

Speed Machines

Fastest Airplane | Boat | Car
SR-71 in flight The Lockheed SR-71 Blackbird is, to date, the fastest airplane ever to streak across the sky, even though it's more than 30 years old. Capable of speeds over 2200 miles per hour—that's more than three times the speed of sound—the SR-71 can fly at altitudes above 80,000 feet. What does it feel like to travel at Mach 3, 15 miles above the earth? Pilots report that, with no view out the window, there's an eerie sensation of motionlessness when cruising in the Blackbird.

To fly safely in this harsh, low-pressure environment pilots must wear a full-pressure suit for protection. Even though the temperature outside the aircraft hovers around -70 degrees F, the sheer friction of flying at Mach 3 heats the leading edges of the SR-71 to 800 degrees F. To help withstand this kinetic heat, the Blackbird's airframe is built almost entirely of titanium and is finished in a special heat-emitting black paint, which helps to cool the aircraft and gives it its nickname.

The SR-71 can operate for about an hour at top speed before it needs refueling—a feat that can be accomplished in mid-air with a special tanker aircraft. The Blackbird is powered by two Pratt and Whitney J-58 axial-flow turbojets SR-71 being refueled in flight with afterburners, each producing about 34,000 pounds of thrust. Studies have shown that when the aircraft is cruising at Mach 3 or above only about 25 percent of the total thrust is produced by the engines themselves. The balance is produced by the unique design of the engine inlet and housing, which is equipped with special afterburners.

The two-seat SR-71 was developed in the early 1960s by the U.S. Air Force as a strategic reconnaissance aircraft. The first flight of an SR-71 was in 1964 at a classified location in Nevada. The aircraft's first operational "sortie" was flown out of Okinawa, Japan in 1968. Most of the SR-71 fleet has now been retired, except for two Blackbirds currently on loan to NASA's Dryden Flight Research Center where the aircraft are being used as "test beds" for high altitude research.

Fastest Boat
The World Water Speed record, like the air speed record, is decades old. Australian Ken Warby set the record in 1978 when he averaged 317.60 mph in a 27-foot jet-powered hydroplane called "Spirit of Australia." The official Ken Warby's Spirit-1 speed test, which consists of two back-to-back runs over a one-kilometer straight-away, took place on Blowering Dam in New South Wales, Australia. And where did Warby design and build this hydraulic masterpiece? Underneath a tree in the back yard of a house he was renting in suburban Sydney. "There was a canvas sheet I used to throw over it when it rained," he told the press.

Attempts at beating Warby's record have come at a high price. In 1980, the previous water speed record holder, Lee Taylor, tried to reclaim his title in a 2.5 million dollar rocket-boat called "Discovery II." The missile-shaped craft was constructed of aluminum, titanium and stainless steel and was powered by a rocket engine that burned hydrogen peroxide fuel. On paper, the power plant generated 8,000 pounds of thrust—or 16,000 horsepower. Taylor believed his boat would surpass 600 mph.

The trial took place November 13, 1980 on Nevada's Lake Tahoe. Discovery II roared through its first pass at 269.85 mph and was decelerating when it appeared to hit a swell. Witnesses reported that the boat veered to the left and suddenly disintegrated, vanishing under the surface of the lake in a matter of a few seconds.

Craig Arfons, a former automotive drag racing champion, was the next to take up the challenge. In 1989, he put the finishing touches on a jet hydroplane called "Rain-X Record Challenger," which boasted a lightweight composite hull and a jet engine that could deliver 5,500 horsepower with the afterburner lit. Arfons calculated that the boat's favorable thrust-to-weight ratio would give it a 200 percent power advantage over Warby's record-setting boat.

The record attempt took place on Jackson Lake near Sebring, Florida. Members of Arfons' crew say his boat reached a speed of 263 mph before it became airborne and began to cartwheel across the mirror-smooth lake. Arfons tried to deploy a safety parachute, but the angle at which his boat was traveling Warby's new boat under construction prevented the parachute from opening. Arfons was killed as his boat shattered around him.

Recently Warby, now 58, has announced his intention to push his World Water Speed Record even higher with a new boat currently under construction. "I'm far too young to be in a rocking chair, so I thought I'd get back in the cockpit."

Fastest Car
The battle to break the sound barrier on land was won exactly 50 years after Chuck Yeager broke it in the air ... On October 13, 1997, a British jet car called ThrustSSC made two supersonic passes across Nevada's Black Rock desert at 760.135 m.p.h. and 763.168 m.p.h. It took British fighter pilot Andy Green exactly 61 minutes to make the two runs, narrowly disqualifying him for an official land speed record, which requires that the two runs be made within 60 minutes. Two days later the first ever supersonic World Land Speed Record was made official when the ThrustSSC completed two runs within an hour at an average speed of 763.035mph. The British team had been sharing the desert with another contender, America's Craig Breedlove. His Spirit of America car had reached a peak speed of 675mph on the Black Rock Desert before crashing during an October 1996 record attempt. During the October 1997 runs it reached 636mph.

They may not get another chance this year; not only is the weather window closing, but the desert surface is now occupied by another contender, America's Craig Breedlove. While both Noble and Breedlove have been relentless in their pursuit of the sound barrier, their approaches have been wildly different. Noble has embraced advanced engineering, employing rocket-sled model testing and computational fluid dynamics in the design of his vehicle. Breedlove, a race car driver since his teens, has assembled a team of mechanics whose goal, according to crew chief Dezso Molnar, was to design "a car as simple as we could possibly make it—with as few moving parts as possible."

The ThrustSSC Noble's Thrust SSC is the larger and heavier vehicle, measuring 54 feet and weighing 10 tons. Two Rolls-Royce engines, salvaged from a scrapped Phantom jet fighter, are anchored to either side of the car's midsection, with the driver sandwiched between them. Together the engines, which burn jet fuel, have a combined power of 55,000 pounds of thrust, or 110,000 horsepower. Breedlove's Spirit of America is slight by comparison—measuring only 47 feet and weighing a mere 4 tons. It has one jet engine, a GE J79, that has been modified to burn regular 92-octane gasoline. Delivering 22,650 pounds of thrust, the engine is positioned in the rear, while the driver is perched at the very front of the vehicle. In terms of its thrust-to-weight ratio, Spirit of America Breedlove's car has a slight advantage over Noble's—2.83-to-1 versus 2.75-to-1, respectively. But clearly power is only part of the equation.

How does one control a vehicle barreling across the desert at speeds over 750 m.p.h.? Noble's Thrust SSC is equipped with two front wheels and a staggered pair of back wheels, which steer the vehicle. The wheels themselves have no tires; they are bare disks of forged aluminum. Breedlove's Spirit of America has three front wheels, set very close together, and two conventionally placed rear wheels. The front wheels do the steering with the help of a "steering rudder," which tips the vehicle's fuselage left or right, controlling it like an airplane. Its tires are made out of a wound carbon composite. For braking, Thrust uses parachutes as well as disc-style brakes on all four wheels. Spirit augments its parachutes with a single braking ski that drops from the cockpit.

The greatest challenge that both cars face is remaining aerodynamically stable over the course of the run. Going supersonic means passing through a critical transonic period where air rushes past different parts of the vehicle at varying speeds, producing pressure and shock waves that influence lift and drag. Of particular concern is the possibility of becoming airborne—or digging in to the ground. Neither car is equipped with ejection seats or escape capsules.

Photos: (1-2) Lockheed-Martin Skunk Works; (3) Australian Information Service; (4) Ken Warby; (5) ThrustSSC; (6) Shell/Spirit of America.

Resources | Teacher's Guide | Transcript | Faster Home

PBS Online | NOVA Online | WGBH

© | Updated October 2000