‘Finlet’ testing on C-17s to smooth airflow is currently underway at Edwards Air Force Base in California, USA. Test teams comprising US Air Force and Boeing personnel have completed the first phase of the Drag Reduction Program designed to lower fuel consumption on C-17s.
According to an Air Force Research Laboratory (AFRL) study, the price the US Air Force pays for jet fuel quadrupled between 2004 and 2012. At the same time, the demand for personnel and equipment to be transported around the world has increased. Airlifters like the C-130, C-17 and C-5 use most of the Air Force’s fuel, approximately 70% in 2012. Of these cargo planes, the C-17 uses the most fuel.
The purpose of the C-17 Drag Reduction Program is to collect data on how airflow is effected with different modifications done to a C-17 Globemaster III.
The modifications are scheduled in different phases of the AFRL testing, first using Vortex Control Technologies finlets and later Lockheed Martin microvanes and fairings. The ultimate goal is to see which, if any, modification reduces drag and lowers fuel consumption.
“The C-17 in one of the highest consumers of jet fuel in the Air Force,” explained Capt. Kevin Meyerhoff, 418th Flight Test Squadron, test pilot. “A reduction of just a few percent can result in significant cost savings.”
The first phase consisted of putting six VCT finlets on the aft part of the fuselage. Although the goal is to reduce fuel consumption by increasing airflow efficiency and reducing drag, it has to be done without negatively effecting what the C-17 can do now.
The second phase of testing will add five more finlets to each side of the C-17 for a total of 16 finlets.
In the third phase of testing, the finlets will be removed and six microvanes will be placed on each side of the aft fuselage.
“The finlets are similar to the strakes, only smaller and attached in greater numbers to the airplane. The microvanes are even smaller, similar to small plastic blades,” said C-17 airdrop engineer Nhan Doan.
The fourth phase will see fairings attached to locations on the wings near the engines and winglets.
Testing is scheduled to be completed this October.
April 8, 2016
