The first flight of the Wright Flyer was not much more than a hop. The Wright brothers’ plane, made of spruce and fabric, got barely 10 feet off the ground and landed 12 seconds later in the sands of Kitty Hawk, N.C.

To celebrate the Dec. 17 centennial of man’s first powered flight, aviation enthusiasts worldwide are racing to build a replica of the Wright Flyer. But there’s a hitch: They’re all having problems getting a copy of the Wrights’ primitive plane airborne.

“We put a man on the moon, and yet we haven’t been able to rebuild the Wright Flyer and fly it,” said Ken Hyde, 63, a retired American Airlines pilot in Virginia who heads a group that’s been working for more than a decade to reproduce an exact flying version. “It’s a lot harder than people think, even with all the technology we have today.”

Hyde, who has the backing of the Wright family and funding from Ford Motor Co., has secured a permit to fly his replica at Kitty Hawk on Dec. 17. And he believes his painstakingly detailed version will fly.

But a group of retired aerospace engineers in El Segundo, Calif., disagree. After conducting wind-tunnel tests, they are convinced that unless flight conditions are perfect, such as the cold temperatures and 27 mph headwinds that the Wrights faced in 1903, an exact replica like Hyde’s just won’t fly.

“Mother Nature participated then, so if Mother Nature doesn’t cooperate, it won’t fly,” said Jack Cherne, a former rocket engineer who helped design the engine on the Apollo lunar lander that put men on the moon. The original Wright Flyer is “a pile of kindling,” he said.

Cherne’s group is building its own Wright Flyer, but with modifications that members say will make it flyable. “We don’t want to build something that will kill somebody,” he said.

Hyde concedes that the Wrights’ first plane “is an unstable airplane, and the wind-tunnel tests bear that out.” But he added, “Changing the airplane will defeat the whole purpose of re-creating the flight. It makes the celebration meaningless.”

Hyde and Cherne are at opposite ends of a fierce debate within the aviation community over how to re-enact the Wrights’ historic flight.

So many are trying to build one that the Federal Aviation Administration in August imposed new inspection and certification guidelines for Wright Flyer replicas. No Wright Flyer reproduction can fly without an FAA airworthiness certificate, even if it tries only to duplicate the modest 12-second flight.

“There is no other invention in history that is being rebuilt like this one,” said Nick Engler, founder of the Wright Brothers Aeroplane Co., which builds replicas of various Wright airplanes. “Where are the guys remanufacturing the Edison light bulb? Nothing catches the imagination like the Wright Flyer.”

Indeed, it took the brothers four years of tests, first in gliders and then with a plane equipped with a gas-powered engine, before they flew into history. The Wrights, who made their living running a bicycle shop, were self-taught tinkerers. After struggling with their first gliders, the Wrights built the first wind tunnel to test different wing designs.

The Wrights built their own 12-horsepower, four-cylinder motor to turn two bicycle chains linked to a pair of hand-carved wooden propellers. To help steer the plane, the pilot lay prone on a wooden cradle on the lower wing, and when he shifted his hips, wires that ran from the cradle to the wingtips warped the surface and provided lift.

The original Wright Flyer, with its 40-foot wingspan, weighed about 605 pounds and cost about $1,000 to build.

For current Wright Flyer devotees, one problem is that the brothers left behind no final blueprint for the original plane. So aviation buffs rely on notes and letters the brothers wrote. But the void in the design details has fueled a debate over what constitutes an exact replica of the first plane.

The drastically different approaches by Hyde and Cherne also have touched off an intense debate among Wright brothers aficionados, who increasingly are splintered into the airplane purists vs. the pragmatists.

“To many of us, the effort to re-create the flight of the Wright Flyer is like what a Mass is to a Catholic,” Engler said. “The Wright Flyer is our sacrament to the first flight.”

Hyde is considered a purist because he wants not only to reproduce the plane exactly the way it was made, including using the same materials, but also to fly it at the exact spot Dec. 17 where the first flight took place and at the exact moment, 10:35 a.m. The National Park Service said it had sold 115,000 tickets for the Dec. 17 celebration at Kitty Hawk.

Cherne’s group, many of whose members worked on the nation’s most advanced aircraft, are pragmatists. They want to build an operational aircraft, even if some modifications and compromises need to be made.

“It’s healthy competition,” said Christian Markow, outreach coordinator for the Centennial of Flight Commission, a panel appointed by Congress to be the clearinghouse for the celebration.