AEDC testing brings unique blended wing aircraft closer to flight

  • Published
  • By Philip Lorenz III
  • AEDC/PA
ARNOLD AIR FORCE BASE, Tenn. --  The Air Force has big plans for the Blended-Wing-Body (BWB) concept, an unconventional-looking aircraft that resembles the B-2 Spirit bomber -- a flying wing, but with smoother mold lines and a more conventional nose.

Engineers and technicians at the U.S. Air Force's Arnold Engineering Development Center (AEDC) recently concluded aerodynamic tests on a two-percent model of the BWB aircraft in the center's 16-foot transonic wind tunnel (16T), bringing it closer to a full-scale flight capability. The BWB has significant potential as a future military aircraft.
The primary objective of the recent testing was to provide external aerodynamic data to evaluate the flight characteristics of the BWB at higher Mach numbers than those applied to the same model earlier in the year at NASA Langley's National Transonic Facility in Virginia.

"The testing at AEDC was conducted to collect some of the higher Mach number data points for this blended body configuration at non-cruise speeds," said Dan Vicroy, research engineer with NASA's Flight Dynamics Branch at the NASA Langley Research Center. "We subjected the model to some subsonic flows, but mainly this test covered transonic speeds."

Testing in 16T began with the model of the BWB in a "clean-wing" configuration, minus engine nacelles and winglets, according to NASA Research Engineer Melissa Carter.

"We always start off with a clean wing," she explained. "Later we added the winglets, then the pylons, engines, all in stages. What we were looking for was a buildup, a drag cost. We wanted to determine what these components will add to the drag. We were looking for both the cumulative and incremental effects on drag for this aircraft."

This cooperative Air Force/Boeing/NASA test was sponsored by the Air Force Research Laboratory (AFRL). AEDC Air Force Project Manager 1st Lt. Ezra Caplan said the coordination between center and NASA engineers was critical in the success of the project.

"This was a team effort in every sense of the word - in both planning and test operations, we were operating on a limited schedule and Air Force Research Laboratory (AFRL) and NASA were operating under a tight budget. ATA Project Engineer Randy Hobbs and his test team worked very closely with the NASA engineers to ensure that we prioritized data requirements and best accomplished the program's objectives. The end result was a very successful test, and both AFRL and NASA were pleased with the center's efforts."

A BWB test vehicle designated the X-48B by the Air Force, soon will begin flight testing at Edwards Air Force Base in California. The unmanned X-48B, which has a 21-foot wingspan, is the result of collaboration between Boeing Phantom Works, NASA and AFRL. Phantom Works is Boeing's advanced research and development organization, which works closely with all Boeing business units, including Boeing Integrated Defense Systems.

According to NASA engineers, the aircraft's Blended Wing Body offers greater structural, aerodynamic and operating efficiencies than the more conventional tube-and-wing design. In essence, the aircraft's design increases lift and reduces the overall drag during flight.

The modular design of the BWB will provide significantly more volume for cargo capacity and will also translate into greater range and improved fuel efficiency. The blended wing body shape will allow for a wide variety of potential military applications, including as a cargo/personnel transport and a refueling tanker.

According to Dennis Carter, aerospace engineer for the Air Force Research Laboratory's Air Vehicles Directorate, the Air Force is considering the BWB to serve as a military tanker with two refueling points and automated refueling capabilities.

"A blended wing body tanker would be able to accommodate simultaneous air-to-air refueling of multiple conventional aircraft or UAVs," he said.

Fuel for the BWB could be carried in wing tanks, leaving room in the body for pallets and troops. In addition to fuel efficiency the blended wing body design would offer significant noise reduction, according to engineers.