Airman Magazine: Good, clean, science
Much of the scientific research Dr. Dahm oversees as the Air Force chief scientist has environmental implications. Changing the way aircraft are flown in formation and research into new engines will have dramatic impacts on the Air Force's fuel consumption. (courtesy photo/David Housch)
Thinking of the Air Staff conjures up the image of generals discussing the future Air Force weapons systems and their employment. That image is partially correct. The staff is made up of generals and they do plan for the future of American airpower. However, making the assumption the members of the Air Staff are strictly military officers overlooks important civilian members. Most civilian Air Staff members have backgrounds in the military; one has a background in good, clean science.
That seat is currently held by Dr. Werner Dahm, the Chief Scientist of the Air Force. To serve in this role, he has taken temporary leave from his position as a Professor of Aerospace Engineering and head of the Laboratory for Turbulence and Combustion at the University of Michigan. Though the Air Force programs he helps oversee range widely in topic and application, some of the most far-reaching will impact the way energy is used in the Air Force.
Whether driving a car or heating buildings, the increasing cost of energy affects nearly everyone. The Air Force accounts for nearly 60 percent of the Department of Defense’s annual fuel use, so developing technologies to use fuel in the most efficient way is crucial to the mission.
Programs to increase energy efficiency range from installation-level initiatives, such as green energy procurement, the redesign of current weapon systems, the development of future weapons systems, and even changes to current operations.
Since more than 80 percent of Air Force fuel is consumed by aviation operations, finding smarter ways to design, build, and fly aircraft translates into real savings. Yet, newer aircraft are already much more efficient that their predecessors. It’s like trying to squeeze better mileage out of today’s highly efficient cars. It can be done but it requires extensive research, radical changes.
Dr. Dahm said there are three ways of increasing fuel efficiency in aircraft: more efficient engines, a more aerodynamic shape, and reducing airframe weight. The Air Force is researching all three of these.
Mobility aircraft account for the largest overall fuel usage, nearly 55 percent of the total Air Force fuel bill. Making these large aircraft more efficient will generate dramatic savings. One of the most obvious ways to improve them is to use more efficient engines.
Dr. Dahm said Air Force Research Laboratory scientists are studying ways to increase the performance of engines through the Versatile Affordable Advanced Turbine Engines, or VAATE, program. “The VAATE program is made up of many smaller projects,” Dr. Dahm said. “The savings from them add up to large increases in fuel efficiency that can be used both in existing and future aircraft systems.”
The largest of these is called Adaptive Versatile Engine Technologies, or ADVENT. This is a radical change in the way gas turbine engines operate, creating the first constant airflow engine. The technologies being developed in ADVENT and other parts of the VAATE program will begin appearing in improvements to fielded engines and new engines in about 10 years or so,” he said.
Fuel savings aren’t limited to redesigning engines either. Additional and dramatic savings can be found by redesigning the way aircraft are shaped.
“For example, by adding winglets to aircraft wingtips we can effectively increase the wing span, and thereby increase the lift-to-drag ratio,” said Dr. Dahm. “We can go even further and change the shape of the entire aircraft from the traditional tube-and-wing design to a blended wing-body design, a shape closer to that of the B-2 Spirit that gives greatly decreased drag and increased fuel efficiency.”
Dr. Dahm added that it’s been known for some time that blended wing shapes are more efficient. The commercial aircraft manufacturers have studied such designs for both passenger and transport aircraft, and the benefits in fuel savings are dramatic. “It is as much a matter of overcoming perceptions of what an airplane ‘should’ look like,” he said.
In the Air Force, such radical designs will likely first appear in transport and tanker aircraft, where the fuel saving are greatest. According to Dr. Dahm, the know-how exists today for building a large-scale demonstrator aircraft to assess practical implementation and operational benefits of the blended wing concept. “Once we decide that the development costs are justified by the fuel savings over its service life, we could begin seeing this new type of aircraft in about a decade,” he said.
Should that implementation take place, it will include new materials that are not only lighter, but stronger as well. The resulting weight savings translate into even further fuel savings.
Such planes may still be years from production, but the places they will operate from are also becoming more energy efficient. According to Dr. Dahm, many Air Force installations are using technology to offset or replace their dependence on fossil fuel.
“Green technology can’t be implemented in the same way at every location,” Dr. Dahm said. “Wind farms are currently providing electricity at Fairchild [Air Force Base, Wash.], but they may not be a good choice for bases where they would produce radar interference.”
Dr. Dahm said geothermal energy is being investigated at Minot AFB, N.D.; solar arrays have been implemented at Nellis AFB, Nev.; gas produced from a local landfill heats hangars at Tinker AFB, Okla.; and at Hickam AFB, Hawaii, solar energy is used to produce hydrogen, which then fuels maintenance vehicles. They’re just a few examples among many uses of alternative energy already in the works across the Air Force.
Together with other members of the Air Staff, Dr. Dahm, as chief scientist, helps decide which technologies the Air Force should invest its more than $2 billion annual research budget in.
“It’s important to balance current needs and future requirements” said Dr. Dahm. Advising leaders on technology opportunities and their operational impacts is a major aspect of the chief scientist’s job.
Recently, Dr. Dahm and members of the Air Force Scientific Advisory Board showed striking impacts on fuel economy that can be obtained by flying aircraft in formation to take advantage of the vortex produced from each wing tip through flight.
He said by having as few as two aircraft fly in formation, a 14 percent improvement in fuel efficiency could be realized. What’s even more impressive is that it isn’t just the trailing aircraft that reaps the benefits, both aircraft benefit.
“If the trailing aircraft can fly in the ‘sweet spot’ produced from the lead plane it decreases the drag on both,” he said. “The main challenge is that sweet spot is constantly shifting, so pilot fatigue increases if they have to stay in that spot manually. Technology can solve that by relatively simple software that automatically uses trim adjustments find the sweet spot and stay in it.”
Dr. Dahm said the aircraft can be separated by a considerable distance and still see most of the benefit and that even dissimilar aircraft benefit from flying in formation.
“The benefit small aircraft see when they fly in formation with large aircraft can be so large that the fuel savings can actually equal the fuel those small aircraft would need flying solo.”
Having a full-time Chief Scientist at the Air Staff level is unique to the Air Force, and reflects the crucial role that technology plays in helping the Air Force achieve its mission. The way the position is filled is also unique.
“Chief scientists temporarily set aside their careers in academia or industry to serve full-time in the Pentagon,” Dr. Dahm said. “It’s been that way ever since Theodore von Karman served as the science adviser to Gen. Hap Arnold, when the Air Force first became a separate service. Having that person be a scientist who comes from outside is essential to providing a fresh perspective and independent advice on research to the highest levels of the Air Force. The job is demanding, but it’s a real honor to be given the opportunity to serve the Air Force and the nation in this way.”
The future of the Air Force and its ability to adapt to rapidly changing energy needs will depend greatly on the direction given by the Chief Scientist. The promise is cheaper, greener and more efficient aircraft and operations, all resulting from good, clean science.
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