Gold rush

DN Staff

June 24, 1996

11 Min Read
Gold rush

Colorado Springs, CO--World-class cyclist Dirk Copeland speeds through his turns at the U.S. Olympic Center Velodrome on a pencil-thin bike with no brakes.

Meanwhile, world champion American swimmer Amy Van Dyken races through her practice laps in the pool without moving her arms or legs.

And, U.S. Rowing Coach Mike Sprakin looks at his computer, not the water, as he positions team members in their boats.

It's all in a day's work at the U.S. Olympic Training Center, where sweat and science link up in the country's latest Gold Rush--the quest for medals in this summer's Olympic Games. Engineers at the Center are developing training devices and equipment that will give athletes a leg up in the race to victory.

The U.S. track cycling team, for example, is hoping a radical new bike design will propel its members to victory. Engineers at GT Bicycles, Longmont, CO, have designed a carbon-fiber composite track bike that produces one pound less drag than a standard track bike as measured in the General Motors wind tunnel. Their work is the culmination of Project '96, the multimillion-dollar, EDS-sponsored, U.S. Cycling Federation program to improve this country's competitive cycling record

Practically invisible. With a cross section that's no more than one inch, the SuperBike II (SB-II) is practically invisible head-on. And, it's the result of a paperless design process enabled by Computervision's CADDS 5 software. "We could never have designed this bike without CADDS 5's capabilities for controlling the intricate surfaces we wanted before machining," says Forest Yelverton, senior research and development engineer at GT Bicycles.

Yelverton and his engineering team eliminated several bicycle members, including the top tube and seat stays, to get the most aerodynamic design possible. Additionally, like most track bikes, the SB-II has no brakes (the cyclist decelerates by back-pedaling) and a single-speed fixed gear. "There are no shelves, edges, or bumps that the wind can see," Yelverton says. Even the seat has no edges or bumps, and all frames are custom designed for a specific rider.

Material selection was a key enginering innovation. The design employs a 90-million-modulus Mitsubishi continuous fiber supplied by Sytec and J.D. Lincoln. Though it retains such high-end-racing-machine characteristics as high stiffness, high strength, and stability, the SB-II weighs only 16 lbs. Traditional road-racing bikes weigh about 21 lbs, and mountain bikes weigh about 26 lbs.

Mavic SA, of France, designed the wheels and cranks for the bike, based on design criteria set by Yelverton and his team. The criteria called for a front wheel diameter of about 565 mm--about 1/3 smaller than a conventional road bike--with a 289 mm radius. The rear wheel is 632 mm in diameter--about 40 mm smaller than a road bike--with a 335 mm radius. Overall length is 1,611 mm, overall height is 750 mm, and the wheelbase is 994 mm.

The CADDS 5 software enabled the engineering team to spot potential problems early on the computer, cutting the physical prototypes to just one, Yelverton says. In fact, that prototype worked so well that the team used it as a spare at the World Championships. Enhancing the effort was Pro/MECHANICA finite element analysis software from Parametric Technology Corp.

Unlike other track bikes, the SB-II doesn't have a diamond frame. It's a single beam from steering to crank to rear wheel, with an integrated beam to hold the seat. CADDS 5 enabled the team to conceive of an advanced construction technique for joining frame tubes at complex intersections. GT Bicycles is patenting the process. In part, it involves using one tool with six or seven inserts to modify it, rather than several different tools.

The SB-II's predecessor, the SuperBike I, is an aluminum bike with most of the same design criteria. It's the version cyclists have been training with. With it, the U.S. teams set three records in the Pan Am Games.

The SB-II could come up against stiff competition from the Germans, among others. Engineers at the Institut FES in Berlin have been using SDRC's I-DEAS Master Series software to design frames for track bikes that will be used by the German Olympic team. The Association of German bicyclists claims the frame has an aerodynamic advantage of 16% over previous designs. FES Director Harald Schaale says engineers used I-DEAS in all design stages, from finite element modeling of calculations with composites and 3-D freeform design, to preparing data for milling of the frame.

Pooling their resources. At the U.S. Aquatics Center, members of the Olympic swimming team are using a specially designed towing system to improve their stroke technique as they increase their speed. Using ordinary off-the-shelf components and extraordinary technical ingenuity, engineers at the Olympic Training Center designed the system in concert with Marty Hull, inventor, former dentist, and president of Zoomers, Inc., a swimming fins manufacturer.

There are overhead cabling systems in two lanes of the pool. One system employs a cable made from Hoechst Celanese's Vectran(R), while the other uses a cable made from DuPont's Kevlar(R). Both operate with about 300 lbs tension. Nylon harnesses, similar to those used in rock climbing, connect to each with a bungee-like cord and stainless-steel cable, and fit around the swimmer. With a Marathon electric motor and Vickers hydraulic pump, the system pulls swimmers up and down the pool about 5-6% faster than their normal pace.

Incorporating safety into the design, the hydraulic motor actually powers the system. A limiter on the cable hits the rocker arm and shifts a valve to reverse direction at the end of each lane in the pool. To avoid damage to the cable from the limiter, modified roller bearings consisting of .50-inch stainless-steel tubing mounted on 3/8-inch rods with T-flange bushings attach to the trip arm.

There are attachments to modify the system for swimmers doing the breast stroke and butterfly, both of which keep the body higher in the water.

"As swimmers go faster, the synchronization between upper and lower body deteriorates, limiting the speed they might otherwise attain," says Tom Westenburg, senior design engineer for the U.S. Olympic Committee's Science and Technology Division. "By operating at constant torque but not constant speed, the tow system gives swimmers immediate tactile feedback so they can analyze motion and adjust their technique to maintain maximum efficiency at higher swimming speeds." Underwater video cameras also aid in after-workout analysis.

For Olympic hopeful Van Dyken, the tow system helped her find the torso position that resulted in the least amount of drag for her. Mimicking a body surfer, she let the system tow her up and down the pool with her hands at her side and her feet still while she experimented with different body positions. She believes it helped her develop the technique that qualified her for five different events at the Atlanta Games.

Row, row, row your sensors. Like swimming, rowing depends on stroke technique--only in this case, it's oar stroke. Using products from Motorola and National Instruments, Olympic Committee engineers designed the Rowing Data Acquisition System to help athletes refine their strokes and help coaches arrange rowers in boats by temporal and power characteristics.

The system consists of four types of sensors:

Conductive plastic potentiometers from J. D. Kay Controls attach to the top of each oar lock to measure oar angles.

  • Hall-effect proximity sensors from Allegro on the oar shaft measure oar force/torque. Mounted with the sensors is a niodimium-boron iron magnet. The magnetic fields weaken as the gap between sensor and magnet changes.

  • A magnetic impeller on the bottom of the hull monitors boat velocity.

  • Accelerometers from IC Sensors in the 1.4 lb electronics enclosure monitor boat acceleration.

Rowers practice outfitted with the sensors on their own oars, while the coach monitors their performance on an IBM laptop. On the screen, graphs show the characteristics of each rower's stroke. Data comes to the coach at 30 samples/second. The coach can review stroke technique immediately, or print graphs later and review detail with the rowers over a couple of Gatoraids.

A Motorola 68HC11 microcontroller is at the core of the electronics for the system. Additionally, Olympic Committee staffer Karla Coughlin customized National Instruments' Labview software for data acquisition.

LabWindows for DOS reads the data and LabView handles post processing. Coaches analyze stroke length, drive time, recovery time, excessive time for the blade in the water, time when the blade is in the water but not propelling the boat, power, effective torque, and stroke-to-stroke consistency, among other variables.

The software allows coaches to analyze multiple graphs simultaneously to compare the performance of different athletes in the same seat position, or the same athlete with different seat positions.

Members of the U.S. Shooting Team are benefiting from laser, sensor, and software technology. An infrared laser from Laser Devices, Monterey, CA, mounts under the barrels of their rifles and projects a 5 mm spot on the target. A video camera picks up the spot and displays it so the coach can analyze the shooter's consistency of aim. Strain gages on the trigger measure the pressure the shooter exerts so coaches can help athletes refine their trigger squeeze.

Inconsistent trigger activation indicates mental lapses, says Olympic Committee engineer and competitive shooter Tim Conrad. "The ability to focus mentally is one of the most critical aspects of this sport," he says.

An in-house data acquisition system amplifies the measurements from the strain gages. The data-acquisition card zeros out the effects of the bridge, and amplifies and digitizes data from the strain gages. Analog Devices provided amplifiers for the system. Motorola provided the HC 11 microprocessor, and Linear Technology Corp. provided the analog-to-digital converters.

All but one of the members of the U.S. Olympic Shooting team have trained with this system.

Though no one should count their medals before they compete, one thing seems certain as we move to the starting line for this year's Olympic Games: With all the technology available to them, "our athletes know they are as well prepared as anyone in the world, if not better prepared," says Chris Carmichael, national coaching director and Project '96 director.

A judge for the judges

There were charges at the last summer Olympics of irregularities in scoring in the boxing events. To reduce the potential for favoritism among judges, engineers at the U.S. Olympic Committee have developed a hand-held electronic scoring system that documents potential scoring inconsistencies.

The heart of the system is a Motorola 68HC05 microcontroller. It communicates to an IBM notebook computer.

When scoring, judges push a button on a hand-held unit to score a punch. The PC traces which button they push and when in the event they pushed it.

According to Olympic rules, after any blow, at least three of the five judges have to push the button to record it as a punch within a one-second window. Consistent early scoring could indicate irregularities. By recording the timing of the scoring and doing a database search, the system determines if one judge is consistently favoring boxers from a specific region.

40 hours before the mast

Olympic sailors piloting the 14-foot, single-person Finn Class boats in this summer's Olympics could be using the world's largest carbon fiber mast, manufactured by Omohundro Corp., Minden, NE.

The tear-drop, foil-shaped 18-foot mast has a foil that's four-inches long and two-inches wide at its base and one-and-one-quarter-inches long and 5/8-inches wide at the tip. It's much stiffer and lighter than previous masts, says Kurt Jordan, president of Jordan En-gineering, who did the structural design and analysis of the mast over a 40-hour period.

But, it's not so stiff it won't bend at all. "There are certain areas of the mast that you want to bend, such as where it comes out of the deck," says Jordan. That's the location of the maximum bending moment, and the mast should flex there fore and aft, yet be very stiff laterally, he says.

To work out the optimum stiffness characteristics and laminant stacking sequence for the carbon fiber, Jordan used ANSYS finite element analysis software. He built a 3-D model of the mast and put in the carbon fiber properties. Then, he did multiple iterations with the software to find the right fiber orientation and selection to reduce stiffness, maintain strength, achieve a low center of gravity, and maintain the required maximum weight of 8kg.

"The non-linear capabilities of ANSYS were key to that effort," he says.

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