Thomas Pynchon, from S-Gerät to Y-Gerät

One of the core plot devices (in so far as there is a plot) in Thomas Pynchon's 1973 novel, _Gravity's Rainbow_, is the S-Gerät: the Schwarzgerät or "black device", made from the plastic Imipolex G. While working on another project (on the history of television), I found a curious set of projects from the war, designated Y-Gerät and X-Gerät, which are part of the so-called [Battle of the Beams](https://en.wikipedia.org/wiki/Battle_of_the_Beams)