Prototype Gyrocopter Crashes in Texas
From this morning's Avweb news...
CarterCopter Claims To Break Mythical Barrier...
"From Exhilaration To Devastation"
... Along with the prototype. The staff at CarterCopter, in Olney, Texas, was busy on Friday afternoon preparing a press release about that morning's success -- they had finally achieved an aerodynamic breakthrough they'd been working on for years -- when news came in that the one-of-a-kind prototype gyrocopter had been destroyed in a crash. Pilots Larry Neal and Brad King were out on a test flight when something went wrong. "We don't know what it was," CEO Jay Carter Jr. told AVweb on Saturday. "Things happened really fast. It was like somebody slammed on the brakes. The nose pitched down and it started rolling to the left. Larry thought it was going inverted." The aircraft righted itself, and Neal and King were able to regain some pitch control just before they hit mesquite trees. The rotor provided enough lift in the descent that it essentially acted as a built-in parachute, Carter said.
The aircraft plowed through the trees at about 70 mph, Carter said, and hit the ground. The landing gear absorbed much of the impact. The cockpit remained intact, but everything else was torn apart. The pilots walked out of the woods to a nearby road, where they were found by CarterCopter staff about 20 minutes later. "That pressurized fuselage is so super-strong, it saved their lives," Carter said. The fuel tank is in the cockpit, a design that some were uncomfortable with, but Carter said this accident proved the wisdom of it. That was the best-protected place, and there was no fuel spill and no fire. The aircraft is not repairable, Carter said.
Despite his disappointment over the loss, Carter said he was "ecstatic" over the success of Friday morning's flight. "We exceeded a Mu of 1 for the first time in history. This has been our goal ever since we started flight-testing in 1998. ... History will prove out the significance of this." The "Mu-1 barrier" is an aerodynamic limit defined by a forward speed and rotor rpm combination that results in advancing (moving into the relative wind) blade tips reaching speeds of twice that of the aircraft. At the same time, the retreating blade tips experience zero airspeed (as they rotate away from the relative wind) on the opposite side -- the entire inboard portion of the blade sees "reverse" air flow. The predicament prevents rotorcraft from achieving high forward speeds (CarterCopter sports small wings). According to the company, the barrier was breached during normal flight-testing Friday morning, while collecting data on a newly developed speed controller for the rotor. Initial data from Friday's flight shows that the airspeed was 170 mph and the rotor was slowed to 107 rpm, for a Mu value of 1.02. A Mu of 1 would enable a gyrocopter to fly up to 300 mph, Carter said.
The milestone attempt wasn't planned but evolved as the rotor proved to be stable as the rpm was decreased. Carter said he believes the breakthrough paves the way for rotorcraft to reach up to Mu-5 and fly up to 500 mph. With vertical takeoff and landing capabilities and the safety of a lifting rotor that acts as "built-in parachute" -- "That's pretty darn good. We hope we'll get the opportunity to build another one," he said. It was a combination of patented technologies that led to the breakthrough. "It's about eight things combined, but the key things that made this possible are the rotor-blade design and the computer-automated controls," Carter said. The data and video from the morning's breakthrough flight are being analyzed. As an element of a current U.S. Army contract the Army is scheduled to verify the calibration and accuracy of the data in the next few weeks.