Six aircraft have been modified for a six-month evaluation before the microvanes, small 3D-printed devices similar to thin blades, are installed across the USAF’s C-17 fleet.
Small, simple and 3D-printed fin-like structures, called microvanes and fitted onto aircraft to reduce drag and subsequently fuel consumption, will soon be rolled out on the U.S. Air Force’s C-17 Globemaster III fleet. Developed by the AFLCMC (Air Force Life Cycle Management Center) and the AFRL (Air Force Research Laboratory) in collaboration with private industry, these microvanes are devices measuring roughly 4 x 16 inches and resembling a thin blade, with a dozen of them attached to the rear of the C-17’s exterior, allowing a one-percent reduction in drag.
“Air Force Operational Energy and Air Mobility Command are entering the final phase of evaluation for Microvane drag reduction technology on the C-17 Globemaster III,” a recent release said. The technology is expected to begin yielding results within seven months and estimated to allow the service to save over $14 million annually in fuel costs.
Cargo aircraft have a peculiarly high drag owing to an upward sweeping fuselage to accommodate a rear cargo door, a shape which is not fully aerodynamically optimized but is dictated by the functionality. Reducing that drag enables military aircraft to ferry personnel and cargo even farther.
Officials have even tied the effort to the broader logistical dimension of the high-end war with peer adversaries, as the U.S. confronts China in the western Pacific. That concern has even been reflected among other innovative projects like the “Pathfinder” BWB (Blended Wing Body) aircraft, where the unique aerodynamic design cuts fuel use by 30%.
Lockheed Martin also recently approved SATFs (Synthetic Aviation Turbine Fuels) for its F-35s, in line with the Air Force’s climate and energy goals. In addition to reducing the carbon footprint, the new fuels allow diversifying fuel types available to the F-35 and reducing dependence on traditional supply chains.
Microvanes a ‘major’ effort for fuel cost cutting
Six aircraft have been currently modified for the six-month long LSA (Logistics Service Assessment), before the devices are installed across the USAF’s C-17 fleet, counting a little over 200 aircraft. The LSA itself will begin after the final two aircraft are modified at Charleston AFB, with the work there expected to conclude by the end of Jan. 2025, an Air Force statement said.
The result of years-long “rigorous research and evaluation,” the microvane technology has also been approved by the U.S. Army to use for paratrooper airdrop. The Department of the Air Force kicked off the final phase of flight testing in Oct. 2023, which comprised air refueling and assault strip operations. Interestingly, the C-17 Globemaster III that acquired the microvanes during the testing retained the devices as a permanent installation. “That aircraft is currently assigned to Stewart Air National Guard Base,” the release added.
According to a Dec. 2022 report by Air and Space Forces Magazine, the AFRL has been working on the technology since 2014, and work to retrofit the microvanes on C-17s began in 2015. Developed originally by Lockheed Martin, they are commercially available for C-130s and have already been installed on some Canadian military aircraft.
In 2021, the DoD contracted Metro Aerospace, which holds the license to Lockheed Martin’s patent on the technology, to explore putting microvanes on Air Force C-130s and “help validate drag-reduction concepts that can be developed and applied to commercial aircraft, other aircraft such as the C-17, KC-135, and future vertical lift.” An official said at the time that the microvanes had cost about $5 million to develop.
On Mar. 7, 2024, the DIU (Defense Innovation Unit) gave an overview of contracts to three companies to research, develop, and prototype drag reduction solutions for legacy aircraft. Beside Metro Aerospace, the other two are Vortex Control Technologies (VCT) and Australian firm MicroTau.
Vortex Control Technologies (VCT) is developing several solutions for the USAF, including ‘Finlets’ for the C-130J and KC-135. Finlets are an array of small fins, attached to the aft-body region of the fuselage, that help to direct airflow and streamline aerodynamics to reduce drag.
Finally, VCT was also selected to develop a solution to reduce C-17 engine pylon’s drag, reducing the strong shock caused by the wing and over-the-top pylons. Meanwhile, MicroTau is developing a sharkskin-inspired ‘riblet’ film that can be adhesively applied to the skin of the aircraft to reduce drag. This solution is already being tested on commercial airlines and was planned to be tested on an AFSOC C-130J Super Hercules in FY2024.
Fuel saving and high-end war
“During flight, microvanes enhance fuel efficiency and extend the mission range by reducing aerodynamic drag caused by the upswept design of the cargo door section,” said the Air Force statement. The structures would be a “low-cost, innovative, force multiplying capability” that enhances mobility support in combined operations. The financial implications have also generated interest from partner nations like Canada and the United Kingdom to add the modifications to their own C-17s.
According to Roberto Guerrero, the Deputy Assistant Secretary of the Air Force for Operational Energy, Safety and Occupational Health, “Every gallon of fuel saved strengthens our readiness and operational effectiveness.” With microvanes on legacy aircraft, the “millions in fuel costs” saved would help maintain the “competitive edge in the era of Great Power Competition,” he added.
Lt. Col. Eric Durkins, commander of the 105th Aircraft Maintenance Squadron at Stewart ANGB, said that they collaborated with Memphis ANGB and engineering teams since the project’s beginning. “This collaboration highlights how partnerships drive forward our mission objectives,” added Guerrero.
He highlighted that the savings realized by the microvanes can be redirected “to fund other initiatives that increase combat capability.” Without naming it directly, the statement referred to the logistically-challenged and “tyranny of distance”-characterized western Pacific theater, saying how in “an era of Great Power Competition” with “logistical constraints and extended mission distances […] fuel will be the margin of victory and a strategic imperative.”
The reduced fuel consumption achieved by microvanes strengthens sustained operations in contested environments as easing of the pressure on fuel supply chains directly translates to enhanced mobility, enabling operations in “geographically dispersed and resource-constrained theaters.” This is a reference to ACE (Agile Combat Employment), which requires aircraft to operate from non-traditional airfields and air bases, with little to none supporting infrastructure.
