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Glider Design Considerations
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The connection between the bottom side(BS) cable and the control bar corner fitting has been a problem for hang glider designers since the beginning. The cable end should be able to rotate at the corner fitting in the proper direction, so it does not bend each time the leading edge spars are folded out and in for set-up and fold-down. Many thousands of production gliders have been manufactured over the years by small and major manufacturers without a proper BS wire connection at the corner fitting resulting in a small number of failures of cables due to short-life fatigue. Knowing they have a fundamental design problem; typically, the manufactures just recommend that their customers replace the BS wires anually.
The bottom side cables, along with the cross spar restraint cables(haul-back cables) are the most important cables on the glider. The BS cables see the highest flight loads, by a wide margin of all the wires on the glider. If any of these wires should fail in flight, its time to throw your reserve. If you are too close to the ground for a parachute to deploy, you're out of luck.
Some manufacturers have figured out adequate BS wire conections to the control bar that prevent excessive stress.
Not being satisfied with the status quo and in his on-going effort to improve ultralight / hang glider hardware, Dick Cheney designed a corner fitting that solves this problem in an elegant fashion. He did this in 1995 for the Predator. This fitting is on every one of the several hundred Predators and Saturns manufactured, and there has never been a cable failure on one of these gliders. After seventeen years of proof, not one other manufacturer has noticed this superb idea and incorporated it into their own corner fitting design.
My personal Predator 142, the "Trapezoid Wing" (made in 1999) has many hundreds of set-up / fold-down cycles and loops in the fourteen years I have flown it. I have left the original bottom side wires on it to demonstrate the validity of Dick's invention. I have made test specimens from old Predator BS cables and tested them to failure. They have always failed at loads above the rated strength of the cable, even those manufactured in 1995. All of this is due to the most innovative corner fitting concept in history. This obviously excellent idea should be on every hang glider manufactured.
Dick had an idea to solve the same problem on his TRX hang glider (circa 1990). This glider had ball-ends on the cables requiring a different solution. Dick came up with something simple, yet elegant. The plastic donut of just the right radius to prevent cable stress.
These are just two examples. Dick Cheney is a design genius with many innovations to his credit. He works at his thriving business in his cnc machine shop and sail loft in Kaysville Utah with more ideas for airplanes and gliders than time to build them all.