Buggy “Sweepstakes” sport combines athletic prowess and engineering skill

Sweepstakes, also known as Buggy, is the sport of pushing small people (usually women) down hills. What makes this a sport, and not just bullying, is the Buggy itself: the wheeled vehicle containing the driver, propelled by the pushers.

The earliest Buggies were made of wood and had four wheels, and the drivers sat upright. Modern buggies have more technological tricks up their sleeves, however. Most are made of carbon fiber and have three wheels, with the driver lying flat on their stomach.

Carbon fiber is the lightest and strongest material choice available, and it is used by most organizations. Some buggies currently in use do have partial metal frames, however. Metal adds weight, which isn’t necessarily a bad thing. Heavier buggies pick up more momentum, but at the same time, they’re harder for the pushers to bring up to speed.

“Most orgs are moving toward lighter buggies, though,” said materials science senior, Patricia Xu. Xu was the head mechanic for the Carnegie Involvement Association’s (CIA) buggy team in the 2014–2015 school year, and served as an adviser in the 2015-2016 school year. Her expertise helped lead the CIA women’s team to back-to-back first-place wins last year and this year; she also helped lead the CIA men’s team to 3rd place finishes both years. It’s safe to assume she knows what she’s talking about when it comes to building buggies.

Some organizations, including CIA, build a new buggy every year. Old buggies are retired when CIA runs out of room to store them, and they’re most often relocated to live with the alumni who worked on building them.

When it comes to building a new buggy, the very first consideration is following the rules, lest the buggy become unsafe, or the team get disqualified. Drivers need to have at least 45 degrees of visibility, and brakes need to be able to stop a buggy at a certain distance, depending on the speed. The buggy has to be built to hold together even at high speeds or when vibrating.

Just using loctite adhesives isn’t enough, Xu explains: “Everything needs to have lock washers [and] locknuts to make sure it stays.” Experimental two-wheel buggies were used in past years, particularly in the 1980s, but were outlawed for safety concerns.

Now, every buggy but one has three wheels. These can be arranged either in a standard trike pattern, with one in the front and two in the back, or in a reverse trike pattern, with two in the front and one in the back.

As far as brakes go, there are two main choices: friction braking or drop braking. “A friction brake works like a bicycle brake,” Xu explained, “by pushing against the wheels or the rims to slow it down.” Drop brakes involve lowering a brake pad to the ground underneath the buggy and dragging it along to create friction and slow the buggy down.

Similarly, most organizations use one of two steering choices, wagon or Ackermann. Wagon steering is when two wheels are connected by an axle, and the driver rotates the entire axle to make the turn. This causes problems because the inside wheel is traveling a shorter distance than the outside wheel, even when they’re turned to the same angle. It also requires enough room around the wheel for it to move forward and backward when the axle turns.

An Ackermann steering system has a fixed axle and each wheel rotates individually. In contrast to the wagon steering, Ackermann steering is angled appropriately at different degrees to match the different distances traveled by the inside and outside wheels. This can help with wear on the tires, as well as increasing traction and grip during turns. In the Ackermann steering system, wheels also don’t make such large and sweeping movements, so less room is needed in the wheel wells.

Less room for the wheels makes it possible to have larger fairings — the outer shells used to increase the aerodynamic shape of a vehicle. “We’ve taken our buggies to a wind tunnel once or twice in the past,” Xu said. However, she also made it clear that aerodynamics are not the most important thing in determining buggy speed. “As long as you don’t put a box on the front, and have it close to an airfoil shape, it should be fine. Buggies don’t go fast enough for it to make a big difference.”

Some of the most important parts of buggies that contribute to speed are the wheel bearings. Making sure the bearings are lubricated, clean, and able to spin freely is vital to keeping buggies moving quickly. The choice of wheels on a buggy also makes a huge difference, and the kind of wheels and treatment they get are some of the more closely-guarded secrets among the buggy organizations.

Almost all wheels are made from some form of polyurethane, a plastics category that includes a variety of products, from foam insulation to Spandex. The exact kind of polyurethane used makes a difference, and so does the treatment they receive. “If you’re watching the races, you’ll notice that some buggies don’t come out until maybe 30 seconds before the gun, and then they’re held off the ground until right before the start,” Xu said. This is because the wheels have been treated in some fashion, either by heat or chemicals. Heating up the wheels can improve speed, but it also makes the material more malleable and liable to deform if left sitting on the ground. Similarly, chemical treatments cause changes in the wheels that need to be preserved until just before it’s go time.

Once the gun has gone off and the race has started, the main speed factors come in. The pushers contribute more than half of the final time, Xu estimated. Without having strong pushers to get up the hills, the buggies won’t be able to speed down the other side on their heated and treated wheels. Once in the free-fall portion, the drivers inside the buggy take over and determine which path to take, also called a line. Although all buggies are confined to the same streets of the course, different teams and different drivers have different opinions as to which line is the fastest.

“You want to take the tangent,” Xu explained, meaning the buggy should travel smoothly from one corner to the next without making sharper turns than necessary. “Turning really hard will scrub speed.”

Turning sharply also increases the chance of the buggy spinning out or fishtailing. Despite being a competitive race, the teams make sure to watch out for each other. The morning of their heat, the drivers will walk the course and plan out when possible passes might happen.

“If a heat is clearly non-competitive, with a slower team, a middle team, and a faster team, they might not talk at all,” Xu said. “But if it’s close, they’ll talk about when passes might happen to make sure there aren’t accidents.” The cross-team collaboration goes to show their dedication to the sport. New members are encouraged to find a team where they fit in well with the culture and the commitment expected, and Xu would rather see someone leave her team at CIA and join another team, than quit buggy altogether.

Attending a certain number of rolls — the practice runs that take place throughout the year — is required to compete on race day. “It’s a big commitment! It’s early, but it’s worth it. Mechanics get up at 4:00 [a.m.] and drivers usually arrive around 7:00 [a.m.],” Xu said. Hurtling down hills at speeds up to 35 miles per hour takes a certain kind of person: small, of course, but also competitive, confident, and not claustrophobic. It also takes a dedicated team of pushers to bring the buggy back up the hills, and a support crew of mechanics to make sure the buggy is as fast as it can be.

The science and technology behind the buggy races add an extra layer to an already fascinating sport, making Buggy an interesting blend of athletic prowess and engineering skill.