Here a project of a Coanda Effect Saucer (CES) stabilized with a 9D0F IMU. The CES UAV, propelled by an electric engine, uses the Coanda effect to take off vertically, fly, hover and land vertically (VTOL). There is no big rotor like on an helicopter and the flight is very stable and safe for the surrounding.

The Coanda Effect has been discovered in1930 by the Romanian aerodynamicist Henri-Marie Coanda (1885-1972). He has observed that a steam of air (or a other fluid) emerging from a nozzle tends to follow a nearby curved surface, if the curvature of the surface or angle the surface makes with the stream is not too sharp.

I use my firmware AutoStab v4.0 installed the ArduIMU+ V2 flat with a special mixer for this device.

Stay tuned on this blog, more to come soon,


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  • Great job Jean-Louis I wish you success especially with your PID gains. Regards, Cliff
  • Developer
    Hello to All, thanks for your interest in my Coanda Effect Saucer blog and for all your comments.
    You will find below an experiment that I have conducted in 2006 about the measurement of the upward thrust Vs the tangential airflow above one of the "petal" of the saucer hull. The shape curve was the same as the CES v1.2 currently under test.

    Today, I have two challenge to meet... The first one is to succeed in a good tuning of the gains of the IMU PIDs for a stable CES hovering, the second is to understand better how to improve the efficiency and the flight enveloppe of the Coanda Effect Saucer in various wind conditions... This is a fascinating challenge...
    Regards, Jean-Louis
  • So independent of whether or not the Coanda craft is more efficient than just a ducted fan, implementing a craft that exploits this affect provides the degrees of freedom needed for one to make a useful vehicle that you can control. A ducted fan be itself does not make a useful vehicle; you still need to add more stuff to the ducted fan in order to control it and perform a mission (like adding stuff to accommodate a payload). This is really cool stuff. Thanks again Jean-Louis for sharing your work.
  • Hi Eric, I agree.
  • Hi Mark, I would tend to think a 'rough' surface would disrupt the smooth airflow and create turbulance thereby
    decreasing the lift. Easy enough to test using Jean-Louis's spoon experiment ie make the plastic spoon very
    rough by using very coarse sandpaper
  • Back to the efficiency question. Here is what I think is going on but please all, chime in because I not an expert. The Coanda craft (CC) can be thought of as having two parts: 1.) a ducted fan and 2.) this specially shaped body below the fan. By itself the fan develops thrust (but not lift). From the CFD simulation posted by Jean-Louis (thanks!), the body generates lift, i.e. high velocity air near the surface "sucks" the craft upward, compared with just the ducted fan by itself. So the CC generates thrust and lift were as a fan just generates thrust. Thus I think the CC is more efficient than just a fan by it self.
  • Thanks Jean-Louis for your drawing and simulations I do like your project and find it very interesting. I have
    demonstrated your last experiment before but not in quite so much detail, I also did'nt know it was called
    the Coandra effect so thanks again. However I'm still not sure if the first part of my theory is correct, namely
    the downward force created by say a motor/propellor in a tube, being the same as the downward force
    created by the exact same motor/propellor, using a Colandra arrangement but without the Colandra effect
    having any influence on the respective forces. Regards, Cliff
  • Developer
    Would a textured surface (shark skin) on the main curved surface help with lift & drag as the air flow would tend to stay attached longer? Maybe you could test my theory? But I don't know a source of this skin. Maybe use 80 grit sandpaper cut with a saw tooth pattern [WWWWWWW] to simulate shark shin.
  • Developer
    Hello, if you want to play in your kitchen with the Coanda Effect, I suggest you to conduct this very simple and proof of concept experiment below:

    Regards, Jean-Louis

  • Conda Cars :))
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