A V formation (sometimes called a skein) is the symmetric V-shaped flight formation of flights of geese, ducks, and other migratory birds. V formations also improve the fuel efficiency of aircraft and are used on military flight missions.
The V formation greatly boosts the efficiency and range of flying birds, particularly over long migratory routes. All the birds except the first fly in the upwash from the wingtip vortices of the bird ahead. The upwash assists each bird in supporting its own weight in flight, in the same way a glider can climb or maintain height indefinitely in rising air. In a V formation of 25 members, each bird can achieve a reduction of induced drag by up to 65% and as a result increase their range by 71%. The birds flying at the tips and at the front are rotated in a timely cyclical fashion to spread flight fatigue equally among the flock members. Canada geese are a common example demonstrating the V formation.
Military flight missions
The Vic formation is also common in ceremonial flyovers and airshow flights.
Air Mobility Command, which accounts for 20 percent of federal fuel usage, is experimenting with autopilot changes to find the best tradeoff between the reduced drag of 'vortex surfing' and the resulting 'ride qualities' of flying through another aircraft's wake.
- USA Today: "Why birds fly in a V-formation" by Traci Watson January 15, 2014
- "Effects of Leader’s Position and Shape on Aerodynamic Performances of V Flight Formation"
- Drinnon, Roger. "'Vortex surfing' could be revolutionary." Air Mobility Command, 10 October 2012.
- Warwick, Graham. "C-17 s Go Surfing, to Save Fuel." Aviation Week, 12 October 2012.
- Holmes, Tony. Spitfire vs Bf 109: Battle of Britain. Oxford, UK/ New York: Osprey, 2007. ISBN 1-84603-190-7.