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Sunday, 24 March 2019

Foamboard Spitfire Build

AREA17 Foam-board Spitfire (Night Flyer Addition)
Based on The FliteTest Spitfire  https://www.flitetest.com/articles/ft-spitfire-build
Find us on Facebook   AREA17

Tools Required
* Sharp Blade               * Clear tape
* Ball Point Pen            * Optional 10mm x 0.5mm carbon blade
* Hot Glue Gun            * Icy pole sticks
* Set Square

Hardware Required to Finish
* Motor Brushless 2826 1400kv 8x6 prop (looking for 180-200 watts)
* 1500-2200 mah 3s lipo
* 25-30 amp ESC
* 3 Mini servos or 4 with an optional rudder
* CoG on Wing Spar line (65mm from leading edge)
* 4 Extension leads
* TX and min 4 Ch RX
* Control linkages and horns
** Optional carbon blade spar reinforcement (10mm x 0.5mm)


Parts Supplied
* Three  Laser-Cut Foam Board Sheets
* Canopy
* Ply Motor and Battery Box


Type of operations
* Crease Line
   o Use a ballpoint pen to create a groove allowing a bend, Typically used for turtle decks
* Cut Lines
  o Use Blade if necessary to out exterior shapes
* Fold Lines
  o Use a blade to cut through the foam only not the paper backing
* Chamfer Lines 45 deg
  o Leading edge 45 deg both sides to allow the leading edge to fold back
  o Ailerons, Rudder, Elevator 45 deg on one side

Getting Started

Fuselage
Note in some cases we have removed the backing on one side as this will be a night flyer, a standard flyer you can leave the paper on.....

Start with the back Turtle deck:
* run a ballpoint pen down the crease lines to allow for folding. Note: by controlling the angle of the pen you can increase/decrease the groove width. You need a wide "V" shape to enable a smooth folded curve.

* peel the foam off the outside edges, this should just leave the paper. This paper strip acts as a glue tab when gluing the turtle deck to the fuselage. 


Now the front Turtle Deck
*as above run a ballpoint pen down the crease lines to allow for an even fold.

* peel the foam off the outside edges, this should just leave a paper tab.

On to the Fuselage
*pick out the foam to create the fold lines and tabs. We find by removing the backing paper first makes the removal of the foam strip easier. We made a handy machine to remove the strip but it is easy remove the strip by bending and prizing out with your fingers or a tapered icy pole stick.


Note leave the wing section cutouts in place, they get removed later

Now we use the power pod as a guide to hot glue the fuselage sides



*Next is the fuselage former's
 *Use a piece of scrap to separate fuselage sides


Note the led lights on this model mounted inside...

*Next Tailplane and Rudder
 45deg chamfer on tailplane side
Use clear tape as a live hinge
The Rudder control surface is optional, if you elect to use the rudder use the same method to create a control surface.

*Its time for the wings
First up chamfer the leading edge about 60 deg on both the inside edges, keep testing making sure it will fold back on its self without pressure. Use clear tape on the outward side to keep the parts together. * Note you do need to remove a lot of foam to get it to fold back with pinching.

Use a pen to create the two crease lines, followed by a 45deg chamfer on the ailerons, the Ailerons need to operate up and down without pressure, use clear tape as a live hinge on the top.


Prepare the two wing spars,  you can simply fold and hot glue. (Optional if you intend hot dogging a flat carbon blade (10mm x0.5mm) sandwiched between will ensure high G maneuvers are safe.) Note the standard foam-board spar is fine for general aerobatics.

Glue the spars into the wings making sure they align when the wings are mated.

The false trailing edge piece is then hot glued in place, using a pen squash the trailing edge down creating a "V" shape to give the right angle when the wing is folded back.

**Special note: When you are happy the wing folds back on itself without a lot of pressure, we can firstly put hot glue on the top of the spar and fold back aligning the trailing edges. Let the hot glue cool and then run a bead along the trailing edge. Fold over and hold in place until set.





The wing servos can now be mounted with hot glue, mouse the servo leads down the wing exiting just in front of the spar, cut a small relief to exit the wings on the top.

Special note: glue the two sides together allowing for 60-70mm dihedral in total, ie 30-35mm each side. This picture shows the assembled with one wing flat on the bench and the other showing the total dihedral on 70mm


 Use hot glue and clear tape on the outside to join the two wings halves.



The next step is to glue the Wing and Tailplane/Fin in place, turtle decks happen when all flying surfaces are aligned and glued. Note: take your time and make sure all the flying surfaces are aligned before gluing. You can put blocks under the wing to help align the tailplane, use a set square to get the fin and tailplane at 90 deg.



Next up is the rear Turtle deck
Start by putting a dob of glue on the peak of the rear formers, we glue the middle first and let dry, then glue the sides.

Now the front Turtle deck
Glue one side of the back section, let dry then glue the other backside. Repeat for the front section

Fitting the canopy
Trim the back turtle deck flush with the former
Trim the front turtle deck at a slight angle
Make a canopy base out of scrap, glue in place
Add pilot if required
Hot Glue canopy onto the base, back former, and front turtle deck


The motor pod is held in via a 3mm ply plate/tongue at the front and a removable bamboo stick at the rear. You then need the hold the motor/battery box in place with the tongue engaged and drill a hole(s) for the rear bamboo stick. This is done with a long drill or by marking and drilling from each side. The location for the rear bamboo stick should about 150mm from the front of the ply box or about 170mm from the front of the fuselage. The stick should penetrate near the top of the box to ensure the battery is not fouled.
The Battery can be placed inside the pod, or for quick changing can be Velcro-ed on the underside.




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