Abstract: Disclosed are exemplary embodiments of systems and methods for gas envelope propulsion. In an exemplary embodiment, a propulsion system generally includes a power plant, and an inelastic gas envelope configured to receive a gas independently of the power plant. The power plant is configured to provide thrust for moving the gas envelope skyward, and the gas envelope is further configured to expel at least some of the gas to provide additional thrust.

Abstract: A wire includes a plurality of carbon nanotube infused fibers in which the infused carbon nanotubes are aligned parallel to the fiber axes. An electromagnetic shield for a wire includes a plurality of carbon nanotube infused fibers, in which the infused carbon nanotubes are aligned radially about the fiber axes. The plurality of carbon nanotube infused fibers are arranged circumferentially about the wire with the fiber axes parallel to the wire. A self-shielded wire includes 1) a wire that includes a plurality of carbon nanotube infused fibers in which the infused carbon nanotubes are aligned parallel to the fiber axes; and 2) an electromagnetic shield that includes a plurality of carbon nanotube infused fibers in which the carbon nanotubes are aligned radially about the fiber axes. The axes of the carbon nanotube infused fibers of the wire and the carbon nanotube infused fibers of the electromagnetic shield share are parallel.

Abstract: Flame-resistant composite materials containing carbon nanotubes are described herein. The flame-resistant composite materials contain an outer layer and at least one inner layer, containing a first polymer matrix and a second polymer matrix, respectively. The outer layer has an exterior surface and a first carbon nanotube-infused fiber material that contains a first fiber material and a first plurality of carbon nanotubes greater than about 50 ?m in length. In some embodiments, the at least one inner layer also contains a second fiber material and/or a second carbon nanotube-infused fiber material containing a second fiber material and a second plurality of carbon nanotubes. When present, the second plurality of carbon nanotubes are generally shorter in length than the first plurality of carbon nanotubes. Alignment of the carbon nanotubes in the outer layer can transfer heat away from the composite material's inner layer(s).

Abstract: A wire includes a plurality of carbon nanotube infused fibers in which the infused carbon nanotubes are aligned parallel to the fiber axes. An electromagnetic shield for a wire includes a plurality of carbon nanotube infused fibers, in which the infused carbon nanotubes are aligned radially about the fiber axes. The plurality of carbon nanotube infused fibers are arranged circumferentially about the wire with the fiber axes parallel to the wire. A self-shielded wire includes 1) a wire that includes a plurality of carbon nanotube infused fibers in which the infused carbon nanotubes are aligned parallel to the fiber axes; and 2) an electromagnetic shield that includes a plurality of carbon nanotube infused fibers in which the carbon nanotubes are aligned radially about the fiber axes. The axes of the carbon nanotube infused fibers of the wire and the carbon nanotube infused fibers of the electromagnetic shield share are parallel.

Abstract: Flame-resistant composite materials containing carbon nanotubes are described herein. The flame-resistant composite materials contain an outer layer and at least one inner layer, containing a first polymer matrix and a second polymer matrix, respectively. The outer layer has an exterior surface and a first carbon nanotube-infused fiber material that contains a first fiber material and a first plurality of carbon nanotubes greater than about 50 ?m in length. In some embodiments, the at least one inner layer also contains a second fiber material and/or a second carbon nanotube-infused fiber material containing a second fiber material and a second plurality of carbon nanotubes. When present, the second plurality of carbon nanotubes are generally shorter in length than the first plurality of carbon nanotubes. Alignment of the carbon nanotubes in the outer layer can transfer heat away from the composite material's inner layer(s).

Abstract: A solar receiver includes a heat absorbing element having an outer surface and an inner surface opposite the outer surface and a first coating including a carbon nanotube-infused fiber material in surface engagement with and at least partially covering the outer surface of the heat absorbing element. Solar radiation incident onto the first coating is received, absorbed, and converted to heat energy, and the heat energy is transferred from the first coating to the heat absorbing element. A multilayer coating for a solar receiver device includes a first coating that includes a CNT-infused fiber material and an environmental coating disposed on the first coating.