'Bird of Prey' VTOL UAV drone

Flight time and versatility will be vastly extended using both multirotor and flying wing technologies.

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Not satisfied with the 10-20 minutes of flight time on your UAV? Longer flight times are convenient and sometimes necessary in UAV operations. Longer distances / more ground covered = more work done in less time.

The body style is a hybrid of a traditional flying wing and delta wing. Eight BLDC motors and rotors can lift the frame clear of ground obstacles. Tilt of the forward drive units will provide thrust.

In the centerish of the main body, an auto-levelling 3-axis gimbal will carry the sensing equipment, be it visual or IR camera, thermal imaging, LIDAR or other. This gimbal will have spherical line-of-site, the body of the craft designed to maximize the extents. The gimbal will be self-contained when possible, with power for the gimbal motors and devices mounted within, giving 360 degree rotation on all axis.

Flight time is increased by the aerofoil lift the craft receives from the wing design. The large surface area will help increase lift.

Control will be achieved with a combination of thrust vectoring and thrust differentiation to minimize moving parts and the need for additional servos and the associated weight.

Several unique attributes will make this drone/UAV different from what is out there.

  • Transition from Vertical Take Off to Forward Flight

    ken.do12/03/2017 at 23:02 0 comments

    To transition from VTO to FF, a few things need to happen:

    1. Forward motion must be initiated.

    2. Rear pusher prop must transition from thrusting downwards, ~90 to rear pusher position.

    3. Vertical thruster coaxial pairs must shut down.

    4. Port covers must close.

    Ideas for transition:

    Once altitude suitable for transition is reached, use servos to set the bottom port covers to an angle that would deflect the thrust of the vertical thruster rearward, gradually increasing angle until closed. At the same time, gradually increase the angle of deflection of the rear pusher unit until proper airfoil lift is achieved. During this transitory phase, the ailerons would be in max up position, gradually descending until stable forward flight is achieved.

    All this can be done either manually or programmed directly into the flight controller, or an ancillary device (onboard or at base station). (Yawing while in VTOL mode can be accomplished by changing the deflective angle of the port covers as well)

    Another seperate idea for this transition is the stop-and-drop method, where once a suitable altitude is reached, vertical thrusting units stop and rear pusher unit pivots to rear-thrust postion. The vehicle drops, nose first, rear thrust pushes it to nominal forward flight speed. Vehicle then levels out for forward flight via ailerons.

  • More design...

    ken.do12/02/2017 at 22:09 0 comments

    Created a 3-D printable port liner that will eventually host mount points for coaxial pairs. Put on fins. Broadened fuselage.

  • Reconsideration of Motivational Apparatus

    ken.do11/28/2017 at 19:53 0 comments

    In reconsidering how this drone is going to move, I have come up with a different idea. Eight BLDCs is a lot of weight, and four coaxial sets means four ports in the airframe; that is a lot of lost wing area, and therefore lift.

    The new idea is to make the VTOL component more like a bi-copter, using two coaxial pairs of drive units. These components will be in two ports. A third single drive unit will be mount rear and center. This unit will have the tilt component and be located just off the extreme back end of the airframe.

    On vertical liftoff, the bicopter pair will provide the bulk of lifting thrust while the lone unit at the back will be pointed vertically groundward and provide only levelling stability.

    At a predetermined altitude, the lone unit tilts in steps to provide pushing thrust until forward flight is established. At this point, the lifting coaxial pairs disengage. The ports through the airframe would then be covered, either with a sliding door, or a hinged door attached fore-ward.

    Control of forward flight will be maintained through a combined aileron/flap actuated by servos.

  • Frame Construction - Part 1

    ken.do09/03/2017 at 02:18 0 comments

    My almost-complete project, Mostly Printed CNC Build, will allow frame creation from a variety of materials. The three that interest me the most however are:


    Graphene-based 3D printing filament

    Reinforced carbon fibre

    Aluminum - The frame can be milled from a soft aluminum. The main shape of the frame, biomorphic or purely structural, can be cut out and then channeled out to reduce weight but maintain structural integrity. Wire routing may also be improved in this way. 

    Graphene 3D filament - although lighter than other filaments will be a heavy option because it will take more material to achieve the structural integrity required. The entire frame will fit within the extents of the print bed. 

    Carbon fibre - can be milled to the correct shape, but will be floppy until reinforced by either another layer of carbon fibre or carbon fibre tubing. This will also add to the weight.

    I would like to try at least two of these materials for frame creation.

  • Softwares

    ken.do07/09/2017 at 04:04 0 comments

    The software to run the BOP will consist of flight control that can switch between VTOL and Forward Flight, OpenAero-VTOL in CleanFlight or similar. The software must be able to take data gathered from motors, telemetry sensors, and power systems and use this data to manage flight systems to manipulate component variables, including number of motors in use, stabilization, low battery auto return, efficiency, etc. Other software details may include autonomous collision avoidance, automated takeoff and landing sequences, and flight planning. Future development of softwares may include recognition of thermal updrafts and adjustment of flight path to coincide with these updrafts to maximize loft and efficiency.

  • Drive Considerations

    ken.do07/09/2017 at 04:03 0 comments

    Due to the extremely different thrust requirements for vertical take-off/landing and forward flight modes, the BOP is equipped with eight drive units. In VTOL mode, all eight are engaged. When the BOP is switched to forward flight mode, four to six of the drive units disengage, allowing greater motor efficiency and thus substantially extending battery discharge time and therefore flight times. These motor/propeller drive units are arranged in a coaxial orientation, with two drive units being stacked together to minimize the number of holes through the body. The top/forward drive units will consist of a 2808 series motor running at 2400 kV and a standard 7 inch carbon fibre propeller. The bottom/rearward drive unit will consist of the same motor as top/forward, but the propellers will be folding props (like those used on gliders) and will fold back when drive unit is not engaged, reducing drag coefficients and increasing thrust effectiveness by a considerable amount. In instances where extreme amounts of power are needed, two or four of these drive units can be engaged (ie steep vertical climb, burst of speed).

  • Frame and body interaction

    ken.do04/20/2017 at 21:29 0 comments

    For a lot of my projects (Raptor V-tail, Laser Rifle, RasPi SmartZoom, etc.) aesthetics are important. In some circumstances, I place form above function, but mostly I try to find a happy fusion of these two aspects of design.

    For the Bird of Prey, I think this fusion is easily achievable. Some of my design ideas:

    - biomorphic frame design

    - translucent skin on wings to provide a view of frame/internals

    - frame can be flown as multicopter without skin in high wind conditions

    - streamlined cover of sensor payload (camera, LIDAR, etc)

  • Overall Design

    ken.do04/06/2017 at 23:17 0 comments

      1. Form: The 'Bird of Prey' is a multi-use long range, long duration, vertical take-off/landing aerial robotic platform that incorporates the versatility of a multirotor with the efficiency of a fixed wing. The fixed wing aspect of the BOP is in a hybrid delta/flying-wing configuration. The BOP has a max AUW of 6kg with the current configuration of motors.
      2. Usage: This VTOL will be used for:
        1. airborne visual photo/videography
        2. airborne thermal photo/videograpy
        3. airborne radio repeater
        4. airborne network node
        5. airborne visual/laser/spectrum mapping
      3. Design: As mentioned above, the hybrid body of the BOP lends itself to VTOL as well as sustained Forward Flight. The BOP transitions from VTOL to Forward Flight by tilting the drive units. All shock sensitive electronics are enclosed and frame/body support structures are in place to allow takeoff and landing directly on the body without inclusion of landing gear. Body will be sealed for dust-proofing and partial or full waterproofing, allowing for inclement weather operations as well as water take-off, landing and below-surface camera work. The skin is seperate and removable from the frame, allowing pure multirotor operation.

  • Control Components - Materials and Shopping list

    ken.do04/06/2017 at 18:17 0 comments


      1. Rotors… Rotors are nylon for cost considerations, unless thrust response is too slow with the flex of these rotors. If response is too slow or thrust is too low, carbon fibre blades can be used
      2. Rotor assembly shaft… Shaft can be of hollow carbon fibre or aluminum (archery shafting)
      3. Rotor motor mounts assembly… ABS or Nylon plastics, held together with stainless steel screws/bolts, attached to shaft through deformation or bolt-through design


      1. Motors… 2808 1760kv x 8
      2. ESCs… 30Amp SimonK Afro x 8
      3. Propellers… (6)7x4 folding prop sets, (2)7x4 non-folding props
      4. (2) PX4 PixHawk with accessories (incl. GPS, OSD, Telemetry Radio, etc.

  • Control Components - Design

    ken.do04/06/2017 at 18:13 0 comments

      1. Tilt Rotor... The BOP uses both rotor tilt and thrust differentiation methods to control speed and direction of motion. The tilt mechanism consists of a hollow aluminum or carbon fibre shaft to which is attached at one end to a gimbal style brushless motor and at the other end a bearing, in the middle is attached a double motor mounting plate for the axial propset.
      2. Thrust differentiation... Controlled by a flight controller, the thrust differentiation system for motion control is entirely electronic and linked to both gyroscopic sensors and remote control radio system.
      3. Flight controller... Using the industry standard pixhawk or openpilot compatible Cc3d Revolution flight controllers, gyroscopic balance will be maintained through manipulation of both the tilt rotor assembly and the thrust differentiation control systems.
      4. Software... The software needed must be able to accept sensor input (airspeed, heading, gyro, power consumption, compass, gps) and use this information to control motion and accessory activation. Motor activation can be regulated by monitoring the draw on each motor set; draw gets too high, more motors kick in.

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