NASA backs X-plane development of twin-hull Aurora D8 airliner

NASA backs X-plane development of twin-hull Aurora D8 airliner
Artist's concept of the Aurora D8
Artist's concept of the Aurora D8 
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The Aurora D8 has embedded engines
The Aurora D8 has embedded engines
Artist's concept of the Aurora D8
Artist's concept of the Aurora D8 
The Aurora D8 taking off
The Aurora D8 taking off
Aurora D8 infographic
Aurora D8 infographic
The Aurora D8 could enter service by 2027
The Aurora D8 could enter service by 2027
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In February, NASA announced that it wanted to use its New Aviation Horizons program to revive the famed X-plane that did so much to advance post-war aviation. Now the agency has awarded a six-month US$2.9 million contract to Manassas, Virginia-based Aurora Flight Sciences to develop a scaled demonstration version of its Aurora D8 subsonic commercial airliner. Described as "changing the paradigm," the D8 is designed to significantly improve airliner performance by 2027.

According to Aurora, the D8 takes its inspiration from the famed Boeing 707 of 1958, which not only introduced the public to single-day world travel, but also used a tube-wing design that redefined passenger aircraft. The first commercially successful jetliner, its swept-back wings, in-wing fuel tanks, and pylon-mounted engines set the standard so that essentially, all modern commercial airliners are derivations of the 707.

Unfortunately, Aurora contends that the 707-based aircraft have reached the law of diminishing returns and are only improving in fuel efficiency at a rate of 1.5 percent per year. The D8 is designed to avoid this problem by recreating the 707's integrated design approach while drawing on Aurora's work on NASA's N+3 Program to produce advanced concepts for subsonic and supersonic commercial transport aircraft.

The resulting D8, named after its chief designer Mark Drela, takes a step forward in airliner design by taking a step backwards. Instead of a narrow fuselage, the D8 uses a "double bubble" fuselage made of two conjoined hulls similar to that on the old Boeing 377 Stratocruiser of the 1940s. Only in this case, the twin hulls have been laid on their side to make a very wide twin-aisle fuselage.

This design not only provides much more interior room than a 737-800, but it also allows the fuselage to act as an airfoil and provide extra lift. Along with composite materials, smaller, embedded high-bypass engines at the rear of the fuselage that improve thrust efficiency due to Boundary Layer Ingestion (BLI), the new fuselage saves weight by allowing for smaller wings and reduces drag by combining fuselage wake and engine thrust.

Aurora says that the D8 is designed to fly at Mach 0.764 (582 mph, 936 km/h) with 180 passengers over a range of 3,000 nm (3,500 mi, 5,500 km). The company also says the design has the potential to cut fuel burn by 71 percent, reduce noise by 60 EPNdB, and cut LTO NOx emissions by 87 percent compared to a best-in-class Boeing 737-800 narrow-body aircraft.

As part of the NASA contract, Aurora will build test components as the company develops a 1:2 scale demonstrator X-plane over the next three years. Aurora says that the D8 could enter commercial service by 2027.

Source: Aurora Flight Sciences (PDF)

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"cut fuel burn by 71 percent" I would fast track that project.
Very good job ! (Figures to be confirmed !)
I think it's a fantastic concept. But unless they incorporate the detachable cabin/parachute concept I've seen elsewhere, I wouldn't want to fly in one. It never gets much coverage, but every now and then, engines "grenade" and tear apart their housings. Usually, the plane can land safely, since the other engine(s), on the other wing, is(are) unharmed by this explosion. Since these two are integrated into the rear of the plane, side by side, such a failure will be catastrophic. One engine shredding, will likely shred the other, leaving the plan completely powerless. Also, it's incorporated into the tail structure, meaning that it could severely damage the rear of the fuselage, leaving the cabin compromised, and the plane completely uncontrollable. Not trying to be a "negative Nancy", but looking at all contingencies, this plane is very unsafe, in my opinion. If there is no cabin separation with parachutes, this plane should never be allowed to be produced as a passenger aircraft.
uncontained engine failure in 1 engine takes out both engines ..I hope the wings can flap fast enough
Imran Sheikh
the design seems to be flawed. compared to central wing design, this design will take greater time to pull the Nose up since the action is to be done by Elevators pushing the tail down while jets will continue to push the plane straight and the main wings being in the back making it a really dis-balanced nose heavy design. or we can sey this design will only land safely in higher speed. this will make the Landings very critical.. to Fix this the front section needs a set of tiny wings 40% thickness of fuselage to safely land this design even in lesser velocity.
Edward Vix
zr2s10 and Michael Cox have make a very good critique regarding safety. Even a Kevlar shroud around the engine nacelle would be insufficient to protect against what I believe is called uncontained engine failure.
Nice concept however..... Boondogle.
No Boeing, McDonnell Douglass, Lockheed? You know, people who build REAL airplanes. NASA has hired a model maker.
A tax waste.
With both engines tucked up above the fuselage and in between the vertical stabilizers, maintenance would be a pure nightmare. Aircraft designers can draw pretty pictures, but they need to consider what it's going to cost to maintain REAL airplanes under REAL operating conditions.
Derek Howe
The double bubble fuselage concept has existed for awhile now. But it's not better then the BWB (Blended Wing Body) design. Their should really only need to be 2 plane designs for passengers. Long & skinny with swept wings for supersonic air travel, and stubby BWB planes for subsonic travel. Money in anything else is frivolous.
alan c
Instead of believing armchair critics who never built anything, listen to Mark Drela explain the concept here; the double-bubble explanation starts at 8 mins.