For a besieged soldier or a disaster victim, a plane dropping supplies is the most welcome sight in the world – unless the drop ends up drifting off out of reach. To help make sure that airdrops end up where they belong, the US Air Force Research Laboratory (AFRL) has awarded a contract to Lockheed Martin to adapt its WindTracer wind measurement system for a Precision Air Drop (PAD) system to help aircrews land supplies faster and on target.
Since its development during World War II, the airdrop has become standard operating procedure for the world’s air forces when delivering supplies in times of war and natural disasters. In principle, it’s a fairly simple job. You take a pallet of cargo, strap a parachute on it, shove it out the back of a Hercules or a similar cargo plane, and the groceries float safely to Earth.
Unfortunately, where a parachute lands depends very much on how the wind blows, as French troops learned in 1954 as they watched in despair when supplies meant for them drifted into the hands of the enemy during the Battle of Dien Bien Phu. For an accurate air drop, the crew needs a detailed profile of the winds, which can vary a great deal with altitude, from the plane down to the ground.
Lockheed’s WindTracer is a commercially available wind-profiling Lidar technology that’s been used at airports around the world for over a decade to give warnings of dangerous wind shears. It works by beaming pulses of infrared light that bounce off dust particles suspended in the atmosphere. As the light bounces back, the WindTracer can measure the speed and direction that the particles, and therefore the wind, is moving. That way, air traffic controllers get warnings about wind shears and other dangerous wind conditions and can warn pilots accordingly.
So it can be delivered to remote bases, PAD will be a ruggedized, miniaturized version of WindTracer set on a pallet for its own air drop. After it is deployed to the ground, troops will hook up to an equally small and rugged telemetry system. The idea is that instead of making several passes over a drop site to gauge the wind, PAD’s lidar measures the wind speeds and directions, and beams the results back to the aircrew, who can compensate when dropping the actual load.
“Currently airdrop missions require several flyovers to accurately determine wind readings, but our WindTracer technology would eliminate the need for so many passes,” says Dr. Kenneth Washington, vice president of STAR Labs, Lockheed Martin's space technology research and development group. “WindTracer is an adaptable commercial system. By developing this prototype, we’re putting this technology on a path for fielding.”
Source: Lockheed Martin
Update (Aug 7, 2014): The text relating to airdrops was edited to reflect the fact that the WindTracer doesn't operate while being dropped from the aircraft, but is ruggedized so it can be delivered to a base via aircraft, where it will then operate from the ground. We apologize for the error.