Self-built flying wing


One of the glass fibre arms of my quad shattered after repeated hard landings on a hard-wood floor, so I have some carbon fibre replacement arms on order. Meanwhile I thought it would be fun to experiment with foam cutting and trying to build a plane from scratch. With inspiration from MyGeekShow I decided to build a flying wing design using XPS insulating foam. One of the advantages of living in the cold north is that thick foam mats (6 cm) is widely available, so there is no need to glue plates together to get the required wing thickness.

The wings were cut using a 26SWG nichrome wire, with a 7 A 12V ATX power supply. The wire didn't get quite hot enough, so the cutting was very slow and I was worried that the uneven progress from tip to root would ruin the airfoil, but I think it turned out pretty nice. I designed my own airfoil with a flat bottom, quite similar to Clark-Y but I made it much thicker because I was worried about the rigidity of the tips of the wings. Turns out that isn't an issue, and I would probably go for a thinner air foil such as MH32 if I should do this again. I would also make the root chord longer to get more wing area. I have more foam laying around, and I'm waiting for a 32SWG nichrome wire which should cut nicer, so we'll see...

In the centre I added a rectangular piece of XPS which i rounded at the tip. I also cut out compartments for battery, receiver and speed controller, and found a nice way to mount the motor. The motor is pointed straight back, not slanted upwards like I see on many models, and I wonder if that is something I need to change. 

3689477132?profile=originalThe wing span is 123 cm (about 48 inches), and the take-off weight is 450 grams. The center of gravity is calculated using the flying wing CG calculator, and if I was to expand the battery compartment to accomodate a larger battery, the CG would not be affected very much.

This is my absolute first attempt at foam cutting and plane building, and I'm quite happy with the outcome. Of course I still don't know if it will actually fly... If it does, and has some lift to it, I might install the APM and a camera - but my gut feeling is that it will be too small for that, and I do have a Bixler kit on order for that purpose.

Parts list:

  • One 6 cm thick XPS foam mat
  • Foam safe glue
  • One glass fibre rod 
  • Two HS-55 servos for ailerons
  • Two aileron control horns and aileron rods
  • One Nippy Black 0808/98 motor
  • Propeller (haven't decided on the right one yet, pictured is a 8x6 RAM)
  • 1300 mAh Lipo
  • Turnigy 8 ch receiver
  • Skywalker 20A ESC

Bottom side (yes, the antenna is too close to the ESC):


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  • Moderator

    @CrashPilot1000 - Delta planes turn by using a mixture of aileron and elevator functions.  When the pilot is flying straight and level and pulls front or back on the elevator control, the plane will move both elevons in the same corresponding direction causing the planes nose to (pitch) pull up to the sky or down toward the ground (just like a conventional tail).  Back at the straight and level flight, if the pilot wants to bank to the left they move (roll) the aileron control to the left, mixing in the radio happens and the elevons on the plane move like this; the left elevon moves up causing drag on the top of the wing which is pushed downward, at the same time the right elevon moves downward causing drag on the bottom of the wing which causes the wing to be pushed upward.

    Let's say that the plane is in about a 45deg bank, the plane may begin to actually turn or move to the left from it's previous straight flight, it may also begin to nose down, but it could also just remain in a straight flight but in a 45deg angle, this depends upon the shape of the plane and it's characteristics.  If mixing in the radio is configured to give up elevator during turns then it will move to stay level or begin to turn depending upon how much UP is mixed in.  To give a sharp turn the pilot pulls back on the elevator control and snaps into a fast turn.  If you can visualize the straight and level UP elevator movement, the turn is exactly the same thing but because the plane is at a 45deg angle the movement is to the left and not straight up.  

    Some deltas actually have Rudders so they have some "Yaw" motion.

    There is more to it, but in a nutshell...

  • I can produce wings up to 110 cm from the foam blocks I have available, so a wingspan of 220 cm + midsection is possible... I will have to wait for the 32SWG nichrome wire to cut that kind of length with the power supplies I have available. The extruded polystyrene bluefoam is brittle, but I don't think the expanded type is any better - although a little lighter.

  • And bluefoam is somewhat brittle, it breaks easily around motormount

  • It's GoPro Hero, very nice camera, if you can stand fisheye effect ;P

    I think it should be even larger than 140cm, maybe 160-180cm and specialized flying wing airfoil (quite thick, more space to equipments), 500W+ motor. Ritewing II like. In calm air not easy to launch, maybe front side of wing technique throw. Earlier I had Multiplex Xeno (120cm), and it gets quite heavy soon, when you put all load on it.

  • Tero, that is a nice wing! What camera was used for this video? My next project is to build a larger plane with more wingspan, I want something that flies well at slow speed, and with enough carry capacity to handle full autopilot and fpv setup.
  • I have something similar:

    140cm span, 10x6 prop, HK Donkey ST3007-1100kv,40A ESC, Rhino 3700mAh 3s,

    about 1kg, little bit underpowered. Airfoil NACA 2412 / 0012. 

    At the beginning of the video you see that plane with full size elevons and depron winglets (changed to EPP lately).

    I have some nose up behaviour, when applying throttle, motor is directed also straight 

  • Moderator

    Get yourself a proper electric prop performance will improve, an APC thin of some sort. Add some fins as well you will need them.

  • The ESC on the bottom just fits nicely with the length of the wires and the CG. I might recess it more and add some padding, but I have a few of these ESC's around so I'm not too concerned about it. 

    It may be slightly underpowered, haven't flown it yet. I'm waiting for the mailman to bring some bullet connectors, none of the local hobby shops have then in stock. The motor was just something I had at hand right now. With a larger motor and battery the CG should stay the same. The weight is 450 grams.

  • Why put the ESC on the bottom? I don't think it will last long there.

    Have you test flown yet? Prop should be ok, the only specs I could find are here:

    How much does it weigh? I get the sense that it could be under powered.

    ÜBERALL Model
  • Great tips, thank you! I had initially limited the range of the aileron servos on the radio, but placing the rods like you say will of course allow full movement and resolution of the servo and should be smoother.

    SaadTiwana: That is clear packaging tape! :-)

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