Edwin Wallet/TU Delft

TU Delft

TU Delft

Guus Schoonewille

Dutch airline KLM turned 100 earlier this month and decided to give itself a birthday present: a shiny, sleek, futuristic-looking, sustainable aircraft. Or at least the possibility of one in 2040. "This could be the next thing," says Dr. Roelof Vos, professor of flight performance and propulsion at Delft University of Technology and the head researcher on the Flying V project. "It at least deserves some investigation."

The Flying V, touted in press releases as "revolutionary," is what is known as a blended wing body, or BWB, aircraft, a design with no distinct wing and a body structure like more conventional aircraft. The shape reduces drag, which means the plane needs less fuel to operate. TU Delft claims the Flying V will consume 20% less fuel than a similarly sized traditional aircraft. "These are estimates," cautions Vos. "We still have 5-10 years of research before we could test a full-scale aircraft."

The design of the Flying V wasn't invented by Vos or even TU Delft or KLM; it was the idea of a Technical University of Berlin student, Justus Benad, working on his thesis project at airplane maker Airbus. He tested a scale model in 2014, and Airbus patented the design but didn't move further on the project. Vos saw the concept in a news article in 2015 and wondered if Benad's calculations were accurate. "I was skeptical," he said. He had two students review the concepts, one of whom went to Berlin to meet with Benad, and, together, they concluded the concept had potential.

Blended wings are rare in the military, let alone civilian aviation

There have been BWBs in use, just not on the commercial market. Lockheed's Blackbird family (A-12, YF-12, and SR-71), which first flew in 1962, was a blended wing design. But it was a Mach 3-reconnaissance plane, not a civilian passenger airliner. In fact, all of the other current BWBs have been used in a military capacity, like the Northrop Grumman B-2 or B-21 bombers.

There's good reason for that. As we noted the first time we saw the Flying V, all planes bank as they turn . In a traditional aircraft, no part of the plane is ever significantly removed from the pivot point. But in the Flying V design, passengers sit in the plane's "wings," which means they would experience significantly higher g-forces.

The Flying V addresses this issue by putting the passengers toward the leading edges and their baggage closer to the wingtips. The researchers have conducted some preliminary testing with Airbus on the forces a passenger would experience and found it within the range of comfort.

Should the Flying V become a passenger aircraft, more than the location of baggage would change. In fact, the entire interior would need a redesign. Which is why another department at TU Delft is involved: Industrial Design Engineering. Professor of Applied Ergonomics and Design Peter Vink has worked on some concepts for how to rethink the passenger compartments to improve comfort.

His group quickly ran into another problem. If passenger seats are lined up as they would be on a traditional aircraft, the seats sit at a 37-degree angle from the direction of flight. Under current airline regulations, all of the seats would require a special harness for passenger safety. That, of course, means more weight, which would increase fuel consumption.

Vink and his colleagues have proposed a number of solutions to this issue, including arranging the seats in a herringbone pattern that is often used in business class. "But that means the person behind would be looking directly at your screen," says Thomas Rotte, an industrial design engineer working on the project with Dr. Vink. In testing, that's something passengers say they don't like. So they are working on other solutions, including bench seats like those commonly seen on trains, and even beds. "Laying down is possible because of the Flying V's interior shape," says Rotte.

The wing is an oval, but while in flight, the pressure would force that to contort into a circle. To combat this, the Flying V will need a rectangular-shaped frame in the interior to hold it in place. When you put a square peg in a round hole, you get some leftover space on either side. One current proposal would be to slide the head of the beds into that space, creating enough room for three bunks.

Landing needs some work

There are other issues the researchers still need to work on. Glide, for one. Commercial aircraft can glide incredibly long distances if they lose engine power and can use this momentum to safely land—this is known as a dead-stick landing. In 2001, an Airbus A330 lost power to both engines due to a fuel leak and glided 75 miles for 19 minutes without power to land safely. The problem with the Flying V is that it glides too much. In the current design, the wings have no flaps and so creating enough drag to slow the plane down enough to land is an issue Vos and his team will need to address.

Take-off and landing create another problem for the Flying V. Most passenger planes take off and land at an angle of 2 to 3 degrees, and even the maximum angle of attack (for example) of a Boeing 747 is just 10 degrees. Commercial airframes are capable of more extreme flying—Boeing wowed spectators at the Paris Airshow in 2015 by showing off a maneuver with a 787 Dreamliner that had it climb nearly vertically. But then it wasn't carrying any passengers or cargo; the Flying V will need to take off and land at a 20-degree angle, which will be a big adjustment for passengers and pilots.

Another likely issue is engine maintenance, since the Flying V's engines are on the top of the airline whereas on most other airplanes, they are underneath. Both the DC-10 and the MD-11 have their engines on the top. "It is a worry," says Vos. "It's fine in New York or here at Schiphol, but the Flying V is intended for long-haul flights, and some operators may not be familiar with the ins and outs." They will at least be able to park the planes—it's the same width as an A350.

Vos and his team have built a 9-foot (3m) scale model of the design, powered by a pair of 4kW electric ducted fan motors to test out the radical design. The model was ready for exhibition earlier in October at the KLM anniversary celebration but has now returned to the university to be prepared for flight testing, which they hope to undertake later this year.

Ultimately, the Flying V is presented as a greener airplane. A 20% reduction in fuel usage is an improvement. But the Dreamliner also uses around 20% less fuel than comparable aircraft, a feat it accomplished by reducing weight through extensive use of composite materials. "The Flying V is only part of the solution for climate change," says Vos. Critics have argued that in order to truly combat the planet's rising temperatures, we all need to fly considerably less. But commercial aviation is an industry that's growing, not shrinking. So anything that can reduce its emissions is a good thing.

Listing image by Edwin Wallet/TU Delft