Crazy-3D an extreme control depron plane. 173 grams of fun for indoor and out.
Oct 13 2011 by FaTe
Reference URL
I wanted a smaller 3D model I could practise 3D indoors both in sport halls or even the bedroom! I used my program PlaneDesigner to create the dimensions of the model and to configure center of gravity (COG), check out the specifications:
  • Wingspan: 60CM / 600MM / 23.62 inches
  • Fuselage length (including tail): 45CM / 450MM / 17.72 inches
  • Tail-span: 225MM / 22.5CM / 8.86 inches
  • Tail vertical height: 78MM / 7.8CM / 3.54 inches
  • A2204-14 brushless out-runner motor, 1450KV, 19 grams
  • Turnigy Plush 12A-E Brushless Speed Controller (Pulsar series)
  • 8*6 and 8*4 Electric flight propellers.
  • Weight without battery: 137 grams
  • Weight with Rhino 2S 610mAh 7.4 Li-po: 173 grams (Flying weight)

You can download the design plan file above,
You will require PlaneDesigner to open the file.

First the video of it's Maiden flight at MVC Pegasus 13th October 2011.

The build:

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Here is the design export from PlaneDesigner for all the critical dimensions. I kept the fuselage height as high as possible which allows for low and slow knife-edge. Remember the fuselage acts as surface area when in knife-edge. HobbyKing strip lights powered on 7.4V (Thank you / Dank u Bjoorn for the resistor change over , there tiny!). The wing and tail cut out, I only had 1/2 sheet of Depron left (Sheet was 99CM * 60CM). Now the fuselage which you can see (12CM) is pretty chunky.

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I use 3MM/1MM/1000MM Carbon Fibre strip to re-enforce the wing and tail by place it in on it's side, while normally it can be bent sideways it will not bend when placed on its side. I first used UHU por to bond the strip in the wing, when dry I used spots of Beli-Zell glue at each end of the rod and in the middle. I have seen many methods for engine mounting over the years but most involve a disk firewall mount (normally plywood) which prevents free passing air through the engine. I prefer a plywood cross mount, this motor has mount holes as part of the case so it's better still. Fixing the mount with UHU glue to just keep it in place use Beli-Zell glue all around the mount sides on the Depron also. Use a little extra on the cross area in the middle. As Beli-Zell expands you can flatten it after about 2 hours when its still damp inside and will keep the shape. Bjoorn showed me a little trick for control rods. Normally on light models like this there is a straight rod and it must be perfect in length otherwise the control flap will be out of position. Instead using carbon fibre as the primary rod I attached metal rod ends by using electrical heat-shrink pipe and a bit of CA glue. The rod is bent with a "V" in line, this allows me to crimp or expand the "V" shape to adjust the rod length perfectly. For decoration I got stoned and went a bit crazy with disk marker pens lol. My club MVC Pegasus decals are simply printed on paper and UHU por glued in place. The are 2 on each wing (top and bottom).

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Landing gear is important to me for most tricks I like. Carbon fibre tubes (4MM diameter) both 20CM in length crossed on the COG line, each end starts at the wing. The weight of the rods was 4 grams. Most people make cheap Depron wheels or use servo wheels which all work fine but I had these from an old model and at only 4 grams I couldn't resist (35MM diameter). Piano wire was used make axles, using electrical heat-shrink pipe again to attach the axles in place with CA glue on each end. To create "hubs" to stop the wheel coming off just use heat-shrink pipe right up against the wheel but not tight it should free-wheel. The HobbyKing Lights I bend over double so there are 3 LEDs on each fuselage side. By making a slit in the depron above the wing I could slide them through. This is an out of focus shot I quite like.

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I love my Sony SLR camera for this kind of shot, after some fiddling with shutter time and such I got this picture. The picture shows exactly how bright it looks to me in real life. Hinges where made using medical plaster tape, the kind of stuff they use on bandages to keep them in place etc. Very light and strong. :) I wanted the radio receiver at the back for center of gravity, the way I calculated this design the battery at the front when right against the front is tiny nose heavy, then it can be positioned back up to 5CM which allows perfect COG or tail heavy for harrier practising or small space flying.

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I emulated a little of the cell pattern structure from the FaTedev.com banner under the wing. Looks a bit odd but in flight there's nothing like big blurs of colour when rolling super fast lol. The servos are 5 grams each, note the rudder/elevator servos are right at the back of the fuselage for very little to no torque loss on the control line resulting in extreme responsiveness. The rudder/elevator servos mounted in place in the rear tail, the aileron servo inverted so the control rods are on top of the wing not below it. The control horns are PCB board cut with scissors.

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More pin-line tape to give some orientation indicators, all servos and BEC line plugged into the Futaba fasst receiver. Note how much Beli-Zell was used on the different stress points, it's not what you would call lots and yet it's very very strong. My Carbon Fibre rod strut across the wing is exactly on the COG line with the landing gear rods directly in front. Most hinge tape when on a surface without a control in only hang a little yet with the surgical tape it totally hangs. Now you can see the battery in place on velcro strips, again it can move up to 5CM backwards to adjust COG.

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The finished product weighing in at just 173 grams! Can see the maximum throw (movement) on the control surfaces which is lots and lots hehe. Now hanging on the wall ready for flight whenever I choose :)

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