Geschichte des Instituts

History – Road Map of Events: 1974-1979

1974-1998 Memorandum of Understanding (MoU) USAF-BMVg/DLR: Aircraft Flight Control Concepts. Common simulation and flight test programs with USAF Flight Dynamics Laboratory (FDL) and Edwards Air Force Base and side-by-side located NASA Dryden Flight Research Center undertaken under this MoU. They included direct lift control effects on steep landing approach flight tests at Braunschweig airfield with the HFB 320 DLC demonstrator aircraft supported by an early TALAR MLS flight path guidance system (1976), and pilot evaluations of time delay and reduced stability effects on handling qualities with LAMARS simulator, Calspan NT-33A variable stability aircraft, and the airborne simulator HFB 320 FLISI. GRATE/ATLAS flight test techniques for unmasking handling qualities deficiencies developed and applied to a variety of test aircraft such as NT-33A and X-29 (1984-87).

USAF and DLR MoU project officers with variable stability aircraft NT-33A
1975 Memorandum of Understanding US Army-BMVg/DLR: Helicopter Flight Control established. Since 1986 changed to Helicopter Aeromechanics. This MoU will eventually become one of the most successful transatlantic basic research activities in the fields of helicopter flying qualities, flight/ rotor control, noise phenomena, crashworthiness, and unsteady aerodynamics involving US Army, NASA Ames and Langley Research Centers, as well as up to five DLR Institutes at Braunschweig, Göttingen, and Stuttgart Research Sites. German industrial participation is later initiated by ZFL- Kassel and supported by the Institute leading in the year 1993 to the IBC (Individual Blade Control) experiment in the NASA-Ames 40x80 ft wind tunnel facility with a full scale Bo 105 rotor which is controlled by high bandwidth hydraulic actuators designed by ZFL.

Bo 105 IBC experimental set-up of ZFL in NASA Ames 40x80ft wind tunnel (1993)
1976 First publication and flight testing of DLR´s 3211 control input signal (Koehler-input). The 3211 multistep input is a series of four contiguous steps with alternating signs lasting for 3, 2, 1 and 1 time units. The length of the time unit is adjustable to center the frequency band of the input around the flight vehicle natural frequency. This input signal is relatively easy to fly by pilots and accepted by the international flight test community for parameter estimation purposes.

1976-1980 Do 28 TNT flight demonstration of an Open-Loop-Gust-Alleviation (OLGA) system designed for the Do 228 commuter aircraft. This project included a unique and comprehensive correlation and validation process of data from analysis, wind tunnel, and flight test (cooperation with Dornier and IMFL).

Do 28 TNT OLGA wind tunnel model aircraft and flight demonstrator
1977 First in-flight simulation with HFB 320 FLISI. This test aircraft was used until 1984 for various flying qualities investigations including effects of direct lift control, reduced stability, and flight control time delays.

In-flight Simulator HFB 320 FLISI with swept forward wing and fly-by-wire control
1977-1978 In-flight simulation of an A310-type wide-body configuration in the landing approach mode with airborne simulator HFB 320 FLISI. First use of a digital model following control law with explicit model calculation.

1978 First flight tests with DLR´s new research helicopter Bo 105 S-123 for the definition of handling qualities maneuvers, investigation of control strategies, and system identification purposes. Several transatlantic flight test campaigns followed to generate flying qualities databases for future helicopter systems. The complementary use of simulation facilities and research helicopters strongly enhanced the research productivity (cooperation with WTD 61, US Army, and NASA).

Bo 105 S-123 (DLR) and UH-1D(WTD 61) with integrated test team of DLR / NASA / WTD 61
1979 First test entry of modified rotor test rig ROTEST in the large German-Dutch Wind Tunnel (DNW). This was also the first customer-paid DNW test program altogether. Due to its unique aerodynamic and aeroacoustic qualities, it was decided by the Institute to conduct all future rotorcraft model testing at DNW. For this reason a special DNW sting adapter was replicated and integrated in the DLR Test Preparation Facility at the Institute in Braunschweig.

(l.)Floor-mounted rotor test rig ROTEST in DNW (1982) (r.)Advanced rotor blade (LAH) testing in DNW with sting-mounted ROTEST (1989)

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