European research centers have begun studying a runway system that would assist takeoff and landing of a theoretical commercial aircraft without landing gear. One of those research centers, France-based Onera, also envisions a different tradeoff for a blended wing body (BWB), where the needs of passenger transport represent a higher priority.
European project Gabriel (an acronym for integrated ground and onboard system for the support of aircraft safe takeoff and landing) suggests using a motorized cart, onto which the fuselage would attach and be supported by a magnetically levitating sledge. At takeoff, the vehicle would help the aircraft accelerate down the runway. The airframe would detach at V2 (initial climb speed). At landing, the vehicle would levitate down the runway and position under the aircraft. The moving platform would synchronize its speed, as well as pitch and yaw angles, with the aircraft, Antoine Guigon, Onera's aerospace department director of foresight, said during a press briefing organized by the French association of aerospace journalists in Paris. The aircraft would then harpoon the cart. The cart would be used for taxiing, the sledge staying on the magnetic track.
The weight benefit, if one only takes into account the removal of the landing gear, amounts to 6 percent, according to Guigon. “However, if you re-optimize the aircraft's design, you cut fuel burn by 18 percent,” he said. Certification would present a major challenge, as would identifying who would pay for the ground vehicle. REA-Tech Hungary coordinated the three-year, €3 million ($3.4 million) study.
Meanwhile, Onera's proposed timeline for future aircraft configurations suggests 2045 could see the entry into service of a blended wing body. As opposed to other concepts, the artist's rendering depicts a distinction between the fuselage and the wing, thereby allowing for a taller cabin, where passengers can stand. Moreover, the more circular the cross-section, the easier the pressurization. Other BWB concepts show very flat fuselages, where pressurization would call for heavier reinforcement of the airframe, according to Guigon.
Onera's concept calls for an 80-meter (262 feet) span. It would occupy a class of airliners including the Airbus A350-1000, at 400 passengers, 8,000 nm of range and a Mach 0.85 cruise speed.
Guigon emphasized the need for demonstrations. “Such a concept increases the empty weight; will it be offset by the improved aerodynamics, the lifting body and the buried engines?” he asked. The industry now needs to decide on whether the BWB is a valid concept for the future, he concluded.