Print Settings
Attention
The wings are designed to print with 0.5 width, 0.3 hight and 3 bottom and top layer
If you print thinner, the perimeter of the upper side will not merge with the perimeter of the inner spars.
If you print thicker, the perimeter will not be printed continuesly in one turn.
The print must go as if you print in spiral vase mode. So you reach at least a smooth surface on the upper side.
If needed, you must try with 0.49 or 0.48 width. It depends on which slicer you use.
The second thing is, if you print with less layer hight, the inner spars will not connect the top and the bottom layer. There will be a gap inbetween.

All parts: layer height =0,3mm, width =0.5 mm
wing
1 perimeter, 3 bottom layer, 3 top layer, hollow
wing servo: 3 bottom layer, 3 top layer, hollow
elevon base: 5 bottom layer, spiral vase mode
elevon: 3 bottom layer, spiral vase mode
elevon interface: no bottom layer, spiral vase mode
elevon horn: 10 bottom layer, 60% infill

fuselage
fuselage front: 7 bottom layer, 3 top layer, 40% infill
fuselage middle: 1 bottom layer, 1 top layer, hollow
fuselage back: 3 bottom layer, 3 top layer, 40% infill
fuselage interface: 2 perimeter 0.4 no bottom/top layer, holow
fin: 5 bottom layer, spiral vase mode
fin cap: 2 bottom layer, 40% infill

Update 08/07/2016
I just noticed that the middle wing parts have an offset of 0.7mm to the outer wing.
I deleted the files and upload the modified parts with added "mod"

Update 10/8/2016
Helmut, who also printed the motor sailplane 
was so kind to share his parts of the splitted fuselage with the associated interfaces.
They are splitted in 4 pieces, the biggest part now is 160 mm.
Thank you Helmut.

Update 10/10/2016
I added templates to align the splitted wing parts of the middle section. Print as much as possible of a template, position it diagonal and shorten only the front of it.
Furthermore, they are important to get exactly the same hole spacing for the plug in mounts.

Update Oct 23, 2016
Servo cables
Attention! before gluing the middle wing segments, the openings for the cables must be cut out. If the edges are welded with a soldering iron, the interrupted print structure is connected.
For the opening on the fuselage you can use a the cover frame (cable cover frame)

Update Jan. 18, 2017
Uploaded wing_rear_center_mod2160
At the previous file were lacking three top layers.

Aligning the middle wing segments
Not only the wing profile has to be aligned, but also the hole spacing for the connections must fit exactly.
For both, I uploaded templates:
template center at the root,
template 160 mm at the inner connection
template 320 mm at the outer connection
Print as much of the stencils as possible (diagonal). shorten it only on the front.(netfabb)
If a larger gap occurs (because of shrinking) between the groove and the spring, it must be filled with glue.

Connectors 6 mm carbon tube
The holes for the connections are only parallel:

In the middle, between the wing halves (99 mm in each side, 198 mm total)
In addition, reinforce these tubes with 4 mm carbon tubes glued into the inside!
At the servo segment (50 mm in the middle wing and 37 mm in the outer wing (133 mm total)
At the wing end (29 mm in the wing and 40 mm in the wing end (69 mm total)
The pipes must not be inserted deeper. There the holes bend and break very easily if you go deeper!

All other connectors are not parallel, that means, you have to plug in the tubes one after the other, and see that you can get them out again, if needed. If both pipes are inside, the wings can not be pulled apart!

Between the two middle wing parts I recommend 60 mm deep plugs (120 mm total)
Between the outer wing parts, I recommend 40 mm deep plugs (80 mm total)

The wing end can be left plugged and, for example, secure them with screws.
All other parts have to be glued and not only fasten with strings! (see video)

I will try not to glue the middle plugging, so that the wing remains plugged into two halves.
For this purpose, I want to make the centering blocks under the wings thicker, so that one can turn a screw in each block. Then clamp together these two screws with rubber bands. (see new image)

Specifications
airfoil: KN209838/HM50T10% - twist: -4.5°
wing span: 1510 mm
wing chord: 259.5/195 mm
aerodynamic center: 116 mm (12%)
overall weight: 1250 g
wing weight: 716 g
fuselage weight 146 g
fin weight 12 g
wing area: 34.9 dm²
wing loading: 36 g/dm²
longitudinal stability (Thies) STFs:
motor: Robbe Roxxy BL Outrunner 2834-08
static thrust: 1000 g (3S Lipo)
battery: Turnigy 1800 mAh 3S 40~50C Lipo
motor camber: -4°
side pull: no
propeller: Aeronaut CAM Aeronaut Carbon Classic 10 x 6"