Topic 3: Flight dynamics in unsteady and non uniform environments

This theme concerns the development of tools and methods (experimental and analytical) to determine the evolving comportment of aircrafts flying with slow speed in a perturbed flight space and/or in a non conventional flight domain.

Contact: Olivier RENIER.

This know-how is historically developed around the realization and the exploitation of flight tests in a laboratory of aircrafts models in the dedicated sites of the ONERA Lille: the vertical wind-tunnel for stalled behavior observation (spin, normal flight recuperation), the flight laboratories B10 and B20 for the characterization of the comportment of the vehicle submitted to wind gusts in a tense trajectory.

Aerodynamic characterization of a motorized configuration in the vertical wind-tunnel,
in order to study the dynamic comportments in the limits of a flight domain.

The objective of this theme is to expand the methodological and experimental Toolbox to answer to various necessities:

– improve the capacity of the predictions, in the risk flight domains

– include the importance of the incertitudes linked to the lack of knowledge or the model simplification

– develop techniques of analysis to guide the experimental exploration to determine, in the best possible way, the representation models according to the exploitation requirements.

Many issues are approached in this theme:

Dynamic comportment post-stall

Many scientific themes concerning the stall existent. In terms of the flows physics, the prediction of flow separation in a smooth surface under a pressure gradient is aside of many difficulties: the effect of the boundary layer state (turbulent or in transition, for example), local geometry dependence. This results in different types of stall that are linked to the flight conditions, the number of Reynolds, etc.

External environment interaction

In the recent years, new applications of flight devices have appeared and need an extensive investigation of the coupling device – environment. Among those, we can mention the expansion of small drones flying in the urban zone for inspection and surveillance missions and the operations involving flight vehicles to transport loads to difficult access zones.

Experimentation definition

The three main issues for the experimentation definition are:

– the predictions reliability: increase the confidence in the comportment predictions, quantify the strategies proposed to the incertitudes and the sensibility to the piloting mistakes

– the safe opening of the flight operation domain in perturbed aerology

– the delays for obtaining those results and the cost reduction.