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The Composite Cryogenic Propellant Tank project will develop and
ground demonstrate large-scale composite cryogenic propellant tanks
applicable to heavy-lift launch vehicles, propellant depots, and
future lander systems. The demonstrations will include near full-scale
(5m and up to 10m diameter) manufacturing (in autoclave and/or out-of
autoclave), as well as loads and environmental testing. Fabrication
and testing will include composite panels, as well as panel joints
to form completed tanks.
The primary objective of the CCTD project is to mature the
technology readiness of composite cryogenic propellant tanks at diameters
that are suitable for future heavy lift vehicles and other in-space
applications. The propellant requirement for heavy lift launch vehicles
with payload capabilities of 130 metric tons is massive, requiring
huge propellant tanks on the order of 10 meters in diameter.
During FY2011, NASA and four industry partners completed a
Phase I activity to develop conceptual designs for 10m-diameter composite
cryogenic tanks with a goal of significantly reducing the weight
and cost from current state-of-the-art aluminum-lithium tanks. These
designs included material trades and structural loads analyses, as
well as fabrication trades, autoclave versus out-of-autoclave options,
tooling, manufacturing and facilities, and inspection and repair.
Designs addressed the permeation of cryogenic propellants, minimization
of micro-cracking, and leak-free concepts. Results from these studies
identified critical features and high-risk issues for 10m composite
tanks, and provided recommendations for starting with fabricating
smaller tanks and performing tests to address these risks. The CCTD
project starts with the results of the 10m tank designs developed
in Phase I, and proceeds with recommendations from industry and NASA
expertise to start with fabrication and testing of smaller diameter
tanks. Boeing, the contractor selected for the Phase II activities,
will design, fabricate, and test tanks on the order of 5m in diameter
or smaller. These smaller diameter tanks will retain the critical
high-risk features of the 10m designs, and employ similar fabrication,
manufacturing, and inspection processes. Critical elements of the
tank, such as joints, splices, and fasteners, will be built separately
and tested in liquid hydrogen to verify out-of-autoclave curing processes
before the 5m tank is fabricated.
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