That for a long time nobody wrote about the trainers here. So I've decided to share my outgrowth with you.
This article was already ready in drafts during the year but it was not completed before. I suppose that it will be useful for somebody. Because winter is going to finish it's necessary to start flying.
The first instance of the model was raised to the sky at April, 9, 2014. Almost at once I've establish two other aircrafts with taking in account all mishits on the first model. I may list all of them namely: chassis mount and quite a long nose (the battery must be shifted on the rearmost position). Finally 3 aircrafts with various kinds of wings were built in. First wing is V-shaped, second one is swept-back wing and third wing uses twisted airfoil. All wings are interchangeable so all of them may be used with any fuselage.
On the photos we will see all of three models in random order. The basic construction approach is the same for all of them. I suppose everything will be clear for understanding. I'm sorry in advance because some of photos were made in low quality. Please ask your questions if necessary.

We are starting from the fuselage. This is the central part on the photo below. It is consist of two pieces of Styrofoam ceiling tiles, and two wood rails are glued in between. Of course, the rails are optional but they withstand the "carrots" wery well. (Translator's note: "Carrot" is slanguage term and it means the specific kind of crash when the aircraft hits the ground vertically and the result looks like the carrot in the garden :-)) I had three "carrots" and I lost propellers only; everything else remains ok.

I've glued the sidewalls in two steps:

At the chassis mount position I've glued in dense Styrofoam. The sidewalls are reinforced by piece of ceiling tile there.

The motor mount is made on 3 mm plywood. It is reinforced by Styrofoam on the top and bottom.

I've used ceiling tiles in two layers in the battery compartment and under the wing. For all other parts a single layered ceiling tile was used.

This is the bottom part of fuselage. It is absent on the drawing as well as all other parts of the bottom. All of mentioned parts must be manufactured in place (in fact).

The spine is also made in place.

This is the first version.

And this is the second version.

I've glued in sticks from Chupa Chups lollipop as fixing points for chassis.

Now we are about the stabilizer.
For some reason I decided to make full-rotary stabilizer.

The basic approach is described here.
The piece of Chupa Chups stick is put on steel bar (axle) and then the bar is bended in "П" character shape. After that the assembly is glued in the stabilizer but the stick must be able to turn around the axle. The wood element must be adjusted on place and it is glued to Chupa Chups stick. So we made the joint. Finally all is glued to fuselage. It is such a thing! It is more or less easy; at least comparing to classical hanging of stabilizer.
But I've used classical hanging for two other models.

Now we are about the wing
Strictly speaking we are about two wings. First wing is V-shaped and second one is straight but it has twist along airfoil.

The first wing.
Left and right wing panels are manufactured separately. We make the "pencil-box" formed by two ceiling tile bands and we taking in account the thickness of the spar.

The rail (spar) is cut for V-shaping. The wing has 23 mm thickness on root and 5 mm on edges. Stoppers are glued in "pencil-box" so the rail reposes on the bottom wing surface. Ready panels are putted on the rail and glued together.

This piece of Styrofoam is cut exactly on the place in fuselage where the wing is installed. So finally the wing is tightly inserted in the fuselage and fixed by rubber rings. This part is glued like this: Styrofoam piece is partially inserted in fuselage hole (1-2 mm must be visible) and then it is fixed by pins. We lay glue on surface and we lean in the wing at correct position. When the glue cling but not dried completely, we remove pins and extract the assembly, after that the Styrofoam piece is fixed by clothespins.

This overhang must protect the servo in case of fall. Because in my experience no fall was happen on this section of wing this part is optional.
I've glued carbon rails in the back edge of wing to protect surface against creasing by rubber rings.

The second wing has constant thickness along the length.

When the leading edge of wing is completely glued and ready, we are starting trailing edge assembling. We put the wing on flat surface and we make marks, thus with marks we may twist both of panels proportionally.

We lay on glue and wait (please refer to glue user manual). By the way, do you see the part in the middle of wing? It is something like semi-rib for more rigidity, also it strengthens junction and resists to rubber rings. It is used in first wing too.

When everything is ready we may see V-shaping on trailing edge.

Besides the third wing exists. It has straight trailing edge and swept-back leading edge without any V-shaping.
I built all of these wings to check how kind of wing may influence flying characteristics of aircraft. Most of all I like the second wing. The model with this wing is stable in fly, newertheless it allows complex pilotage. The third wing is intended for high-speed flights. And first wing becomes boring soon.

This is how I made the chassis on first model (without plywood).

And what happens with it at the end of season. Repaired (glued) fuselage is the result of "carrot" (the battery has destroyed sidewall).

Just a photos, no comments.

The drawing.

Wing span - 960 mm
Length - 870 mm
Weight: w/o battery - 475 g; with 3S 1000mAh - 565 g; with 3S 1300mAh - 575 g

The motor (not exactly the same but previous one) HobbyKing 2824 Brushless Outrunner 1300KV

Turnigy Multistar 30 Amp BLHeli Multi-rotor Brushless ESC 2-6S V2.0

Turnigy™ TGY-TG9e Eco Micro Servo - Long Wire Version 1.5kg / 0.10sec / 9g

Something like this!

This is the translated version. You can read the original Russian article here.