Building the wing

The wing is build in two seperate halves first.
When both halves are ready the will be glued together and the center section will be re-enforced with 3 layers of 80gram glascloth.

Required glue:
- medium thick CA (Green ZAP)
- white glue

This description is based on one wing half, you will need to repeat the steps for the other wing. Take care you build a left and right wing !!

Please notice: the balsa ribs are fragile, take care and apply only small force. If a rib does break, use CA

Collect the wing-ribs from the sheet of 2mm balsa sort them on size
and then create two equal stacks of ribs also get the 4mm balsa root-rib.

prepare the ribs: - for all ribs, use a small file to square off the corners where the 3mm ply main spar will be located. - carefully sand the remainders ofthe holding tabs

collect the spars, you will need:
- 1 main spar from 3mm ply
- tappered top and bottom spar from 3mm ply
- leading edge spar 3mm balsa, this is the one with the slots recessed
- aileron spar, 3mm balsa, this is the one with the slots , similar as the mainspar
- trailing edge strip, 1mm ply

Prepare the spars:
- use a small file and square the corners of the slots in the main-spar.

Start building

You will need a complete flat building area of at least 100x40cm. It is usefull to have two or more flat and heavy strips of metal or wood. I use 20x20x3 x 1000mm brass and some lipo packs as weight.
you also need pushdown pins

Take the main spar, and carefully slide the ribs into the slots. No glue is required yet. take care that the top of the wing is flush with the top of the spar. If this does not align you might need to file the corners of the slots a little more.

Take notice that the root-rib has a recessed area at the leading edge. The recces should point to the center of the wing.

The root and tip rib might need a push-pin to hold them in place

Place the main spar on the building surface and weight down the ribs and spar so the building tabs are all on the building board.

Locate the leading-edge balsa spar, put a small amount of white glue in the slots and carefully place the leading-edge on the front of the ribs. Take care the top of the spar aligns with the top of the rib.

place some more weight on the wing and let dry.

take one of the tappered spars, test fit the spar in the top of the ribs. For a good fit, it helps to sand the edges of the spar a little round. If the spar fits flush with the top of the main-spar, remove it. place a drop of glue on each rib place glue on one of the long edges of the tappered spar (the side that will get in contact with the main-spar) place the spar in it's slot and use some clamps to press the tappered spar against the main-spar and let dry.

time to place the trailing edge. The trailing edge needs to be placed in the small and fragile slots on the rear of the ribs. There are two steps that makes this a bit more easy: 1) sand the the front of the leading-edge (the side where the little holes are) a little tappered or round. 2) test fit the trailing edge first on each individual rib. this will clear possible left over material from the CNC cutting.

slide the trailing edge into these small slots. (yes I know this is not that easy)
allign the ribs with the small holes. If satisfied with the fit and position, place a small drop of CA on each rib/leading edge. let dry



Put a small drop of CA into each corner of the main-spar and each rib. Only on the front of the main-spar.
time to place the trailing edge. The trailing edge needs to be placed in the small and fragile slots on the rear of the ribs.
There are two steps that makes this a bit more easy:
1) sand the the front of the leading-edge (the side where the little holes are) a little tappered or round.
2) test fit the trailing edge first on each individual rib. this will clear possible left over material from the CNC cutting.


Sand the frontside of the trailing edge slightly tappered or round. This will help to slide the trailing edge in the small slots at the rear of the ribs.


When the trailing edge is in place, allign the ribs with the holes. Then put a little drop of CA on each rib.


take one tappered spar, this will go on top. Testfit the spar in the slots.


put some white glue on the rib-area where the spar will be placed


put white-glue on one edge of the spar and place the spar in it's slot. Wipe away any access glue.


Use some clamps to press the tappered spar against the main-spar.


Turn over the wing (up-side-down)

repeat the steps for the tappered spar, but now for the bottom.




Locate the balsa aileron spar. Test fit the spar by gently wiggling this one in the wing ribs. If the spar fits in all ribs, remove the spar, put some whit glue on each rib and place back the spar.




Use a sanding block and sand the leading edge flush with the ribs. Take care not to damage the ribs.


Draw a line in the middle of the spar (about 5mm measured from the front of the mainspar), this line will be the rear of the front balsa sheet. From one sheet of balsa cut a part, 81cm long, 70mm on one side, 42 mm on the other side.


Use white glue on the spar, the ribs and the leading edge and press the front wing sheeting against the centre line and weight down. Use pins to bend the sheet to match the leading edge. Remove access glue from the main-spar area as this will cause trouble for the rear sheeting.


Use a new sheet of 1.5mm balsa together with the remaining balsa from the front wing cover. Create a piece of balsa large enough to cover the rear of the wing. Then use white glue on all the contact area's and place the rear wing sheeting with weights and/or pins and let the wing dry on the building board.

Work on the bottom of the wing


Important: there a several things that needs to be done before the bottom sheting can be glued
Up to the moment that the bottom sheetings is placed the wing can warp. So take care to keep the wing flat.


  • Remove the wing from the building board and clean the building board from all dust, drops of glue etc.



  • Cut a strip of 4mm balsa, this will be used as support-spar for the trailing edge. The strip needs to be 81cm long, 17mm on the tip and 9mm on the root.
  • Turn over the wing, place the support spar under the leading edge and use some pins to hold it there.



  • double up the area on the rootrib where he wing hold-down bold will be.



  • double up the root rib in the area where the recessed area is.



  • sand or cut the building tabs from the ribs, also sand the notches/tabs from the main-spar.
  • Sand the leading edge in shape with the ribs



  • mark the aileron area by drilling a 3mm hole in the corner of the aileron spar and the outside of the rib.
    In the picture I drilled the hole one rib to far to the tip. The hole should be one rib more to the root-rib
  • at the tip, mark the rear of the aileron spar so we can draw a line later on.



  • place the servo cable



  • Important step
    Time to glue to nose-sheeting. When this is glued and dry, the wing will get most of it's warp-resistence.
    Make sure the support-spar is in place, weight down the rear of the wing. Then glue the nose-sheeting in place using weights and pins



  • When the nose sheeting is dry, the rear sheeting can be glued in the same way as was done at the top of the wing.
    Make sure you keep the support spar in place.

  • sand the sheeting flush with the root-rib, the tip rib, the leading edge and the trailing edge.



  • after sanding the leading-edge flat, add a strip of 4mm thick balsa.
    I used two layers of 2mm balsa scrap



  • glue the 3mm-tip-rib in place, taking care that the rear-end of the rip alligns with the 1mm-ply that is now sandwiched in the trailing-edge
  • Sand the sheeting on top and bottom of the trailing-edge, take your time. You should end up with a 1mm thick TE

  • Roughly sand the leading-edge into shape, the final sanding will be done when the wingtip is glued and aileron-seperated



  • glue the wing-tip (the stack of layers of balsa/ply/balsa/balsa) in place. Take care the 3mm ply layer is alligned with the 1mm TE

  • sand the wingtip flush with the wing. Also roughly sand the wing.



  • roughly place the servo frame on the wing, then cut a small hole first (see red-square)



  • Then work toward the front and then to the root-rib to find the bottom-left corner (as referenced to this image). Place the servo frame in this corner, draw the outside of the frame and cut out the square.



  • Glue the servo frame in place, take care it is flush with the wing sheeting




  • You should end up like this, two beautiful handbuild wings, well doneNext step, cut out the ailerons



  • On the top of the wing, you should already have the reference line from the 3mm hole to the tip, this is the rear of the aileron spar.
    Now draw a 90degrees line to the trailing edge, starting in the corner with the hole. And repeat at the tip, about 1 cm from 3 ply tip-rib. Then draw the same lines but 3 mm to the inside



  • Repeat at the bottom, make sure the lines at the TE allign.
    The line parallel to the aileron spar should now be 6mm



  • Use a scroll-saw to carefully cut the sides of the aileron. I use the scroll-saw only for cutting the 1mm ply, the rest is done with a scalpel



  • use a scalpel to cut trough the sheeting in the middle of the two lines parallel to the aileron spar. Repeat at the bottom
    Then use a scroll-saw to cut the ribs



  • You should now have the aileron and wing seperated. Time to clean up the mess



  • Sand the sheeting flush with the aileron spar. Try to make this as straight as possible



  • if you not already did this, but now it's time to glue some re-enforcement in place that will hold the aileron-horn. Just two layers of 3mm, slightly tappered is enough



  • Then glue in place in the opposite area of the servo-hatch.



  • cut the top of the aileron sheeting on the 3mm line, and the bottom on the 6mm line. Then place the hingeline of the aileron on a flat piece of sandpaper and then sand the aileron on the hinge line flat, The hinge line will be angled.
    See also a couple of pictures further on.



  • Cover the sides of the aileron with 1.5mm balsa
    Glue a wide strip of 3mm balsa to the hinge-line, take care you do not warp or bend the aileron



  • After sanding, the aileron should look like this, ready to use oracover-hinge which we will do when the wing is joined.



  • Wings ready to be joined. Take some time to check the leading and trailing edge. Then sand the wing with grid 800 as smooth as you can, remove the sanding dust with a sticky towel.

  • Next step: Joining the wings