الطائرة الجديدة متوسطة الحجم من بوينج

The New Midsize Airplane would have been sized between the 757 (front) and 767 (rear) in the middle of the market

الطائرة الجديدة متوسطة الحجم من بوينج (New Midsize Airplane ؛ NMA)، أو New Midsize Aircraft، (وثقافياً يشار إليها بالموديل Boeing 797) هي مفهوم طائرة خطوط جويةاقترحتها بوينج لملء قطاع منتصف السوق.

 التاريخ

 2016

The 737 MAX 10 remained the largest and heaviest Boeing 737 variant ever and is likely ended up the ultimate development of its family. Yet to be certified to enter commercial service as of 2025, the MAX 10 still has considerable operating range disadvantage comparing to its direct competitor Airbus A321neo, especially with the A321LR and A321XLR.

 2017

Silhouettes of Boeing NMA concept at right between 787-8 on top and 737 MAX 10 on bottom, as presented at Paris Air Show 2017

 2019

Considered 767-XF concept

The 767-400 is the largest and currently the latest commercial version of the existing 767 series.

A new-generation General Electric GEnx engine.

 2020

The 787-3 is a abandoned variant of the Boeing 787 Dreamliner family, being equivalently sized to a 787-8 but was adjusted for shorter flights.

 2022

There is currently no modern engine solution available to directly replace the 200 كيلونيوتن (45،000 lbf)-class PW2000 (pictured) and RB211 that power the 757.

 المحركات

The engine selection process is reminiscent of the competition to power the 777-200LR/300ER at the end of the 1990s, which shaped the turbofan market for the subsequent years. Rolls-Royce proposed the Trent 8104 growth demonstrator, Pratt & Whitney proposed a scaled-up PW6000 (wanting to limit the competition to two suppliers), while GE won exclusivity with the GE90-115B performance and GECAS 777 orders. Rolls-Royce obtained the same exclusivity for the A350 and later the A330neo, pushing P&W out of the widebody engine market and precipitating its narrowbody comeback with the PW1000G.

The engines on the new Airbus A321neo - including A321XLR and being currently the largest narrowbody aircraft in production - are certified at less than 150 كيلونيوتن (34،000 lbf). That being said, the A321 is a much smaller and lighter platform than the 757-200, being intended for shorter-ranged operations.

The GENx-2B - exclusively powering the Boeing 747-8 - is cited as a feasible available option to re-engine and modernize the existing Boeing 767 platform. However, with a certified thrust of 300 كيلونيوتن (67،000 lbf), it is significantly overpowered for virtually all narrowbody NMA concepts.

The 45،000 lbf (200 kN) thrust was typical of the 1960s' first generation of high-bypass-ratio turbofans: the GE CF6 for Douglas DC-10, the Rolls RB211 for Lockheed Tristar, and the Pratt & Whitney JT9D for Boeing 747. This market was quickly left behind as aircraft and their power requirements grew, leaving the RB211 for Boeing 757 (until 2005), or the Pratt PW2000 for Boeing C-17. Newer technology enabled 10:1 or more bypass ratios and overall pressure ratios of at least 50:1 at top of climb. This level of thrust is above modern CFM LEAP or Pratt PW1000G single-aisle engines, but well below Rolls-Royce Trent or GEnx widebody ones.

It falls below the 50،000 lbf (220 kN) limit for CFM International, and thus a scaled-down GE9X core could fit a new low-pressure system. Pratt could reach it by growing from the 33،000 lbf (150 kN) PW1133G for the A321neo. Rolls could propose its UltraFan development, a geared turbofan based its new Advance core, but it is primarily focused on its larger, 100،000 lbf (440 kN) engine. The GTF cost more than $10 billion to develop, and RR was facing financial difficulties which could be accelerated by being left out of the EU Clean Sky initiative as a result of Brexit. Both could join together, but have historically been moving in the opposite direction, as Rolls sold its 32.5% stake in International Aero Engines to Pratt parent United Technologies in 2011, essentially selling the ghost of the geared IAE SuperFan proposed for the A340 (supplanted in 1987 by the CFM56).

 See also

• Boeing New Large Airplane
• Boeing Yellowstone Project
  

 وصلات خارجية

• Joe Anselmo; Jens Flottau (July 8, 2016). "Airlines To Boeing: 'Get Moving' On Middle Of The Market Aircraft". Aviation Week Network.
• Gregory Polek (March 13, 2017). "Boeing's '797' Taking Shape as Twin-aisle Design". Aviation International News.
• Julie Johnsson (March 7, 2017). "United Looks at Boeing's 'Paper Plane' and Likes What It Sees". Bloomberg.