Its still only a model, but NASAs X-48 recently passed a major milestone with its 100th flight. The blended wing body aircraft is a joint project between NASA and Boeing to explore the flight characteristics of a design that may become the efficient airliner of the future.

We first saw the X-48 three years ago when we spoke with one of the test pilots who fly the 8.5 percent scale model. This is not, however, your typical R/C plane. With its 21-foot wingspan, its packed with a host of sensors much like its larger X-plane cousins. Back then the X-48 was in its B configuration with much of the flight testing aimed at learning more about the slow speed flight characteristics typical of take off and landing.

The current model, X-48C, is the same plane but modified to investigate noise-shielding concepts with a blended wing body design. The goal is to make airplanes that are quieter on the ground. One key change being tested is mounting the engines on top of the fuselage and shielding them with both the horizontal and vertical tail surfaces.

The first 92 flights of the X-48B used three small, 50-pound-thrust turbojet engines that extended beyond the back of the aircraft. Eight more recent flights, including the milestone 100th, with the X-48C used two 89-pound-thrust engines. The vertical surfaces that had been winglets on the X-48B were moved to the tail, and the back of the aircraft was extended two feet to completely shield the engines from the ground.

Reducing the noise footprint of airplanes, especially airliners, is a key driver of new aircraft designs. Boeings newest airplanes, the 787 and 747-8, and the Airbus A350 incorporate several features aimed at making them quieter from the perspective of people on the ground.

NASA says the joint X-48C research project with Boeing will likely include 20 more test flights before the blended wing body program is completed. With funding tight, its looking like the agencys plans for a 737-sized, piloted blended wing body X-plane are going to be put on hold.

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NASA ’s Mini X-Plane Marks a Milestone