Blast OFF!!!
Posted on 11/30/2004 10:13:12 AM PST by presidio9
Outsiders look at the GlobalFlyer, a single-seat airplane designed to make the first solo, nonstop, unrefueled flight around the world, and wonder how a pilot could function for 70 hours in a cigar-shaped cabin so snug he cannot even get out of his seat.
But the pilot, Steve Fossett, has another problem in mind: fuel.
Technicians at Scaled Composites, the company that built the plane, like to call it the Flying Fuel Tank. At takeoff - on Jan. 4 or as soon thereafter as the weather permits - it will weigh as much as a 50-seat commuter plane. If it is successful, it will land nearly three days later weighing less than a medium-size S.U.V.
On a recent test flight here it did not so much take off like a jet (which technically it is) as glide into the sky. Fully loaded, it will need more than two miles of runway to lift off.
The GlobalFlyer is first of all a feat of engineering - building a plane strong enough to climb into the sky with so much fuel and efficient enough to fly almost 20,000 miles without refueling. It is also a test of the pilot's skill and of human endurance.
Mr. Fossett, glider pilot, sailor and balloonist, is being sponsored by Virgin Atlantic Airways, whose name is pasted prominently on the ungainly GlobalFlyer. Scaled Composites of Mojave, Calif., also built the Voyager - the two-seat propeller-driven plane that went nonstop and unrefueled around the world in 1986 - and SpaceShipOne, which took home the $10 million X Prize in October for the first private flight into space.
The Voyager, it turned out, was almost too fragile to complete the trip: when the Smithsonian took it apart to get it into the Air and Space Museum on the National Mall in Washington, technicians found cracked flanges in the main spar, the backbone of the wing. (The plane hangs above the information desk at the main entrance to the museum.)
But technology has changed since then. The carbon-fiber and epoxy material is about the same, said Burt Rutan, the company's founder and the planes' designer. But the main spar of GlobalFlyer, which is 110 feet long, is all one piece, built at near room temperature. In the 80's, composites had to be cooked in an autoclave, making such big pieces impossible.
The wingspan is about the same as that of a Boeing 737-900, but there the similarity ends. The oddest part about the GlobalFlyer is what engineers call the "fuel fraction," which is the percentage of takeoff weight that is in the fuel. Lately the GlobalFlyer breaks the fuel fraction record with each new test flight, but on its round-the-world attempt it will be at its most extreme ratio, 82 percent fuel. In contrast, at maximum takeoff weight the 737-900 is 24 percent fuel, with a range of 3,160 miles.
The GlobalFlyer has a system of 13 separate fuel tanks. Managing them is essential to minimizing wing bending and keeping the plane balanced during its metamorphosis from lumbering tanker into featherweight.
A pilot of Mr. Fossett's skill can handle that transition, the engineers say. But he will need more than skill.
While the plane has an autopilot to maintain heading, course and altitude, it still needs work before the flight. No pilot can stay alert for 70 straight hours and, as Mr. Rutan put it, "No one's willing to sleep with the autopilot yet." In a single-seat airplane, sleep is a serious problem.
The Federal Aviation Administration, concerned about a groggy pilot in the last stages of the flight, is considering ordering that the plane take off from Edwards, so that the flight's final hours, with the exception of the last few minutes, will be over uninhabited ocean. But mission planners are leaning toward an old air base in Salina, Kan., with a suitably long runway, so that if the fuel runs out 1,000 miles short of the destination, the GlobalFlyer will be over land.
The plane is supposed to cross the North Atlantic, Europe, the Persian Gulf, India and the Pacific, but the route could be changed during the mission, depending on weather forecasts. The cruising altitude is above most of the weather, but not all of it. And to save fuel, the climb to cruise will be a leisurely 12 hours; descent will also be slow.
But time aloft is so long, and the cruising altitude so high, that the designers switched from ordinary jet fuel to a mixture that is less prone to freezing.
For Mr. Rutan, the GlobalFlyer is an audacious attempt to one-up the Voyager, another of his creations, which his brother Dick flew, with another pilot, Jeana Yeager. That was about 72 percent fuel at takeoff.
Under rules laid out by the international federation that keeps aeronautical records, "round the world" means at least the distance around the Tropic of Capricorn. The plan for GlobalFlyer is 19,864 nautical miles, or 22,859 statute miles. The Voyager did 24,900, which is just short of the distance around the Equator.
This time the plane will use a single jet engine, the same type used as half the power plant for corporate jets. The engine will run during most of the flight well below its ordinary cruise setting, the designers say. Mr. Rutan says jets are so reliable that "it's safer to fly over a long ocean with one turbo-fan than two piston engines."
If it quits at 45,000 feet, or about 9 miles, finding a landing spot is probably not a problem, because it can glide about 30 feet for each one foot loss in altitude, giving it a range of nearly 300 miles before the pilot would have to land, ditch or bail out. But the GlobalFlyer is such a wonderful glider that it would be a challenge to descend fast enough to find breathable air.
The reason is that to maximize its cruise efficiency, and maintain a "clean" wing with as little drag as possible, it has no spoilers, the wing-top devices that are used to reduce lift when the plane has to land. It also lacks flaps, the devices at the rear of the wing that extend to provide extra lift at takeoff.
And to save weight, the Flyer lacks most of the safety devices common to modern planes. It has no deicing system for the wings or windows. It has no radar to spot weather or other traffic. It barely has brakes; engineers removed a rotor from each disc brake.
"In order to build a plane light, you have to build it with very little safety margin," said John Krueger, a mechanic and composite fabricator, standing amid the yucca bushes and jack rabbit tracks at the edge of the 15,000-foot runway at Edwards Air Force Base, watching the liftoff of a test flight on Nov. 17. "When it's this heavy, the margin is very small," he said.
Even the emergency oxygen supply may be too small to keep the pilot alive if the cabin depressurizes at cruise altitude. A bigger system would weigh 12 pounds more, and Mr. Fossett, 60, said he was not sure that it was worth the weight. "A friend of mine suggested I go on a diet," he said. (He put his weight at 213 pounds.)
The Flyer looks like two planes flying in close formation. Mr. Rutan designed it with two huge booms, each with a tail at the back; the huge wing; and a small fuselage in the middle.
It is almost a single-use airplane, although Mr. Fossett said he might fly it again after a round-the-world trip. While new airliners use increasing amounts of composite materials, aviation experts say that the Flyer probably does not advance the technology they use. It could break new ground that would be useful for other kinds of planes, though, including high-altitude drones sent aloft for long periods, for communications, surveillance or other purposes.
Mr. Fossett, interviewed by telephone from South America, where he was seeking to set new records in gliders, said he looked on the trip mainly as a piloting challenge. He said the autopilot was coming along as Jon M. Karkow, the project engineer and main test pilot, got more experience with the plane, but added, "If I'm having trouble with the autopilot, then I will absolutely not fall asleep."
Scaled and Virgin refused to discuss the cost of the mission.
"I wonder if the Smithsonian will take it," said one Scaled technician, Clint Nichols, watching it take off. Then he added, "It's weird enough."
There you go, A pre-flight cosmic butt-blaster cocktail!
Depends.
ping
Like an amphetamine the size of a golf ball. Recently I read an article on sleep that talked about a drug that keeps you awake without the speed-like side effects.
22,859 / 70 = 326.56 mph. Probably the reason for the jet, though a turboprop would be more fuel efficient.
Check the numbers. It will either never leave the ground or it will not make it around the earth.
Range for a fully-loaded 747 is about 5200 nmi, or roughly 25% of the way around the world. That assumes a constant payload weight (not true if the payload is fuel) and a standard fuel load (also not true if the payload is fuel).
You may be correct, and I'm not an airplane performance guy, but I think that, given these factors, a suitably-modified 747 could probably get pretty close to making it.
Not enough lift in the wings of a 747. Look at the wings on that pic and consider that it is all composite.....a lot lighter than aluminum.
Wow ~ that's wild! :)
If you check the numbers you will see that you MIGHT be able to carry 50% more fuel on takeoff. Even with the decreasing weight during flight, that won't get you around the world.
Blast OFF!!!
The man is a force of nature. He set out to smash every significant sailing record, and he did. Ditto ballooning.
Maybe so -- I can confirm your 50% number. Not a performance guy, so I can't challenge your other assertion.
On what?
[rimshot]
On the pilot.
I'm glad they lost the canard like the Voyager had, which caused the cabin to pitch up and down in turbulence.
current Max range = 6100 miles
Earth circumference = 24901 miles
you would need fuel in fuselage for 18801 extra miles or about 3 times current Max range
and therefore 3 times current main tank capacity in the fuselage
(not considering increased GW effects on range which is stupid but ok to make this silly point)
fuel for current max range = 48445gals
6.7 lbs/gal * 48445 gals = 324581 lbs (you probably see what's coming)
weight of fuel needed in fuselage = (324581*3)lbs = 973774 lbs
This is an order of MAGNITUDE greater in weight than the current max passenger weight. The whole plane weighs less than 800,000!!!!
Thank you for playing.
,,, Fossett never sits still - always something on the go.
This is very cool
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