On Wednesday, June 17, 2015 at 11:34:01 AM UTC-4, jfitch wrote:

While the battery issue was a good argument long ago, it isn't valid anymore. A single 10AH lithium will run what most people have in the cockpit - including an active transponder - for more hours than there are daylight. The equipment is much more power efficient, and the batteries better


If the FAA can get behind putting a non-TSO'd LiPO4 battery in a certified aircraft, then the only real question is whether there is any reason to treat gliders differently than other GA aircraft:

Due to the tapered nose, it is difficult/impossible/expensive to squeeze a full complement of modern gadgets into the panel of many gliders. When gadgets are installed above the original panel, they compromise 'see and avoid'. 'See and Avoid' is profoundly important because gliders routinely fly in formation and in close proximity to each other. TABS, Transponders, ADS-B add little value in formation flying.

Likewise, the non-display-parts of avionics compete for limited space with O2 tank, survival gear, water etc.. When space gets tight, getting everything to fit gets expensive. Glider manufacturers put low and strict limitations on the weight added equipment and luggage. The sensitivity of gliders to weight and balance add additional constraints.

Due to space limitations and/or carbon fiber, it can be difficult to get the proper spacing between the antennas of multiple avionics devices and at the same time obtain the desired range and directional coverage. Externally mounted antennas increase drag and are subject to damage in off-airport landings. The preference for internally mounted antennas makes it harder to achieve a compatible and effective array of antennas.