EDWARDS AIR FORCE BASE, Calif. --
EDWARDS AIR FORCE BASE, Calif. -- The 418th Flight Test Squadron is completing the final three of five phases on the Air Force Research Laboratory’s C-17 Drag Reduction Program using 3-D printed parts by Lockheed Martin at Edwards Air Force Base, California.
The squadron is testing parts in various configurations to see if external modifications can reduce drag and improve fuel efficiency.
Areas on the C-17 showed excessive drag and were targeted for improvement during previous simulations and tests.
A combination of laser positioning for locating, and sealant, bonds the parts to the aircraft. The 3-D laser positioning allowed the team to skip the design and build an installation tool that would only be used during flight tests. The bonding simplifies installation and more importantly leaves the aircraft in its pre-test condition after removal at the end of the flight test program.
“A one-percent improvement in drag reduction will result in 7.1 million gallons of fuel reduction per year,” said Bogdan Wozniak, 418th FLTS, project engineer. “One-to-two percent drag reduction could translate to $24-48 million dollars in fuel savings per year.”
The first two phases of testing were completed in the spring. The tests were conducted with two different configurations of parts made by Vortex Control Technologies.
Currently, the team is preparing to test the fifth, and final, configuration using the Lockheed Martin parts. They third and fourth phases, consisted of placing 12 microvanes toward the aft of the C-17 and then adding three fairings to each wing. The fifth phase will keep the 12 microvanes and six-total fairings with the addition of two fairings on each winglet.
At least three flight tests are conducted with each phase – lying qualities regression flight and cruise performance flights at .74 and .77 mach. The team will also conduct airdrop tests in December to ensure the microvanes do not interfere with the C-17’s airdrop mission.
The flights are always the same to ensure the data collected in each phase can be accurately compared to each other. The 418th FLTS is also using the same C-17 for all the flights. The plane is on loan from Joint Base Lewis-McChord, Washington, along with four maintenance Airmen.
“Aircraft and atmospheric data are collected with the aircraft flying straight and level at a constant airspeed and constant altitude with low winds and low air turbulence at 90 degrees to the wind to mitigate head- and tailwind effects,” said Wozniak.
Each flight requires eight hours to acquire sufficient data for the analysis. Flight data is collected and put into a computer program developed by Boeing that puts out parameters for lift and drag and then compares everything to see how much drag is reduced.
The flight tests here are the final stage of AFRL's program following computational fluid dynamics simulations and wind tunnel tests with a scale model. The data collected will be sent to AFRL at Wright-Patterson Air Force Base, Ohio, to see if any of the modifications increase streamlining and reduce drag. After that, Air Force leaders will ultimately decide whether or not any of the modifications should be implemented throughout the C-17 fleet.
The test team at Edwards consists of 412th Test Wing personnel, Lockheed Martin and Boeing contractors along with representatives from Canada, the United Kingdom and Australia, who have a stake in the program.
The final flight for the C-17 Drag Reduction Program is expected to happen in December.