Literature indicated that existing wind tunnel wing models possessed aeroelastic properties unrepresentative of High-Altitude Pseudo-Satellites (HAPS). Therefore, this research aimed to develop HAPS representative aeroelastic wind tunnel wing models. Two wing varieties were constructed, wind tunnel destruction tested, and aeroelastically analysed with the geometrically nonlinear aeroelastic analysis code ASWING. The destabilising influence of increasing static unbalance was observed at alternate 25% and 75% of chord main spar locations. Ground vibration testing validated structural natural frequencies calculated from static stiffness test data. Model destruction occurred near the predicted flutter airspeeds at incidences from 0.17 to 4.17 deg, following subcritical limit-cycle oscillations, stall-limited bending-torsion flutter, and torsional divergence. Analysis of first bending and torsion mode phase and damping with airspeed revealed bending-torsion flutter instability of both wing designs. The 25% chord spar wings failed exclusively in flutter, whereas several 75% chord spar wings exhibited post-flutter divergence, qualitatively matching predictions. Linear stability analysis of the wing motion, composed of large static deflections with superimposed low amplitude oscillations, remained physically meaningful due to linearisation of the geometrically nonlinear deformed structure about the deformed equilibrium. The results show that the aeroelastic behaviour of highly flexible wing models is accurately predicted by ASWING.