To feed warplanes that have been guzzling gas in enormous quantities over Iraq, the Navy has taken the unusual step of removing bombs from four of its 12 F/A-18E Super Hornet fighter jets and replacing them with fuel tanks, converting the high-performance jets into airborne gas stations.

The move comes as the air campaign shifts from bombing fixed targets to bombing Iraqi troops and weapons in the field. For those missions, pilots need to circle over Iraq for long periods, awaiting calls to strike Iraqi units menacing U.S. ground forces making their way toward Baghdad, said Rear Adm. John M. Kelly, who oversees operations of three U.S. aircraft carriers in the Persian Gulf.

Dozens of jet fighters flew from the Lincoln today and loitered in the skies just south of Baghdad, waiting for calls from the ground to hit Iraqi tanks, troops or artillery. But pilots interviewed after returning from those missions said that murky skies made it difficult to see the ground. None said they dropped bombs.

Capt. Scott Swift, deputy commander of the air wing on the Lincoln, said he came up with the idea of converting Super Hornets into tanker planes after traffic jams developed high above the clouds around conventional tankers and several pilots had to abort missions because they couldn't get enough fuel. "We were cutting sorties drastically to optimize fuel," Swift said.

Air wing squadron leaders said much of the daily planning of the air war has been dominated by strategies for optimizing mid-air refueling. "I've never been involved in something of this size and scope," said Cmdr. Paul Haas, an 18-year Navy veteran who leads the carrier's F-14 Tomcat squadron. "There are so many assets competing for fuel."

Missions flown from the Lincoln often call for pilots to refuel twice -- once on the way to a target, or "killbox," area and again on the way back to the ship. Any flight lasting longer than 90 minutes usually requires mid-air refueling; the latest missions to support ground troops demand about four hours of flying.

And "if you don't have gas, you can't do the mission," said Lt. Cmdr. James Haigler, 34, who flew a Super Hornet that was converted into a gas tanker today.

Previously, jets on the Lincoln relied on Navy S-3 Viking tankers, which can fly off carrier decks, or Air Force KC-10 Extenders, a modified version of the civilian DC-10 airliner. Because neither of those types of planes carries defensive weapons, they do not fly into Iraq, where they might face Iraqi missiles and fighter jets.

Instead, they fly patterns over the Persian Gulf or friendly countries such as Kuwait, forcing the strike planes to fly out to them for gas and then fly back another long distance to reach targets inside Iraq.

But a Super Hornet functioning as a tanker still carries air-to-air missiles such as Sidewinders on its wings and a Vulcan 20mm cannon in its pointy nose. And it can give out twice as much fuel to other jets as an S-3 tanker, Swift said.

"It's revolutionary in what it's doing for naval aviation," said Swift, who worked on the development of the Super Hornet, a new plane that made its combat debut over Afghanistan. He and others say the flexibility confirms its value.

The Super Hornet can carry five fuel tanks, two under each wing and one under the belly. To give out fuel, the plane drags a tube with a steel basket at the end that resembles a badminton birdie. The refueling plane approaches from behind, inserts a retractable probe on its front right side into the basket and draws fuel.

The only people aboard the Lincoln who were unhappy about the reconfiguration of the jets were the pilots told to fly them as tankers, a task that many consider humdrum. "I'd rather be dropping bombs," said Haigler. "But whatever they need to get the war won."