Installed stores are items like fuel tanks and weapons which are carried by the aircraft externally on pylons or in internal weapon bays. The very complicated nature of the airflow around an aircraft and the stores that are attached to it means that wind tunnel tests remain an important part of most store integration programs. Wind tunnel tests provide the large quantities of high quality data needed to provide store loads throughout the aircraft’s operational envelope with speed and reliability.
For some full models the use of an internally mounted balance is not possible, i.e. models with full ducted air flow (where there is insufficient room remaining within the model to house a suitable balance). In these cases, the pressure measuring method is utilised to acquire sufficient data to enable loads to be obtained by integrating pressures over the whole model or indeed for individual portions of the model.
Wind tunnel tests provide the high quality balance or pressure data, depending on the methodology used, needed to determine the loads on the overall model or control panels.
We have a world leading capability in the manufacture of stores, support mechanisms and balances completed to the very highest standards including bespoke stores with free-floating seeker heads and with spring-loaded free-floating canards or fins.
ARA is also a world leader in the provision of small panel balances together with many years of experience in the use of pressure measurement techniques for overall models and control panel loads.
During the wind tunnel test a sequence of different store configurations together with various control panel settings are tested. Some of the typical measurements made during such a test are listed below:
- Aerodynamic loads on stores, store and launcher assemblies and store and pylon assemblies
- Carriage behaviour of stores mounted in tandem, side-by-side or in configurations
- Effect on adjacent stores due to store release
The measurement of aerodynamic loads on stores and store assemblies is obtained using purpose built force and moment balances installed inside each store. In addition, the overall loads on the parent aircraft may be measured with a main model balance installed inside the parent aircraft. If this is not possible then extensive pressure plotting measurement techniques are utilised and the resultant data integrated to provide overall loads.
- Incidence range: -10° to +40°
- Sideslip range: ±40°
- Roll range: ±180°
- Overall model loads
- Individual store/multiple store assembly loads
- Control panel load measurements
- Use of oilflow visualisation to investigate surface flow phenomena such as separation bubbles and trailing edge separations
- Up to 220 channels measured at up to 10 data points per second
- Measurement of several hundred steady state pressures recorded at up to 10 data points per second