Boeing 747-8F Performs Ultimate Rejected Take-off

Imagine you're driving at the maximum speed allowed on a major highway and you have to suddenly stop the car.

In April, a fully-loaded 747-8 Freighter with worn-out brakes attempted an aborted takeoff on a California runway. The rejected takeoff or maximum brake energy test is one of the most dramatic for a new airplane.

It's basically what Boeing test pilot Captain Kirk Vining had to do recently with the new 747-8 Freighter during one of the most dramatic airplane certification tests. However, instead of a 4,000-pound (1815 kilograms) car, the 747-8 weighed in at close to one million pounds.

"In the emergency event that we have to make a rejected takeoff at these heavy weights, it takes a long distance for the airplane to stop," says Capt. Vining.

The Boeing 747-8 Intercontinental and 747-8 Freighter are the new, high-capacity 747s that offer the lowest operating costs and best economics of any large passenger or freighter airplane. Both are on track to make their first deliveries later this year after certification.

To simulate the ultimate rejected takeoff (RTO), crews loaded the airplane above its maximum takeoff weight of 975,000 pounds and installed a set of 100% worn-out brakes.

In April, the Boeing Test & Evaluation team brought the 747-8 Freighter to a long runway in California to simulate the ultimate rejected takeoff (RTO). Crews loaded the airplane above its maximum takeoff weight of 975,000 pounds (443,181 kilograms) and installed a set of 100% worn-out brakes.

"It's down to the studs," says Andy Hammer, the 747-8 flight test manager. "They've got them machined down so there's basically no material left."

Capt. Vining taxied the airplane out to the start of the runway and began the takeoff roll as usual by pushing all four engines to maximum thrust.

Just as the airplane was going over 200 miles per hour (320 kilometers per hour), Capt. Vining slammed on the brakes. To channel maximum energy to the carbon brakes, he was not allowed to use the thrust reversers.

"It's just brakes," says Hammer, explaining why the condition is also called the maximum brake energy test. "The whole intent is to demonstrate that under the worst conditions you can safely bring the airplane to a stop."

"The whole intent is to demonstrate that under the worst conditions you can safely bring the airplane to a stop." Andy Hammer, 747-8 flight test manager

"It went amazing," says flight test engineer Cassie Martin. "The [deceleration] was exactly what we expected. Great stopping, no major faults."

But stopping was just half the challenge.

The kinetic energy from the moving airplane was transferred to the brakes in the form of tremendous heat, estimated to be more than 2,500 degrees Fahrenheit or 1,400 degrees Celsius. As expected, the brakes glowed a bright orange as smoke poured out.

Firefighters arrived and were available to act in an emergency, but certification requirements called for the airplane to sit unassisted for five minutes.

After the airplane comes to a stop, it's estimated to be more than 2,500 degrees Fahrenheit (1,400 degrees Celsius) inside the brakes.

"And that's to simulate that if you were at an airport, you wouldn't necessarily have the fire department right there," says Hammer.

By design, special fuse plugs in the tires were activated, deflating the tires before they exploded. At the five-minute mark, firefighters moved in with plenty of water. While the tires and brakes were damaged, the rest of the airplane remained in great shape.

"This was the worst case," says Hammer. "So when the airplane is in service, you can be assured that at 975,000 pounds, with worn brakes, worst center of gravity, and worst cut speed that you actually can stop the airplane."

Source: Boeing Feature Story

Note: This is an Original Video. Ask first before borrowing.

Altumkell Productions 2011

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Category:

Science & Technology

Tags:

• boeing
• 747-8
• freighter
• airplane
• ultimate
• rejected
• take-off
• fully
• loaded
• RTO
• certification
• test
• feature
• story
• aviation
• airport

[panicslayernabz]

10 people are airbus employees

[Joseph9536]

Long live the 747

[bicyclingideas]

incredible

[DementedButtHole]

15 people developed a crack on their wings.....

[MegaHillview]

@xerocytesteve Ok.thanks for the heads up.

[xerocytesteve]

OOPs, this comment was supposed to be directed to SirD

[xerocytesteve]

@MegaHillview

You are incorrect in your statement. While spoilers do indeed create drag and help to slow the aircraft, their primary purpose is to provide down pressure on the undercarriage to maximize braking and tracking especially when touching down on wet runways.

[MegaHillview]

@SirDeanosity actually the spoilers don't add extra weight.It creates more drag,which helps slow the aircraft.The force acting there, will be along the longitudinal axis instead of vertical.Nevertheless,that test was awesome.We had many incidents,where pilots were looking to exit the active ramp at the nearest turn -off on landing, which resulted in greater wear of the tires and break units.Our engineering department told them to use the thrust reversers initially and utilize the runway's length

[SirDeanosity]

@MegaHillview Perhaps the use of the spoilers is intended to produce maximum weight on the gear so as to prevent skidding of the tires.

[SirDeanosity]

@panicslayernabz Airbus hired 5 more people.

[MegaHillview]

OK, but what about no Spoilers too?

[MegaHillview]

As an aircraft mech.had my fair share of changing all the brake units and tires on the same aircraft on the tarmac after a hard landing.no need to go to the gym to lose weight.Another thing,that odor emanating from the wheels is not nice at all.had to do an inspection of the struts/bogey and sent it on its way.It was a turn-around flight and this was done in the freezing rain.Next time there's a delay, passengers,its for your own safety and spare a thought for guys like us.