Ground facility interference on aircraft configurations with separated flow

Abstract

Analysis of recent test results obtained on strut-mounted aircraft models has revealed the presence of test facility interference effects. In addition to dynamic support interference, coupling with unsteady wall interference effects can be present even when the model is relatively small in relation to the test section size. This coupled support/wall interference is expected to be more prevalent in pitch-oscillation than in roll-oscillation tests. Significant interference of this type was identified in dynamic cross-coupling data obtained on the standard dynamics model (SDM) oscillating in pitch. On the other hand, small distortions of the antisymmetrical static rolling moment characteristics and of the longitudinal aerodynamic characteristics measured on a 65-deg delta wing are shown to be attributable to the effect of direct support interference on vortex breakdown. For the oscillating delta wing, the support interference produces asymmetries in the measured longitudinal aerodynamic characteristics, which decrease with increasing roll rate.