At the University of Leuven (KU Leuven) we are working hard on improving performance of multi-rotor UAVs in terms of flight speed, endurance and possible payload, with the application of automated aerial transportation in mind. Our approach is to add wings to a multi-rotor and make a transition between hover and cruise flight in order to decrease the required power for flying at high speeds. In order to reduce the number of moving parts, and therefore extra weight and points of failure, we only use differential thrust for controlling the UAV throughout all flight phases

In the summer of 2014, our first prototype was presented, the “ VertiKUL "

This UAV made a transition of 90°, producing 100% of its required lift from the wing in cruise flight. Also see this post. We noticed that flying in windy conditions, however, was challenging. Especially the automated landing was hard. Therefore we decided to improve the wind resistance of the UAV by reducing the wing size. Therefore, part of the required lift in cruise flight is still produced by the propellers that now operate at 45° with respect to the direction of flight. The result is a very wind tolerant, efficient and fast multi-rotor: VertiKUL2



Design specifications:

-          5kg total mass

-          60 to 70km/h cruise flight

-          + 25km of range (we still have to validate this)

-          Pixhawk flight controller with adapted ArduCopter 3.2.1 firmware

-          1kg of payload possible (20x15x10cm)

Because of the transitioning, it was hard to include a landing gear to land on a flat surface. Therefore we decided to land on an inclined surface, or a box as in the video.

We developed a new approach for controlling these transitioning VTOL UAVs with promising results and applicable on a wide range of VTOL UAV designs that are controlled by differential thrust as multi-copters. More info will follow…


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  • Fantastisch werk jullie vlamingen! Keep going! Wish you all the best and lots of success! I am pretty convinced that vtols will provide the better options compared to multikopters regarding cargo. There is still plenty of “space“ remaining 4 design with Vtols as only a few options (compared to multikopters) were endeavoured sofar.

  • Would it be a plausible design modification to rocket the vessel from a launchpad (from the point of origin) for reserving additional battery life? Of course, the creators did mention something about the development of mid air battery swapping. 

  • humm, any thoughts of rotating wings using a gyro to maintain wing attitude rather than rotating rotors? 

  • Nice one Bart, Jon and Dries.

    This would also be usefull to fulfill scenarios for emergency teams to get a fast situational awareness.

  • worth of flight, please verify the data. this the most elegant solution i've seen so far, imho.

  • We will measure power-speed curves for this one, with different payloads and flying at constant speed and altitude. I would be very interested to compare the measurements to other UAVs with a total take-off mass within the range of 5 to 6 kg. If anyone already did this, or will do so on his multirotor: let me know! :)

  • Yeah, I'd be interested in that data too. Or even just some measurement of power required to fly a 1kg payload at speed.

  • A cool test would be to plot throttle out vs airspeed with and without the plane fuselage( just a quadrotor frame). Would be a great way to visualize performance increase. 

  • 3D Robotics

    Impressive! I want one ;-)

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