Finite wing lift during water-to-air transition

Wings are used for numerous applications in both air and water and their lift generation in either domain is well understood. However, the lift generated by a wing when it is transitioning out of water and into air has not been quantified to date. This experimental study aims to examine the lift generated by a wing as it performs this water egress. An aspect ratio 4, NACA 0015 wing is translated at constant velocity to investigate the effects of starting depth under the surface, angle of attack, and egress velocity. For all test cases, the wing is translated at constant velocity for at least two chords prior to piercing the surface and the lift profile during the egress is similar for all tested starting depths. The angle of attack affects the time-dependent lift after start and the distance traveled to achieve steady state due to flow attachment changes. However, the angle of attack was not observed to affect the lift profile during egress. The lift history is strongly dependent on egress velocity. Lower velocities register a large lift overshoot followed by a negative lift undershoot before the egress is complete. Higher velocities do not exhibit either overshoot or undershoot and exhibit a more linear transition profile.