Shell rotor assembly for use in a control moment gyroscope and method of making the same

A shell rotor assembly for use in a control moment gyroscope, the shell rotor assembly comprising:

• a first shell member having a first wall portion and a first rim portion formed integrally in one piece;
• a second shell member having a second wall portion and a second rim portion formed integrally in one piece;
• and
• a shaft assembly disposed at an approximate center of the shell rotor assembly and extending between the first shell member and second shell member;
• wherein the first rim portion is attached to the second rim portion by an electron beam welding process, whereby a heat-affected area, formed by the electron beam welding process, joins the first rim portion to the second rim portion, the heat-affected area is located over only a portion of lateral surfaces of the first rim portion and the second rim portion wherein the lateral surfaces are configured in a direction which is perpendicular to the shaft assembly wherein the first rim portion includes a first alignment feature and wherein the second rim portion includes a second alignment feature configured to engage the first alignment feature whereby the first shell member and the second shell member are arranged concentrically with one another as a result of engagement between the first alignment feature and the second alignment feature wherein the first alignment feature serves as a backstop to limit the extent of the electron beam welding process.