A surprisingly simple tweak is making a venerable military transport aircraft more efficient. Literally gluing a few microvanes to the rear fuselage of a C-17 Globemaster III cargo plane can result in fuel savings in the tens of millions of dollars.
Introduced in 1995 as a replacement for the workhorse Lockheed C-141 Starlifter, the Boeing C-17 Globemaster III has become a major logistical asset for not only the US Air Force, but the Royal Air Force, the Royal Canadian Air Force, the Royal Australian Air Force and others. However, even after three decades of service, there is still room for improvement.
One nagging problem that the Globemaster shares with the Lockheed C-130 Hercules is its rear section, which is marked by an upswept rear when the cargo door is raised. This causes some drag and turbulence problems even with the best aerodynamic design and is one reason why the empennage with the rudder and stabilizers are raised well away from the fuselage.
As part of a modernization program, the Air Force Research Laboratory (AFRL) , the Air Force Lifecycle Management Center, and private industry have teamed up to find a way to reduce this drag without major modifications to the airframe or the need for shelling out a lot of taxpayer money.
The result was a 3D-printed 4 x 16-in (10 x 41-cm) microvane attached to the fuselage using adhesive. That may not seem very secure, but sticky stuff is often the best thing for the job. Just remember that the brake pads on your car are stuck on with adhesive next time you tap the pedal. Screwing them on would result in stress points, ripped off pads, and a big jump in car insurance premiums.
Set in a series of steps on the rear of the fuselage, a dozen of these microvanes catch the airflow over the aircraft and consolidate them to produce a 1% reduction in drag. That translates into a 1% reduction in fuel consumption.
That doesn't sound like much, but the AFRL claims that when the vanes are installed on USAF and Air National Guard and Air Force Reserve aircraft, the project will pay for itself in seven months and save US$14 million annually, along with reducing demands on supply chains in forward areas. In addition, other nations have also shown interest in adopting the technology.
"Every gallon of fuel saved strengthens our readiness and operational effectiveness," said Roberto Guerrero, Deputy Assistant Secretary of the Air Force for Operational Energy, Safety, and Occupational Health. "By adding modern technology like microvanes to our legacy aircraft, we’re saving millions in fuel costs and building capability critical for maintaining our competitive edge in the era of Great Power Competition."
Source: AFRL
Update (Feb. 3, 2025): The above article originally stated that the C-17 Globemaster III was a replacement for the C-130 Hercules, when it was a replacement for the C-141 Starlifter. Our apologies for the error, which has now been corrected, and thanks to the readers who pointed this out.
