeles 56min faster than the Sovereign and 44min faster than the Hawker 800XP.

The G100's Honeywell TFE731-40 turbofans are retained, with revised engine electronic control software increasing thrust 5% on take-off, to 4,420lb (19.7kN), 6-7% on climb and 4% in the cruise. A tail-mounted Honeywell RE100 auxiliary power unit is standard.

New Rockwell Collins Pro Line 21 integrated avionics include four 305 x 255mm liquid-crystal displays, in side-by-side pairs in front of each pilot. The displays have been adapted to incorporate some of the philosophy of the PlaneView integrated flightdeck in Gulfstream's large business jets, including a full-width horizon on the primary flight display, says Pres Henne, senior vice-president, programmes, engineering and test.

Electronic charts

Standard avionics include dual flight-management and attitude heading reference systems. Options include Collins's IFIS integrated flight information system, which displays electronic charts in a single installation, while dual systems provide electronic flight bag capability, says Dixon. Database updates will be loaded via a USB memory stick, rather than floppy disk.

System enhancements include G200-style nosewheel steering through tiller and rudder pedals. The fuel system is simplified, the door seal improved, and reliability of the flat/slat system and hydraulic pumps increased. Eight wing speedbrake/spoiler panels, twice the number on the G100, reduce buffet and balanced field length.

Input from a G150 customer advisory group formed by Gulfstream has resulted in over 100 design changes, Dixon says. Other improvements target the top 20 dispatch reliability issues with the G100, several by using G200-type systems.

The G150 is the first IAI-built business jet to be designed with Gulfstream input, and the latest in a line of Israeli business jets that began in the early 1970s with its Westwind development of the Jet Commander. IAI went on to develop the mid-size Astra and super mid-size Galaxy, which became the G100 and G200 following Gulfstream's 2001 acquisition of IAI's business jet joint-venture Galaxy Aerospace.

Business jet manufacture accounts for two-thirds of the IAI Commercial Aircraft Group's $400 million in annual sales. That figure is set to increase with introduction of the G150. IAI produced only four G100s last year and will build the final four this year. In its place, the company is planning to produce 16 G150s next year and at least 24 in 2007, says Dany Kleiman, production division general manager. Tooling is in place to produce four aircraft a month, he adds.

IAI set aggressive goals for reduced development and non-recurring costs, says Kleiman. The partners will not divulge the development cost, but it is modest, says IAI president Moshe Keret. Sources say the Israeli company has invested $80 million in the programme. The G150 is IAI's first digital design - with everything down to the rivets electronically defined and stored as three-dimensional solid models using the Unigraphics computer-aided design system.

Digital design

The G150 is "heavily machined", says Kleiman, with extensive use of high-speed machining to reduce cost and weight. The forward and aft fuselage bulkheads are single-piece machined components, whereas in the G100 and G200 they are built up from sheet-metal detail parts. Parts are pre-drilled, to speed assembly, using the digital design database. The wing-body fairing is composite and is the first certificated part produced using a liquid resin infusion process developed by IAI, says Kleiman.

IAI is aiming for a cycle time of eight months from the start of parts manufacture to delivery of the green aircraft. This has been achieved with the G200 - which spends four months in manufacture and four months in assembly - and is to be reached with the 12th G150, says Kleiman. Most detail parts manufacture is outsourced, with IAI focusing on machined components and final assembly. Denel Aviation in South Africa produces the tail section and Sonaca NMF Canada provides the wing skins. Two jigs at IAI can each be reconfigured within 2h to allow assembly of either the G100, G150 or G200 wing, with a combined throughput capacity of six a month.

After rejigging the joining process to reduce mating time for the G200 from 14-15 days to five, IAI has introduced new technology for the G150. The wing, centre, rear and forward fuselage sections are mounted on pillars that move up and down under computer control, a central workstation providing visual confirmation when alignment is within tolerance.

Assembly of the first G150, aircraft 201, began in July last year and the airframe was complete by mid-December. The aircraft was rolled out on 18 January, and first flight is scheduled for 18 May. IAI plans an aggressive seven-month flight test programme leading to Israeli and US certification in the first quarter on next year.

Two aircraft - one instrumented and one production standard - are to undertake a 75-flight, 235h test programme. This sounds short, but the G150 will be approved as an amendment to the G100 type certificate. IAI also points out that it certificated the Galaxy/G200 in 11.5 months - two instrumented and one production aircraft logging 810h in 270 flights.

Real-time telemetry data reduction minimises the need for post-flight analysis and increases flight-test efficiency, says IAI. The second G150, aircraft 202, will be used primarily for function and reliability testing. Aircraft 199, actually the second airframe to be assembled, is the static test article, and will be used for limit load tests before first flight.

US completion

IAI will certificate the "green" G150, which will then be delivered to Gulfstream's Dallas, Texas completion centre for installation and supplemental type certification of the interior. Whereas G100 outfitting is performed at Gulfstream's Appleton, Wisconsin site, G150s will be completed alongside G200s in Dallas.

Customer deliveries will begin in the third quarter of 2006 with aircraft 202, which Gulfstream will use as its demonstrator. This will be followed by the first of 50 firm and 50 option G150s for US fractional-ownership operator NetJets. Plans call for aircraft 201 eventually to be stripped of its instrumentation and refurbished for sale.

At $13.5 million, the G150 is competitively priced against Cessna's newcomer, the $14.2 million Citation Sovereign, and within reach of the market leader, the $12.9 million Hawker 800XP. Refreshed with a new cockpit and cabin, the 800XP continues to sell well, but with the newer G150 and Sovereign becoming available, the mid-size market is becoming the latest business-jet battleground.

Gulfstream G150 specifications

Wing span



2 x TFE731_40AR-200G

Length overall


TO thrust




Max operating Mach


Max TO weight


Long-range cruise


Basic operating wt


Cruise altitude


Max fuel weight


Take-off distance


Payload, full fuel


Landing distance




Source: Flight International