Abstract: A helmet impact absorption system is provided. The absorption system will include inner and outer layers that sandwich spaced apart viscoelastic polymer elements in an activated engagement, so upon impact to the outer layer the engaged viscoelastic polymer elements become “activated”, compressing and releasing the majority of the impact force through a dispersion of non-threatening heat. Each inner and outer layer may comprise two separable hemispheric portions secured along an interface for providing further impact absorption through enabling convulsive give between the respective two separable hemispheric portions. The inner layers are dimensioned and adapted to accommodate the head of a human wearer.

Abstract: A method is provided for fabricating a coolant channel closeout jacket on a structure having coolant channels formed in an outer surface thereof. A line of tangency relative to the outer surface is defined for each point on the outer surface. Linear rows of a metal feedstock are directed towards and deposited on the outer surface of the structure as a beam of weld energy is directed to the metal feedstock so-deposited. A first angle between the metal feedstock so-directed and the line of tangency is maintained in a range of 20-90°. The beam is directed towards a portion of the linear rows such that less than 30% of the cross-sectional area of the beam impinges on a currently-deposited one of the linear rows. A second angle between the beam and the line of tangency is maintained in a range of 5-65°.

Abstract: A propellant feed system for swirl-coaxial injection of a liquid propellant includes a reservoir having a bottom plate and at least one tube originating in the bottom plate and extending therefrom. The tube has rectangular slits defined in and distributed tangentially and evenly about a portion of the tube that is disposed in the bottom plate. Drain holes are provided in the bottom plate and tunnels are defined in the bottom plate. Each tunnel fluidly couples one of the drain holes to a corresponding one of the rectangular slits. Each tunnel includes (i) a bend of at least 90°, and (ii) a straight portion leading to its corresponding rectangular slit wherein the straight portion is at least five times as long as a hydraulic diameter of the corresponding rectangular slit.