AKRON—Specially developed Goodyear tires probably will head to the moon and possibly as far away as Mars in the future.
NASA has teamed up with the company to develop an airless tire to transport large, long-range vehicles across the surface of the moon for a planned Apollo moon landing. The mission is aimed at greater exploration of the planet along with development and maintenance of a lunar outpost, according to Vivake Asnani, NASA's principal investigator at the administration's Glenn Research Center in Cleveland.
NASA wanted tires that could go farther longer with a far heavier pay load, so it needed to change its original moon tire requirements dramatically, he said.
It took more than a year and a half, but Goodyear came up with a Spring Tire, which weighs 40 pounds, has 800 load bearing springs and is designed to transport much heavier vehicles over greater distances than its predecessor, a wire mesh tire used on the last Apollo Lunar Roving Vehicle.
“What the Good-year-NASA team developed is an innovative, yet simple net- work of interwoven springs that does the job,” Asnani said.
“The tire design seems almost obvious in retrospect, as most good inventions do.”
But it wasn't obvious when a core group of four people—most of them from Goodyear, with about 20 engineers serving as consultants—began working on the project at the tire maker's Akron Innovation Center.
Replicate tires were produced by the company, after which it was charged by NASA to come up with a tire that could support 10 times the weight of the original Apollo moon tire and travel at least 2,000 kilometers compared to its predecessor's capability of about 125 kilometers.
The tire had to be made with the same materials used on some previous moon tires to minimize the risk because those materials proved they could work on the moon, according to Jim Benzing, Goodyear's lead innovator on the project. “We also decided on a radial tire to increase load carrying capacity and durability versus the original Apollo bias wire tire,” he said.
Goodyear technicians built quarter section prototypes and tested for load carrying capacity, deflection and other needs. It started as just single bead wires made into a “Slinky,” Benzing said. “They could not transmit torque, so we had to hold the individual wires in place” and started a wire weaving process. That increased road carrying capacity but cut back on durability.
“Then we started using springs as spacers between the radial wires. This significantly increased our torque transmission and load-carrying capacity.”
The team then focused on its durability problem with the use of cables.
The tests went on and on with one problem eliminated and another arising until one night “the light went on and we started weaving springs along their axis,” Benzing said. “Immediately, we knew we had the solution to the problem.”
It was a long and cumbersome process, Benzing admitted. Team members often worked until as late as 3 a.m. for months and quite a few weekends. “But,” he marveled, “how awesome is it to have your technology travel to the moon, Mars and beyond?”
The present version of the Spring Tire features a rim made of high-strength aluminum and a spring steel (piano wire) core, plated to eliminate corrosion and increase lubricity,” Benzing said.
It was installed on NASA's Lunar Electric Rover test vehicle and put through its paces at the Johnson Center's Rock Yard in Houston where it successfully completed the test process.
“This tire is extremely dur-able and extremely energy-efficient,” he said. “The spring design contours to the surface on which it's driven to provide traction. But all the energy used to deform the tire is returned when the springs rebound. It doesn't generate heat like a normal tire.”
In the spotlight
NASA liked the tire so much it highlighted the project during a recent exhibit at the Rayburn House Office Building in Washington. After discussing the technology with 10 to 15 members of Congress and about 60 staff-ers, Asnani said “virtually everyone I spoke with was blown away by the idea that this technology may one day be used, not only for extraterrestrial vehicles, but also, perhaps, for vehicles on earth.”
Goodyear also developed the original lunar mission pneumatic tires used on a Modular Equipment Transporter, a two-wheeled, rickshaw type cart that carried instruments, geological tools and photographic equipment on Apollo 14 in 1971.
Traditional rubber pneumatic tires have little use on the moon, according to Goodyear's engineers, principally because rubber properties vary significantly between the extreme cold and hot temperatures experienced in shaded and sunny areas of the moon. In addition, they said, unfiltered solar radiation degrades rubber and pneumatic tires pose an unacceptable risk of deflation.
After the MET was used on Apollo 14, it was replaced by the Lunar Rover Vehicle on Apollo 15, 16 and 17.