ARKANJ

 

Arkanj is a high performance sailplane intended mainly for competition F3F and performance sloping. Its profile was especially conceived for the use of camber flap, a very little adjustment in camber changes the flight plan completely. It is necessary at the time construction to set the model up with the least amount of play in the control system.

To be able to exploit all the conditions it is essential to be able to ballast. The ballast tube and weights are an option and are recomended for flying in all conditions.

Arkanj was especially conceived for the 4 axes. I.e. that its control surfaces (2 ailerons which bends down at the same time as the flap) are very effective. This configuration also makes it possible to benefit from crow airbrakes (the 2 ailerons which rise and the flap bends down at the same time) very effective. The radio installation uses 2 servos for the ailerons (JR DS368 or similar), 2 Servos for the v tail mounted on their side. The nose is pre cut for you already. A strong servo without play for the flap (Futabe S9202 or JR DS811) as well as a programmable radio.

Painting is of an acrylic type which does not like solvents. It is necessary to avoid alcohol and other white spirit. Best it is to use soapy water or WD40 to clean the wings. I recomend that you rub out the finish with a auto polish for best results.

The duration of construction is of approximately 14 hours.

 

Caractéristiques Techniques

 

Span :                                  2840 mm

Surface :                             55 dm2

Profil :                                MG SPECIAL

Length :                               1400 mm

Weight :                              2000g

Wing loading :                   36 à 54g/dm2

1.    List of Accessoires

Included in the kit.                           

n    Control horns for all surfaces.

n    Ball links

n    Wing screws

n    v-tail horn wire.

n    2  carbon v-tail pushrods.

n    1  carbon flap pushrod.

Also needed.

n    5 & 30 minute epoxy

n    Micro balloons.

n    Small servo screws.

n    F/G chop.

n    CA.

n    Masking tape

n    Tube of 100% Silicone

 

2.    Construction of the Wing.

The ailerons are 30% of the cord. These have been cut for you.


 


 

 

You are tying the skins together and stiffening the control surface against possible flutter ! Do not skip this step !!

 

2.1    Installation of the control horns.

The installation of the control horns is done classically. We recommend ball links for an easy assembly on the ground and a tight linkage. Drill a hole into the microballon fill and epoxy in the ball link assembly. For the ailerons and the flap make the pivot 15mm from the lower skin and in line with the hinge line.


 

2.2    Installation of aileron servos


Both aileron servos are installed in each end of the central panel. Dig polystyrene between the 2 blocks of hard wood, which are located between the 2 wing rods. Microservo with metal gears are recomended then screwed on these blocks of wood. The head and the top of servo exceed in to the tip panel, dig some foam for clearance. The skin under-surface must then be cut out in a T to pass the control horns during the assembly of the wing. This installation has the advantage of not weakening the wing and of avoiding an additional connector. During assembly on the ground it is enough to connect the ball link to the horn on the aileron and to secure the panel with electrical tape.

 

 

It is also necessary to bore a hole of 8mm in the fuse in the center of the wing saddle but offset ½ inch to pass servo wires to the RX. It is advised not to bore the wing in the center, but to shift the hole  1/2 inch to not interfere with the flap linkage. You can install a Deans or Multiplex connector.

 

2.3    Wing attachment.

The wing is attached to the fuselage by 2 screws. The wing is reinforced at the places planned for the screws and are done for you.

3.    The stab

3.1    Installation of the stab.

Fill the elevator LE with epoxy and micro balloons like the wing.in step 2. Epoxy the pin in the aft tube with ¼ inch protruding from the root. This will engage the hole you will drill in the fuse. Be sure to align the stab to the stab fillet on the fuse for proper incidence.

 

    

 

 

3.2    Installation of the stab links.


The control horns are made from piano wires of 2mm of diameter. It is necessary to cut 2 piece of 70 mm length,  solder a ball link ball to one end, bend them to 20 mm of the ball with 55° (approximately!). Then bend the other end with right angle (or better) so that control surface with the neutral, which gives us a symmetrical clearance so that it is inserted in the control surface approximately 1 cm. Then hollow out the LE of the control surfaces of stab about 35 mm to insert the end in the control surface. Epoxy in place.

To finish the stabs, scotch tape the hinges and applying a silicone joint as for the ailerons.

4.    The fuselage

4.1    Wing attachment

Mark the position of the wire hole exit to mate with the wire hole on the fuslage pylon.

4.2    V-tail

The carbon stab rods are pre-attached with cyano. It is necessary to reinforce the joint with epoxy and chopped fiberglass or carbon (provided) impregnated with epoxy. The stab rods will then be solid with the fuse. Slide the stab on the rod and mark the drill point for the alignment pin. Then with a small file open the pilot hole to get perfect alignment with the fuse fairing without slop.

 

Pull a loop of strong string through the hollow carbon stab rod as shown. Wet out a strip of carbon tow with slow set exoxy twice the length of the combined stab rods. Pour a bit of epoxy down the tube and wrap the string around the center of the tow. Gentaly pull the carbon tow into the center of the tubes, pass the V joint and let cure. Be sure to tape the rods so you don’t get epoxy everywhere. This will make the rods solid and much stronger.

 

4.3    Inner Nose.

The inner nose ballast access needs to be cut by the builder.

 Make a cut so ballast access is gained. I suggest that you round the corners of the cut to relieve stress. I recomend that you reinforce an area inside the inner nose with a piece ½ x ½  1/8 plywood and epoxy so later in assembly a ¼ hole can be drilled horizontally through the inner nose and ballast tube to secure the ballast in the tube.

 

Place the inner nose in the nose cone and mark a line around the inner nose. Prepare the inner nose for expoy bonding to the fuselage by sanding the inside of the fuselage with 220 grit and the paint from behind the line of the inner nose. Place masking tape over the fuselage and forward of the line to keep excess epoxy off the model.

 

Mix some 30 minute or longer curing Epoxy and micro balloons and epoxy the inner nose in position. Do not use too much! Check alignment as necessary. Remove the excess epoxy carefully when the epoxy is not quite set up. At this stage the epoxy is firm and easy to remove by cutting it clean with a razor blade flush with the fuselage. You must have a flat bond line so the nose cone will fit flush with the aft fuselage.

4.4    Installation radio

The fuselage receives the servos for the V-tail, the servo for the flap, the receiver and battery pack of 5 1400mAh cells. While placing the battery pack well in the nose one should arrive has a correct centering without much lead. Place the 3 servos in position shown on the photo and test fit in the fuse with the pushrods. It is best to make a hardwood side rail to secure the v tail fuse servos.

 

 

 

 

 

4.5    Pushrods.

 

The 2 v-tail pushrods will be made out of carbon tube with inserts of threaded rods with each end stuck to epoxy. The fine adjustment will be made turntable installed by screwing - unscrewing of the covers. The carbon rods are sufficient and that makes it possible to pass under the carbon stab rods without problems.

 

The flap rod will be produced same manner with a carbon tube. For the length, the method is the same one as for the control surfaces of stab.

 

4.6    Ballast

 

To draw the best from Arkanj one needs ballast. It is equipped with a ballast compartment in the fuselage which can receive steel tubes that can be filled with lead for more weight. So that their center of gravity is always maintained make some wood spacers the same length when full ballast is not used. Drill a ¼ hole compltly through the inner nose and ballast tube to pass a wood dowel that will secure the ballast in position. The nose cone will capture the dowel.

 

 

5.    Center of Gravity

C of G

 

 

 

 

 

 

 

110 mm from leading edge which can be moved forward by 5mm by placing +- 25g in nose

 

for first flight

 

 

 

 

 

6.    Control set up

Settings and mix settings

 

 

 

 

 

 

 

 

 

 

 

 

 

The three flight settings are - Speed ( min drag ) , Optimal - ( min sink ) , Duration

 

For all settings + = down and -= up when glider is in normal attitude ( not inverted )

 

The values are in mm measured at the trailing edge.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Speed

Optimal

Duration

 

 

 

 

 

 

 

 

 

Ailerons

 

 

 

 

 

 

 

Camber

0

+3

+5

on control switch

 

 

-30

-30

-30

on aileron stick

 

 

+24

+18

+14

 

 

 

 

 

 

 

 

 

Winch Launch

 

+12

 

 

 

 

 

 

+9/0

 

Elevator to flap setting

 

 

 

-20

 

Airbrakes ( landing )

 

 

 

 

 

 

 

FLAP

 

0

+4

+7

 

 

 

Winch launch

 

+14

 

 

 

 

Airbrake (Landing )

 

+30

 

 

 

 

Elevator/Flap mix

 

+10/0

 

 

 

 

 

 

 

 

 

 

Stabilizers

 

 

 

 

 

 

Normal

0

+1

+1

 

 

 

Elevator

 

+9/-7

 

 

 

 

Rudder

 

+10/-9

 

 

 

 

Winching

 

+2

 

 

 

 

Airbrake ( Landing )

 

+4

 

 

 

 

7.    Flights

7.1    First flight

The first flight will be done without ballast, all the control surfaces exactly with the neutral, centering with 105mm of the leading edge.

7.2    CG tuning

Move back CG to 110mm of the leading edge according to your impressions. It will be necessary to compensate with down trim, it is normal. Reasonable back limit being 110mm. Familiarize yourself with the sailplane before adding ballast.

7.3    Ballast

One can ballast Arkanj to fly by strong wind.

6.4  Camber.

Add a bit of positive camber for light slope lift. You will be surprised.