The Olympic torch relay represents an emblematic start to the games. Former Olympians and members of the public carry the Athens Olympic flame until the Opening Ceremony, marking the official start of the games.

Starting with the 1936 Berlin Summer Games and the 1952 Oslo Winter Games, each iteration featured a new torch design that reflected the identity of the host nation in addition to displaying the Olympic flame throughout the torch relay. This year, the games kick off today, July 23, with the lighting of the “Cauldron Celebration” in Tokyo. Expect this to happen just after 8 p.m. Tokyo time, or 7 a.m. EDT.

Creating a unique and functional torch is a huge undertaking. Identical torches must be made for each runner in the relay before the first lighting of the Olympic flame in Greece. The whole process of designing, modeling, prototyping, testing, and manufacturing actually begins years before the games themselves start.

The design of the Olympic torch

The basic elements of an Olympic torch are simple. It must contain a fuel canister and a discharge system to support the combustion of the flame; the Olympic flame must be clearly visible when burning and withstand extinction under extreme conditions; and it should be of manageable weight and shaped so as to be easy to hold. Beyond that, the unique design of a particular host city is left to the organizing committee.

The concept design of the Tokyo 2020 Olympic torch. Courtesy of Tokyo 2020.

Typical torches are 15 to 32 inches in length. Materials of the past cover a wide range – aluminum has been a popular choice in recent years, but various types of natural wood, other metals, glass, and resins have made up torches.

Design teams submit a portfolio of ideas to the committee, which then selects a smaller group of finalists. The final teams are invited to come back after a short period of time with a plan to obtain the required materials and fabricate the proposed design, according to Jay Osgerby, co-founder of design studio Barber Osgerby, who was behind the torch of London 2012..

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Each torch is designed with the host country in mind. In the case torch Tokyo 2020, designer Tokujin Yoshioka was inspired by the traditional flower of Japan, which is the cherry blossom. Yoshioka also fashioned the torch from recycled aluminum from temporary housing built in the aftermath of the Great East Japan earthquake and tsunami in 2011, according to the Tokyo organizing committee. About 30 percent of each individual torch contains this recycled aluminum.

Old Olympic Torch Designs: London and Salt Lake City

For London 2012, the triangular shape of the torch signified the Olympic values ​​of excellence, friendship and respect, the Olympic motto of “Citius, Altius, Fortius”, in addition to commemorating the third time that London was the host city. Each torch also had 8,000 perforations to represent the 8,000 torch bearers and the 8,000 mile relay route from Greece, then through the UK and Ireland.

Prior to manufacturing, the London 2012 stage designers went through many stages of prototype fabrication and material evaluation to optimize the final design. David Brook.

The 2002 Salt Lake City Winter Games torch featured an aged metal finish to signify the American West and copper to represent Utah history. Once the initial concept was finalized, the 2002 torch was handed over to a team from the Georgia Institute of Technology for 3D modeling and prototype development. Tim Purdy, Senior Lecturer in Industrial Design, led the modeling team. “We used 3D printing technology to basically make two prototypes of the torch,” he says. Prototypes were as far as 3D printing could take the torch. “There was nothing existing at the time in the [3D printing] an industry capable of withstanding extreme heat, so we had to go for more traditional methods, ”Purdy says of the move from prototypes to manufacturing.

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Even in 2012, for London, large-scale 3D printing of the torch was considered, but was abandoned in favor of more reliable metal welding and laser perforation. “It was important to the committee that the torch technology represented the technology in the UK,” said Osgerby, who designed the torch with his colleague Edward Barber. “Back then, 3D printing and laser sintering were booming in the automotive industry, Formula 1 and aviation. While Osgerby says laser sintering was a promising option, the committee ultimately decided the technology was too new and they couldn’t afford to turn it around.

Fueling the Olympic flame

Just as important as the outer design of the torch is the inner workings of the fuel canister system that feeds the flame visible at its top. In fact, according to Tecosim, the engineering company that collaborated on the 2012 London Torch with Barber Osgerby, the first measurement in deciding what type of fuel and which fuel system to use was the size of the cartridge. The canister determines how much space is available in the aesthetic design and how much fuel is needed to produce a yellow flame that is at least 10 inches in height, with a burn time of at least 10 minutes.

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Once a fuel canister is selected, the next consideration is the type of fuel that will be used. The seven most recent Olympic torches were fueled by substances such as propane, butane, or a mixture of the two. The designers of the London 2012 torch explored an alternative to green fuel that combined elephant grass and coconut oil, but it was ultimately scrapped for the final torch due to ignition issues. and extinguishing the flame, explains Osgerby. The Rio 2016 design team also researched an ethanol biofuel alternative which did not materialize due to the irregular brightness of the flame in harsh weather conditions. The two design teams ultimately opted for a mixture of propane and butane.

While butane gas can be stored at a lower pressure than propane, it requires higher temperatures to be converted from a liquid in the canister to a gas, the state in which it is flame fueled. Liquid propane, on the other hand, evaporates to gas around -40⁰F, so a mixture of 55% propane and 45% butane was chosen to balance the safe fuel pressure in the canister with a temperature of lower evaporation.

The Tokyo 2020 torch features a fuel tank and burner system similar to its London 2012 counterpart. Courtesy of Tokyo 2020.

Tecosim says the burner system itself is very similar to that of a hot air balloon. Liquefied gas is removed from the cartridge with a long sampling tube that runs the full length of the torch. From there, the fuel is distributed through a stainless steel coil that wraps around the burner at the very top of the torch, just below the base of the flame. Here, the fuel is heated very quickly and converted from a liquid to a gas before being sent to the flame through the burner nozzle.

Finally, the gas is released through a special valve in the burner unit. “The valve was designed and calibrated to allow an exact mixture of gas and air to create the desired highly visible yellow flame,” explains Tecosim.

Since the fuel is withdrawn from the tank in liquid form, the fuel flow required to sustain the flame is maintained because “the high thermal energy supplied by the torch flame allows the liquid to evaporate into a gas, before it is released. ‘it does not reach the burner. nozzle, ”explains the engineering company.

While the principle behind all gas powered Olympic torches is the same, important factors in the design and season of the games create specific engineering challenges. “As an example, the Turin 2006 Olympic Winter Torch had a predominantly solid body design with a closed torch head, and the London 2012 Summer Olympic Torch had a heavily perforated body design and head. burner open ”, explains Tecosim. As a result, each torch system is unique.

Torch test: wind and extreme temperatures

Along with the development of aesthetic and technical prototypes, the torch is subjected to a variety of tests to ensure that the flame can withstand extreme weather conditions, high altitudes and even a drop during the relay.

In the case of the London 2012 torch, the tests were carried out in the BMW wind tunnel in Munich, Osgerby explains. The torch has been tested at temperatures ranging from 23⁰F to 104⁰F, wind speeds of up to 50 miles per hour, various humidities, driving rain and simulated snow, all at variations in the angle of torch relative to the air flow in the tunnel. “In support of the climatic wind tunnel tests, several hundred hours of torch airflow testing were performed, using a large industrial fan and a nozzle manufactured to increase airflow speeds,” explains Tecosim.

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Additionally, the torch was dropped from a height of 10 feet onto concrete ground and tested aloft at the top of Mount Snowdon, where the wind gusts were over 50 miles per hour. Tests like these are typical for torch verification.

Series production of torches

The final step in the long process of developing the Olympic torch is the making of the thousands of torches needed for the torch relay. The manufacturer, like the design, varies from year to year depending on the materials and specifications required.

After the first piece of aluminum was punched through the required 8,000 holes, the London 2012 torch was robot welded into its final shape. Gold color was applied to the surface at the end of the process. Lee Mawdsley.

In 2002, Coleman, a U.S. outdoor equipment maker, made the metal components for the torch while the glass mattress topper was obtained from an overseas supplier, according to Purdy. In 2012, manufacturing logistics were handled by The Premier Group, an engineering company based in Coventry, UK. Each torch faces unique challenges in scaling the torch design – for Salt Lake City the glass top was very fragile, and for London a new laser cutter was obtained in order to cut the 64 million circles required for the group of 8,000 torches.

“In fact, we got a new laser cutter, capable of cutting 16 holes per second,” says Osgerby, one of the torch designers. The final laser-cut product debuted at the first leg of the Torch Relay in May 2012 and made its final appearance at the opening ceremonies 78 days later, officially kicking off the games with the lighting of the Olympic flame in London and continuing the tradition of its unique predecessors.