1. Which balances are contained in this database?
The inventory of balances in the US and Canada are contained in this NASA owned and maintained database. Some of the balances are noted as retired or no longer in use in the database, including them is to depict that their design exists. Any balance no longer in service will be marked accordingly in the database.
2. How do I use this database?
The database is designed as a tool for the ground testing aeronautics community, to allow the user to search for known balances in the national inventory. The database is configured to allow the user to search by the defined parameters on the home page. Selecting a balance of interest will display the balance details, including contact information for the responsible facility/center.
3. How do I update information in the database?
If you are a responsible facility and have additions, deletions, or modifications to the existing database content, please contact Patsy I. Tiemsin 757-864-5310
4. What are the different balance types?
Fundamentally, there are three types of balances: 1) force, 2) moment and 3) direct-read. Force and moment balances define the basic mechanical design of the balance. Force balances are typically multi-piece designs, and moment balances can be either single-piece or multi-piece designs. Direct-read balances define the electrical design of the balance.
Balance Name and/or Serial Number
Unique names or identifiers used to distinguish all balances from one another. Each balance will have a unique name as shown in the database.
Cooling Shield (Water Jacket)
The cooling shield, or water jacket, is typically a sleeve that is installed over the balance that allows for active cooling during use to minimize large steady-state temperatures and transient thermal gradients. Typically a balance will have a cooling shield, or water jacket, if it's used for high-speed testing at supersonic or hypersonic conditions.
Custodian
The custodian is the person at each organization that is ultimately responsible for keeping track of each all balance property.
Direct-Read Balance
A direct-read balance resolves the applied load vector into a vector of measured component loads consisting of three forces and three moments [NF, PM, SF, YM, RM, AF]. A Direct-Read balance is fashioned such that the component loads are directly proportional to the bridge outputs. There are two common Direct-Read balance designs. The first is analogous to either a Force or Moment balance with changes to the wiring. By appropriately connecting pairs of strain-gages from the forward and the aft bridge locations, new bridges are formed with output proportional to total force and total moment in each plane. The second common Direct-Read balance design usually consists of a dedicated section for measuring normal and side force with strain-gages placed forward and aft on relatively short beams. Pitching and yawing moments are measured on the same beam with strain-gages located in one X-axis location similar to a Moment balance. Models attach, and therefore transmit their loads to the balance, at the forward end of the balance while the aft end is attached to the model support system. All the balance types measure axial force and rolling moment directly. Various methods and mechanical designs are used, but for each balance type, all associated bridge outputs are proportional to the applied axial force or rolling moment. Balances typically have one or two sets of axial force and rolling moment bridges. In an optimized balance design, the strain-gages are located such that the interaction effects on the first bridge are opposite in sign to the interaction effects on the second which are wired in parallel to minimize interactions.
Dummy Balance
A dummy balance is a non-operational balance that has the same size, shape and identical interfaces to the live balance. The dummy balance is used during many tests to provide a stronger joint in between the test model and the non-metric support to perform test fits and checks. Not all balances have a dummy balance.
ECN
Equipment Control Number
Flow-Thru
A balance that has the capability to bring air on or off the test model. These types of balances can have internal/external air bellows built into the balance, or through holes in the balance that are used to route air to the test model.
Force Balance
A force balance resolves the applied load vector into a vector of measured component loads consisting of five forces and one moment [NF1, NF2, SF1, SF2, RM, AF]. The forward (NF1) and aft (NF2) normal force component loads are measured in the balance (X-Z) plane and used to calculate the normal force and pitching moment. Likewise, the forward (SF1) and aft (SF2) side force component loads are measured in the balance (X-Y) plane and used to calculate the side force and yawing moment. The Force balance uses a floating frame arrangement to measure the forces acting on the balance. Models attach to and transmit their loads through the outer shell. The outer shell attaches to the inner rod through load sensing elements. The loads applied to the outer shell are transmitted to the inner rod through the force sensing elements. This arrangement is sometimes referred to as a floating frame or shell balance. The aft end of the inner rod is attached to the model support system.
Manufacturer
Organization that manufactured the balance.
Moment (Single- or Multi-Piece, Beam) Balance
A moment balance resolves the applied load vector into a vector of measured component loads consisting of five moments and one force [PM1, PM2, YM1, YM2, RM, AF]. The forward (PM1) and aft (PM2) pitching moment component loads are measured in the balance (X-Z) plane and used to calculate the normal force and pitching moment. Likewise, the forward (YM1) and aft (YM2) yawing moment component loads are measured in the balance (X-Y) plane and used to calculate the side force and yawing moment. The Moment balance uses a cantilevered beam design to measure the moments acting on the balance. Models attach and therefore transmit their loads to the balance at the forward end of the balance while the aft end is attached to the model support system. Moment type balance designs can be wired electrically as Moment balances (5F/1M) or Direct-Read (3F/3M)
Rotating or Prop Balance
This field in the database identifies whether the balance of interests is a rotating or propeller type balance.
Semi-Span
Large balances mounted in the floor or sidewall for semi-span model testing. Generally speaking most Semi-Span balances are designed to measure five components of aerodynamic load simultaneously [NF, AF, PM, RM, YM]. A few balances contained in the inventory measure all six components of aerodynamic load.
Status of Calibration
The calibration status identifies the date of the most recent calibration.
Store Balance
Smaller balances that are used to measure loads on stores; some are used with captive trajectory support systems.
SVS Template
The SVS templates are unique pieces of hardware used to calibrate balances on the Single-Vector System (SVS) at NASA Langley. The SVS template typically attaches to the calibration fixture during calibration. Not all balances have a SVS template.
Taper Size
The taper size is defined by three unique parameters. 1) Maximum taper diameter, 2) Taper length and 3) Taper ratio (typically in units of inches/ft). This parameter only applies to balances with a non-metric taper. Flange mounted balances, internal or external, will not have any values for the taper size.