Ducted Fan Drone Uses 1 Rotor For VTOL

Multi-rotor fixed-pitch aircraft – quad, hexa, octa copters – are the current flavor of the season with hobby and amateur flight enthusiasts. The serious aero-modeling folks prefer their variable-pitch, single rotor heli’s. Defense and military folks, on the other hand, opt for a fixed wing UAV design that needs a launch mechanism to get airborne. A different approach to flight is the ducted fan, vertical take-off and landing UAV. [Armin Strobel] has been working on just such a design since 2001. However, it wasn’t until recent advances in rapid-prototyping such as 3D printing and availability of small, powerful and cheap flight controllers that allowed him to make some progress. His Ducted Fan VTOL UAV uses just such recent technologies.

Ducted fan designs can use either swivelling tilt rotors that allow the craft to transition from vertical flight to horizontal, or movable control surfaces to control thrust. The advantage is that a single propeller can be used if the model is not too big. This, in turn, allows the use of internal combustion engines which cannot be used in multi-rotor craft (well, they’ve proven difficult to use thus far).

[Armin] started this project in 2001 in a configuration where the centre of gravity is located beneath trust vectoring, giving the advantage of stability. Since there were no hobby autopilots available at the time, it was only equipped with one gyroscope and a mechanical mixer to control the vehicle around the vertical axis. Unfortunately, the craft was destroyed during the first flight, after having managed a short flight, and he stopped further work on it – until now. To start with, he built his own 3D printer – a delta design with a big build volume of 400mm3. 3D printing allowed him to build a structure which already included all the necessary mount points and supports needed to fix servos and other components. The in-fill feature allowed him to make his structure stiff and lightweight too.

Intending to build his own auto-pilot, he experimented with a BeagleBone Black connected to a micro controller to interface with the sensors and actuators. But he wasn’t too happy with initial results, and instead opted to use the PixHawk PX4 auto-pilot system. The UAV is powered by one 3-cell 3500mAh LiPo. The outside diameter of the duct is 30cm (12”), the height is 55cm (22”) and the take-off weight is about 1.2kg (2.6 pound). It has not yet been flown, since he is still waiting for the electronics to arrive, but some bench tests have been conducted with satisfactory results. In the meantime, he is looking to team up with people who share similar interests, so do get in touch with him if this is something up your alley.

If you want to look at other interesting designs, check this UAV that can autonomously transition from quadcopter flight to that of a fixed-wing aircraft or this VTOL airplane / quadcopter mashup.

22 thoughts on “Ducted Fan Drone Uses 1 Rotor For VTOL

          1. There is no ambiguity. One may say “ten square millimeters” to mean 10mm^2, or “ten millimeters squared” to mean (10mm)^2 or 100mm^2.

    1. Actually not as much as you think. A quadrotor’s propulsion components also are it’s control components. There is no weight penalty of control mechanisms that do not contribute to lift/thrust. That being said any direct lift method outside of low speed or hover will be inefficient compared to a wing.

      1. I should have been more clear–thrust vectoring by actually tilting the thruster is tough because of the added structural and actuator requirements. Setups that vary relative RPM (like a quadrotor) can be simple and light!

  1. The algorithms that drive these things are cool, but I don’t see this design as being good for anything but reusable fast-high-altitude and space stuff to beat the economics of current orbit tech.

    I’ve been waiting for someone to do a variable pitch pendulum drone using a single high diameter rotor and current consumption that is at least 50% more efficient that quads or variable pitch dusted and can handle weather dynamics better without special controls..

    1. I saw a live demo of a startup that has a similar drone on kickstarter, forgot the name though. Main advantage is that is safer and sturdier than a normal quad. But they are very susceptible to wind.

  2. Awesome!

    I would’ve imagined something more like a really slow rocket. I wonder if they could use the funny control methods like a reaction wheel. I have a little single-motor copter toy that spins around a lot, I think the aero-smart people call this “precession”, to avoid flying off randomly.

  3. The cylindrical wing has a definite advantage in time of flight and range once the craft is aloft and flying horizontally. The wing contributes significantly to the lift at high speeds so the prop speed can be reduced conserving power and making for a quieter flight (important for some applications).

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