"Airless tires under study for Army Humvees"

Airless tires under study for Army Humvees
By Robert Imrie
ASSOCIATED PRESS
January 5, 2007

WAUSAU, Wisc. -- A team of mechanical engineers funded by the Pentagon
has an idea for saving the lives of troops in Iraq: An airless tire
that won't go flat if shot or hit by shrapnel from a roadside bomb.
The tires, which are under development at Resilient Technologies,
are filled with compressed polymers, or plastic, instead of compressed
air. The tension of the plastic provides strength, allowing them to
work just like air-filled tires, said Ali Manesh, the company's chief
technology officer.
The idea isn't entirely new, but Mr. Manesh is convinced he's found
ways to overcome problems that have plagued other airless tires -- such
as dissipating the heat buildup that occurs when they're driven. A
handmade prototype has been built, he said.
A flat tire on a vehicle such as the Army's Humvee, especially in
urban warfare, makes it vulnerable to an ambush, said Mr. Manesh, a
mechanical engineer who spent five years developing his idea before the
$11 million government contract was awarded.
"You can have all the armor in the world you want on a vehicle, but
if the tire is vulnerable, it is going to stop the vehicle. What the
military hopes to do is develop the next generation of tire to help
alleviate that problem," said Jim Dobbs, a Resilient Technologies
spokesman.
The goal is to have an airless tire survive what Chief Executive
Officer Robert Lange calls the damage of "something shy of a land mine"
so the vehicle can still drive away from the danger.
Resilient, a private research company founded in 2005, is owned
equally by Augusta Systems Inc. in West Virginia, American Science and
Technology Corp. in Chicago and WADAL Plastics Inc. in Medford, Wisc.
Its only income so far is the defense contract, Mr. Lange said.
The company also is seeking a patent for its invention.
The dream is to produce an airless tire -- so far called the
"nonpneumatic tire," or NPT -- that could be sold commercially for
passenger cars, he said.
Seven engineers and an office manager work at Resilient's office at
a Wausau industrial park, testing and retesting models of Mr. Manesh's
theories.
It is not a matter of whether his ideas work, only when, Mr. Manesh
said. "The theory of it is sound. From theory to manufacturing, there
are always glitches. Then you have to try to iron those out."
Charles Pergantis, a mechanical engineer for the Army Research
Laboratory in Maryland, said Resilient has developed a "somewhat
different structure" for an airless tire than has been done before.
"I think they have put together a good plan of attack on how to
develop this thing," he said. I am not sure if they are going to meet
all the successes that we want. They have some very, very interesting
designs. It does sound very exciting."
Mr. Manesh refuses to discuss the details of his invention because
a patent is pending.
Mr. Pergantis said the Army uses what are called "run-flat" tires
on some vehicles.
They allow a vehicle some mobility even if the tires are flat. An
airless tire is the next step, he said.
Paul Mehney, a spokesman for the Army's Tank Automotive Research
Development Engineering Center in Warren, Mich., said the Army is
interested in an airless tire for logistics reasons, too.
A smaller supply of tires would be needed because they would not be
changed as frequently and they might be lighter than conventional
tires, Mr. Mehney said.
The Army uses up to 200,000 tires for Humvees a year, said Lt. Col.
William Wiggins, an Army spokesman at the Pentagon.
Mr. Pergantis of the Army Research Center said airless tires must
provide comfort, no vibrations and little noise, in part because of the
sophisticated electronics used in military vehicles.
Mr. Pergantis, who is monitoring Resilient's research, said it is
much too early to predict whether the company's innovations clear the
way for an airless tire that meets the Army's needs.
"They are a small company with some big ideas," he said. "They have
a good team. They want to become another Goodyear."

I can see one problem with this: tire pressures are specified based on
the vehicle's wheel loading (among other factors). The same tire mounted
on two vehicles with different weights will have different inflation
pressures.

I'm sure the compressibility of the polymer filler material can be
tailored to provide the same effect. But since it can't be altered after
manufacture of the tire, this will lead to a bewildering quantity of
tire part numbers.

--
Paul Hovnanian
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