Abstract: A six component balance for use in measuring forces and moments on an aircraft model in a wind tunnel or the like. The balance is mounted on a wind tunnel sting by means of a sleeve that surrounds and is spaced from a central core. The central core is connected to a model by support bars passing through slots in the sleeve from the core. Core ends are secured to the sleeve and support the central core through a plurality of webs. A plurality of strain gages are mounted on the webs to detect strain on the webs resulting from forces and moments applied to the model. This system measures six components, i.e., lift force, drag force, side force, pitching moment, yawing moment and rolling moment.

Abstract: A variable load cell arrangement operative for precisely measuring loads over a range beyond the range of a single conventional single low range load cell. The arrangement includes a low range measuring element positioned in a case and having one end adapted to be connected through the case to a load and the opposing end coupled to a fixed reference. A variable pressure means, such as a controllable bellows, is interposed in the case between the load element and an end of the case whereby a predetermined force may be selectively applied to the load measuring element in a direction opposing the load to relieve the strain on the element and permit it to continue to function in an extended range. Electrical circuits, including Wheatstone bridges, are coupled to the load measuring element and provide an electrical output indicative of the applied load and an electrical output that is used to control the variable pressure means.

Abstract: An improved wind tunnel six component balance having an outer shell assembly that receives a tubular inner rod and an axial member that is received within the interior of the tubular inner rod. The forward and aft ends of the outer shell assembly are connected to the inner rod. The loads imposed on the forward and aft ends of the outer shell assembly are transferred to the inner rod and into the tunnel support system. The central annular section of the outer shell assembly is connected to the axial adapters (four each and into the central disk of the axial member. The principal areas of the axial element are the central disk member, the flexures (two sets forward and two sets aft), the forward and aft gauged sections, and the forward and aft disk members. Normal force, side force, and rolling moment are carried by the outer forward webs of the outer shell assembly. The axial member will transfer the majority of the axial force then the forward and aft outer shell webs.

Abstract: An improved wind tunnel six component balance that is capable of accurately measuring low loads and high loads. The variable range balance has low load axial elements that will measure low loads precisely. When the load is increased over the low range capability of the measuring elements, in either the positive or negative load direction, pressure is applied to either the forward or aft bellows that are mounted in the inner tubular rod of the balance. This pressure applies a counter balance in force that reacts against the load applied. The results of this force is that the low loads links will always stay on range.