Abstract: Described herein are noise attenuating ducts and vehicles using these ducts for environmental control systems. A duct comprises an exoskeleton structure and a sound-absorbing structure, disposed within and conforming to the exoskeleton structure. The exoskeleton structure provides external mechanical support to the sound-absorbing structure thereby helping to maintain the tubular shape of the sound-absorbing structure. This external support does not interfere with the airflow inside the sound-absorbing structure. Furthermore, the external positioning of the exoskeleton structure allows the integration of various support mounting features for the installation of the duct in a vehicle. In some examples, the exoskeleton structure comprises a plurality of enclosed openings to reduce the weight of the exoskeleton structure and provide additional flexibility.

Abstract: Ram air inlets for use with aircraft environmental control systems and other aircraft and non-aircraft systems are described herein. In one embodiment, a ram air inlet configured in accordance with the present invention includes an inlet lip spaced apart from an inlet housing. An inlet door is moveably attached to the inlet housing, and includes a first surface portion, a second surface portion, and a transition region extending between the first and second surface portions. The first surface portion is moveably positioned at least approximately forward of the inlet lip. The second surface portion is fixed at an angle relative to the first surface portion, and is moveably positioned at least approximately aft of the inlet lip. The transition region is positioned at least approximately adjacent to the inlet lip to form an inlet opening therebetween. Movement of the inlet door in a first direction reduces the size of the inlet opening to thereby decrease the flow of ram air through the inlet.

Abstract: Ram air inlets for use with aircraft environmental control systems and other aircraft and non-aircraft systems are described herein. In one embodiment, a ram air inlet configured in accordance with the present invention includes an inlet lip spaced apart from an inlet housing. An inlet door is moveably attached to the inlet housing, and includes a first surface portion, a second surface portion, and a transition region extending between the first and second surface portions. The first surface portion is moveably positioned at least approximately forward of the inlet lip. The second surface portion is fixed at an angle relative to the first surface portion, and is moveably positioned at least approximately aft of the inlet lip. The transition region is positioned at least approximately adjacent to the inlet lip to form an inlet opening therebetween. Movement of the inlet door in a first direction reduces the size of the inlet opening to thereby decrease the flow of ram air through the inlet.

Abstract: A helmet shell structure utilizing a first inner layer of epoxy resin shaped into a head covering of a desired size and configuration. A second layer of woven fabric is placed atop the first layer of epoxy. A third outer layer of epoxy resin is laid atop the second layer and is cured to a transparent state such that the second layer of woven fabric is visible through the third outer layer of cured epoxy.