Birds do it. And one day, so might the Air Force.
It's an aerial maneuver known as "vortex surfing" where cargo planes in a V formation ride the cyclone of upward pressure that spills off the wings of another plane flying roughly 3,000 feet in front. Special software developed for the large C-17 Globemaster III, allows the trailing plane to stay in the sweet spot of an upward draft, providing significant fuel savings.
The Air Force successfully tested the concept last month. Now scientists at the unit that manages cargo and tanker planes must find the money to complete this efficiency project at a time of ever-shrinking budgets.
"We've seen birds fly in 'V' formations. They do that for a good reason," says Donald Erbschloe, chief scientist at Air Mobility Command, based at Scott Air Force Base, Ill.
The Air Force consumes 75 percent of all of the federal government's aviation fuel. Air Mobility Command alone requires 25 percent. A fuel efficiency office was already looking at the low-hanging fruit to use these resources more efficiently, says Erbschloe, including removing weight from the aircraft, washing the engines and changing the plane's center of cargo.
"To make it to the next step, to get the really good single- or double-digit improvement in fuel efficiency, it's going to require investment," he says.
The tests in July accounted for a 10 percent greater fuel efficiency for the trailing aircraft riding on what Erbschloe calls "free lift." He and his colleagues must now find between $3 million and $5 million for the remainder of the project, which is a collaborative effort between Air Mobility Command, the Air Force Research Laboratory, the Air Force Material Command and Boeing.
If ultimately approved, final testing could begin as early as 2014 and put into place by 2016. The drawdown in Afghanistan will likely be completed before the military can benefit from these savings.
So far the testing has only been on the C-17, which already had flight guidance computers that could accommodate the new software. Staying within the vortex sweet-spot would be too difficult for a pilot to handle manually, says Erbschloe.
It also precludes multiple planes from trailing another. Slight modifications the software must make in-flight would incrementally magnify for a series of planes trying to stay on course with the one in front of it. Vortex surfing also makes the ride for the trailing aircraft slightly rougher, but not enough to damage the aircraft or distract the crew.
Erbschloe envisions a future where aircraft would use this technique in groups of twos or threes for several missions in and out of the U.S. per day. Some creative planning and flight scheduling could revolutionize how the military responds to crises abroad, moves cargo across the ocean or supports fighter aircraft in what are known as "coronet missions," he says.
Vortex surfing could also allow planes to carry less fuel and more cargo, or fly for longer. The military could likely pass this technology on to the commercial realm, he says, and with it 5 percent or 10 percent savings to private cargo flights.
Future tests on other aircraft could also include commercial passenger flights, Erbschloe says.
Air Mobility Command is now looking for the funding for an Advanced Technology Demonstration, a military procedure to prove the worth of a new program or operation. Erbschloe and his team are putting together a funding pitch for the beginning of September.