Smart fault-tolerant air-data sensor for aircraft flow angles measurement

This paper deals with the development of a smart multi-hole probe for aircraft air data sensing. The system aims at the calculation of static and total pressures, the angle-of-attack and the angle-of-sideslip starting from the elaboration of the pressure measurements on holes. The probe is characterized by fault-tolerant capabilities with respect to the loss of pressure data, and it is developed as an embedded system including MEMS sensors and a control electronics for multiple reconstructions of flow measurements. The basic idea for the reconstruction algorithm is that, for typical aircraft envelopes, flow angles are small (<15° for both attack and sideslip), and the shape of the pressure field around the stagnation point of a hemispherical body is essentially independent from the flow angles. Thus, once characterised the flow at the aircraft installation for zero angles of attack and sideslip, the reconstruction can be performed by minimising the errors between the five pressure measurements on the probe tip and the predictions of a set of models imposing different locations of the stagnation point. The geometry f the probe is designed and validated by CFD simulations, with the basic objective of enabling the algorithm to reconstruct the flow angles even in case of a pressure data loss. The work describes the initial phases of the system development, from the conceptual phase, up to the manufacturing of a first prototype used for the wind tunnel tests.