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The U.S. Army is looking to improve its aviation technology and recently called upon the Arnold Engineering Development Complex – National Full-Scale Aerodynamics Complex (NFAC) at Moffett Field in Mountain View, California, to advance this effort.
Engineers from Sikorsky Aircraft Corporation and The Boeing Company, in partnership with the U.S. Army Combat Capabilities Development Command Aviation & Missile Center Army Aviation Development Directorate, recently conducted a series of tests at NFAC to support the development of the SB>1 Defiant, a military helicopter being developed for the Army’s Joint Multi-Role Technology Demonstrator (JMR TD) program.
The goal of this wind tunnel test was to validate the aerodynamic performance and flight mechanics of Sikorsky’s X2 Technology aircraft. These configurations, which are being utilized on the SB>1 Defiant, include a lift-offset coaxial rotor system, composite fuselage and rear-mounted pusher propulsor that provides increased speed.
The SB>1 Defiant, which made its first flight in March, is a technology demonstrator for a medium-lift utility helicopter. Future uses of this type of air vehicle could include attack and assault, troop transport or medevac.
The testing was conducted throughout the first half of 2019 and concluded in mid-June. To accomplish the tests, a 1/5 scale model of the SB>1 Defiant airframe with powered coaxial main rotors was placed in the NFAC 40- by 80-foot wind tunnel.
Measurements included forces and moments on the various components, as well as fuselage, empennage and blade surface pressures.
David Wang, NFAC test engineer, said the recent tests expanded on data collected from a JMR wind tunnel entry conducted at NFAC in 2016 by gathering data at faster speed ranges.
“From the NFAC perspective, the wind tunnel test was successful,” Wang said. “The test customer was able to collect performance and handling qualities data for their subscale model up to their maximum design flight speed.”
Data collected during the recent tests is undergoing review and analysis. It is unknown at this time if there will be future testing of the SB>1 Defiant model at NFAC.
The full-scale SB>1 Defiant flight demonstrator is currently undergoing ground and flight tests at Sikorsky’s flight test facility. According to the Sikorsky-Boeing JMR Team, data from SB>1 Defiant will help the Army develop requirements for new utility helicopters expected to enter service in the early 2030s.