The US Air Force (USAF) and Boeing have completed the first phase of Air Force Research Laboratory's C-17 Drag Reduction Programme.
During the first phase, six Vortex Control Technologies Finlets were fixed on the aft part of the fuselage of a C-17 Globemaster III aircraft assigned to Joint Base Lewis-McChord, Washington, US.
USAF 418th Flight Test Squadron test pilot captain Kevin Meyerhoff said: "The C-17 is one of the highest consumers of jet fuel in the Air Force.
"A reduction of just a few percent can result in significant cost savings.
"The cost savings these devices may offer are entirely dependent on the C-17 still being able to fulfil its mission in the Air Force.
"Our testing focused not only on fuel performance, but also on any impacts that the devices may have on the flying qualities of the aircraft.
"This includes the C-17's ability to perform critical air drop missions."
Set off to help reduce fuel costs for the USAF, the C-17 Drag Reduction Programme aims at collecting data ways in which airflow is affected with different structural modifications to a C-17 Globemaster III.
418th Flight Test Squadron project manager Steve Salas said: "Our end goal is to reduce fuel consumption while maintaining military utility."
"This programme has the potential for significant savings in C-17 fuel costs, helping the Air Force stretch its budget even further, while maintaining force readiness."
The next phase of testing will involve adding an additional number of five Finlets to each side of the C-17 aircraft.
The third phase of testing will see the Finlets being removed and six Lockheed Martin microvanes will be placed on each side of the aft fuselage.
The fourth phase will see fairings attached to locations on the wings near the engines and winglets.
The mentioned structural modifications are expected to manipulate the airflow around the aircraft, helping reduce the C-17 fuel costs.
The test series is scheduled to be completed this October.
Image: The C-17 aircraft. Photo: courtesy of US Air Force / Kenji Thuloweit.