Interesting indeed. Are you certain you don't mean a Schottky Diode. These are extremely fast switching and classically a design choice for even faster switching than anything required for this application as opposed to tunnel diodes which are classically used for RF detection and mixing up to microwave frequencies. I would like to know more about the use of a tunnel diode in the application of a joy stick, where a linear control is required well below the ms timing is needed to model that of an acutal rudder movement or that of any flight control trim. Thanks