German technical experts visit AEDC for discussion on future collaboration

  • Published
  • By Philip Lorenz III
  • AEDC/PA
ARNOLD AIR FORCE BASE, Tenn. --  Some of Europe's top wind tunnel and ground testing experts recently visited AEDC to work with their counterparts here on continuing a data exchange agreement (DEA) between the governments of Germany and the United States that dates back more than 30 years.

"The data exchange agreement we have with Germany is for wind tunnel testing, test techniques, equipment and the like," said Tom Best, AEDC's director of engineering and technical management.

Every two years, Best and other representatives from AEDC collaborate with the engineers and scientists in Germany to discuss new capabilities. He said this year it was AEDC's turn to host the meeting.

"Those are the 'official visits,' [however] there is [also] regular correspondence where we try to work on certain projects in between those visits," Best said. "[During the recent visit] we discussed a lot of things that each of us is jointly working on so we could learn from what each of us are doing. We reported on the past collaborative activities that we've done and we talked about new areas of collaboration."

Past projects have included the Transonic Technology (TST) Wing Demonstrator model that was tested in Europe, NASA and AEDC back in the 1990's.

Best said the two countries compared wind tunnel data and data derived from the use of computational fluid dynamics.

The TST was also known as the German Dornier Alpha jet.

"There was also flight test data on the TST configuration," Best said. "All of us learned lots from those tests about wind tunnel effects on data and about extrapolating wind tunnel data to flight."

Best said another example was AEDC's collaboration on data comparisons between the G-Range free-piston shock tunnel configuration and the High-Enthalpy Shock Tunnel Göttingen (HEG) in Germany.

"We all learned a lot about diagnostic tools that work in that regime and how the flow can be contaminated with the driver gas," he explained.

The HEG of the German Aerospace Center is one of the major European hypersonic test facilities.

Dr. Georg Eitelberg, the director of the DNW, a joint German and Dutch Wind Tunnel organization headquartered in the Netherlands, said his first visit to AEDC occurred around 20 years ago, with subsequent trips to Arnold and also to NASA's facilities over the years.

"The visits were impressive enough for me to return for multiple visits and also to want to expose my younger colleagues to the capacities and capabilities of the AEDC and NASA experimental facilities," Dr. Eitelberg said.

He said that as impressive as all of the facilities are in physical size and technical sophistication, their usefulness is validated by the intelligent people who operate them.

Dr. Eitelberg emphasized the importance of collaboration, using the data exchange agreement as the mechanism.

"Even though the DEA is approximately 30 years old - I believe it is actually 36 years -both parties to the exchange agreement are engaged in continuous development," he explained. "It is mutually stimulating to compare developments and discuss the motivation for priorities. In the case of common interest, further specific collaborative activities can be defined. As examples from recent past, measurement of real gas effects in hypersonic re-entry conditions and benchmarking of PSP (pressure sensitive paint) come to mind."

He also spoke more about his impressions of AEDC and another place his group visited this time around, the AEDC National Full-Scale Aerodynamic Complex (NFAC) in northern California.

"The experimental complexes of the Air Force exceed in size anything we have in Germany and the Netherlands, although we pool our resources," he said. "Nevertheless, with a certain pride, I claim that our people are every bit as capable as those of the AEDC/ATA, and that forms the basis of our long term exchange. Our facilities are smaller than those of the NFAC and the high speed facilities at AEDC, but still large enough to be used in the process of developing new aerospace vehicles, mainly civil transport aircraft."

Dr. Eitelberg said he is optimistic about what lies ahead for the U.S. and Germany in the way of future collaboration.

"Further benchmarking activities for wind tunnels are probable, as well as joint improvements of measurement accuracy in the wind tunnels," he said. "The latter is particularly suitable for data exchange, as it concerns intellectual activities such as the concepts of design of experiments and/or accounting for unsteady perturbations of steady measurements. There are no limitations to the initiatives of the participating scientists, when improvements of ground simulation of flight are attempted."