For Release: March 19, 1998
RELEASE NO. 98-013
Lightweight and Durable Structures
NEW MATERIAL TESTED FOR FUTURE SUPERSONIC PASSENGER JET
Researchers at NASA Langley are testing a new material that may
one day be used to build a future supersonic passenger jet. The
materials used to build this future jet must endure speeds of more
than 1,500 mph, altitudes of 65,000 feet, and aircraft surface
temperatures over 300°F. The materials must be strong,
lightweight, durable and tolerant to damage.
In a recent test, two 40 inch by 80 inch panels were subjected
to more than 400,000 pounds of force before they cracked. "We are
testing these panels to study the effects of damage from foreign
objects that may penetrate through an aircraft structure," said
David McGowan, a NASA aerospace engineer in charge of the tests.
"The structure must be able to support the proper amount of load
with this type of damage to receive FAA certification. The tests we
perform determine if the structure can meet these design
requirements, which it did in both cases."
The two test panels were built by The Boeing Co. in St. Louis,
Mo. with a new material called PETI-5, developed at NASA Langley.
LaRC PETI-5 is a resin material that is combined with graphite
fibers to make what's called 'prepreg' tape. Many layers of this
tape are then heated under pressure to form a piece of composite
"It was necessary to develop a new [composite] material under
NASA's High-Speed Research (HSR)
Program because no material existed that met the temperature and
durability requirements," said Rodney Ricketts, manager of the HSR
Structures and Materials program.
"In the HSR Program we have developed resin and adhesive
materials that meet the requirements for the high-temperature
composite structures. NASA started with test-tube quantities in the
laboratory just 3 years ago, and now commercial material suppliers
are producing 1,000 lb. quantities for Boeing, Northrop-Grumman and
Lockheed," Ricketts said.
Since 1990, NASA and its industry partners have been working to
develop technologies for a future supersonic passenger jet. The jet
conceived by NASA's High-Speed Research Programwould carry 300
passengers across the Pacific Ocean in just four hours, at tickets
prices only 20 percent over comparable, slower flights.
"During earlier parts of the program, we studied many different
structural concepts," Ricketts said. "Now, after much design,
analysis and testing, we have selected two. This has allowed us to
focus on the lightest weight, highest performance designs and move
from testing small coupons and elements to testing large panels
such as this. Eventually we will test a large section of a
fuselage, approximately 15 ft in diameter and 30 ft in length."
"We have an entire series of tests planned at NASA Langley to
evaluate skin panels with foreign object damage," McGowan said. "We
will be repeating the first two tension tests on other panels, and
we will also be testing a series of flat and curved panels using
compression. All of these tests are leading up to the tests of a
full section of the fuselage."
"These [recent] tests also give us much needed data to determine
if our analytical models are capable of predicting what will happen
when the panel is loaded with [foreign object] damage," McGowan
said. "The predictions for the ultimate failure loads of the panels
that we obtained from our analyses were very close to the actual
values. We've realized though, that there are parts of our analyses
that need to be refined to better predict certain aspects of the
structural response. We are addressing that right now, and we're
confident that we'll have even better predictions for the next
series of tests. The confidence in our analytical models to predict
the behavior of these panels lets us reduce the number of expensive
tests to be performed in the future."
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