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Hybrid FPV racer

Posted by Marko Thaler on April 27, 2016 at 2:30am
In Airnamics we wanted to do something just for fun and make an FPV racer that is a cross between a multi rotor and a fixed wing. It opens up completely new performance capabilities because you can use the wing as the main lift device, an air break, or anything in between.
On the other hand we would like to combine classical drone racing with gaming aspects. You would have a limited amount of energy available per lap but would unlock additional energy reserves every single lap for reaching specific goals (e.g. highest top speed, highest continuous g-load, quickest lap time, proximity flying, etc.).
 
The racer is built on top of our UAS development platform but we would consider developing an open source based production version if the market feedback would be favorable.
We would sincerely appreciate your opinion about the system. How interesting do you find it? Any suggestions on how to make it even better? Thanks for sharing!
Tags: fpv, drone racing, fixed wing, hybrid, multi rotor, racer
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  • Marko Thaler May 2, 2016 at 11:54am

    We'll definitely develop a really simple and robust airframe with a snap-on wing. Pylon racers are extremely fragile. We had to quite substantially reinforce the stock wing on the prototype. Also the airfoil is not optimized for speed and wing-load profile of a hybrid.

    I am very reserved about scaling it up to F5D because it is already a monster in terms of performance. I would like to maximize the fun factor not necessarily the ultimate performance, because you would severely limit the number of pilots capable of flying it and additionally increase safety concerns. Because of the forces on the airframe the cost would go up to ridiculous levels. I would like to keep it small and robust (something like 300mm wingspan).

    We'll probably dedicate a page either on our website, here on the forum, or something similar. I'll let you know.

  • Chris Jackson May 2, 2016 at 12:42am

    S400 pylons are pretty small internally, I dont think even a standard 36x36 pixracer board would fit into most, probably with the except of the LP1.1 which is pretty roomy inside. http://www.hjk-speedwings.de/epages/62907075.sf/en_GB/?ObjectPath=/...

    Or scale it up to a full F5D sized model? 

    Definitely go inrunner and a S400 APC pylon prop for forwards propulsion, get a lot more out for what goes in. 

    Keep up the good work, is there anywhere to follow the progress? 

    LP1.1 SpreadTow
    LP1.1 SpreadTow Carbon Gewebe HJK-Speedwings LP 1.1 mit 6 Zylinder Hotliner Setup HJK-Speedwings LP1.1 The LP1.1 is constructe…
  • Marko Thaler May 1, 2016 at 3:00am

    What do you suggest to include in the open source platform?

    • Pixracer Autopilot & power distribution board (for powering all periphery components) integrated into one PCB,
    • slimmed down PX4ESCs that connect directly into the main autopilot board (CAN),
    • simple and robust CF frame on which you fix all the integrated PCBs and the main wing.

    I would suggest to keep the weight and size down as much as possible for safety and robustness reasons. Probably around 300 grams MTOW would be ideal. Something like 1306 motors for vertical propulsion. Your thoughts? Any other suggestions or ideas? Thanks!

  • Chris Jackson April 30, 2016 at 2:17am

    I think im in love! please make this opensource, I went through a bit of a S400 pylon "phase" a few years ago...

    Incredible machine, and piloting, I want one bad.

  • Marko Thaler April 28, 2016 at 5:52am
    John, I completely agree with you! I think the question that was lost in the thread is about adding gaming aspects to the usual FPV track racing (as stated in my initial post). This brings additional strategy layer into play because you have to fly efficiently to preserve energy, but at the same time be aggressive enough to collect additional energy rewards that enable you to be more competitive on the lap times (racing end game). Is this something that would be worth exploring? From the tech side its doable with an additional layer of hardware and software to measure and synchronize everything between all the competitors on the track.
    I believe autopilot performance, as you already stated, is quite comparable but in general there are very big differences in system safety assurance. Autopilot is only one link in the safety chain. For adequate safety you have to, among other things, monitor all system components, compare actual and predicted performance, and handle all the discrepancies adequately. You also have to assure the basic system architecture is redundant / fail-safe. This is where I see the biggest improvement potential in the space. Of curse at the end of the day the pilot holds the ultimate responsability for safe operation since no UAS system can be completely fool proof.
    BTW, the FBW throttle brings a lot to the efficiency front in this hybrid setup. In manual mode you can decrease the efficiency pretty quickly by pushing the vertical motors more than would be needed because of lift generated by the wing. 
  • JB April 28, 2016 at 5:10am

    Hi John. 

    I agree. Pilot skilz are to often overlooked. That's why my first question was how does the control system work.

    In this case it's essentially running a quad controller on a airplane with forward motor, and all attitude control is via the quad motors only.  You can hear the forward motor running most of the time, even during the aerobatic maneuvers, and "transitions" between forward and hover flight are only a consequence of what the forward speed is at that time, as the quad keeps it airborne all the time. This is how I started with my hex pusher with skyfun wings last May.

    BTW a PXH running Copter code it works fine as well, and with alt-hold it's a blast to "drift" around the sky with a pusher hex(Thorax), and even without the wings the hex does +100kmh with just a 300W pusher motor. The proper pylon setup makes it even faster of course which makes this way more awesome though! ;-)

  • Developer
    John Arne Birkeland April 28, 2016 at 12:53am

    I feel the need to point out that what we are seeing in the video is a skilled RC pilot doing maneuvers in manual (basic stabilization only) mode.

    Don't get me wrong, this is a something new and a novel approach that deserves credit.

    But my point is that mature autopilots have now reached a point where performance is pretty much similar, and even more important that in general there is to much focus on the autopilot and to little focus on pilot skills.

  • Marko Thaler April 27, 2016 at 9:02pm

    I've received a couple of questions through other channels and wanted to post the answers here as well. Maybe somebody will find it useful.

    For manual mode any FC for racing quads with suitable firmware could be used to control the hybrid racer. You would just have to use an additional channel for horizontal motor thrust control and show some piloting skills. We haven't made any extensive tests of other FCs and firmwares but all the top selections for FPV racing should do the trick (at least in theory). The only COTS FC we tested was Naze32 with Betaflight from BorisB and it worked. If somebody wants to build a similar setup to ours and starts testing right away, that would probably be a safe starting point. I am sure there are other options out there that are just as good or even better but we haven't explored them. I will also be eager to see what Tridge and the team have been working on with PXH2. Cheers.
    borisbstyle/betaflight
    Open Source Flight Controller Firmware. Contribute to borisbstyle/betaflight development by creating an account on GitHub.
  • Marko Thaler April 27, 2016 at 1:49pm

    Answers to JB's questions 5 and 6:

    • We do not use reverse thrust for added control authority. No need to.
    • In FBW throttle mode the additional lift from the vertical motors/props that are used for attitude control is compensated for with reduced lift on the wing through reduced angle of attack. In manual mode you have to compensate that manually (through thrust reduction or slight pitch down correction).
  • MR60
    Hugues April 27, 2016 at 8:21am

    quite impressive! I love when the plane stops abruptly lifting its nose like a cobra.

This reply was deleted.