Samenvatting

Sub-scale Flight Testing (SFT) is potentially useful in predicting aircraft flight behaviour,
especially in the case of unconventional designs for which legacy information is unavailable
and wind tunnel tests are unable to predict aircraft dynamics. A necessary condition for SFT
is the design of properly scaled models. However, even in case of perfect scaling, the sub-scale
model needs adequate flight performance and handling qualities to enable the execution of
flight tests. Thus, the (static and dynamic) stability and control (S&C) and handling qualities
(HQ) of sub-scale designs should be evaluated accurately as well as quickly, to allow conceptual
design iterations. To this purpose, we propose the use of a 3D panel method (3DPM) for the
generation of the non-linear aerodynamic database, in combination with a non-linear flight
dynamics analysis. Two main challenges affect the proposed approach. The first concerns
the validity of the low-fidelity 3DPM data for the assessment of the sub-scale design S&C
and HQ. The second is about the time consuming and error-prone pre/post-processing activity
demanded by the hundreds of analysis cases for the aerodynamic database generation. The first
issue is investigated by predicting the longitudinal S&C performance and HQ of a sub-scale
design using 3DPM analysis and comparing them with the prediction from wind-tunnel test
(static) data supplemented by (dynamic) data from 3DPM. Both models appear trimmable and
stable and the difference in their HQ are quantified, thus verifying the suitability of 3DPM
analysis for sub-scale design assessment. The pre/post-processing challenge is tackled by the
development of a knowledge-based engineering application to automate the aerodynamics
database generation, reducing the time needed for geometry modeling, discretization and post-
processing of hundreds of cases from weeks to hours. The proposed methodology and its
flexibility are demonstrated in this paper, where a commercial 3DPM code and an in-house
developed non-linear flight dynamics analysis tool have been used to assess two sub-scale
designs, one conventional and one based on the box-wing configuration.