A lumbar support that works
If the seat/chute combination in the sailplane you usually fly gives poor lower back support, sitting can become very uncomfortable in a short time. Hard landings and crashes in gliders are also notorious for producing injuries arising from poor alignment of the spine. Pieces of rolled up foam, and other soft material is often used to alleviate this back support problem, but it is an unsatisfactory solution because such material is not firm under load and never stays in the right place.
My experience was that without additional back support for the RS-15 seat geometry, a flight became terrible after a couple of hours. Other gliders may have similar problems with varying degrees of discomfort (my personal opinion is that 1-26 and 2-33 seats should be illegal!).
You can custom build a firm, simple lumbar support for yourself from a piece of 'blue board' Styrofoam insulation. The diagram shows its general size and shape (somewhat exaggerated in thickness). Starting with a 10"x 12" piece of 2" board, carve the saddle shaped surface into it using a long bladed knife such as a bread knife. Note that the thickest part is about a third up from the bottom. Experiment a bit with the support in place while you are seated in the glider and trim until it feels right. If the seat pan is curved the backside of the support will also have to be shaped.
When you wear a chute, the support must be placed between it and your back, and it must be as low as possible when you are seated.
When the fit is correct, you won't even notice it after a while (telling you it's doing its job perfectly), though at first it may feel odd. Once the shape is right for you, strap it with a few windings of duct tape to protect the fragile corners and fit it into a cover made from an old towel or other similar cloth to keep the support clean and absorb sweat.
A more ambitious project is to use the support as a mold for a fibreglass model once it has conformed itself to you and the seat back after some use.
Courtesy of "6/98 free flight"