Active Control of a hybrid actuation system for aircraft vertical fin buffet load alleviation
Bibliographic record
Abstract
Abstract Twin-tail fighter aircraft may experience intense buffet loads when flying at high angles of attack. One such aircraft is the F/A-18 where the broadband buffet loads primarily excite the first bending and torsional modes of the vertical fin, resulting in significant vibration and dynamic stresses on the vertical tail structure. This buffet phenomenon reduces the fatigue life of the aircraft structure while decreasing mission availability. An international technical co-operation program was initiated to develop a novel hybrid actuation system to actively alleviate the buffet response of a full-scale F/A-18 vertical fin. A hydraulic rudder actuator was used to control the bending mode of the vertical fin using rudder inertia forces. Multiple macro fiber composite actuators were distributed optimally to provide maximum induced strain control authority for the torsional mode. In order to develop an effective control law, a system identification approach was conducted to obtain a state-space model of the vertical fin using open-loop test data. An LQG control law was selected to minimise the dynamic response of the vertical fin at critical locations. The effectiveness of the control law was verified through extensive simulation prior to closed-loop experiments. The LQG control law demonstrated high robustness in all excitation load conditions; both bending and torsional vibration modes of the vertical tail were suppressed effectively and simultaneously. The dynamic stress and acceleration response at critical locations were also reduced significantly. A closed-loop experiment was conducted on a full-scale F/A-18 empennage using the IFOSTP test rig, and the experimental results verified the effectiveness of the control law development methodology used for the full-scale hybrid buffet load system for the F/A-18 aircraft. In addition, the ground vibration test demonstrated that the hybrid actuation system is a feasible solution to alleviate the vertical tail buffet loads in high performance fighter aircraft.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".