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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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  • JB April 27, 2016 at 8:06am

    Thanks again Marko. I sent you a PM.

    5. Are you also using reverse thrust on the quad for "control authority"?

    6. Do you suffer from any negative affects from autorotation of the quad props at speed? ie always climbs?

  • Marko Thaler April 27, 2016 at 7:13am

    A very quick answer - I'll post a more detailed one later if needed:

    1. There are no active control surfaces on the wings - the motor arms are mounted over the factory cut aileron surfaces so you can not move them even if you would put a servo in.
    2. I would have to check the airfoil that is used on Sokol racer (you need calculated polar diagram for the airfoil), but based on the aerodynamic response I would assume around 1.4kg would be doable, but on the limit. We used COTS ESC's and haven't logged the current draw. I would need to calculate it. You get around 2.5 minutes of flight time in full attack acro mode (31A average current draw).
    3. Yes - in the low speed setup.
    4. Agree.
    5. Yes and to get optimal control authority. Second answer - not always.
  • JB April 27, 2016 at 6:40am

    Thanks for the detailed answers. Just a few more if you have the time:

    1. Are you really using no control surfaces on the wings? So you're flying with quad motor attitude control only? Sweet! Reminds me of when I started with my pusher prop hex! :-)
    2. What speed do you need to go for 1.4kg on that airframe? What roughly is the amp draw in max forward and normal hover?
    3. Lol we're using the Cobras as well but with CF 6x4.5, but on 1.8kg airframe...they're awesome for Power/weight. Are you using them on both the quad and horizontal motors?
    4. Yaw control: Our frame is carrying 8000mAh 4S for forward range (60km@100kmh), is larger and therefore a bigger moment. Your smaller/lighter frame is likely the reason for better yaw then. V-tail quad will help I think. Also a asymmetric motor layout could make for a cleaner profile.
    5. In the video you have the forward quad motors inverted. Is this to keep the wing aerodynamics clean? Also do you use ESC brake/regen?

    Regards JB

  • Marko Thaler April 27, 2016 at 5:50am
    The answers to your questions:
    • There are no movable control surfaces on the racer. If you do not need extreme dynamics / torque vectoring, movable control surfaces in horizontal flight are significantly more efficient.
    • Racer was in manual mode on the video, but based on the architecture we use, adding autonomy is relatively straightforward.
    • Airframe donor in the video: Sokol 28" speed 400 pylon racer (MTOW: in the video around 750g, could probably go up to 1.4kg, but the airfoil isn’t really optimized for this kind of wing-load, you would have to go really fast to be “efficient").
    • We use our proprietary and redundant autopilot with our own code base - developed with Airnamics Simulation Environment and Airnamics Electronics Suite (more info can be found on our services page).
    • Basic propulsion setup: LiPo 4S, 1300mAh; Cobra motor CM2206/2100 with some 5 x 4.5 x 3 props, its good for around 140 km/h, for really high-speed flying the horizontal thrust motor and prop have to be more speed optimized.
    • Control setup: two options - direct forward motor control on a separate channel or FBW. In FBW case autopilot measures the indicated airspeed and angle of attack. Based on the airfoil used and calculated polars it estimates the generated lift. It than throttles the vertical thrust motors up or down based on required lift at any point in time.
    • Secret sauce about the yaw control: I don’t know about that, we always had such yaw control. You just have to be careful that electronic heading lock (yaw control) is not counterproductive to "aerodynamic heading” produced by the tail in fast forward flight. In a classic PID yaw controller the integral part can get you in trouble in fast forward flight.
    Thank you all for your kind words. If you have any additional questions or I have missed something, please let me know. Thanks!
  • Developer
    Andrew Tridgell April 27, 2016 at 5:19am

    wonderful! This really sets the benchmark for aerobatic quadplanes

  • Maxime C April 27, 2016 at 5:14am

    I would be a hobbyist customer for sure :)

  • JB April 27, 2016 at 5:00am

    I've watched the video at least ten times now...and it looks better every time! ;-)

    1) If you want to open source the platform I'd say PXH/PX4 is the way to go. (PXH2 coming soon too) I'm not sure if you know but Tridge has been working very hard on the quadplane code and it works well. Do you have autonomous flight as well, or only manual?

    2) You raise the age old question of the "business case for open source" conundrum! It's not that easy to make a profitable business out of any technology, sharing that technology through making it open source, makes it even harder, because the IP that has value is compromised. Regardless, there are some potential customers in this space, that would fund the development of the platform, as a sport, to promote their drink brand....PM me for more.

  • Marko Thaler April 27, 2016 at 4:41am

    Thanks for the compliments! Our startup is in a funny situation - all the IP was initially developed for the Airnamics R5 UAS. Because of lagging legislation for such a high-performance UAS (60kg MTOM), we put the R5 program on hold (end of 2013). A spin-off IP from that program was our UAS development platform. Based on that we started offering custom development services. These services enable an extremely fast custom UAS / robotics system development (initial proof of concept prototype for the C1 cable camera motion system took us 5 weeks with 3 engineers, the FPV racer prototype in the video took about 3 weeks with 2 engineers to develop).

    There are two questions:
    1.) What if we open source the hybrid racer platform and integrate it with PIXHAWK / PX4?
    2.) We know our UAS development platform is very valuable, but how can we maximize its usefulness? Open sourcing the complete platform would probably be great for the community, but we would have to show our investors an economically viable business model at the same time. If you guys have any suggestions on how to do that, I am all open...
    I'll answer all the technical questions in the next comment.
    R5
    Imagine you can move freely through space. Gravity is no longer an obstacle. You can take a look at the world from any position and angle you ever w…
  • Moderator
    Gary Mortimer April 27, 2016 at 4:38am

    Ohh F5D outstanding effort.

  • JB April 27, 2016 at 4:27am

    Marko that is just "plane" AWESOME! :-D

    And I thought I was "sophisticated" with our quadplane setup...geez!

    You have exactly the type of performance I'm looking for and have always conceived being possible with a quadplane. The trick is to get the balance of performance of each the quad and the plane side, and use each components strengths to assist the other in flight. For example use the quad as the "air based airport" to get the plane up to speed without the "runway" and the plane and forward motor to overcome the inefficiencies of quad forward flight, along with flaring in flight to airbrake etc.

    Your demonstration is what I'm hoping to achieve, in a much more boring and mundane fashion (!), with the current master version of APMPlane/Quadplane, that also uses forward motor thrust instead of forward quad pitch. Obviously I'd fully support going open source, and have discussed the aspects of quadplane FPV racing elsewhere here on the site before, with obsessive passion. Let me know if I can help in anyway!

    The most immediate questions that come to mind:

    • MTOW and airframe used (Some sort of Pylon?)
    • Autopilot and code used (Please be PXH compatible!)
    • Propulsion setup
    • Control Setup (separate forward motor throttle or FBW?)

    I also note that you have massive yaw control which I have not yet seen on a quadplane before, even without a quad v-tail config. What's your secret sauce? ;-)

    Regards JB

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