It was the stunt heard 'round the world: On Wednesday, as Google (GOOG) co-founder Sergey Brin prepared to promote his latest pet project, a team of sky divers leapt from a zeppelin hovering over San Francisco's Moscone Center, landed on the roof and hand-delivered to Brin a pair of Google's "Project Glass" computing glasses -- all while connected in real-time to the Internet so those below could see the action from the divers' perspective.

It was such a hit that on Thursday, the company did it again -- and, breaking the maxim that good magicians never reveal their tricks, let slip the details of how they pulled it off.

The death-defying demonstration started as a tongue-in-cheek suggestion about six weeks ago. A team of Ph.D.'s and computer scientists, taken by the challenge, started working full-time on how to send a signal to a tiny, head-mounted computer screen 4,000 feet in the air.

"It's too high for cell coverage, and regular Wi-Fi wasn't reliable enough," said a Google spokesman. "At one point, we used a wok with a Galaxy Nexus phone taped to it."

Meanwhile, the company rustled up some of the world's best professional sky divers, including Palo Alto native J.T. Holmes, who's done jumps for Red Bull and Hotels.com.

(The latter once filmed him booking a hotel room while in free fall.)

Bill Dause, who owns the renowned Parachute Center near Lodi where Holmes and Co. trained for the stunt, likened the degree of difficulty to driving in the Indianapolis 500.

"Winds change, there's updrafts and downdrafts near buildings," said Dause, who's been in the business since 1964 and in some circles is half-jokingly suspected of being parachute legend D.B. Cooper.

Dause said jumping out of the dirigible was key to the stunt's timing. "An airplane has to fly around a big, wide circle," he noted. "With this blimp, they could essentially hover."

Actually, it wasn't a blimp but a zeppelin, operated by Mountain View's Airship Ventures. The giant, helium-filled craft -- one of only two in the world -- docks at Moffett Field near Hangar One, where Brin still hopes to get federal permission to keep his private jets.

Considering that the cheapest seat aboard the airship costs $350 for a 45-minute cruise, and that Holmes and his team went through multiple practices with specialized equipment, it's fair to say the stunt set Google back a few bucks.

"We aren't sharing a dollar figure, but as you can imagine, it was expensive," allowed the company spokesman.

Besides cutting a check, the search giant had to secure the cooperation of Federal Aviation Administration officials in San Jose, Oakland and Washington, D.C., along with that of the San Francisco mayor's office and police and fire departments.

"FAA safety inspectors observed the jumps, and they went off without a hitch," said Ian Gregor, a spokesman for the agency. The biggest key was getting FAA permission to let the zeppelin operate with the door open.

"We got very lucky today in that everything went off so seamlessly," Brin said in a posting to his Google+ account -- which, incidentally, features a photo of him sky diving.

Zany stunts, of course, long have been part of Silicon Valley's makeup. At Sun Microsystems, April Fools' pranks included a giant arrow running through the fifth-floor office of CEO Scott McNealy and the disassembling of Chief Scientist Bill Joy's Porsche (which was reassembled on an island in a man-made lake; he had to row out in a dinghy to retrieve it).

Still, Neil Cohen, a veteran valley public relations and marketing guru, said he couldn't' remember a stunt in this weight class.

"With so many moving parts, so much stuff could have gone wrong," he said. "I wonder what the backup plan was."

Contact Peter Delevett at 408-271-3638 or pdelevett@mercurynews.com. Follow him at Twitter.com/mercwiretap.