Rucked sail

The horizontal strut near the top of the control frame was a 'soaring bar'. The harness risers passed in front of this device, effectively moving the hang point forward. Many standard rogallos were trimmed (without a soaring bar) nose-up. Manufacturers claimed that this was a safety feature for when a beginner lets go the control bar -- the glider stalls rather than dives. An alternative explanation is that they miscalculated the hang point. In any event, flying for long periods while continuously pulling in made your arms tired. The soaring bar was a crude but effective means of changing the trim.

The keel tube was inside the sail so the glider bag -- not everybody had one -- was tied to the crosstube.

See how the upper rigging side cable dug into the sail, causing a span-wise crease. Solutions included immensely tall king posts, crosstubes that extended eighteen inches beyond their junction with the leading edge, and 'sail clearance towers'. The latter were short vertical struts attached to the crosstube ends (protruding a couple of inches beyond the leading edge junction). The simplest solution, adopted in gliders such as this Wasp 229B3, was to ignore it.

The site here may be Melbury Hill, a base leg away from Compton Abbas airfield.