Following a request from NASA, Goodyear last year developed an airless tire designed to transport large, long-range vehicles across the surface of celestial bodies such as the Moon or Mars. The tire, constructed out of 800 load bearing springs, is designed to carry much heavier vehicles (up to 10 times) over much greater distances (up to 100 times) than the wire mesh tire that Goodyear helped develop for the Apollo Lunar Roving Vehicle (LRV). The Spring Tire has now been recognized with a so-called “Oscar of Innovation” at the 44th Annual R&D 100 Awards in Orlando, Florida.
The development of the Spring Tire, like the original Apollo lunar mission tires, was driven by the fact that traditional rubber, pneumatic tires used on Earth aren’t suited to the Moon. This is because rubber properties vary significantly between the extreme cold and hot temperatures experienced in the shaded and directly sunlit areas of the Moon.
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Additionally, unfiltered solar radiation degrades rubber, posing an unacceptable risk of deflation for traditional pneumatic tires. And with the Moon being outside of any roadside assistance service area and lunar missions looking to minimize cargo, a spare could be hard to come by.
“With the combined requirements of increased load and life, we needed to make a fundamental change to the original moon tire,” said Vivake Asnani, principal investigator for the project at NASA’s Glenn Research Centre in Cleveland. “What the Goodyear-NASA team developed is an innovative, yet simple network of interwoven springs that does the job. The tire design seems almost obvious in retrospect, as most good inventions do.”
The Spring Tire was installed on NASA’s Lunar Electric Rover test vehicle last year and was put through its paces at the “Rock Yard” at NASA’s Johnson Space Center in Houston, where Goodyear says it performed successfully.
“This tire is extremely durable and extremely energy efficient,” noted Jim Benzing, Goodyear’s lead innovator on the project. “The spring design contours to the surface on which it’s driven to provide traction. But all of the energy used to deform the tire is returned when the springs rebound. It doesn’t generate heat like a normal tire.”
Another advantage of the Spring Tire is its ultra-redundancy. Asnani points out that the tire doesn’t have a “single point failure mode” like pneumatic tires. Where one hard impact can cause a puncture and deflate a pneumatic tire, such an impact would damage only one of the Spring Tire’s 800 load bearing springs. Additionally, the Spring Tire’s combination of overall stiffness and flexibility allows off-road vehicles to travel fast over rough terrain with relatively little motion being transferred to the vehicle, says Asnani.
Goodyear says the tire might also have applications on Earth but hasn’t announced any plans to release it for Earth-bound vehicles just yet. The Spring Tire also isn't the only airless tire technology staking a claim for Moon missions. A Tweel-based Lunar Wheel from Michelin is also being evaluated by NASA for use in future Moon missions.
The R&D Awards were established in 1963 by the editors of R&D Magazine, (then known as I-R 100s in keeping with the magazine’s original name of Industrial Research), to identify the 100 most significant, newly introduced research and development advances in multiple disciplines. The Spring Tire received a 2010 R&D 100 Award in the Mechanical Devices category. Previous award winners include the automated teller machine, the fax machine, the liquid crystal display and HDTV.