DM-165 Dalotel (Depron)

Introduction

The Dalotel DM-165 is a French aerobatics aircraft of the 60's, designed by Michel Dalotel. It is a two-seater tandem and low wing. The full-size airplane unfortunately did not have the expected success despite interesting performances. It is in RC that the Dalotel will be popular, especially thanks to Hanno Prettner, who won an aerobatic competition in Las Vegas with a model of this airplane in 1978.

For my third article on this site, I propose to you this small Dalotel of 1 m wingspan built in depron, easy and fast to build, for a nice and slow aerobatic flight.

Specs

• Wingspan : 1000 mm
• Lenght : 800 mm
• Weight : environ 500 gr
• Center of gravity : between 85 to 90 mm from the leading edge at the root.

Equipments and materials :

In order to build this Dalotel, you will need :

• 3 mm depron
• 6 mm depron
• 5 mm plywood
• 1 mm aluminum for the junction wing spar
• Transparent plastic for the canopy
• Epoxy glue
• Hot glue
• Cynaoacrylate glue

• Motor : 1000 kV 22 mm (https://hobbyking.com/fr_fr/turnigy-2213-20turn-1050kv-19a-outrunner.html)
• ESC 25A (https://hobbyking.com/fr_fr/turnigy-plush-25amp-speed-controller.html)
• Propeller 8*4 APC
• Battery3S 1000-1300 mAh
• 4 servos 9gr (https://hobbyking.com/fr_fr/turnigytm-tg9e-eco-micro-servo-1-5kg-0-10sec-9g.html)

The build

The goal when I drew this plan, was to make a Dalotel easy and quick to build. I knew that imposing a 1-meter wingspan and a foam lightweight construction would make it possible to re-use much of the material available in the workshop drawers. Even if you buy everything you need, you get by for less than 60 € the complete plane, which remains honest.

The plan is of course available for download on this page, it consists of 3 PDF files:

• The first shows all the parts making up the fuselage
• The second one allows to see in detail the assembly of the fuselage
• The third contains all parts for the right half-wing, as well as views of the assembly and the wing spar.

Fuselage details

Fuselage assembly

Wing

Tip : You can print the plan in multiple A4 pages by selecting the "poster" option in the print window.

Begin by cutting all the pieces, the materials and the quantity are indicated on the plan (note that the lines in tiled points are lines of folds). Do not immediately cut the vents and the airfoils on the sidewalls F2, because this may weaken them during the assembly.

The fuselage

We'll use the piece F1 as a basis for building the fuselage. The sides F2 are slightly fold at the dotted lines to match the shape of F1. To easily fold depron, use a skewer for example and crush the fold line (as if you wanted to cut it). The depron thus crushed will be easier to fold, but do not go too fast when folding, at the risk of hearing an unfortunate "clack" ... And of course, be careful to make a right side and a left, do not twice the same! (It may seem obvious, but in the action, we quickly make this kind of small error). Then glue the sides on F1 like this:

By checking that the pieces are squares between them during the drying of the adhesive (Hot glue or cyano for depron). Then glue the frames C1 and C2 inside. We will now stick the motor support, cut in 5 mm plywood, and drilled according to the fixing of the engine that you will have chosen. It is bonded with epoxy 5 min between the two sides F2 and on the front of F1. S2 depron reinforcements are also glued with epoxy. I do not have an anti-torque angle on the motor support, these can be adjusted by adding washers between the engine and the support, for me I did not have any worries by putting everything at 0 °.

Let’s pause the inside of the fuselage to do its top.

Glue the different formwork supports from S5 to S9, respecting their position indicated on the view of the assembled fuselage (here too, hot glue or cyano).

The part H1 is the front formwork (on S7 and S5), and H4 is for the back (on S8 and S9), with all the fold lines corresponding to the interlayers of the full-size plane. These two pieces must be cut in the direction of extrusion of the depron (refer to the green line) in order to be able to curve them without breaking. Do not hesitate to check the adjustments several times before gluing. I also advise you not to try to glue the whole piece in one go if you use a quick glue, glue one side then the other for example, or the top and then sides.

Then come the empennage. Begin by glue together the two fixed parts E1 and E3, part E5 serves to raise the stabilizer. There are two possibilities for installing the horizontal moving parts: either you connect the two pieces E4 with a U of steel rod or a piece of wood, or the two flaps are driven separately. In the first case, it will be necessary to make a hole in the vertical stabilizer, and in the second case the control rod will separate in two (with a small domino) in the fuselage.

The articulation can be done with Blenderm or hinges inserted in the thickness of the depron, according to your preferences.

We will again turn the fuselage to finish the lower part, I advise you at this stage to make a small support in polystyrene to not damage the stabilizer or the future canopy when working on the underside, or when mounting the wings on the airfield.

Attach the motor if it's not already done, and connect its ESC and check its direction of rotation (reverse two of the three power cables of the motor if it does not turn in the right direction). Route the battery and receiver power cables through the C1 frame, then close the front of the fuselage with the H2 part.

Then install the servomotors and the control rods that pass through the second frame C2. Once this is done and the neutrals set, you can close the fuselage with part F3.

The 2 H3 parts are patterns in order to do the two large side intakes, hood features of the Dalotel. Before sticking them to the fuselage, consider cutting a hole in the sidewall for aeration of the ESC.

The wing

Let's put the fuselage aside to now do the wing.

It’s built in two half-wings, which are then glued together with a dihedral of 4 °.

Glue together the two spars to make only one of 12 mm thick, then glue it to the intrados, with the top side at the root.

The intrados is then chamfered at the leading edge, as well as the extrados in 3 mm (use a cutter with a new blade and finish with abrasive paper).

Then glue the reinforcement to the trailing edge, then chamfer the entire width with abrasive paper.

We will now glue the extrados, but before that, bend it slightly by rubbing it on the edge of a table or on your thighs, it will facilitate the bonding.

Glue a strip of tape to the leading edge, on the underside of the intrados, so that it extends half the width. On this half that exceeds, come to paste the extrados. Make sure the tape is correctly glued over the entire length before proceeding the next step.

Before definitely closing your half wing, you must first glue its servo of aileron with its arm which protrudes to the intrados, as well as the reinforcement of the landing gear if you have chosen to put one.

Now glued the leading edge, the top of the spar and the trailing edge and finally fold the extrados, keeping the trailing edge with masses during drying. I have said masses, not clamps as I sometimes see, and let dry on a flat surface, to avoid twisting. Repeat these steps for the opposite half-wing.

As long as the half-wings are not yet assembled together, take the opportunity to redraw the contour of the airfoil at the root on the fuselage, respecting the height (between the underside and bottom of the fuselage) indicated and then cut it.

Cut the wing junction spar in a 1mm aluminum sheet using a shear, then bend it in the center. Then stick with epoxy on the spar of one of the half-wings (in the right direction), then glued the protruding half and the root section in order to glue the two half wings together. The two cables of the servos must go through the extrados, passing by a slot that you will have cut out before. Now reinforce the junction between the two half wings with a strip of tape.

We now proceed to install the wing for the first time, for this insert the wing in the fuselage until it is centered (do not worry for the servo cables, it will pass by forcing a little ;) ). Then check that everything is centered with a measuring tape as well as the parallelism between the wing and the empennage, then stick only the intrados to the fuselage by inserting cyano depron between the two. All you have to do now is cut the underside of the fuselage just in front of and just behind the wing, to get a removable wing.

For the fixation of the wing there is two choices available : You can use a classic fixation with rubberbands. Alternatively, use screw and nut using the part S3 glued on 6 mm depron, all glued with epoxy. In the second case, you will also need to put a centering pin in a round of wood or carbon tube of kite for example.

We begin to see the end! Cut the ailerons in the trailing edge, then chamfer them on both sides before installing your preferred hinges (3 per aileron is sufficient). Finally install the control rods as well as the horns which can be cut out in a phone card for example.

Finishing

At this stage, the plane is already ready the maiden, but a Dalotel without canopy and without paint is not really "alive".

For the painting, I used Liquitex brand yellow and black acrylic bombs. And for the black bands, they are made using a Posca felt (it is a paint felt, I think it exists only in Europe) and a plastic ruler turned over to avoid the burrs .

The registrations and other details were cut in self-adhesive paper for printer.

I chose for my part the livery of the only full size Dalotel, with its second registration to change a little of the classic "F-PPZE".

The canopy is made in three panels cut either in transparent bottles of  soda or in a guard page sheet and glued with cyano on the fuselage. Each panel is then connected with a strip of plastic or tape and the outline is then painted with a brush.

Et voilà ! The Dalotel is now ready to go into its element!

The flight

Aligned on the threshold of the runway, the Dalotel seems to expect only one thing, to go!

We put the "gases" gradually, and the Dalotel very little loaded to the dm² takes off alone after 5 - 6 meters or less, it takes a more than reasonable climb slope. It is the moment to make its first turn, one feels then a slight adverse yaw, which can be easily countered with the rudder or by programming a differential on the radio. After 2-3 strokes of trim to make it fly straight, it's time to go down for the camera (the video is available at the bottom of the page) the low pass in front of you are a treat, whether on the belly, In touch and go, slipping or even upside down, with fairly little correction to the elevator despite the simple convex airfoil.

After the low pass, one goes on a vertical climb to try the stall turn, that passes very easily thanks to the very effective rudder. The barrels are quite slow and require to compensate a little with the rudder and the elevator so that it remains well in the axis. The loopings, immelmanns and other split S are only a formality for the Dalotel, but always slow and realistic.

After 6 min flight with a battery of 1000 mAh, it is time to land. The Dalotel, again very light, tends to lengthen a bit and want to take off at the slightest gust of wind, but it is not vicious and will accept to pose gently by insisting a little.

Conclusion

In conclusion, I think I can say that I have reached my goal of designing a small Dalotel easy and fast to build, perfect in 2nd or maybe 3rd model, hoping that this article will make you want to build one , And who knows may be that this plan will allow a greater number to discover this legend of French civil aviation ...

And again sorry for my bad english.