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Engineering a land speed record

Grenestedt arrives at the Bonneville Salt Flats.

The enclosed streamlined motorcycle, or streamliner, that Joachim Grenestedt built looks like a miniature airplane with no wings. Its tiny cockpit seems far too small to fit a person of average size, much less Grenestedt—who stands 6 feet, 4 inches tall.

Grenestedt built the streamliner to set a land speed record, but the contorted position he must assume inside the cockpit hardly permits him to drive, let alone race. He must lie almost flat on his back, and safety restraints are strapped so tightly against his body, arms, ankles, knees and thighs, that he can barely move his left foot to change gears.

Add to this the streamliner’s low center of gravity, which makes the machine difficult to balance and wobbly at low speeds. And steering is a bit counterintuitive: to go left, Grenestedt must steer right, causing the streamliner to lean, and then steer left.

None of this kept Grenestedt, a professor of mechanical engineering and mechanics, from achieving a goal he set for himself five-and-a-half years ago.

On Sept. 2, Grenestedt navigated his streamliner across the snow-white, marvelously even surface of the Bonneville Salt Flats in Utah at a speed of 133.165 miles per hour. He shattered the previous U.S. land speed record of 125.594 mph for 125-cc engines running on gasoline.

“There were many impressions,” Grenestedt says of his improbable dash across the desert. “New sounds, new smells, new feelings, new sights. There were too many impressions to really sort out, because there was no blood running through my veins, just adrenaline.”

Twin engineering passions

If speed is Grenestedt’s first engineering love, composite materials run a close second.

As a teenager, Grenestedt built and raced remote-control boats in the lakes of Sweden. He has gone on to construct cars and powerboats, and to advise Lehigh’s student racecar team.

As director of Lehigh’s Composites Laboratory, Grenestedt has built ships, airplanes and even the deck of his house out of carbon and glass fiber composites, often in the form of sandwich structures with honeycomb or foam cores.

Composite materials, he says, are strong, easy to shape, resistant to corrosion and efficient. Being lightweight, they also boost speed.

Grenestedt resolved to challenge the U.S. land speed record in 2004, during his first trip to the Bonneville Salt Flats. With an almost perfectly flat terrain, the area is home to the Bonneville Speedway—and to many of the world’s land speed records. Grenestedt watched many runs and talked with drivers and engineers.

When he read the rule book for land speed racing, he made up his mind.

“I was looking for a new project at that time,” he says. “I had checked into dragracing, but I found that its rules discouraged innovation; they were too restrictive. The rules for land speed racing have stringent requirements for safety, but impose few other restrictions. I did some calculations on the back of an envelope for aerodynamic drag, power and acceleration, and I saw that it should be possible to beat a number of records without spending a fortune on engines.”

Grenestedt worked on the streamliner for five-and-a-half years. Bill Maroun, a technician at Lehigh and his partner on many other projects, helped him with welding and accompanied him to Bonneville.

He had only a handful of opportunities to test-drive the racer.

“My very first run with the bike was a few years ago,” he recalls. “I had mounted the wheels, but I hadn’t yet installed the engine, brake, or any other systems. I took the machine out on the street in front of our house and rolled it down a slope. My seven- and 10-year-old sons acted as my brakes, pulling on a long rope to stop me. I also used training wheels to avoid falling over and damaging the fuselage.

“For my second test, I installed the engine and kept the training wheels. I really started to learn to drive the thing.”

Grenestedt with Bill Maroun: "I love cramming myself into small vehicles."

The next run, and the last outing before Bonneville, came last year at the Maple Grove Raceway in Mohnton, Pa. There, Grenestedt was able to rev the engine higher and complete a quarter-mile.

Contending with salt and wind

At Bonneville, Grenestedt completed shake-down runs of 75 mph and 100 mph, and tried out the parachute brake deployment to stop the streamliner. Just before stopping, he electrically deployed two skids, one on each side of the streamliner, for the vehicle to lean on.

“This was the first time I had pulled the brake ‘chute. It felt like a gentle tug, with no hint of pulling to the side. The skids came out nicely and I was able to stop.”

On his third and final shake-down run, Grenestedt reached 122 mph while contending with two new phenomena—the slippery salt surface and a light but steady crosswind.

“The streamliner was not nearly as stable as it had been on the asphalt at Maple Grove. I had new tires for Bonneville—high-speed slicks with a round cross section—whereas I had more square tires at Maple Grove. But I think the real difference was that the salt was more slippery than the asphalt.

“I also think the slight crosswind made it feel less stable. I had to lean into the wind but steer straight, which fights natural steering. This time I did not pull the brake ‘chute, but coasted after the finish line. It was a strange feeling letting off the throttle and hardly losing any speed. The streamliner is so aerodynamic that it maintains speed very well while coasting.”

13,000 rpm and a new speed record

The 11-mile-long international raceway at Bonneville contains a “timed mile” at its midway point. Drivers use the first five miles of the track to accelerate and the final five to slow to a stop. They repeat the process in the opposite direction, and their official time is determined by averaging the two speeds achieved over the timed mile.

“After my third trial run, I thought I would be able to break the record in my class,” Grenestedt says. “I mounted a smaller rear sprocket to get more speed for the same engine rpm. My first run on the 11-mile course went fine. The launch was good, the acceleration good, the engine temperature was high but not dangerously so.

The streamliner reaches peak velocity on the timed mile.

“It was quite exciting seeing the speed creep up to 120, 123, 125, to the record of 126 and finally to 133. By this time, the engine was revving at 13,000 rpm, well past its peak power at about 11,800 rpm. In other words, I should have been able to go quite a bit faster if I had used an even smaller rear sprocket.”

His pursuit of the land speed record, says Grenestedt, allowed him to tie together his favorite engineering themes.

“Much can be achieved with good engineering and aerodynamics,” he says. “I love cramming myself into small and fast vehicles, and streamliner motorcycles are right up that alley. I wouldn’t feel comfortable at all driving a supersonic streamliner, but I felt great driving at the speeds I designed my streamliner for.

“I also enjoy the carbon and glass fiber work, and I have a soft spot for two-stroke engines from my days racing remote-control boats.

“All in all, this project suited me very well.”

The race at Bonneville will be his last on the salt flats. Grenestedt says he is retiring from land speed racing. Two years ago, however, he founded Lehigh’s Land Yacht Club. Several students have joined and made the trek to Lake Ivanpah, a dry lake in the California desert. There, in March, they watched a land yacht named the Greenbird set a new world record—126 mph—for wind-powered land speed racing.

Grenestedt won’t disclose his plans. But his students have built a tire-testing rig and tried it out at Lake Ivanpah, he says. And the club has purchased an airplane glider that will be cut up and converted into a high-speed land yacht.

“If I were a student today,” he says, “nothing could keep me from getting involved in a project like this.”

Bonneville photos by Jan and Agneta Isidorsson

Story by Kurt Pfitzer

Posted on Friday, September 25, 2009

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