The Air Force is looking into simple physics to help cut down fuel costs. Popular Mechanics reports that two USAF C-17s took off from Edwards Air Force Base on a specific mission: find the formation that will produce the optimal air vortices. The planes have special wingtips that produce these swirling air coils.
The science behind is called drafting. These air vortices created by the wingtips can give other planes in specific positions to get a "free lift." Trailing C-17s need to be positioned 2000 to 6000 feet behind the lead plane. This position allows the planes behind to benefit from the upward draft caused by the air vortices of the lead plane. This provides lift at no fuel cost to the trailing planes.
The maintenance of correct formation of the C-17s is possible by tweaking the flight control computer so the "autopilot could maintain the correct distance and stay within the updraft part of the vortices," and that all that was needed to achieve this was to change ""a few dozen lines of code in the autopilot."
The formation is a V and is called vortex surfing and uses the same principles that geese use when flying long distances. Flying in this formation from California to Hawaii saved 6% in fuel and the ride back saved 10%. Since Air Force Command conducts more than 80,000 flights per year, even single digit percentage savings from fuel amounts to millions of dollars.
Current findings point to the ideal position of a drafting plane at 3000 feet portside of the lead. A second drafting plane must stay 6000 from the lead starboard side. This is already close to current Air Force formations but the findings pave the way for formation data for many other types of aircraft in active duty for the Air Force.
