Radar-evading technology for the mysterious helicopters that carried out the U.S. special operations raid of Osama bin Laden's walled compound in Pakistan was spawned in the early 1990s at the classified Area 51 installation in Southern Nevada, according to sources close to the black projects facility.
One source familiar with operations at the secret location along Groom Dry Lake, 90 miles north of Las Vegas, said a smaller version stealth helicopter -- an angular, two-seat McDonnell Douglas 500 with sharp edges, riveted body, gull-wing doors and black-brown coating -- would fly "two or three times a day" during 1992 and 1993.
"The rotors, the entire body and even the canopy system on it was all integrated into that material," said the source, who spoke on the condition he not be identified because of security obligations.
The source said the craft was difficult to land. " It had to land on a special trailer so it could be maneuvered into the hangar," he said, noting that the landing gear consisted of skids, not wheels.
His account confirmed a Review-Journal story from 1995 that quoted an unnamed former base employee who said the project was code-named "T.E.-K," which stood for "Test and Evaluation Project K."
At least two of the prototype stealth helicopters were stored near the southern end of the installation in Hangar 8, according to accounts from both sources.
The Groom Lake source on Friday said, "This was the test bed, the original one, to see if you could exploit it and turn it into something bigger."
He said work began on stealth helicopters at the installation in the early 1990s following production of the F-117A Nighthawk attack jet that was tested there and developed under a tightly guarded program.
And, that's what apparently happened with black project helicopters 16 years after the Review-Journal revealed the existence of Project K, according to John Pike, director of globalsecurity.org, a military information website. The radar-evading helicopters that shuttled Navy SEALs to bin Laden's compound in Abbottabad, Pakistan, could have evolved from the Groom Lake test bed in the early 1990s.
The raid aroused the curiosity of aviation buffs after one of the helicopters made a hard landing. The SEAL team blew up most of the crippled aircraft before they barreled out of the compound, but the tail section with a "hubcap" to hide movement of the rear rotor and reduce noise remained intact.
"I would have no way of knowing whether it was technology from the test bed applied to the MH-60 or a prototype for an entirely new design," Pike said.
"I suspect from looking at the wreckage that it's a heavily modified MH-60 (Black Hawk) but that's erring on the side of caution."
He surmised that the bin Laden raid helicopters were probably tested against foreign radar systems around the high-tech Area 51 installation. While there are other locations to do such testing, Pike said, "Groom Lake is the best place in the world where you're not going to be seen."
Pike estimated there aren't many of these larger stealth helicopters in existence. "It would not be very many. In the low dozens."
He said today's black program budgets are "somewhere in the billions and billions of dollars." They are as big as the so-called Star Wars era of the Reagan administration "except under Reagan we knew where it was being spent. Today we don't."
The beginning of the military's stealth development efforts predated the Reagan administration when Ben Rich, Lockheed Martin's "father of the stealth," started the F-117 design in December 1978 at the Skunk Works plant in Palmdale, Calif. The full-blown combat version followed successful test flights at Area 51 of a prototype, dubbed Have Blue.
The F-117 fighter-attack jet made its first flight on June 18, 1981, and the first war-fighting Nighthawks were based at the Tonopah Test Range.
They launched the era of using stealth technology to attack heavily protected, high-value targets.
After the stealth program was declassified in November 1988, the first warplanes were deployed in combat over Panama during Operation Just Cause in December 1989 to help spur the surrender of military dictator Manuel Noriega.
In the Persian Gulf War in 1991, 36 F-117As bolstered the allied effort against Iraq by bombing targets in Baghdad.
The original wing at Tonopah on Nellis Air Force Range was relocated to Holloman Air Force Base, N.M., after the Persian Gulf War, with the first plane arriving at Holloman in May 1992.
Fifty-nine production models were made, with the last rolling off the line at Lockheed's Palmdale plant on July 12, 1990. Seven were destroyed in crashes, including one lost in combat over Yugoslavia on March 27, 1999, in the Kosovo war effort.
Two F-117As spearheaded the U.S.-led invasion of Iraq during Operation Iraqi Freedom in March 2003. They flew unescorted over Baghdad and dropped bombs on Dora Farms, where intelligence sources thought Iraqi leader Saddam Hussein was hiding.
Besides radar-evading helicopters, the F-117A with its oblique, batlike shape and secret black coating blazed the trail for today's stealth jet, the F-22 Raptor, which, with the F-35 Joint Strike Fighter, is replacing the Nighthawk.
On April 22, 2008, the last four Nighthawks arrived at the Tonopah Test Range where the fleet was retired. The black jets are mothballed in hangars in classified storage with their wings unbolted .