BIRDS DO IT, WILL JETS DO IT? TESTS PROBE IF FLYING FORMATION SAVES FUEL.

Byline: Jim Skeen Staff Writer

EDWARDS AIR FORCE BASE - Borrowing an idea from nature, NASA is looking to see whether airplanes can save fuel by flying in formation like geese.

Just as migrating geese and other birds fly in a V formation to save energy, two National Aeronautics and Space Administration Dryden Flight Research Center F-18 jets are testing the effect of flying one jet in the upwash of air coming off the wingtip of a plane in front of it.

``The fundamental idea is to see if airplanes can fly in a V formation similar to the way geese fly and see a fuel savings,'' said Bob Meyer, Dryden's director of aerospace projects.

Early indications are there is a potential for a 10 percent to 15 percent fuel savings for the trailing aircraft. There's no change to the lead aircraft, researchers said.

The expectation is that the planes would periodically switch follower and leader, just like geese do.

Called Autonomous Formation Flight, or AFF, the program controls the test aircraft using Global Positioning System satellite signals and measurements of aircraft movement.

The system keeps the trailing aircraft within a ``sweet spot,'' the best spot for uplift in the vortex - a whirling stream of air - coming off the leading airplane's wingtip.

``You don't have to fly Blue Angel or Thunderbird close. You can fly one to two airplane lengths behind,'' Meyer said.

An automated system is necessary because pilots would have too much work to fly aircraft at the precisely proper positions.

Once the concept is proved with the F-18s, dissimilar aircraft could be surveyed to determine their ``sweet spot,'' enabling formations of virtually any varieties of aircraft to enjoy the fuel savings.

The AFF jets flew formation flights for the first time this February. They verified an initial ability for the control system to hold within 5 feet of the best position, beating a goal of 20 feet set for that stage of the program.

A second stage of flight tests, completed Wednesday, was aimed at mapping out the vortex effects on the trailing aircraft.

The third phase of the program will involve full-up tests of the system, in which the trailing aircraft will be in the vortex of the lead aircraft to test fuel savings.

When that phase of the program will be conducted is an open question. NASA is trying to get the overbudget International Space Station project back on track financially and that is causing ripple effects throughout the agency.

The final phase will cost about $3 million or $4 million. Dryden is looking at how to reshape the program in view of the financial uncertainties and is also looking for possible partners. UCLA and Boeing are already doing some of the work in the program.

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Photo:

(color) The system being tested keeps the trailing aircraft within a ``sweet spot,'' the best spot for uplift in the vortex - a whirling stream of air - coming off the leading airplane's wingtip.