Looking To The Past To Recreate The Future
The Goodyear Tire & Rubber Company and NASA recently took a
small step backward, in order to make one giant leap forward and
help prepare for future missions to the moon and to Mars.
Goodyear and the NASA Glenn Research Center recently completed a
jointly-funded project for the development and production of 12
replicates of the original wire-mesh moon tire used on the Apollo
Lunar Roving Vehicle in the early 1970s. This was the first step
toward understanding this unique non-pneumatic tire technology, and
its applications on both the moon and Earth.
"Although there was some reference material for designing the
replicate tire, there was little detail about the manufacturing
process," said Goodyear Project Leader Rick Laske, noting how the
team had to reinvent techniques to recreate the wire mesh tire.
The team examined one of the moon tires on display at the
National Air and Space Museum in Washington, DC and corresponded
with two retired members of the Apollo Lunar Roving Vehicle team,
who each had a tire that had been given to them as a souvenir for
their work. Examination of the original moon tires provided the
primary reference information for judging the quality of the
replicates, according to Vivake Asnani, NASA's principal
investigator.
Four major components comprise the tire and wheel design: mesh,
tread, inner-frame, and hub. The mesh is woven from piano wire and
the tread is a series of metal strips intended to protect the mesh
from impact while providing increased contact area for floatation
in soft soil. An inner-frame, comprised of a relatively rigid metal
structure, prevents the mesh from over- deforming during impact,
while the hub holds the mesh and inner-frame together and connects
the assembly to the vehicle.
"Before the wire mesh could be woven, 3,000 feet of wire had to
be custom- crimped and cut into 800 pieces," said Laske. A hand
loom was designed to weave the crimped wires into a rectangle
measuring approximately 100 inches long and 25 inches wide. Each
end of the rectangular weave was then interlaced by hand to form a
cylinder, which behaves in a manner similar to a child's finger
trap puzzle, lengthening and shortening with changes in its
diameter.
Sides of the mesh cylinder were pulled down and clamped to a
circular jig, roughly the size of a wheel hub, to give the mesh the
shape of a tire. Then the jig and mesh were baked in an industrial
oven to relieve residual stress from the wire.
The 12 replicate tires were evaluated for geometry, stiffness,
and other performance factors, and compared against data from the
two antique moon tires, as well as limited measurements taken in
the 1960s. "The measurements indicate that the original and
replicate wire mesh moon tires have nearly identical mechanical
properties," said Asnani, "We are now testing the replicates to
determine their traction and endurance capabilities. These data
will enable NASA and industry to determine possible applications
for the wire mesh tire."
Goodyear isn't the only company hoping to get a piece of moon
pie.
As ANN reported, Michelin is also working on a
prototype lunar tire.
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