The Air Force is weighing making aerodynamic upgrades to one of its primary cargo aircraft to cut fuel consumption and have a lighter environmental impact.
The Air Force Research Laboratory (AFRL) and the Air Force Life Cycle Management Center are undertaking airworthiness certification to fit microvanes on C-17s as part of a project that has been in the works for years.
“Microvanes™ for the C-130, a Lockheed Martin Corporation patented technology licensed to Metro Aerospace, bring performance enhancement and cost reduction for the Hercules aircraft as well as other large aircraft with steep aft ramp designs. Although the flat cargo ramp and door on the C-130 provide exceptional airdrop and rescue capability, this same feature creates a significant amount of drag due to the abrupt change in airflow.”
“Microvanes are small aerodynamic components specifically designed to reshape the air flow around the aft cargo door. When adhesively surface mounted to each side of the fuselage, these devices effectively reduce drag, reducing fuel and engine thrust requirements.”
According to the Air Force, fitting the parts could save millions of dollars in fuel yearly.
According to Air & Space Forces Magazine, Ed Clark, an AFRL engineer, is pleased with this advancement on an existing aircraft for fuel efficiency and mission enhancement.
The microvanes are a prime example of “bringing modern technologies forward on an older aircraft,” said Clark, an AFRL’s Material and Manufacturing Directorate’s Future Force Energy office employee.
AFRL began working on the technology in 2014, Clark said. C-17s have been fitted with microvanes since 2015, he added.
In collaboration with the Air Force, Lockheed Martin developed microvanes for the C-130. Metro Aerospace, which holds the license to Lockheed Martin’s patent on the technology, has already installed them on Canadian Armed Forces aircraft of the type. In addition, the Department of Defense awarded a contract in 2021 to Metro Aerospace to put microvanes on Air Force C-130s and “help validate drag-reduction concepts that may be applied to commercial planes, such as the C-17, KC-135, and future vertical lift aircraft,” among others.
According to a Lockheed Martin study, cargo planes have always had high drag in that area because of the upsweep in the fuselage required for the rear cargo door, which the microvanes may help reduce.
To ensure that the microvanes could be tested without disrupting the service’s 220 aircraft fleet, the Air Force Research Laboratory took several new steps. The C-17s have occasionally been stretched thin and required to conduct massive airlift operations with little notice. The AFRL team sought to minimize disruption to the fleet.
Using Computational Flow Dynamics (CFD), the group designed, tested, and evaluated the efficiency of the components. Microvanes are printed from DuraForm GF/DuraForm ProX GF composite material, reducing the difficulty of producing and fitting them to the aircraft.
According to Clark, modern design tools allowed the team to create “a safe and integrated improvement to the aircraft without affecting operations.”
“This 3D-printed device can be installed in a short time using Air Force aircraft maintenance personnel,” he said.
According to the Air Force, the C-17s with microvanes installed save around one percent in fuel over regular C-17s. In addition, the reduction in drag saves the Air Force fuel by reducing the workload of the engines. According to the Air Force, those savings are considered significant if applied to the entire fleet.
“The Air Force anticipates that the microvanes, when installed on all C-17s, including Air National Guard and Air Force Reserve aircraft, will save over $10 million per year in fuel costs,” according to a statement from the Assistant Secretary of Air Force for Energy, Installations, and Environment’s office.
The $5 million expended to date on microvanes development is what Clark said. AFRL is hoping to finish C-17 airworthiness certification soon.
“Our goal is calendar year 2023 with added flight verification and in service testing in the first half of the year,” Clark said. By next year, “the Air Force will determine the best option for production of the microvanes for the C-17 fleet.”
According to Sergeant Major Bryan Dillon, the C-17 fleet will be retrofitted with microvanes in 2023.