Constraints on Wind Tunnel Testing Frustrate Engineers Written 29 July 2015
Panelists: Doug Garrand, Aerospace Testing Alliance; Michael Mastaler, NASA; Michael Holden, CUBRC; Michael McWithey, Lockheed Martin Corp.; David Schuster, NASA’s Langley Research Center; Roger Simpson, NASA’s Stennis Space Flight Center
By Hannah Godofsky, AIAA Communications
Wind tunnels have been a key part of the testing and validation process in aerospace for a long time. However, the operational capacity of those systems is being threatened by several outside forces. Budget cuts and the use of computer simulations have made the use of wind tunnel facilities to conduct testing seem a luxury to engineers.
“In today’s budgetary climate, large, costly facilities naturally become a prime target for mothballing, closure or divestment to offload the financial burden,” explained David Schuster, a NASA technical fellow with the NASA Engineering and Safety Center at NASA’s Langley Research Center, during the 2015 AIAA Propulsion and Energy Forum panel “Evolution of our National Ground Test Capability,” which discussed the role and capabilities of wind tunnel testing in this new environment.
Doug Garrard of the Aerospace Testing Alliance expressed optimism about the state of wind tunnel testing in the U.S., saying several facilities operated by the military are the best in the world.
Michael McWithey, manager of Wind Tunnel Testing Labs with Lockheed Martin Corp., said many of the facilities in the U.S. are aging as they were built following World War II or during the Cold War to compete with Germany and Russia. He explained that in the absence of a similar threat, many U.S. wind tunnels have been closed or moved offshore as a result of budget constraints.
Computational fluid dynamics modeling of air flows using software programs also has reduced the need for some wind tunnel testing. Michael Mastaler, associate director of the Advanced Air Vehicle Program with NASA’s Aeronautics Research Mission Directorate, emphasized that wind tunnel testing should play a complementary role to the use of computer simulations. He said wind tunnels continue to have some unique capabilities that software programs do not and that it is those unique capabilities that must come into play before the cost can be justified.
“The primary reason we are here and our assets are here is to support the NASA programs,” elaborated Roger Simpson, program manager of the Rocket Propulsion Test Program Office with NASA’s Stennis Space Flight Center.
Michael Holden, vice president of aeronautics with CUBRC, a nonprofit wind tunnel testing facility, spoke about the advances that have been made on the technology side of ground testing. He said the CUBRC facility has some very advanced capabilities, including that missiles can be tested at Mach 20, a level that would duplicate a vehicle’s effects of actually flying the missile.
Component testing can run up to 30,000 feet per second, Holden said. He described some of the chemical and technological constraints on this type of testing, including the introduction of unknown variables at high speeds and the inconsistency of results.
According to the panelists, wind tunnel testing may continue to become rarer, but it will never go away entirely. Though companies and agencies have a responsibility to be prudent and ensure that resources are not being wasted, no software program can fully eliminate the need for lab experiments. Wind tunnels and the skilled employees that operate those facilities are still needed to develop new aerospace vehicles.