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  • That's really neat.

  • Hi Kristaps,

    I think your synchronized tandem is a great accomplishment and I am sure it has practical applications.

    When I was talking Big Russian Helicopter I was actually talking about MI26:


    You definitely do not want to be in or anywhere near one of these things when things start to go pear shaped.

    In the name of good taste (and common sense) I have not linked a video showing the unfortunate results.

    Those rotor blades carry incredible inertia and they are not easily or quickly stopped by anything.

    Your Big Latvian Tandem is much more practical. :)



  • Hi to everyone,

    This is indeed built by us, guys from UgCS. (

    The aims of this project were:


    1) Learn to create a control system for a non-standard helicopter when there is no room for a crash. In the beginning of the video you saw a bit of modeling – at first we did all the work on the ground in a simulator. As a result, the helicopter is now able to take off, fly a route and then land by itself and we did not have a single crash.


    2) Create a trusted platform for ourselves to work with heavy and expensive payloads. For instance, today, even though the ESC of one of the engines failed, the helicopter was still able to land with just one engine.

    We chose the Pixhawk flight controller because it`s pretty much universal and, more importantly, open source. Actually, the code, analog to ours, is available on github, if anyone is interested.

    We`re not trying to achieve a specific flight time or payload capacity. This heli is able to fly with one 12S battery from Align 800 for about 10 minutes and is most likely able to lift around 10 kg.

    This heli is going to stay in our lab, altough we built it as a part of a larger project for one of our clients.

    Gary – this is not “Big Russian”, it`s “Big Latvian”. We are from Riga, Latvia. We`re calling this heli our “two-headed dragon” :-)

    But, you know, probably the best thing about this helicopter is the sound!

  • coax helicoter is overlapping 100%  

  • If you bolt two of these together you would have an amazing quadcopter. :-)

  • Nice!

  • Cool but why use a tandem instead of a regular single?
  • Hans, sure, it could be done on a petrol motor.

    Non overlapping vs. overlapping, the efficiency comes out about the same, to overlap of about 30-40%.  Some studies suggest that 30% overlap is actually more efficient than non-overlap, but the testing doesn't show this.  The 5% theoretical benefit is lost in the standard deviation. 

    For sure, non-overlapping non-timed rotors would be mechanically simpler.  But the frame would also be much larger.  Keep in mind, that while you may reduce the drivetrain complexity, it still requires a robust frame linking the two rotors. Most of the flight loads from both rotors need to pass through the center section.

    It's almost like building a flying bridge.  What you see in the video may work for gentle flight with no payload.  But doesn't look strong enough for lifting a heavy payload.

    By comparison, a single rotor helicopter, only require a structure strong enough to suspect the load directly under the main shaft, plus the tail rotor structure which is only required to withstand about 10-30% of the main rotor load.

  • great,that's great,It proves that pixhawk  is all about.

  • Can they do this with a petrol engine?

    Wonder what weighs most, a larger framework or system for overlapping the propeller? Non-overlapping will likely have better efficiency of the propellers.
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