Keystone Engineering Company

Ian Ballinger

Wayne H Tuttle

Robert Manning

A rigid structure propellant management device (PMD) liquid storage tank includes an outer shell and internal structures inside the outer shell that include a plurality of vertical columns each made up of a stack of individual storage cells. Each of the storage cells has solid vertical sidewalls and top and bottom capillary windows that allow vertical liquid transfer between adjacent cells in a vertical column. The top and bottom capillary windows in each of the storage cells have permeabilities that result in a selected direction of liquid flow in each column. A piping and valve system may be connected to the top capillary window of a top storage cell and to the bottom capillary window of a bottom storage cell of each vertical column, configured to allow controlled liquid transfer between adjacent vertical columns so that locations of empty cells in the tank as liquid is drawn from the tank achieves a selected column by column drainage sequence and controls a center of mass of the tank.

Center of mass control of liquid tanks for spacecraft use

A metallic positive expulsion fuel tank with stress free weld seams may include a first hemispherical shell with a first edge; and a hemispherical rolling metal diaphragm with a first edge attached to the first hemispherical shell along matching first edges. A second hemispherical shell with a first edge may be attached to the first edge of the first hemispherical shell by a first weld seam thereby forming two interior chambers separated by the hemispherical rolling metal diaphragm. A pressurized gas inlet may be attached to the first hemispherical dome; and a fuel outlet fixture may be attached to the second hemispherical dome. The first weld seam may have been stress relieved by a localized post-weld heat treatment confined to an immediate vicinity of the first weld seam.

Stress relieved welds in positive expulsion fuel tanks with rolling metal diaphragms

A metallic positive expulsion fuel tank with stress free weld seams may include a first hemispherical shell with a first edge; a pressurized gas inlet attached to the first hemispherical shell; and a metallic cylinder with first and second edges attached to the first hemispherical shell along matching first edges by a first weld seam. The tank may also include a second hemispherical shell with a first edge attached to a fuel outlet fixture. An elastomeric diaphragm may be attached to the fuel outlet fixture on the second hemispherical shell. The second hemispherical shell may be attached to the second edge of the metallic cylinder along matching edges by a second weld seam thereby forming a positive expulsion fuel tank with two interior chambers separated by the elastomeric diaphragm. The first and second weld seams may be subjected to a localized post-weld stress relief heat treatment in which heating of the tank is confined to a distance of 2 inches (5.08 cm) of the first weld seam and a distance of 2 inches (5.08 cm) of the second weld seam such that the stresses in the first and second weld seams are relieved and the elastomeric diaphragm is unaffected by the heat treatment.

Stress relieved welds in positive expulsion fuel tanks with elastomeric diaphragm

A method of forming a thick wall section on a specific region of a thin wall spinformed metallic tank shell includes forming a thin wall metallic tank shell blank by spinforming a metal sheet over a mandrel and removing the tank shell blank from the mandrel. The method further includes mounting the blank in an additive manufacturing system and adding metallic structural features to the tank shell according to a 3D model stored in memory in the additive manufacturing system.

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Anaheim Hills, CA, United States of America

Ian Ballinger