A joint NASA / Boeing team has completed the first phase of flight testing of the X-48B scaled-down flying wing model at Dryden Flight Research Center [California]. The unmanned, 227-kilogram hybrid wing aircraft with a manta ray silhouette is being developed as part of NASA's Environmentally Responsible Aviation [ERA] project, which aims to develop the technologies needed to create quieter, cleaner [emissions] and the fuel-efficient aircraft of the future.
Flying Laboratory - X-48B allows NASA to test and evaluate key technologies. The passed tests revealed the aerobatic and flight qualities of this type of aircraft at speeds typical for takeoff and landing.
“This project is a huge success,” says Fay Collier, ERA Project Manager. "Bottom line: The team has proven the ability to safely fly tailless aircraft in the low speed range." Until recently, Collier was NASA's Principal Investigator for the Fixed Geometry Subsonic Wing Project, which marked the beginning of a relationship with Boeing to develop the X-48B core technology. The ERA project is part of NASA's research program to develop advanced technologies before transferring them to industry.
NASA and Boeing complete first phase of flight testing of X-48B miniature flying wing
On March 19, 2010, the team completed the 80th and final flight of the first phase of the project, which was launched almost 3 years ago on July 20, 2007. In addition to NASA and Boeing, the team includes the British company Cranfield Aerospace and the US Air Force's Dayton Research Laboratory.
In the mid-2000s, NASA determined that low-speed flight control for a given wing geometry was a design challenge. This problem and the task of constructing a non-cylindrical pressurized fuselage have been the starting points of research work since then. The ultimate goal is to develop technology for environmentally friendly aircraft that produce less noise, burn less fuel, and emit less harmful gases.
“These 80 exploration flights provided the engineers with invaluable data to enable the team to complete the full initial test cycle,” said Tim Risch [Tim Risch, Dryden X-48B Project Manager]. The team focused on three main goals: expanding the range of operational modes of flight, determining flight performance, testing the limiting software of the aircraft control system.
The first goal [widening the range] was realized on 20 flights in one year. During these flights, the aircraft conducted various air maneuvers to determine the overall flight capabilities, overall stability, and flight characteristics.
The second objective [performance] focuses on stall testing to determine the boundaries of controlled flight, engine off maneuvers to determine aircraft control in the event of one or more engine failure, and flight parameters identification to assess how flight control movements affect aircraft behavior. …
On 52 flights between July 2008 and December 2009, engineers determined the aircraft's dynamic performance by sending computer commands to the X-48B's flight controls and measuring how quickly the aircraft responded to an input signal.
The third and most important target was "combat" with the limiter, where the remote pilot deliberately exceeded the specified controllability limits [eg angle of attack, lateral slip, and acceleration] to test whether the aircraft's computer could keep the flight steady. Eight test flights confirmed the functionality of the software limiters and gave the team confidence that a reliable, flexible and safe control system could be developed for this type of aircraft.
Testing of the X-48B will continue this year, after installing and testing a new computer. The next series of flight tests will focus on additional studies of identification of flight parameters.
NASA has a second hybrid-wing aircraft, the X-48C, which has even lower noise levels than the X-48B. Flight tests are being prepared to determine other controllability factors.
