Airbus and Boeing are planning new narrow-body aircraft in the 2025-2030 time-frame, when new technologies could provide the substantial advantage over today’s aircraft. New engine technologies have enabled re-engining of existing programs, which need at least 10 years of production to recover the costs. But the question is what comes next?
There hasn’t been a breakthrough in basic aircraft design since the swept wing, with engines below the wing, was introduced with the B-47 after World War II. While technologies have improved, the fundamental layout and look of jet aircraft hasn’t changed much since the 707, except for fewer and larger engines.
Engines keep getting larger with more bypass air aiding fuel economy. Engine placement will likely be a key element of the next generation airframe design. With large fan engines, hanging them under-wing creates tremendous drag. Alternative placement for engines that minimizes drag will be important in new designs.
Laminar flow has been studied for years, and does work. But it doesn’t take much dirt or foreign material to disrupt that flow, and we don’t yet have giant car-wash equivalents for aircraft. Nonetheless, we believe the operational issues with many innovative technologies will be solved before the next generation of narrow-body aircraft is developed, and that they will be incorporated into those new designs.
The need for game changing technology may be best illustrated by the CSeries, E2-Jet, MS-21 and C919, each of which will be newer designs than the 737 and A320 family, and offer advanced technology. Playing leapfrog will be necessary. The question is to what degree?
How radical might the break from tradition be? The following illustrations provide a clue to what advanced design teams are thinking.
Next generation engines like the GTF from Pratt & Whitney will continue to evolve. Placing large fans atop, rather than beneath the wing of an aircraft is possible. While open rotor engines have promise, their drawbacks of noise and lower speeds may preclude their immediate impact. Hybrid-electric propulsion is viewed as a serious option, and Airbus has a small two-seat electric aircraft that is a research tool. While a full hybrid may not be possible, electric motors could provide ground taxi and systems operations for the aircraft.
The world moved from four-engined aircraft to twin engined aircraft due to more efficient engines and maintenance cost. But what if that could be turned around, and smaller engines be made more efficient and reliable than larger ones? Could we see a return to multiple engine configurations? Researchers at one major engine company believe that it may be possible to optimize the performance of next generation aircraft with multiple engines, particularly as engines become more reliable and advanced monitoring systems can predict failures and maintenance requirements in advance.
The 787 and A350 have pushed the frontiers for the use of carbon-fiber reinforced plastics for structural components on aircraft. The next generation of composites will only improve upon the strength to weight ratio of these materials, and will likely see costs come down as manufacturing processes become more efficient. Processes that were once manual lay-up of composites have transitioned to resin transfer molding for some applications, like wings, and in future will focus on improving the manufacturing processes for composites, including out of autoclave manufacturing. Material science continues to improve the strength to weight ratio, critical for aerospace applications. Some names to watch include Cytek, Henkel, Hexcel, and Toray as composites become a viable alternative to aluminum.
The promise of additive manufacturing is the ability to create metal components of unusual design by building them up, rather than cutting away metal. This enables creating parts that can specifically perform a function while minimizing weight. Because the material can be built up, specific requirements can be met more cost-effectively. Of course, designing the parts requires an entirely different way of thinking for engineers, most of whom were trained to cut a block of metal rather than create a part by building it layer by layer.
Currently, additive manufacturing processes are rather slow, with some small components requiring eight or more hours in an expensive machine. While manufacturing labor costs are low, as there isn’t much to do other than to load and program a machine, capital and engineering costs remain quite high. But that equation is changing, and with more efficient additive manufacturing will come more efficient parts.
New processes that utilize bars of material rather than powdered metal are enabling additive manufacturing of the equivalent of forgings on a cost-effective basis with reasonable throughput today. In the future, we would expect those processes to improve as well. Competition will increase, and traditional methods of production will soon be in transition.
The objective of an airline is to keep its assets in the air as much as possible, as that is how they earn their keep. Until recently, aircraft haven’t been designed for easy maintenance, nor have systems been in place to monitor components and replace them before delays or cancellations become problematic.
The Bombardier CSeries is the first airplane designed specifically for LRU maintenance, with a hatch for easy access for every LRU on the aircraft. This speeds maintenance and parts replacement, when required, and is unique in its design.
Aircraft and engine health monitoring systems with substantial data outputs and bandwidth are now entering service with the GTF and LEAP engines, CSeries, E2, and other new airframe programs. Generating petabytes of data per year, the key to success will be trend analysis and predictive when components are likely to fail, and taking action before they do to avoid cancellations. Because aircraft have redundant systems, the next generation of management systems will include a cockpit interface to automatically switch away from failing systems to back-ups before problems occur, increasing both reliability and safety of flight.
Designing aircraft for maintenance may also result in “quick change” components that can be more easily accessed, on slide-out racks for removal, and wired into the aircraft via connector junctions that save time in removal and installation. Once ignored, aircraft mechanics are becoming a key input source for future designs.
While looking out a window is always fun while flying, windows create drag and inefficiency. Cameras could project what you are flying over onto the sidewall, making it just as effective as a window. The dramatic advances in communications and audio-visual technologies will enable new passenger experiences. Imaging overlaying a map on a view outside the aircraft on the seat-back in front of you; every passenger has a window seat.
As technology continues to improve in storage efficiency, the possibility exists in a few years that every movie ever made in every language could be available on board for viewing. Bandwidth for live television, or even calls or video conferences, could be arranged on-board. Photonics will be the next frontier in communications.
Seating technology can change as well. On a typical wide-body, there is a lot of wasted space between the top of a passenger’s head and the ceiling – typically enough room for additional seats, or at least an upper berth for sleeping. Interior designs will continue to evolve to become even more efficient, and providing more options and revenue possibilities for airline customers.
The Future is Closer than We Think
If Airbus or Boeing decide to take the risk and produce an industry-changing design in the 2030 time frame, the game changes again. And it may be necessary, as by then, Irkut’s MS-21 will be in service and competitive with the A320neo, and the C919 from China will also be in service, and while not expected to be as competitive, will take a portion of the Chinese domestic market. Airbus and Boeing may need a leapfrog to continue their dominance of two large air transportation markets, Russia and China, as their domestic aircraft continue to improve. Commercial aviation has always been a game of leapfrog. The question is who takes the next great leap forward and has the courage to play “bet the company” on a new design?
© 2016, Ernest S. Arvai. All rights reserved.