Concerns hang glider harnesses with slider in ultralight and winch tow.
With modern harnesses, which are equiped with a so called slider, it can become difficult to get from the upright into the prone position, when footlaunching on tow. If the pilot remains in the upright position it is not always possible to reach the necessary towing speed. Climbing too high, with the weaklink breaking, or a lock out can be the consequences.
In detail, several factors contribute to this: Position of the harness main support in relation to the pilots center of gravity, adjustment of the slider if existent, position of the tow release, height of the pilot above the base bar, towing speed, VG position if existent, bar pressure and speed potential of the glider.
A problem usually occurs only if several disadvantaging factors are combined. E.g. fast tow plane, slow hang glider, high pilot position above the base bar, tailheavy slider harness.
The problem does not occur if the take off is done from a trolley.
We recommend to perform a "dry run" if a new harness is used, to find out, how difficult it is, to get from the upright position into the prone position.The first take offs should than be performed by conventional footlaunch from a mountain, or towing from a trolley.