  The unsteady lift of a high-angle-of-attack, flat-plate wing encountering
finite-length obstacles is studied using towing-tank force measurements. The
wing translates from rest and interacts with a rectangular channel, ceiling, or
ground obstacle. Variations with angle of attack, obstacle length, mid-chord
height to the obstacle, and starting distance between the wing leading edge
(LE) and obstacle (typically 1 chord) are examined. For channels, as the gap
height decreases, circulatory-lift peaks attributed to leading-edge vortices
(LEVs) are the largest, and from the second peak onward occur earliest. This is
likely from wing blockage enhancing the flow speed. The lift reduces while
exiting a channel, and is lowest afterward if exiting during a lift peak. For
ceilings, the first circulatory-lift maximum increases for smaller
LE-to-ceiling gaps, but for gaps of 0.5 chords or less, subsequent peaks are
below the no-obstacle case yet still earlier. For grounds, with lower wing
height the first circulatory-lift peak is larger but the second peak's behavior
varies with angle of attack, and the lift decreases near the ground end.
Grounds affect peak timing the least, indicating a reduced influence on the
LEV. Changing the starting distance to a channel alters the lift, likely from
different LEV timing.
