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Store Separation

Store separation testing is vital before a new store (such as a missile or a fuel tank) can be used in service on an aircraft. These tests are used to ensure that a store, on release, is able to clear the parent aircraft safely without endangering the aircraft or pilot.

ARA has developed the Two Sting Rig (TSR) system which we believe to be the most accurate system to meet this requirement in the world with its’ unique store release simulation capability. Using this, positional accuracies can be measured to within 0.05 inches, or 1.25mm.  The TSR system achieves this level of accuracy through monitoring the relative positions of lights mounted in known positions on the store and aircraft, using a calibrated camera system.  Using this system allows ARA to add value in the area of store release testing (due to efficient and accurate testing) especially when compared with the expensive alternative of flight testing.

The TSR has been used at ARA since 1979 and has been used to support store integration programs in a wide variety of production and developmental aircraft including Stormshadow, Raptor and Brimstone integration on Tornado and Harrier in the UK. International customers include Saab Scania with Gripen, KAI with the T-50 and Lockheed Martin with the F-16.  

Why ARA?

If a customer works with ARA they can take advantage of:

  • Stores positioned in location and attitude with superb accuracy levels: Pitch, Yaw = ± 0.15°; Y,Z = ± 0.15mm.
  • Store movement is continuous allowing for excellent productivity, for example up to 15 trajectories, up to 30 grids (grid survey test technique) and up to 20 traverses (freestream traversing technique) per hour is possible.
  • Decades of experience testing a wide range of stores and aircraft.
  • Efficient test campaigns: all set up data validated before entry into the wind tunnel reducing costs for the customer.
  • Advanced release techniques including extremely high incidence tests.
  • A comprehensive range of trajectory simulation parameters.
  • A comprehensive range of internal balances for measuring store loads. 

Why the Two Sting Rig system?

The TSR is used for the following store release testing techniques:

1. Captive Trajectory Simulation (CTS)

By using a combination of measured and simulated loads the TSR accurately predicts a highly dynamic store release. A full range of release conditions can be simulated including:

  • Ejector forces
  • Rocket forces
  • Control forces
  • G-forces due to pull-up or push-down manoeuvres
  • Fin deployment
  • Pivot Hook release
  • Rail constraint
  • Autopilots

2. Grid Survey

Store aerodynamic loads are measured at a predetermined array of positions and attitudes to create a database of the spatial variation of the loads in proximity of the aircraft. These loads can then be used in off-line six-degree of freedom computer trajectory programs.

3. Freestream Traversing

The TSR is used for freestream traversing without the presence of the parent aircraft to measure the aerodynamics of the isolated store.

4. Flow Survey

In addition to the freestream traversing technique, flow angularity and pressures are measured around the parent aircraft model using flow angularity meters and pitot rakes fitted to the TSR. 

5. Free Drop Tests

These tests are conducted using mass and inertia scaled stores. Free drop tests can be useful to predict release trajectories involving extreme store attitudes and tumbling stores. The releases are recorded using high speed digital cameras and the recordings are analysed post-test to determine the trajectory.