Maneuverable BoxCopter - Rear Motor Servo Mod

This project started when I had a desire to film over water but was limited by safe landing sites as I would mainly be flying while on a small boat.  To overcome this I decided to use Jake Well’s BoxCopter design which meant that I could land and take-off from the water.  However, I still had concerns about getting the quad close enough to the boat for easy retrieval.  Preliminary testing showed that the BoxCopter could be moved about on the water, but it wasn’t highly maneuverable  –  too much forward elevator just made the front /bow become submerged causing it to either dramatically stop or spin off course.  What it needed was more thrust in the direction of travel.

The inspiration of how to achieve more maneuverability came from the tail assembly of my tricopter.  Like many Flitetest followers, my tricopter is based on David’s RCExplorer design (which I absolutely love – so much fun to fly and can take heaps of abuse when doing proximity FPV…).  I simply used the design for the tail servo assembly on the two rear motors of the BoxCopter to enable them to pivot forward and backwards - providing more directional thrust.  I then mixed their movement in with the elevator control and a switch to activate the mix.  This meant I could fly as normal with no tilting but all I needed to do was flick the switch and I could have the motors tilt when it was on the water.  The BoxCopter also turns very well when the motors are tilted as the rudder input also applies differential thrust.

Below is some test flight video that shows how it flies and operates on water.  This has some flying with tilting motors (‘boat’ mode) and it flies quite well.  The only issue I found was when I applied hard back elevator as the tail tended to drop more than normal.  You can certainly use this to stop in a hurry though!  I will definitely be using this modification in other projects.

 The BoxCopter design made from a cake container for floatation (and to keep the electronics dry).

 All the flight electronics were secured to the underside of the lid by either velcro or hot glue.  External security camera (for FPV) is only covered in electrical tape but seems to provide enough weather proofing – at this stage anyway!  

 Close up of the tilt mechanism.

 To ensure that both servos moved in the same direction I reversed the motor leads on one servo (arrowed), as well as reversing the leads on the potentiometer inside the servo.  This meant I could use a Y-harness to connect both servos and I only needed to mix one channel in with the elevator control.