One of the topics that we cover in the Aerodynamics lecture within our MIT Private Pilot Ground School (link to all of the slides and videos) is the industry inertia that results in all airliners looking more or less the same: tube plus wings.
It turns out that this is not an efficient way to build an airplane. The most fuel-efficient approach is a “lifting body” in which the fuselage is optimized to produce lift. With aluminum-and-rivet construction these probably haven’t made sense commercially, but now that airliners (e.g., Airbus A350 and Boeing 787) are made from composites, the complex shapes of a lifting body airliner might not be dramatically more expensive to fabricate.
Who is crazy enough to try to turn the academic dream into a commercial reality? KLM:
The Dutch national airline announced that it is helping fund the development of the Flying-V, a lifting-body-esque flying wing aircraft designed by Delft University of Technology student Justus Benad.
The designers say the Flying-V will use 20% less fuel than an Airbus A350 while carrying about the same number of passengers, 314. Roelof Vos, project leader at TU Delft, highlights the Flying-V’s efficiency as an important component of an industry eventually headed toward electric propulsion. According to CNN, Vos claims that ”aviation is contributing about 2.5% of global CO2 emissions, and the industry is still growing, so we really need to look at more sustainable airplanes. We cannot simply electrify the whole fleet, as electrified airplanes become way too heavy and you can’t fly people across the Atlantic on electric airplanes—not now, not in 30 years. So we have to come up with new technologies that reduce fuel burn in a different way.”
These folks are taking the long view:
A flying prototype is promised by October 2019, but the design isn’t expected to enter service until 2040.
It might not be an efficient way to fly an airplane, but maybe it is an efficient way to build one. All the parts of one can currently be shipped via rail or guppy style aircraft, allowing for distribution of production. A large lifting body will only be able to be shipped by a larger lifting body (or perhaps a space shuttle transporter) kind of setup.
I think these things would have to be built like ships, laid down in giant cleanrooms with giant vacuum autoclaves nearby, and they would have to be finished on the site. I guess airliners are the kind of thing where it doesn’t matter so much were they are actually constructed, but this would most certainly centralize things. I wonder if Scaled Composites is ready for this kind of thing?
https://www.reuters.com/article/us-boeing-derailment/boeing-737-fuselages-damaged-in-train-derailment-idUSKBN0FA0QD20140706
Beechcraft went bankrupt engineering the composite “Hawker 4000”. Then Cessna bought their assets, built the same jet with the same specs but made it out of aluminum and called it the “Longitude”. There must be a reason Cessna chose not to continue with composites…
Bowing did the math and rejected this idea when they inherited such a project in an acquisition.
A passenger compartment has to be high enough to accommodate standing men in the 95 percentile of height. Add to that overhead luggage and underfoot “plumbing.” That wing/body thickness reverberates out to the overall dimensions of the aircraft.
Verdict: It only works on huge capacity planes, for which there is no market.
They also considered freight-only planes. Loading was the bottleneck there, as well as problems with the smaller airports that freight often goes to.
Another problem: during normal angle banking turns, passengers away from the center axis are being zipped up and down quickly. Bring back barf bags!