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It's been dragged, dropped, soaked, and forced to hover, shudder and flutter.
Boeing test pilots have been subjecting the new 747-8 Freighter to a series of punishing tests as part of the extensive program to certify the airplane.
"Some people may even call it abusive," says Capt. Mark Feuerstein, the 747-8 Chief Test Pilot. "It certainly requires a lot of forethought to execute some of the maneuvers."
In all, the four 747-8 Freighter test airplanes are nearing 1,500 flight hours, the half-way mark toward certification. Capt. Feuerstein, who has been in the flight deck for many of those test hours, calls it an amazing machine.
"If I had the chance to talk to a new 747-8 pilot, I would tell them be excited. It's a great airplane. It's going to deliver on the promise of better efficiency, better performance, payload and a quieter machine, but best of all from a pilot's perspective, they're going to enjoy flying it," says Capt. Feuerstein.
In November, Capt Feuerstein and other Boeing test pilots took turns dragging the airplane's tail on a California runway. The velocity minimum unstick test was critical in figuring out the lowest speed at which the freighter can take off.
It was not an easy maneuver to pull off.
"It's a balance between being forceful and being gentle," says Capt. Feuerstein. "We want to be forceful to get the plane's tail moving down towards the runway, but of course we want to be very gentle when we set the planes tail down."
In another test of the airplane's takeoff performance, the 747-8 Freigher this fall broke its own record by taking off at 1,010,000 lbs. Earlier in the year, the freighter set the heaviest takeoff in Boeing history by soaring into the sky while loaded down with 1,005,000 lbs.
"If I had the chance to talk to a new 747-8 pilot, I would tell them be excited." Capt. Mark Feuerstein, 747-8 Chief Test Pilot
Meanwhile, the ground-effects issue that emerges when the airplane is close to the surface after takeoff and prior to landing, was also explored. Test pilots over several days in October commanded the 747-8 Freighter to basically hover over the runway.
The test helps verify the jet's stability and control and compiles data for the engineering team to finalize the auto-land system.
"You do it with an airplane coming in at a side angle, if there's a crosswind, different weights of the airplane, different flap settings, says Michael Teal, the 747-8 Chief Project Engineer. "The objective is really understanding and simulating what the airplane can see in service."
Gravity-defying tests continued in the clouds. Pilots purposely put the freighter into a stall to make sure it can recover. Time after time the airplane met the challenge.
"Usually in most of the stalls that I've flown, I merely relax back pressure on the column to neutral column and the airplane recovers just fine," Capt. Feuerstein said of the 747-8 Freighter.
"We have implemented fixes on the airplane and we're now driving toward all of the fundamental testing we have to complete and certify the airplane." Michael Teal, 747-8 Chief Project Engineer
The pilots also are verifying that the airplane can dampen vibrations when they intentionally pulse or excite the control surfaces. While the 747-8 Freighter officially cleared flutter testing earlier in the year, the program continues to test for flutter as it refines the flight control laws.
"We made significant progress in resolving the issues we found during the flight test program," says Teal. "We have implemented fixes on the airplane and we're now driving toward all of the fundamental testing we have to complete and certify the airplane."
While the pilots put the freighter through its paces, Capt. Feuerstein says it's the engineers who really make a difference.
"Our engineers are the real heroes," says Capt. Feuerstein. "We've been able to understand problems and design fixes. And the results have been nothing short of fantastic."