THE 737 STORY: Smoke and mirrors obscure 737 and Airbus A320 replacement studies

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While officially downplaying the prospects for next-generation replacements for the A320 and 737, Airbus and Boeing are increasingly engaged in the early study stages, with formal initiatives launched on both sides.

According to industry insiders Airbus calls its A320 replacement study the NSR, or New Short Range aircraft. NSR is baselined against the A320-200 for overall performance and cost terms and is aimed at a provisional service-entry date of 2012-13. The NSR study, also referred to by its US competitor as the “A-1”, is believed to be broken into an initial three-phase effort. Phase 1, already completed, evaluated overall performance and operating cost targets, potential market assessments and technology candidates.

Phase 2, believed to be under way, is thought to be fine-tuning predicted improvements in fuel burn, emissions, noise and operating costs per hour. A planned Phase 3 – possibly timed for mid-2006 – is expected to examine industrial implications concerned with partner workshares, technology development goals and airline advisory input.

Overall design concepts revolve around an all-composite primary fuselage and wing structure, more-electric systems, advanced aerodynamics (including natural laminar flow and unstable, low-drag configurations), several cross-section options and integrated avionics with provision for enhanced vision systems (EVS).

Boeing calls its 737 successor study the 737RS, or Replacement Study. Initial work on the Yellowstone 1 (Y1) is now understood to represent just one of several possible replacement concepts. Y1 is one of the three Yellowstone new-generation studies emerging from the broad-based “Project 20XX” advanced technologies initiative behind the Sonic Cruiser and subsequently the 787. Y1 is thought to cover the 100- to 200-passenger range; Y2, which became the 787, covers the 200- to 350-seat range; and Y3 covers the range for what could eventually become a successor to the 777-300/300ER in the next decade.

According to industrial sources, Boeing has accelerated the pace of the 737RS study effort and even plans to make its initial pass on prospective supplier teams by mid-2006. The RS/Y1 concept is based around an all-composite 787-like structure, fly-by-wire, more-electric system architecture, EVS-integrated avionics flightdeck, and a cabin cross-section “wider than A320”. Aerodynamic improvements include a longer span wing, single-slotted flaps, raked and blended-winglet wingtip options, blended fin root and 787-like Section 41 (nose and flightdeck).

Initial results from both NSR and RS/Y1 studies have, apparently, been less than stellar. Acting completely independently, the two studies have come up with similar results for their individual concepts, which fall far short of the ideal targets set for the 2012 timeframe airliner.

Airbus NSR Phase 1 results, for example, are believed to have indicated that if all the advanced technology (available and considered mature and sufficiently low-risk for entry into service in 2012) was poured into the aircraft, the best specific fuel consumption reduction would be 4%, the best operating cost reduction 3% and the best emissions reduction would be 5%. The numbers are also said to be within 0.5-1% for all parameters for the initial phases of Boeing’s RS/Y1.

These results therefore mean the aggregate benefit of all the combined results indicates a maximum efficiency improvement of only around 9-10% over the current A320/737 models. Given the estimated $7 billion development pricetag (airframe, systems and engine technology) involved in the NSR, insiders say Airbus in particular is asking if the venture is “too much, too soon”.

While this would, on the face of it, dent the hopes of anyone hoping to see a new generation in the near term, mid-term market pressure could still force the issue. There are some operators such as Southwest Airlines that have openly called for the start of work on a new aircraft to counter the rising cost of fuel, even if the improvement is “only” around 10% better than today’s aircraft.

Engines therefore remain the key, as acknowledged by Boeing Commercial Airplanes vice-president sales Scott Carson who says “right now, there is no engine. To build a 737 replacement without a next-generation engine would be a dreadful mistake for us to make.” Airbus chief executive Gustav Humbert says there are no imminent plans to create a new single-aisle aircraft to succeed the A320 family, with timing being dictated by market demand and the emergence of new engine technology. “Both Boeing and Airbus will need an all-new engine, which the engine manufacturers say will not be ready until 2013-14, so the possible entry into service of such an aircraft could be possible around the middle of the next decade,” he says.

With this in mind, Pratt & Whitney plans to challenge CFM International’s dominance and is leading a push to demonstrate a 30,000lb-thrust (133kN) class geared turbofan (GTF) on Boeing’s forthcoming Quiet Technology Demonstrator programme, set for flight testing around 2008.

Although the GTF is not necessarily the solution preferred by Rolls-Royce, P&W’s main International Aero Engines partner, P&W commercial president Steve Heath says IAE is “the partner we’d need to do a programme like this. The days when P&W owned 80% or more of the engine are not here any more because of the investment you need to make something like this.” For the moment, Boeing‘s official view is “if it ain‘t broke, don‘t fix it”.