Mike Delaney was named as head of Boeing’s four-year-old aircraft development organisation in April. The veteran Boeing executive immediately inherited a conceptual puzzle often called the “middle of the market (MoM)” study, a proposed aircraft family with widebody payload and range performance and, somehow, narrowbody economics.

Despite being on the job less than four months, by the eve of the Farnborough air show Delaney seems to have made up his mind about the MoM.

When this journalist prefaced a MoM question with the word, “if”, as in, “If Boeing were to do something …,” Delaney interrupted, saying: “Not if. It’s when.”

To be sure, Boeing’s board of directors has not made a go-ahead decision to launch such a MoM aircraft family. But, some details about the aircraft’s structure and configuration have been decided.

The aircraft’s wing will be composite and fabricated at the newly opened composite wing centre in Everett, Washington, which is building the wings for the 777X, says Delaney. But other questions – metallic or composite fuselage, for example – are still a matter of internal debate and external discussion with potential customers. Meanwhile, Boeing has narrowed the thrust requirement from a range of 40,000-50,000lb to “40-ish”, says Delaney: “It’s not 50.”

If Delaney’s engineering team seems resolved about the overall plan, their colleagues in marketing only see a lot more work to do. Randy Tinseth, Boeing’s vice-president of marketing, recalls a meeting with Delaney in mid-June about the MoM: “I told him, ‘We have 150,000 questions we have to answer, and maybe we’re on 100.’”

For Boeing’s part, questions over the size of the market have been resolved. Although Airbus argues the MoM is already addressed by a combination of the A321neo and A330neo families, Delaney believes that represents the outer-fringes of a total addressable market of 4,000 to 5,000 aircraft. Tinseth says Boeing’s MoM would target a segment of that market that represents potential orders of 2,000-3,000 aircraft.

After establishing the payload/range curves and fuselage cross-section, the most important questions to answer are how to price the MoM – and then, not least, whether that price is more or less than Boeing’s development and production costs.

Speaking to the ISTAT Americas conference of aircraft traders and valuers in March, Tinseth appeared uncertain that Boeing could resolve those price and cost issues satisfactorily. Three months later, Delaney indicates that Boeing’s aircraft development organisation is making significant progress in addressing those concerns.

In meetings with customers, a consensus has formed around the aircraft’s price tag, and it correlates with Boeing’s expectations for an aircraft sized between its narrowbody and widebody families, Delaney says. “We haven’t thrown out a number and they haven’t thrown out a number that says this won’t work,” he says. “If you think about that price-space it all homes in around an area and the airline executives and our guys are pretty close, plus or minus a few.”

As the pricing is locked in, Boeing has to design a development schedule and a production system that can deliver the aircraft profitably. The 787 programme offers a cautionary tale, with Boeing labouring to overcome a more than $30 billion bill for deferred production costs, with a programme-level break-even point set after delivering 1,300 aircraft. For the MoM concept, it is clear Boeing prefers a more profitable scenario.

“It’s not easy, [but] it is not impossible,” Delaney says. “We are not there yet, but in the last six months [the engineering] team has closed the gap pretty good. We have a couple of knowledge points we need to overcome. I am much more optimistic that we can figure our piece out by the middle of the next decade.”

“It’s coming faster than you think,” says Delaney, who seems impatient to get MoM into product development. When the payload/range curves and the fuselage cross-section are fixed, his engineers can begin work on the preliminary and detailed design.

Delaney’s impatience correlates with directions from Boeing Commercial Airplanes chief executive Ray Conner. In an internal “town hall” meeting with Boeing employees in March, Conner told them he wants to move beyond a go-ahead decision on the MoM study by the end of this year. The internal go-ahead decision would precede an authority-to-offer decision by Boeing’s board of directors and subsequently an official programme launch.

Boeing’s objective is still to deliver an operational MoM aircraft sometime in the “middle of the next decade”, a window that could be broadly interpreted as anytime between 2023 and 2027.

Aircraft development programmes are often lengthy affairs. Boeing may have intended to field the 787 five years after programme launch in 2003, but production setbacks and design problems stretched the development phase to eight years. Afterward, Boeing adopted a more conservative scheduling philosophy. The 777X and 737 Max are each ambitious re-engining programmes, but both reuse the existing fuselage cross-section and structural material system. Boeing, however, allowed the 777X and 737 Max team seven years and six years, respectively, to complete the development phase.

For the MoM concept, Boeing wants to return to a more aggressive scheduling philosophy for the development phase. Delaney notes that the 777-200 was launched in 1990, flew for the first time four years later and entered service a year after that. The MoM will be “based fundamentally on a 777 type of schedule,” he says.


Four years ago, Boeing opened the discussion about the MoM concept by pointing to the broad gap in payload and range performance between the 220-passenger/3,200nm 737 Max 9 and the 787-8, which can fly up to 7,100nm in high-density configurations and accommodates around 300 passengers. Initially, that strategy was interpreted as a belated attempt to increase the abilities of the 757-200 and 757-300, two over-powered narrowbodies, to either carry up to 240 passengers or fly up to 4,100nm.

Then, Boeing’s designers and marketers started a four-year-long series of discussions with a diverse set of 36 potential customers. They broadly divide into three sets of preferences for the range and payload performance of the MoM, Delaney says.

“You have the group that wants to fly more people, you have the group that wants to fly more range, and you have the group that wants to fly more people [and] more range,” he says.

The result is an aircraft quite unlike anything that has come before, either from Airbus or Boeing. Airlines’ preferred number of seats ranges between 200 and 270 – about 20% above the 757-200 or 757-300, but roughly matching the capacity of 767 variants. Most customers also want an aircraft that can fly 4,800nm to 5,000nm – that’s also about 20-25% farther than a 757-200, but between the ranges of the 767-200 and 767-400ER.

The aircraft’s hybrid nature has raised questions about the significance of capacity below decks for what is called “belly freight”. In the widebody market, filling up the cargo compartments with standardized LD-3 containers often makes the difference between a profitable route and a loss-making one. Belly freight is more of an afterthought in the narrowbody market. In fact, unlike the A320, Boeing does not offer a factory configuration of a 737 cargo compartment that can hold a standard container, although customers have options for aftermarket retrofits.

For the MoM segment, Boeing’s research indicates that belly freight is not a major consideration among customers. When asked if the aircraft must be sized to carry an LD-3 container below the passenger deck, Delaney shook his head “no”.

“[The airlines] are really thinking about the passenger experience. That’s the priority. It’s the passenger that’s more the priority in this marketspace,” Delaney says.

That response opens the possibility of designing the aircraft with a fuselage cross-section optimised for passenger comfort. Some analysts, including Merrill Lynch’s Ron Epstein and Leeham’s Bjorn Fehrm, have previously suggested that Boeing’s MoM concept calls for an elliptical fuselage design that is wider than it is tall. Alternatively, Boeing could revive the 4.17m-diameter cross-section of the 7J7, a single-aisle concept that was cancelled in 1989. The 7J7, wider by 0.22m than the A320, featured six-abreast rows of seats with two aisles or one much wider single aisle, allowing faster boarding and de-boarding as well as the ability of passengers to get around the catering trolley to reach lavatories in-flight on long routes.


The MoM concept may be a clean-sheet design, but Boeing won’t be starting from a completely empty sheet of paper. With the 787, 737 Max and 777X, Boeing has launched three major product families since 2003, and each brings a set of sometimes painfully acquired, mature technologies that can be adapted for the MoM aircraft family.

In discussing such opportunities, in fact, Delaney provided new insight into the real purpose of the composite wing centre, the 1.3 million square foot factory erected to fabricate the 777X wings made from carbon fibre reinforced plastic. The 787 also featured a composite wing fabricated by Mitsubishi Heavy Industries in Japan, but for a cost that greatly exceeds the expense of building a metal wing. For the 777X, Boeing’s objective is to build the composite wing for a price similar to the cost of a metallic wing. If that cost target is achieved, Boeing’s next objective is to determine whether that process can be scaled down to a smaller wing, yet preserve the production efficiency.

“There’s a whole bunch of lessons or objectives in this building beyond just supporting our 777X aeroplane,” Delaney says.

Other key technologies originally developed for the 787 also could be adapted for the MoM aircraft family. Delaney noted that Boeing introduced the Core Computing System (CCS) for the 787, a set of two racks each holding a set of eight general processing modules. The CCS has already been adapted for the 777X family and is available for the MoM family, Delaney says. The 787’s pioneering more-electric architecture is another set of technologies that could be adapted, he adds. Among the unique tasks for the 787’s electric system are pressurising the cabin and de-icing the leading edge of the wing, eliminating pneumatic systems driven by the inefficient extraction of bleed-air from within the engine airflow.

Not everything about the MoM, however, can be adapted from existing technology in production by Boeing or suppliers. Delaney cited two technologies that will need to be invented: engines and the efficient integration of the engine and the nacelle.

Engine technology has already come far since GE Aviation and Rolls-Royce proposed a host of new technologies to make the engines on the 787 several percentage points more efficient than the power plants for the 767. For the 737 Max, CFM International introduced a new generation of composite material for fan blades and the engine case, along with ceramic matrix composites in the turbine shrouds and a modulated system for air extracted from the compressor to cool components in the turbine. Meanwhile, rival Pratt & Whitney introduced a gearbox to optimise the rotation speeds of the low-pressure turbine and the inlet fan, allowing the geared turbofan engine to feature a highly efficient 12:1 bypass ratio.

“Clearly we think all three engine companies need to give us the next step. We want the next step of whatever they have to offer,” Delaney says.

Pratt & Whitney, for example, has discussed a second-generation gearbox technology, replacing the 3:1 gear ratio of the existing geared turbofan with a 4:1 reduction ratio. That 25% increase could dramatically expand the bypass ratio beyond the 12:1 system offered by P&W today. The bypass ratio is a relation of the airflow diverted around the core of the engine to the stream directed into the combustion path.

As bypass ratios grow larger, the fan diameter of the engines must also grow larger. That requires a step-change in the sophistication of the integration of the engine with the encapsulating nacelle and its mounting on the wing.

“When you get to a certain fan diameter you have to understand how to wrap it with the right nacelle because you can easily lose whatever fan diameter gain you had with a poor design of the nacelle,” Delaney says. “So we’re investing in those technologies.”

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Source: Cirium Dashboard