A pusher prop is not necessarily needed in a VTOL configuration.
Based on the User’s initial post and some of the first replies, the better solution as previously stated was to obtain a plane type RC unit and reconfigure it for VTOL. This involves some ducted fans cut and placed into the wings that rotate 90 degrees from vertical into horizonal positions during flight.
As the aircraft then rises in the vertical state and as the Ducts rotate, it will self-convert from the vertical to the horizonal state. The transition is sloped towards the front of the aircraft. Once fully transitioned, the slope declines to its full horizonal state and the aircraft is then flown in the traditional manor as an RC plane.
For landing, the reverse is performed with the ducted fans rotating their 90 degrees back to the vertical state. Again, the flight slope is experienced and the aircraft will also slow down naturally during the declining slope. With a little practice, one can learn the proper distance to the landing pad and pre-judge the declining slope so that the aircraft is positioned correctly for its landing. The pilot ensures the aircraft is facing into the wind so that flaps and rudders can function correctly for minor adjustments, along with a few nudges of the ducted fans here and there for a proper vertical landing on a pad.
It is the thrust of the Ducted fans that do the work, not a third push prop. There are no third push props on Osprey. It is the same principle being described. The pilot understands the slope and transitions to and from VTOL into/from horizonal flight and uses it accordingly.
All of which can be software controlled with servos on an RC. But its a airplane platform to initially build from, not the proposed one in the initial posting. Locate a V Tail RC plane as the base to design from. The Ducted Fans will do the initial lift and once rotated 90 degrees, then propel like a prop driven plane. Servos can do 180 degrees so if your center position is the vertical, +90 would be forward and -90 could also be used at times to perform a reverse motion and landing. You would want the fan units to be non ganged, meaning you can control each one’s servo position, separately. This could also be a software option to gang them together or control them separately. Un-ganged control allows for vertical rotations while in place in a hover in addition to the flaps and rudder.
And to account for aerodynamics, you would want both a clockwise turning ducted fan, and a counter clockwise turning one on the other wing. The two would cancel out the tendency for the craft to naturally spin which ever way the props were turning, if both are either CW or CCW ones. This also can be used for very small rotational adjustments in place while hover, by slowing down one ducted fan. The natural change if rotations between the two motors will cause a rotation, very very slowly, since one fan is spinning faster then the other, causing a rotational drift that is proportional to the number of times one motor shaft spins verses the other motor shaft. What you are doing at that point is reducing the counter rotation effect that normally is used to cancel inherent rotation. RC transmitters have Trim adjustments on them. Normally you would trim the props so they cancel out rotation. Adjust the trim slightly and one will spin faster or slower then the other prop in the fan, causing the rotation to reappear instead of canceling out. Again, this also can be controlled with software, if that is your approach. The software would be controlling the trim and not the RC controller.
So no, a pusher prop is not necessarily needed if the proper thrust is used the ducted fans.
Hope this helps.