One thing we had introduced earlier was having two vertical stators in the duct just behind the propeller. Stators are fixed mini-wings that are used to re-direct flow from a ducted fan. In our case they were being used to offset the forces of the propeller swirl that encountered the small portion of the vertical tail extending below the tail boom. Those lower verticals were down in the prop wash and caused the nose to drift to the right after the aircraft left the ground.
The stators were tested and worked well to remove the nose right tendency, but they did make it harder to change the prop pitch. The engineering team solved the problem of how to get rid of the small verticals for production vehicles, as we felt that having those small vertical stators was not a good long-term solution. Then we became free to move the small verticals anywhere we wanted for test flight. In this case, it was cleaner to put them above the main verticals, just above the horizontal tail. The whole purpose in this was to be able to remove the vertical stators from the duct and get a closer approximation of our future production vehicle. We have done that, and you can see the small vertical tail pieces above the horizontal tail wing in the image below. The rudders are still off, but doesn’t this look a little like the verticals for an F15 Eagle? Too bad this isn’t our solution for production vehicles, but we think the production solution will be sleeker and will easily fold up inside the duct for ground use.