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NASA the National aerospace plane will

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launch horizontally fly directly into

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space complete its mission and land

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horizontally like the Space Shuttle

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advanced air-breathing ramjet scramjet

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engines being developed by a national

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team led by NASA and the Air Force will

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allow NASA to fly at up to 25 times the

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speed of sound because significant heat

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will be generated by the NASP s--

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tremendous speeds advanced engine and

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engine seal designs are necessary

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unlike rocket engines that carry large

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heavy oxygen tanks the air-breathing

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engines under development for the NASP

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extract oxygen from the air

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these engines will efficiently scoop and

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compress air to burn with the hydrogen

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fuel temperatures in the engine reach

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over 5,000 degrees Fahrenheit with

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pressures exceeding a hundred pounds per

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square inch to operate at speeds up to

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25 times the speed of a bullet

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the NASP engine must meter the

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combustion flow going through the engine

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duct much like your car's fuel valves

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the articulating nozzle panels in the

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NASP engine will tailor the flow for

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to prevent the hot potentially explosive

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combustion gases from escaping past the

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panels high-temperature seals are

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required around the panel's perimeters

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these seals must withstand extreme

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temperatures seal highly distorted

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sidewalls and resist abrasion over the

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life of the engine advance seal concepts

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are being developed at NASA's Lewis

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research center these seals are made of

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high-temperature ceramic materials able

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to operate at temperatures up to 2300

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degrees Fahrenheit above this some form

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of active cooling must be employed to

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stay within the operational limits of

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the material one leading concept under

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development is the ceramic wafer seal

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which consists of multiple ceramic

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wafers mounted in a channel of the

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articulating engine panel the seal

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accommodates and seals the large

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sidewall distortions through relative

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sliding of adjacent elements much like

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the behavior of a deck of cards another

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approach is the ceramic rope seal which

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is braided out of high-temperature

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ceramic fibers that maintain flexibility

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at temperature both seals are preloaded

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against the adjacent walls by a series

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of spring-like bellows the hot

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performance of the two seals were

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measured at NASA Lewis using the

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specially designed test fixture

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though one cannot see the seals in this

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picture the seals are mounted behind the

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front wall of the hot test rig tests

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have shown that the ceramic wafer seal

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has very low leakage even at

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temperatures exceeding 1,400 degrees

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Fahrenheit it seals both flat and

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distorted walls equally well tests of

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the braided ceramic rope seal identified

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key construction variables that can be

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optimized to meet the target flow goal

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high temperature seal technology

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developed under NASA is immediately

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beneficial to numerous aeronautical

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space and industrial applications high

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temperature seals will be required on

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advanced high-temperature combustors and

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nozzles being designed for future

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commercial and military supersonic

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aircraft NASA PI temperature seal

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technology can provide an extra margin

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of safety over the low-temperature o

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ring seals of the shuttles solid rocket

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motors and improve gap seals for the

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shuttles main engines

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the innovative seal work performed by

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NASA Lewis under the NASA program has

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earned four US patents over the last two

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years while R&D magazine recognized the

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ceramic wafer seal as one of the most

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significant new technical products of

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1990

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NASA the National aerospace plane is

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serving as a national focus for

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advancing the state-of-the-art in access