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SEATTLE – The single most important question in commercial aircraft manufacturing over the last 24 months has been whether Boeing will finally launch a new mid-sized airplane (NMA) to address the so-called middle of the market (MOM) between its Boeing 737 single-aisle narrowbodies and Boeing 787 twin-aisle widebodies.
Boeing’s current “offering” in this market segment is the Boeing 737 MAX 9, the largest member of its next generation 737 MAX narrowbody family. But the 737 MAX 9 has been beaten soundly by rival Airbus’ A321neo in a market segment that aerospace analysts increasingly view as crucial over the next two decades.
Since mid-2015, it has been clear that Boeing would have to take some action to combat the threat of the A321neo. And while there is still no formal movement, developments over the last six months point to Boeing moving ever closer to revealing its approach to the MOM.
Our latest market intelligence comes from the pre-Paris Airshow bookings held by Boeing last week in Seattle. At the briefing, presentations from Ihssane Mounir, the VP Global Sales and Marketing; Mike Delaney, the VP & GM Airplane Development; and Kevin McAllister, the President and CEO, Boeing Commercial Airplanes, all touched on the NMA and the various approaches that Boeing is considering.
originally posted by: Zaphod58
a reply to: FredT
When you're talking about making a product that has to have the landing gear redesigned, because you stretched it so far that the existing landing gear doesn't work, you're taking it too far and it's time to move on to something new.
Although the engine is unchanged, the fuselage is lengthened so the main landing gear must be modified to enable adequate clearance of the longer body for rotation on takeoff and landing and to ensure the aircraft remains stall rather than pitch-limited.
The original plan was to lengthen the MLG however since the fan diameter is unchanged an easier solution which requires less changes to the wheel welll has been adopted, namely a "semi-levered" design which is more commonly known as a trailing-link, similar to that used on the 777-300ER and 787-10, that shifts the rotation point slightly aft. It is also believed that the gear will also be telescopic and contract during retraction to fit into the existing wheel well.
737 MAX vice-president and general manager Keith Leverkuhn said in Feb 2017 ."Boeing has been evaluating multiple “good ideas”, including a shift from the 737’s traditional oleo strut to a trailing link landing gear design, A key criteria in the final decision (of the MAX-10) later this year will be the inherent reliability of the landing gear design,"
Keith Leverkuhn said on 2nd May about the -10 MLG: “The design focus is on the upper portion of the gear as it integrates with the actuator. In this area, within the tight confines of the existing wheel well, Boeing’s new design will do some “clever folding using a link mechanism at the top,”
"The lower section of the leg is also modified with an additional shock strut that fits inside the same forging. This moves the contact point aft a little bit. That’s fundamentally what we are doing and yes, it will look like a trailing link gear. We want to make it maintainable, reliable, and we are going to need that gear to get the performance we want out of the -10 but I’m confident in the solution set,”
When talking about testing Leverkuhn says: “The kinematics are tricky. How do we take this fundamentally longer gear and make sure it folds up nicely in the gear well. So we do drop tests to understand the structure we have sized is appropriate and another rig test around the function of the new gear. We will spend most of the year doing that, but we are really zeroing in on it,” Boeing is constructing two gear test rigs, one for functionality and the other for robustness.