Fuel availability is a security imperative for aircraft fleets, and tactical dependence on fuel will critically tie global fleets to investments in new drag-reduction technologies that optimize fuel utilization. Roberto Guerrero, Deputy Assistant Secretary of the U.S. Air Force for Operational Energy, recently wrote in Defense News that “when we use our assets more efficiently in peacetime, we build a more energy-aware culture that will better prepare our airmen for tomorrow’s fight, if and when it happens.”

Adopting sustainability measures today directly affects operational and national security, and it benefits us all to find ways to use less. In its 2019 Sustainability Report and Implementation Plan, the Department of Defense states that its sustainability efforts “focus on mission assurance, operational readiness, and cost-effective business practices.” The report goes on to add that, “The Department strives to maximize the efficient use of mission-critical energy, water, and material resources...[to] ensure we are prepared when threats arise in the future.”

The commonly held, and mistaken, notion is that fuel efficiency compromises performance, a bias we’ve experienced firsthand in our work with Microvanes. Strategically surface-mounted on the aft body of rear cargo airframes, American-made Microvanes reshape tail section airflow, reducing the significant amount of drag created on aircraft like the C-130, C-17, L-100, and KC-135.

A typical Microvane prior to installation.

When a plane is flying, a considerable number of vortices are generated coming off the top and bottom of the wing. These vortices travel down the side of the aircraft, ultimately joining each other at the tail. For planes you fly everyday like a 737, this is not as big an issue because the fuselage is relatively straight. But, the aircraft that benefit the most from Microvanes are cargo transporters that have severe upswept tails.

The reason? The aforementioned vortices that do not play a role on a straight fuselage aircraft play a major role with upswept tail aircraft. When the vortices meet in the back, they form a massive disruption that creates a significant amount of drag. Microvanes destroy this vortex in the back by redirecting the airflow to another area on the plane without harming or negatively affecting any handling aspect of the aircraft.

Green Manufacturing for Aerospace Components

One distinguishing feature of Microvanes is that they are one of the only 3D printed parts approved and certified by the Federal Aviation Administration for use on the exterior of an aircraft. Not only does this mean that they can be produced through green manufacturing, but it also introduces cost and supply chain benefits in terms of the need for raw materials, production time, part warehousing, and installation. In fact, according to the United States Environmental Protection Agency, aircraft account for 12 percent of all U.S. transportation greenhouse gas emissions, which 3D manufacturing helps address by requiring low energy sources, no raw materials, and producing minimal to no scrap or waste.

This 3D printing using lightweight composite materials allows Metro Aerospace to elevate the quality, standard, and integrity of products. Meanwhile, more streamlined workflows cut lead times and costs, getting products to market more quickly. This lean manufacturing means Microvanes can be delivered nearly on-demand with shortened lead times and without the costs of expensive storage. Additive manufacturing also allows for adjustments and design changes that can be thoroughly validated up front to avoid costly errors that lead to waste, scrap, rework, and retooling – a benefit that isn’t limited to Microvanes and has yet to be fully capitalized on in the aerospace industry.

Sustainable Options for Aerospace Components

From the traditionally accepted definition of a sustainable solution, Microvanes, currently used by fleets across five continents, reduce fuel consumption, carbon emissions, and engine wear through lower turbine inlet temperatures (TIT). According to engine manufacturer guidelines, reducing TIT by 30°C through conservative operation can increase an engine’s life by as much as 250 percent. As a drag-reducing technology, Microvanes actually provide that lower temperature without compromising performance. Instead of choosing extra life or extra power, the pilot achieves both.

Take the experience of Lynden Air Cargo, which is part of the Lynden family of transportation companies with service extending around the world. The company’s fleet consists of eight civil C-130s (L-100s), the largest in the world, that carry oversized and bulk freight to remote and challenging destinations, as well as to some of the world’s most devastating disasters. They support customers in the mining, construction and energy industries and have mobilized operations to support projects around the globe, including the Department of Defense Air Mobility Command and the Civil Reserve Air Fleet (CRAF).

Tail section of a cargo plane being prepped for the installation of Microvanes.

Headquartered in Anchorage, Alaska, Lynden has been awarded multiple Green Stars in Alaska for its intense focus on green initiatives. But, transporting cargo internationally with a L-100 requires a significant amount of fuel given the less-than-aerodynamic design of large rear cargo aircraft, which presents challenges from both cost and environmental perspectives. As a leader in sustainability initiatives, Lynden believes going green is good business, and that small changes can add up to big savings for business and the environment.

Given its focus on improving fleet operating efficiencies, Lynden had been tracking drag-reducing Microvanes and chose to pilot them on a single aircraft after the Canadian Air Force and U.S. Coast Guard installed them on their large aircraft. Lynden evaluated Microvanes on one aircraft for several months, taking in-flight cruise data and correlating it to fuel uplifts, and saw a statistically significant difference between pre- and post-Microvanes performance. They were doing what they were supposed to do.

Translating Sustainability into Improved Performance

Microvanes installed on the tail of a military transport aircraft.

During the Microvanes pilot program, Lynden realized a 3.03 percent increase in indicated air speed (IAS) at cruise, creating a reduced fuel consumption and ultimately reducing carbon emissions by an estimated 505,764 pounds over an average year of flying. After seeing this 6.7 knot increase, Lynden continued testing and calculated an actual 7 knot gain. The Microvanes cleaned up the airflow and reduced the drag, which allowed pilots to increase air speed at the same power settings. With them, they actually had to either reduce the power setting sooner or reduce speed, both of which reduced the fuel consumption and engine temperature.

The results of the pilot program led Lynden to install Microvanes on all eight of its L-100’s. Lynden pilots flying with Microvanes reported an unabated climb directly to cruise altitude without the need to step climb when carrying a heavy cargo and fuel load. Crews also noticed they were hitting higher than expected speeds and having to throttle back sooner, which gave them the option of getting to destinations earlier, or throttling back to a lower setting to keep the same schedule but use less fuel.

The Cost of Going Green

Microvanes installed on the tail of a Lynden L-100 cargo plane.

Cost is usually incurred when sustainable solutions are first implemented, but the sheer nature of fuel- and drag-reduction technologies like Microvanes is that they ultimately pay for themselves. Lynden’s resulting fuel savings will allow the company to recoup the cost of the Microvanes within approximately 15 months since completing installation across the fleet.

Rather than require a fleet to be taken out of commission, which also has a price in terms of lost service, installation of Microvanes can be completed in less than a day.

Based on countless Computational Fluid Dynamics (CFD) analyses run, the ideal array of Microvanes has been calculated to ensure they are located in the correct position on each airframe. These locating guidelines are included in the Service Bulletin offered for customers to use when installing the vanes.

Additionally, the nature of 3D printed components like Microvanes is that they can be placed and bonded to the exterior of an aircraft using an epoxy system without affecting the aircraft body or any other systems. The longest process tends to be waiting for the adhesive to cure. Contrarily, riveting would not only take more time, but also add weight, decreasing total drag reduction, and affecting internal systems on the underside of the fuselage where Microvanes are placed.

Shift the Paradigm

Is aerospace ready for sustainable solutions that can be produced more quickly and designed more precisely with less error and waste? What if those solutions can also reduce drag and improve performance? Is it unreasonable to ask so much for the future of aerospace component manufacturing? Perhaps a better question would be why we aren’t considering 3D printing for more aerospace and defense parts and components?

This article was written by Tricia D'Cruz, Founder/Managing Director of Catalyze Dallas (Dallas, TX). For more information, visit here .


Aerospace & Defense Technology Magazine

This article first appeared in the August, 2020 issue of Aerospace & Defense Technology Magazine.

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