Internal Balance

Force Balance

Our Hybrid Force Balance has the advantages of both the single piece moment balance and the multi-piece force balance; balance designs are tailored to requested load capacity and geometry. The Hybrid Force Balance directly measures two forces (one forward and one aft of the Balance Moment Center) in the normal force and side force planes and measures rolling moment and axial force. Pitching moment and yawing moment are resolved from the forces and known distances to the Balance Moment Center (BMC). This design has reduced deflections and higher frequency response than a moment balance while maintaining a high level of accuracy.

The balance is reliable, with redundant bridges and features a fail-safe captive outer shell. The larger load capacities for the smaller diameter of the Hybrid Force Balance meets future testing needs: a wind tunnel balance capable of providing accurate model loads data under high combined loading conditions while allowing the model to maintain its aerodynamic shape at the sting exit.

Features and Benefits

  • Rigid – Accurate – Reliable
  • Flexibility in axial load range selection
  • Temperature effects reduced
  • Integral Flexure Design with improved performance
  • Cross Hatch minimizes risk of galling
  • Unique design permits significant increase in roll moment by reducing allowable normal force
  • Captive design of metric model interface
  • Thick walled taper design with increase factor of safety
  • Internally mounted cable connector provides access for easy cable maintenance and replacement if needed
  • Design allows for a variety of taper interfaces to match customer existing inventory of stings

Additional Information

Moment Balance

The Moment Balance is manufactured from a single piece of material with separate sections to measure each of the forces and moments (5 moments and 1 force). Moment balances can be very accurate with load capacities that are high; however, the moment balance has larger deflections when compared to a Hybrid Force Balance. The moment balance has a low dynamic frequency and the ability to absorb large dynamic loads. Smaller diameters are possible and costs are reduced.

Air Balance

Calspan has decades of experience with air (flow-through) balances. Air balances are used where power simulation is required but a subscale engine (simulator) cannot be used. Multiple air supply systems bridge the air across the metric gap of the balance, minimizing momentum effects. The balances can provide for suction at the inlet, exit nozzle flow (exhaust pressure), and the ability to vary the ratio. Each air supply can be individually controlled. The air supply tubes run internal to the balance core.