RE: Position of throttle while taking vertical nose dive?
Most of our trainers and sport planes with exposed mufflers, thick wings, tricycle landing gear without wheelpants, and boxy fusilages are so aerodynamically dirty that they probably couldn't reach VNE even in a verticle dive at full throttle. The exception is fun fly/3-D planes which have a very low VNE because of how lightly they are built and sailplanes because they are so clean.