Moments and Milestones: Max Takeoff

Moments and Milestones: Max Takeoff

The Boeing behemoth on its first flight (with Lockheed T-33 chase plane), last February.
The Boeing behemoth on its first flight (with Lockheed T-33 chase plane), last February. Royal S. King

When wide-body jet transports entered service, the Federal Aviation Administration determined that their turbulent wakes were violent enough to require that other airplanes be well separated from them. When a wide-body’s pilot talks to air traffic control, he appends the word “heavy” to the flight number. When controllers hear “flight 607 heavy,” they know they have to provide the aircraft following that flight with greater separation than they’d allow behind a smaller airplane.

But Boeing test pilot Paul Stemer really meant it when he called in “heavy” during a takeoff on August 16, 2010, from Victorville, California. He was flying a freighter version of the Boeing 747-8, test aircraft RC521, along with Bob Stoney, a pilot with the Federal Aviation Administration, and when the wheels left the ground, they recorded the heaviest takeoff weight ever in the history of Boeing: 1.002 million pounds.

One of the reasons they chose Victorville for flight tests on this new version of the 747 was the airport’s extra-long 15,000-foot runway. In this particular test, they used about 10,500 feet of pavement to get into the air, so they weren’t cutting it close, but when you watch that much runway go by and there’s only 4,500 feet left, it can get your attention. Andy Hammer, Boeing’s 747-8 flight test manager, described the flight as routine: “In flight test, we test the airplane’s capabilities above and beyond the normal operating conditions.”

In fact, other big airplanes have greater takeoff weights. The Airbus A380 freighter advertises a takeoff weight of 1.3 million pounds, and the six-engine goliath from Ukraine, the Antonov An-225 Mriya (or “dream”), takes the crown at 1.323 million. The giant Antonov was designed to carry the Soviet Buran space shuttle, and only one was ever built.

According to Boeing spokesman Tim Bader, “The mission on the August flight was to demonstrate cruise at the actual design takeoff weight of 975,000 pounds.” Another 747-8 freighter, aircraft RC501, had already taken off at that weight, setting the previous record. Technically, the weight of the RC521 as it taxied out was 1.005 million pounds, so it burned off about 3,000 pounds of fuel before it took off. And after takeoff, it burned enough fuel climbing to its cruise altitude to bring its weight down to 975,000 pounds.

Before the FAA awards it a type certificate, every airplane is tested to see how it performs at various weights. Sometimes test aircraft are weighted down with water tanks, but for this flight, heavy steel plates were anchored to the freighter’s cargo deck. Aircraft are also flown with the payload weight moved forward or aft to the maximum design limits to see how they perform.

The 747-8 is the result of a prolonged competition between Boeing and Airbus during which Airbus ended up developing the A380, which is now the world’s largest airliner. Boeing opted to build the smaller 787 but to incorporate a lot of features never seen in a transport aircraft before. Among these are a composite structure and new General Electric engines that, together, should cut the cost of operation by about 20 percent, compared to the previous generation airliner, the 767. The 747-8 has a new wing and will also use the GEnx-2b engines of the 787, although the ones on the 747-8 will provide bleed air from the engine’s compressor to pressurize the cabin, whereas the 787 will use separate electric compressors. With the delays it has incurred, the 747-8 freighter should reach customers in mid-2011.