It does exist: The Hovering Cobra
The Cobra design was sold to a Company NZ if my memory serve me good, so not to legal to copy........they have a long tail moment, yes I did have one, that I purchase from Falcon Hobbies.
The tail twisted very badly in flight went doing aerobatics but after a little mod she still twisted but it stayed together.....I lost the plane at a fun fly, the elevator servo screw back off just enough to let the arm rotate by itself....yes my fault.
I took a few pictures during construction.
Daniel D.