External Load Aeroelastic Certification Request
External load aeroelastic certification process carried out at TÜBİTAK SAGE,
- Aeroelastic Ground Vibration Tests (HYS 120)
- Finite Element Model Update
- Aeroelastic Analysis
- Flutter Flight Tests (HYS 210)
In this way, the aeroelastic effects of external loads (missiles, smart bombs, etc.) on the air platform to be certified are investigated and analyzed. The stages to be covered within the scope of the aeroelastic certification process are determined in the light of experience and according to the level of criticality.
Within the scope of aeroelastic certification, it is examined whether the air platform is subject to aeroelastic instabilities within the predefined flight envelope limits in the external loading configuration of interest, and the flight envelope is updated for the relevant external loading situation, taking into account the aeroelastic instabilities that may be encountered.
TÜBİTAK SAGE has the capability to perform each stage of the external load certification process with its own facilities and the support of the 1st Air Supply Maintenance Center Command/Air Forces Command.
Aeroelastic Ground Vibration Tests (HYS120)
HYS 120 aeroelastic ground vibration tests (Ing. Ground Vibration Test, GVT), defined by "MIL-HDBK-1763 Test 120", constitute the first step of the aeroelastic certification process. The purpose of HYS 120 ground tests is to experimentally calculate the frequency, damping and mode shapes of the elastic modes of the air platform/external load configuration to be tested for use in theoretical aeroelastic calculations.
YTT System Features
Hardware
- Pneumatic Suspension System
- Electromagnetic Modal Shakers
- 168-channel SCADAS III Data Acquisition System
Software
- LMS Test.Lab Structures Acquisition
- LMS PolyMAX
Gauges
- Accelerometers
- Dynamic Load Meters
Finite Element Model Update
At this stage, the element properties in the aerial platform/external load finite element model, which consists of shell and beam elements, are systematically changed so that the mode shape and natural frequencies of the finite element model match the modal data obtained from the MCC.
The design variables of the finite element model are updated as a result of the optimization process until the error between the modal properties of the finite element model and the modal properties obtained from the Ground Vibration Test is minimized.
Aeroelastic Analysis
In this stage where aeroelastic analyses are performed, aeroelastic criticality prioritization of all air platform/external load configurations to be aeroelastically certified is performed, critical configurations that require flutter testing are identified, and a flutter test matrix with velocity-altitude pairs is created.
Flutter Flight Tests (HYS 210)
HYS 210 flutter flight tests, defined by "MIL-HDBK-1763 Test 210", constitute the final stage of the certification process. The purpose of HYS 210 flight tests is to examine whether the air platform/external load configuration to be tested is subjected to any aeroelastic instability within the predefined flight envelope. After the tests, the flight envelope is updated if necessary for the relevant external load case.
During the flutter flight tests, the aeroelastic modes of the air platform are driven by the flutter propulsion system and data are collected under specified flight conditions, and the data received through the mobile telemetry station are used in real-time modal analysis for damping estimation.
Hardware/Software
- Flutter Drive System
- Mobile Telemetry Station
- SCADAS III Data Collection System
- LMS Test.Lab Flutter Testing
