After more than a month of delays, the balloon DaVinci TransAmerica was launched here this morning near the Pacific coast, shooting straight up into a windless gray drizzle as hundreds of bystanders cheered, shook hands and beeped their car horns.

There was a final postponement for more than three hours, before the 10-story-high helium balloon, which is attempting the first nonstop piloted crossing of the United States, was cut loose from a tow truck. It then rose at the rate of 300 feet a minute and disappeared almost immediately into the low clouds.

Piloted by Vera Simons of McLean, Va., and carrying a crew of three, the craft took off toward the east, drifting at nearly 50 miles an hour in a fair weather system that was expected to take the balloon to the western slope of the Rocky Mountains today.

At midday today, the four balloonists were flying above the clouds at about 14,000 feet. In crystal-clear, 38-degree skies, they could see 14,410-foot Mount Rainier to the north in Washington state and to the south the snow-spotted spine of Oregon's Cascade Mountains.

As the balloon drifted east, the crew radioed all was silent as it moved at windspeed in a Dayglo orange gondola adorned with the names of the companies that have put up more than $250,000 for the flight. The Seven-up Company had banners and patches and sent along 100 empty aluminum cans of its soft drink to be distributed to the nation's governors upon the balloon's landing.

Louisiana-Pacific, a wood and paper conglomerate, sent tiny balloons that will be dropped across the country. The finder is entitled to a free fir tree.

The the cheese making town of Tillmook, which donated police to control the crowd that began gathering here at 3 a.m., also placed an advertisement on board. It said: "Good luck from the town of cheese, trees and ocean breeze."

Before Simons climbed into the gondola here at 8 a.m., she paced back and forth in the morning darkness on an abandoned Navy air station runway here. "I'm ready. I'm ready. I'm ready," she kept repeating to herself.

The German-born balloonist, her blond hair sticking out from beneath a leather flying helmet, said further delays would have skuttled the planned six-day, 2,295-mile flight, which is supposed to end in Norfolk. Like nearly every aspect of the flight preparations, today's launch was plagued with delays.

In the past two months, the DaVinci flight has been delayed by bad weather, provoked court battles between two major television networks and triggered an investigation by a federal agency. At 3:55 a.m. today however, past problems were overtaken by fear that the balloon would not lift off at all.

When filled with 216,000 cubic feet of helium, the balloon resembles a clear, tear-shaped envelope. But this morning it looked like a huge, empty plastic sandwich bag.

The gas needed to lift the load of 8,488 pounds was being pumped far too slowly. Because of an error in selecting the hoses that transferred the gas from tanker trucks to the balloon, the flight first had to be delayed one hour from its scheduled 5:15 a.m. lift off.

The delay endangered the craft's chance of catching the ridge of a fair weather system that the balloonists have been waiting for since the beginning of August. Long-distance balloons ride such ridges like a surfboard on a wave.

"If we miss it, we simply won't get to the East Coast," said Dr. Rudolph J. Englemann, director of the DaVinci project, as he waited at 6 a.m.

Moments later, Bedford, Mass., meteorologist Bob Rice, the project's weather expert, told Englemann by phone that the balloon launchers should hurry. He said the good winds could pass them by.

But the launching experts, who flew here on Sunday from Minneapolis, were led by Soren Swenson, 65, who has launched hundreds of balloons and who says he refuses to be hurried.

"The thing about the balloon now," Swenson said as the balloon crew anxiously waited for him to finish the rigging, "is that it has got so much life it becomes a vicious monster."

Swenson's six-man launching team then slowly attached the balloon to the gondola, at the same time keeping the balloon's 8,950 pounds of lift tied to a 32,000-pound tow truck.

As the sun was coming over the nearby Coast Range mountains, Simmons was told to board the gondola, check a helium release valve, and prepare for liftoff.

Englemann kissed his wife, Virginia, goodbye, telling her he would see her again in Virginia. The other crew members, Dr. Fred Hyde, an eye surgeon from Prairie Village, Kan., and Randy Burch, a camerman for NBC television, climbed aboard the fiberglass gondola.

A warning was given that there were two minutes left before liftoff. Then, Swenson, the veteran balloon launcher, notcied that he had goofed. The balloon couldn't move.

Swenson had forgotten to attach a cable to the release pin that would detach the balloon from the tow truck.

"I forgot," he said simply.

Since pulling down the balloon's rigging would have taken too much time, a truck with a "cherry-picker" was summoned by radio. Soon a worker was aloft attaching the cable while Englemann complained from inside the gondola that high altitude winds might be changing for the worse.

At 8:16 a.m. the pin was successfully yanked and the balloon jumped from the ground, rising into strong westerly winds at 5,000 feet.

Englemann said the DaVinci project "would just have to hope" that the balloon had gotten into the weather system quickly enough to be carried to the East Coast.

"We'll know in three days. Then, if we missed it, we won't be going anywhere."