ARNOLD AIR FORCE BASE, Tenn. -- The Propulsion Test Branch within the Arnold Engineering Development Complex Test Division tests the powerhouses of U.S. military aircraft and missiles to prove their worthiness for the warfighter.
“Our mission is to provide decision makers actionable data through safe, efficient and unbiased test and evaluation on the performance of the world’s most advanced aeropropulsion systems,” said Lt. Col. Lane Haubelt, chief of the Propulsion Test Branch.
A team of engineers, craft workers, technicians and others work together to conduct tests ranging from developmental altitude testing to accelerated mission testing to environmental testing while simultaneously looking to the needs of future tests.
“We continue to be the world leader in jet engine ground testing,” Haubelt said. “We are continuously improving and upgrading our capabilities to support our current workload and to prepare for the next-generation engines that will come through our cells.”
Developmental testing conducted in the altitude test cells at Arnold Air Force Base generates data about the operability and performance of an engine.
“Our altitude test cells can reach Mach 4.0 with altitudes up to 100,000 feet,” said Joel Nalin, lead test analyst. “Our large J and C cells were critical in the development of current military engines like the F-135 for the F-35 and the F-119 for the F-22. Our smaller T cells aid in the development of cruise missiles like the F-415 in the Tomahawk Land Attack Missile.”
Operability testing capabilities of the Branch include distortion screen testing and blade tip timing.
To perform inlet distortion screen testing, the Propulsion Test Branch relies on the expertise of fellow AEDC organization – the Aerodynamics Test Branch – to provide the data about the distortion patterns. Screens then are constructed to simulate the distortion, and testing is conducted to determine how engine performance and stall margins are effected.
The blade tip timing capability provides information about the vibrations of an engine by using lasers to measure the deflections in the spinning sections of an engine. Vibrations are a source of wear and tear on an engine.
Operability capabilities also include air-start testing at different altitudes and engine in-flight relight testing.
Performance testing provides engine manufacturers with fuel efficiency data. In the test cells, engines are outfitted with in-flight thrust, airflow and fuel measurement systems. Commercial aircraft also utilize this type of testing.
Accelerated mission testing, or AMT, is conducted in the sea level test cells at Arnold AFB. During an AMT, an engine is run in a way that simulates missions representative of what would be encountered over seven to nine years of operational usage, but condensed to six to nine months.
Information gathered during these tests enables the maintainers in the field to anticipate issues and manufacturers to develop more durable and reliable parts.
“The end result of an AMT is learning about how well an engine can meet the long-term needs of those relying on the weapon system,” said Yancee Burchett, test engineer.
In the sea level cells at Arnold AFB and in the McKinley Climatic Lab at Eglin Air Force Base, Florida, the Propulsion Test Branch is capable of conducting environmental testing to measure engine durability, functionality and survivability under different conditions.
“By running the engine in this environment, we can gain a better understanding of how well the engine can withstand these conditions before being fielded,” said Rachel Garrard, test manager.
Engineers can subject engines to freezing clouds in the C cells and observe the effects on the engines using high-speed and high-definition cameras. At McKinley, the team can generate dust, blowing sand and rain, snow, solar cycles, salt fog and spray, and temperature extremes.
The suite of capabilities operated by the Propulsion Test Branch provides vital information to prepare for flight testing and further the knowledge of currently fielded engines.
“The Branch has played a critical role in developing warfighter capabilities since the dawn of the jet age,” Haubelt said. “As we look towards the future, we intend to leverage our capabilities to meet the challenges of an ever-changing environment. We will continue to judge that the capabilities of the next generation of propulsion systems will meet the needs of customers and, ultimately, be given their trial by fire.”