ASK-13 photos

Pictures in chronological order, best viewed with at least 1280 pixel width screen.

Jig-saw the parts out of plywood. The parts drawings have been glued with water-dissolvable glue, so it can be taken off later.

Wing mounting tubes need to be glued very accurately, so use some pieces of wood to support and guide. Metal epoxy used as glue.

Clamp & glue the front part of the skate to a supporting piece of balsa before putting it in the hull.

Image below.
Note the rigid support bench and the accurate supports for the fuselage ribs. It is very important to have these ribs fixed in the right position and orientation. The bench is made from a pair of iron L-profiles, with an MDF shelf screwed on. Water dissovable glue is used for the temporary connection of ribs and supports. Start with the ribs F4 and F5, since these will be used to fix the wings to.
Also note the 1mm ply platform mounted inside ribs F2 and F4 and resting on the wheel casing. This platform will be used for receiver, batteries and elevator/rudder servos.

Acupuncture, or healing with needles. The skin is glued onto the frame, piece by piece, with balsa glue. You need to let the glue dry thoroughly, or the skin will get off again.

The nose has been roughly sanded into shape, final touch follows when the side skin and the top of the nose is glued on.

As can be seen on the left, the hull is fairly straight. Caution must be taken however, since the tail can still rotate a bit until the sides are glued on. But before that can happen, the Bowden cables need to be placed.

The final fuselage rib F10 is glued on the back. This must be done carefully, by sanding of the backside, in order to get it precisely square to the hull and in parallel with the leading edge. The top block and ribs are mounted, sanded flush and finally the cladding is glued on.

The moving part of the rudder also needs some care, to prevent any twisting. Start with the bottom and leading edges, since thee are thickest and can be pinned to the table to make sure they are in the same plane. Next the top block and finally the trailing edge are glued on. The ribs are cut to fit, and the whole frame is sanded into shape before glueing the balsa skin.

On the left the final result can be seen. The lot needs to be shaped a bit more, but this will be done after mounting the hinges.

Image below.
This is the current state, next step is to build the elevator and mount it onto the fuselage.

The skin is glued onto the elevator frame, held tight with a lot of clamps. The aft edge is made from a thin 1mm balsa strip, where the ribs are glued into small gaps. The skip is glued onto this strip, an sanded into shape after the glue has dried.

The final picture shows the result, after a first layer of shrinking dope. This is before the elevator is split along the main spar, which will divide it into a fixed and a moving part.

The top part of the nose is built up after adding a 1mm ridge around the ply rib.

Layers of 8mm balsa are cut to approximate size, sanded to fit the front of the cockpit and then glued into place.

After a lot more sanding the nose has finally taken the shape it should have, sort of. The photo on the left shows the result, as well as pretty much worn down skin material since the light is shining through...

The attachment point of the wing is glued on, as much as possible perpendicular to the wingtubes. Ultimately, the wing angle is determined by the tubes themselves, but you don't want too wide a slit at the attachment point.

As shown on the left, the wing itself is started. First the bottom cladding is layed out, and the bottom part of the spars glued on. Then the ribs are sanded out of a stack of 2mm balsa, clamped in between two templates.

The ribs 1..5 are made of 2mm plywood, and need to be cut out with a fine jigsaw. Ribs 1..3 stick out on the bottom side, and will push down the local cladding. Therefore these ribs can only be glued-in after the rest of the wing has enough rigidity to be lifted from the bench.

The spar is a box construction, which combines high stiffness with low weight. The top and bottom strips are 2mm thick, and taper from 6mm at the root to 2mm at the tip. These strips are connected with 1.5mm pieces of balsa between the ribs, which in fact provide the stiffness in the length direction.

To the left, an overview is shown of the current status of the left wing. The 1mm top and bottom cladding will also make a box construction, and provide maximum rigidity.

The placement of the wooden dowels in the root of the wing is quite critical. I started with the front one, and found that the back dowel location was off by 2mm. Concluding, the best way to do this is to match the rib R1 with the counter part on the hull, before drilling the holes for the dowels. Only then drill the holes in ribs R2-R5.

Above the wing is shown as it will be carried on the hull.

Left, the same process is shown for the starboard wing. Here the fitting was much better and no correction was neccessary.

Top left, the mounted servo can be seen. Space between ribs was just not sufficient, so a cutout had to be made. The servo rests on a 1.5mm balsa floor, which is flush with the wing bottom. The original wires were cut, and an extension cable is inserted to connect the servo to the receiver.
The aileron still has to be cut out at this stage, but before that the wing cladding and nose will be added.

Top right the bottom view

Left the empty compartment in the starboard wing.

Top left, the finished left wing is shown.

Top right the the first time outside with wings mounted. There's light at the end of the tunnel!

Below follow pictures of the finished bare casco.