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.> . .... -- -I ' --. , S- Transportation Aircraft Flutter Testing slogan for Dynamic Engineering Inc. (DEI) is When activated, the DEI Flutter Exciter alternately "mobilizing minds and materials in research and deflects the airstream upward and downward in a rapid development for land, sea, air, and space." That manner, creating a force similar to that produced by an blend of talent and technology came together in 1972 to oscillating trailing edge flap. Because the system runs on establish DEI of Newport News, Virginia. The core of very little electrical power, rather than tapping into an early work by the company was building aircraft models aircraft's hydraulic system, several benefits are realized. for wind tunnel testing at Langley ~ese&chC enter. Among them, because the DEI flutter components are a During his 34-year employment at Langley, Wilmer "strap-on" type of hardware, cost and complexity of Reed gained international recognition for his innovative fitting the system on the aircraft can be lessened. The research, contributions and patented ideas relating to DEI Exciter is readily adaptable to a variety of aircraft. It flutter and aeroelasticity of aerospace vehicles. In the is effective on all fued wing and rotorcraft applications, early 1980s, Reed retired from Langley to join the from single-seater to airliner-sized vehicles. engineering staff of DEI. While at DEI, Reed recognized DEI sub-scale flutter exciters are also available to the need to increase the safety and minimize the cost incorporate into wind tunnel flutter models, permitting and hazards associated with aircraft flight flutter testing. an aircraft builder to pre-qualify a vehicle design. He thus conceived and patented the DEI Flutter Exciter, In recent years, DEI used its skills to fabricate a now used world wide in flight flutter testing of new or complete set of fan blades for the National Transonic modified aircraft designs. Facility (NTF) at Langley. DEI has applied its ideas on The Flutter Exciter system provides dynamic force suspension techniques to NASA work on large, flexible input to stimulate structural vibration modes of an space structures. More than 1,000 tasks have been aircraft in flight, and through all its flying conditions. completed for Langley alone. Employed by NASA This innovative product generates programmed sinusoi- Ames-Dryden, the employee-owned group was also dal forces at controllable frequencies, amplitudes, phases contracted to work on NASKs F-1GXL flight test and sweep durations. By inducing these forces, structural program. vibrations on the aircraft can be damped. Twenty-five years after creation, DEI has grown to The DEI Flutter Exciter is controlled directly by the several hundred employees with $20 million in annual pilotloperator through a digital Cockpit Control Box sales and has expanded its aerodynamic analysis tech- and Avionics Box electronics and software. The Exciters niques to justify its company claim: "Where imagination are powered by DC servo motors through interconnect- takes shape." ing cables. Small fued vanes are mounted at the wing tips and tail tips of an aircraft. 1 Dynamic Engineering Znc. 5 Flutter Exciter mounts at the wing tips and tail tips of an aircraft to damp out structural vibrations.