A challenge - An autopilot to fit in this




This is the Vladimir models Graphite 2e.  It is a fairly typical skinny, lightweight, efficient fully moulded motor glider.  Despite its 3.1m span there is not much space for anything.




The removable nose section is filled with motor ESC and battery.  It just fits a 36mm diameter motor.

The receiver, rx battery and BEC is mounted somewhere under the wing. 

No room for servos up front, they are mounted in the tail fin. 

There is plenty of space in the hollow wings.  Access to that space is limited to the 4 servo hatches.

The compact UDB2 is now looking like a tight fit at 38*70mm.

I do not own an APM but that is looking like a 40*75mm double decker.  No hope!


Am I expecting too much?  Is this skinny super-model just too needy?

Should I stick to my trusty Cularis with its middle age spread, healthy dose of cellulite (foam) and numerous surgical implants?

If you wish to see more pictures and a video have a look here






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  • Can somebody post the dimensions of the boards. Did search Google and everywhere - nothing came up.

    Thanks for the info!

  • Matt, I'm with a college group that makes UAV gliders. I suggest that you make a new cowl to accommodate the autopilot. 

    Great discussion. We once made our own skylark variant.3692501751?profile=original

  • Just got FedEx with my Graphite 2E today. Trying to do the FPV with Autopilot.

    The way I see how it's could be done is to re-mold the nose section to fit all the equipment in it. At least that was my idea and I am glad I found this discussion.

  • Para, 

    Nice to see your proxima project posting.


    The graphite is not built yet but I have a Kontronik Kira 500-30 to put up front.  Should be 500W off 3 cells and 950W peak of 5 cells.


    I have a Multiplex Cularis flying on a UDB2 plus a servo expander/failsafe.  It is capable of controlling all 6 servos plus ESC.  The trouble is that UDB2 doesnt know how to measure and use airspeed.  Most of the refinements are about trimming the glider airspeed.  UDB2 is getting too old to support many new developments.


    Well refined glider control is going to become popular.  There is a growing number of UAV gliders out there.


    A compact autopilot would help many of us.  There is a small group of us working on a board to board communication system connecting electronics modules together.  This will help to distribute functionality and reduce board size. 


  • This is a great model! Your flight scenario and the model require individual channels for ailerons, preferably also for the  flaps. High performance thermalling means small roll angles and some flaps to stay in the minimum sink range. Do any of the available autopilots allow that? 

    I have a 36mm motor in my Proxima II glider and I have got an APM, IMU, Mediatek GPS and Xbee inside there, but the body is much fatter than on the Graphite. My guess is to use a tiny autopilot and put some stuff in the wings and further back in the fuselage. Since the nose section is removable you may  mount everything with precision in a cylider like arrangement and stick it  all into the fuselage?

  • Moderator

    Me too!  That platform, "my meadowlark" is kind of stuck on finding the easiest part... the project box!  I need it to be long'ish but not wide or expecially tall.  Looking for 8"L X 3" W X 3" T.  (hard combo). Will go with two that fit if I need to, but holding out for one.

  • An airbag!  The "I want" feature that every UAV dreams of.

    It is not going to work for me but I would very much like to see yours working.


  • Moderator
    @Matthew, you should google the skylark II landing videos... VERY COOL, I'll post one when I get home from work.
  • @Brian, That is one of the more elegant UAVs around.  I like it.  Landings are going to be interesting with that bomb hung underneath.  The first thing I thought for building that pod was a plastic coke bottle.


    @Rory, The point of this is to evolve the autopilot to fit the airframe. It is an attempt to not make a compromise to the airframe to fit the autopilot. The Graphite is a highly evolved machine.  It is this shape for a very good reason.  Some history:


    Sometime in the 70's a multi-task RC glider class called F3B was created.  The class demands 3 tasks, speed, duration and distance.  This is the Formula 1 of RC glider sports (most expensive and time consuming)


    In the early 90s? someone decided to put an electric motor on the front of an F3B and F5B was born.

    Competition in these two classes is intense.  Every year new generations of aircraft are built, tuned and tested with the worlds elite pilots and designers. That is hundreds of people evolving a class of aircraft for 40 years.  We can presume that the design is pretty well optimised by now.  The Graphite 2 is based on that optimised technology.

  • Moderator

    @Matthew, the plane I posted is called the "Skylark II" by Elbit Systems.  I'm making my version, called the "Meadowlark " of the plane using square carbon tube and an old Aerobird Extreme main wing (tail will be scratch balsa).  The pod I'm planning is a simple radio shack project box.  Hopefully I can find one that is only about 2.5w x 2.5h x 8-10 (what ever is big enough to hold my electronics (or most) and the battery.  The system for holding the main wing to the fuse will be molded cf/fg, conforming to the wing shape on top and gently down to the boom.  This piece will clamp the wing and boom into position and allow for adjustment of cg/payload.  This mount will serve as a secondary place for electronics. No picks yet, but here's another shot of the Skylark II.



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