Like most people with a conservative engineering mindset, I usually assume that major commercial technologies are designed to work reasonably close to the limits of current fabrication technologies (currently practical materials, subsystem performance, etc.). Then something like this comes along:
…an MIT-led team has designed a green airplane that is estimated to use 70 percent less fuel than current planes while also reducing noise and emission of nitrogen oxides (NOx)….the MIT team designed two versions: a higher technology version with 70 percent fuel-burn reduction, and a version that could be built with conventional aluminum and current jet technology that would burn 50 percent less fuel and might be more attractive as a lower risk, near-term alternative.
(MIT News, 17 May)
A new configuration with better aerodynamics, and a reminder that hundred-billion-dollar-scale opportunities are sometimes unexploited.
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“a reminder that hundred-billion-dollar-scale opportunities are sometimes unexploited”: makes me wonder what other examples there are from history of massive opportunities that went unexploited for a long time. Financial innovations come to mind, e.g., the creation of the stockmarket could presumably have occurred much earlier than it did.
The 2 MIT planes do not look that innovative compared to designs that have been looked at in history. Would these designs fail to shape future aircraft design as well, for similar reasons – expensive to construct, unrealized efficiency gains, etc.
I would be more interested to know why blended wing aircraft that have been touted for efficiency for many decades have never taken off. One assumes engineers have seriously looked at the designs and major airframe manufacturers are always looking for a more fuel efficient, and preferably cheaper design to compete with.
I suspect that there may not be an unexploited area at all.
Is it clear that these designs rely only on current fabrication technologies? According to the article they’re targeted at 3 generations of planes out, serving the needs of 2035.
If the designs do rely only on now-current fab, they’ll be unoptimized for then-current fab, ie perhaps not a good example of design-ahead.
Well, a design is a design is a design. Last year, the magazine Air&Space Smithsonian did a story on “The Perfect Airplane,” hypersonic, green, and quiet. As if!
>http://www.airspacemag.com/flight-today/The-Perfect-Airplane.html
@ Tolley —
The MIT team also designed a blended wing-body aircraft of the sort you describe:
These may be problematic because of greater differences in the structural design, and (in a literal, geometric sense) not fitting existing airport and related infrastructure.
It’s natural and well-motivated to doubt any particular apparently-large opportunity is both real and unexploited — as I said, I usually doubt it too. Aerospace is a bit odd, however.
Having been a grad student at in Aero-Astro at MIT, I have some familiarity with this area (but maybe a bit of bias regarding MIT studies…), and I’ve long been impressed by the conservatism that results from the interaction of large aerospace corporations with regulatory bodies.
The history of drag reduction using “winglets” is illustrative. Winglets are about as un-radical as they look:
Note that there are no moving parts, and little or no added bending moment.
Winglets can reduce drag by ~4% — quite a lot, for a small increment of physical innovation — yet they didn’t reach large passenger aircraft until 1990, after decades of gestation.
@ Linksvayer —
Re. the adequacy of current manufacturing technology, the NASA spec did call for designs 3 generations ahead, and a 70% reduction in fuel consumption, but I’m referring to what MIT describes as the “version that could be built with conventional aluminum and current jet technology that would burn 50 percent less fuel and might be more attractive as a lower risk, near-term alternative.” This is intended “to replace the Boeing 737 class aircraft”.
As I mentioned above, I come from of an MIT aerospace background, and although I’m at least a bit skeptical of the proposed wing improvements (fancy structures, fancy aerodynamics…), the practicality and weight advantages of the fuselage design seem pretty obvious. These result directly from a reduction in pressurized volume per unit floor area, achieved in a wider body with a structure remarkably similar to that of traditional single-tube designs.
@ Regis —
Indeed. There hasn’t yet been a hypersonic jet that can carry a pilot. Not even experimental, and not for lack of yearning.
The materials problems are really bad.