KOR MODEL Zlin Z-37A Cmelak User manual

Zlín Z-37A Čmelák ("Bumblebee”) -
1 530mm
Assembly Instructions and recommended equipment of the RC model

2
Parts needed for the finishing of the model:
Carbon Strip (stringer) - 5x0,6 mm 3 pc
Pushrod connectors (linkage stoppers) 6 pc
Adhesives:
Cyanoacrylate (CA) glue (super glue) thin +
medium
Activator (Kicker) for Cyanoacrylate glue
Polyurethane (PU) glue (e.g. Ponal PUR glue in
bottle or UHU PU MAX in bottle or Purex Rapid)
Epoxy
Technical information:
Wingspan: 1530 mm
Overall Length: 920 mm
Flying weight: ~1 700g
RC Functions: Rudder, elevator, ailerons, motor (throttle), flaps (optional: spreading unit activation)
Recommended equipment:
Brushless motor: Turnigy 3639 1100kv (~500W) 1 pc
+ shaft extension (~70 mm long) 1 pc
Electronic Speed Controller (ESC): 40 A 1 pc
Propeller: APC 13x4“ + Propeller adapter 1 pc
Servos: 20 grams with Metal Gear 6 pc
Battery: 3S Li-pol 2700-3000 mAh
Receiver: minimum 5 channels
Parts included in the set:
Fuselage parts 4 pc
Center section of the wing with flaps 1 pc
Outer Wing parts with flaps (Left + right) 2 pc
Outer Wing parts with ailerons (Left + right) 2 pc
Engine cowling 1 pc
Engine shutter –3D printed part 1 pc
Walking grid –3D printed part 1 pc
Tail group (empennage) 3 pc
Plastic nuts + screws 2+2 pc
Plywood plate 1 pc
Main Landing gear wire (Left + right) 2 pc
Tail Landing gear wire 1 pc
Main Landing gear plastic covers 2 pc
Tail Landing gear plastic cover 1 pc
Main Landing gear wheels 2 pc
Tail Landing gear wheel 1 pc
Steel wire for pushrods (ø 1 mm) 1 pc
Wheel stop collars ø 4 mm 2 pc
Wheel stop collar ø 2 mm 1 pc
Foil for windscreen & windows 3 pc
Plastic tubes for landing gear braces
Set of Fiberglass parts (engine bulkheads, control horns, hinge levers)
Tools needed to assemble the model:
A sharp knife or scalpel, pins, drywall sanding mesh, steel ruler, soldering iron, paint (water based,
synthetic or color sprays: Montana, Duplicolor, PrismaColor…) and common modelling tools.
All parts are glued with super glue (CA), unless stated otherwise.
Before starting the assembly, read carefully the Assembly Instructions!

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Assembly procedure:
(If you purchased a spreader unit along with the model and you want to spread, remember to create
the space in the fuselage behind the cockpit –hopper (spreader material reservoir). It can be made
later as well, but it will be more difficult.
When assembling the fuselage, some weight can be saved by making the rear fuselage lighter - by
scooping out material, this can avoid additional weight in the front. It must be noted, however, that this
may affect the durability of the model. We recommend leaving a wall that is at least 15-20 mm thick.
The electronics will be located inside the fuselage above the wing, the battery and Electronic Speed
Controller (ESC) between the wing and the engine mount.
Wing:
(The wing is attached to the fuselage by two screws and dowels).
All larger EPP (Extruded Poly-Propylene) parts are to be glued by the following procedure:
Apply the PU glue to one of the surfaces to be joined and only in the center of the part, approx. 8-10
mm from the outside perimeter of the part shall not be covered with the PU glue to avoid the PU glue
foaming out of the surface and making the joint less attractive. Then put both glued parts together,
align them and fix together with pins. When both surfaces match each other, apply thin CA glue to the
whole outside perimeter of the joint. The CA glue prevents the PU glue to foam out of the joint.
First glue the parts of the outboard wing sections together, i.e. glue the part with the aileron to the
coresponding part with the flap cutout. Do this for both outboard wing sections. Then glue both
outboard wing sections to the wing mid section.

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Make a slot with a sharp knife into the underside of the wing, for the milled fiberglass spars and carbon
stringers, 90 mm from the leading edge at the wingcentre (approx. 60 mm at the wingtips). The bottom
spars have V-Form for the wing dihedral and an eyelet roughly in the center of the bottom side for
mounting of the landing gear. Extend the spars with a 5x0.6mm carbon stringer till the end of the
wings with an approximate overlap of 65 mm on the spars. With the remaining part of the stringer,
connect both spars in the wing mid section.
Cut the slot for the spars and stringers on the upper side of the wing in the same way. (Make the slot
for the spars with a sharp knife and push them in - you can use a small hammer). Level the wing on a
flat surface (table or floor), check the wing is straight and with the same dihedral on both wing tips,
then glue the spars and stringers into the wing with thin CA glue.
"Spread" the spar and carbon stringer joint so that the glue soaks deeper inside.
Level the flap according to the aileron and attach with pins from top (the depth of the wing in the mid
section including the flap is 298 mm).

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Cut slots at a right angle into the flaps at a distance of 120
mm for the 90° levers creating hinges (shorter inner flaps in
the wing mid section - 130mm distance). Use the extended
levers in the flaps (for flaps control) on the place, where the
wing mid section is joined with the outboard wing section.
Cut slots into the wing for the oposite parts of the hinges,
which have to be glued together according the following
image (push two pieces of wire through the parts, then glue
them together) 
Before gluing all the hinge-levers into the wing and flaps, push a long piece of steel wire through all
hinges of each flap in order to level the hinges and properly align the flaps with the wing. (Check for
ongoing trailing edge and maintaining the shape of the airfoil). Glue all the hinge parts with thin CA.
After you glue the hinges in place, remove the steel wire and clip short pins, about 5 mm long, push
them back into the hinges, and add a drop of thicker CA glue on both sides carefully.
Cut the aileron servos into the wings idealy in front of the stringer and cut a slot for the lever into the
aileron in the servo lever axis. Push the servo cables into a slot made with knife and bring them (along
with the flap servo cables) to the center.

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Create a "pocket" in the mid wing section from the top of the profile (covered by the fuselage), and
lead all the servo cables from the ailerons and flaps there and add connectors.
In the center of the leading edge of the wing mid section, cut two
vertical slots at a distance of 90 mm for connecting plates -
dowels. Mark the place of the cut according to the counterpart.
Take particular care here !!!
Glue the fiberglass plate for even distribution of screw pressure to the bottom side of the wing profile in
the centre of the wing.

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Place the landing gear wire on the bottom side of the wing and mark its location (approximately 5 mm
of the wire will be inserted through the spar). Create a 4 mm wide slot in the EPP for the landing gear
wire so that it is aligned with the wing profile. Place the roughened fiber glass plates on the wire at a
distance of 55 mm and cut slots and push the plates into the wing mid section. DON'T GLUE THEM
YET. Place the flap servos in front of the spar with the levers as close to the wing mid and outboard
section joint as possible. Lead the servo cables underneath the landing gear towards the middle of the
wing - along with the aileron servo cables.
After comparing both landing gear wire positions, thoroughly glue the fiberglass with thin CA glue into
the wing. Don't glue the wires itself.
Glue the landing gear plastic covers to the landing gear wire with epoxy, paying attention to the correct
orientation. (Extruded glue can be wiped off with a rag soaked with acetone - it does not damage the
plastic).
The plastic covers can be painted with the same paint as the whole model after degreasing with
acetone.
After the wing was painted:
Insert the ø2 mm plastic tubes in the designated distances from the main landing gear, under the
angle of the bracing struts, 20-30 mm deep, let them protrude 40-50 mm and glue them into the wing.
They will serve as a guide for the bracing struts when the landing gear bends/springs. Prepare the
struts from the ø3 mm tube at an approximate length of 100 mm, paint them, slide them on to the ø2
mm plastic tubes and glue them to the prepared pins on the landing gear plastic covers. Struts facing
backwards (to the trailing edge) must be slightly shorter because of the bending/springing of the
landing gear.

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Install the wheels and secure them with stop collars.
Glue the slots to the end of the wing using fiberglass holders after the wing and slots painting.

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Fuselage:
Cut the ruder servo vertically into the side of the vertical stabilizer in its widest point. Cut the elevator
servo into the fuselage under the horizontal stabilizer. Create a groove in the fuselage for servo cables
all the way to the wing mid section.
Place the pre-bent tail landing gear wire with one installed fiberglass plate (20x40 mm) at the level of
horizontal stabilizer leading edge on the fuselage inner side. Cut the fiberglass plate into the upper
part of the fuselage and cut a groove for the gear wire. Glue to the fiberglass plate into the fuselage
carefully, not to glue the wire itself. The second fiberglass plate will be glued on later after the fuselage
was glued together. Create the groove for the landing gear wire and the upper fiberglass plate also in
the oposite half of the fuselage.
Scoop out enough space for the Electronic Speed Controler in the front bottom part of the fuselage.
Lead the groove for the power cables above the wing and forward to the engine bulkhead. Do the
same for the battery.

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At this point you can prepare space for the hopper if the spreader will be used, ideally a cylindrical
shape with a diameter up to 60 mm.
Place the extension servo cables connected to the servos into the prepared groove. Glue both
fuselage halves together, apply the same method as described above in the wing section (PU + CA
glue). Do not apply glue on or around the tail landing gear wire.
Glue together both parts of the horizontal tail surface and reinforce
it with a 5x0.6 carbon stringer along the entire length from one
side. Cut and glue the control lever into the elevator in the servo
lever axis using CA (1 from 4 pcs - different shapes than those
used as the flap hinges). Carefully glue the horizontal tail surface
to the fuselage with PU + CA glue. Before applying CA, check the
perpendicularity to the fuselage.