https://en.wikipedia.org/wiki/Filper_Research_Beta

*'The results of the initial flight tests were very disappointing. The Beta 200A exhibited the following undesirable characteristics:

• Significantly under powered.
• A tendency to pitch nose down during transition to forward flight.
• The "Gyroflex" rotor could not be controlled by force only.

Attempts to enter into forward flight were unsuccessful; The N5000F was tested in hover only.'*