Kraga Roa II User manual
Roa II build guide 1.0
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Development of a new plane and support of the old ones is very time consuming. Only with your help I can
focus fully on this project and spend some quality time with my family.
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Printing
You need to use two printing methods to print all parts:
1. Solid parts (fuse and accessories). Use dense infill. This is common
way of printing objects and these parts should be printable on every
printer.
2. Shell parts (wings). Use 0% infill and no horizontal
surfaces (thickness of the shell is one layer). Only this
way you can achieve required weight of the plane.
You can check what method to use on what part in bill of
materials table.
Other recommended printing settings:
•Nozzle size: 0.4 mm
•Layer thickness: 0.19 mm
•Rafts: yes
You can use any material you like, only limitation is high temperature from ironing when covering
assembled parts. Heat from the iron can deform the parts. Although I was not able to damage any
part and I tried to cover many materials (ABS, PLA...), please test film covering on your testing
part.
One of the goals when designing KRAGA models was to use minimal or no support during printing.
Removing support after printing is big pain and you can easily destroy your part. That is the reason
why you should use default orientation of all parts during printing. There are only a few parts from
whole plane which require support, the rest of the plane should be support-free.
I strongly recommend to mark every printed part with it's name (I'm using masking tape for that).
There are many parts in this plane and from each part there is also mirror side which can easily
cause confusion during assembly.
I also recommend to print parts in bulks, especially smaller parts like ailerons or moving section on
the plane tail. Otherwise there is not enough time for material cooling in each layer and you might
end up with rough layers, ugly edges or print fail.
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Preparation for assembly
KRAGA Roa II plane consists of parts that are printed and parts that you need to buy separately
(they are not included in sold product) – carbon tubes and pinned hinges.
List of required parts:
dimensions count
carbon tube ⌀ 2x1 mm 1 m10
carbon tube ⌀ 3x2 mm 1 m5*
carbon tube ⌀ 4x3 mm 1 m4
carbon tube ⌀ 6x4 mm 1 m2
carbon tube ⌀ 8x6 mm 1 m3
carbon tube ⌀ 10x8 mm 1 m4
carbon tube (woven) ⌀ 14x12 mm 800 mm1
covering film 4 m1
pinned hinge ↕ 16x28x1.2mm 26
folding propeller 13 x 8 in 1
spinner ⌀ 45 mm 1
screw M2 8mm22
⌀2x1 mm – means tube with outer diameter of 2mm and inner diameter of 1mm
* 2 pieces of 3x2 mm carbon tube are meant to be used for tail linkage with threaded couplers and metal clevises
And of course you need all the common accessories like clevises, push rods (horns are printed so
you don't need those) and servo extension cables (2 pieces of 90 cm cable for aileron servos). One
way how to make custom pushrods is using 2x1 mm (or 3x2 mm) carbon tube glued into threaded
couplers and screwed into metal clevises (picture below).
Next step is to cut carbon tubes and rods into smaller pieces, which will be used as spars, joiners or
boom of the plane. Don't forget to mark every piece to avoid confusion during the assembly.
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Carbon spars
part dimensions count
Wing section 1:
Main carbon spar ⌀ 10x8 mm 745 mm4
Secondary main carbon spar ⌀ 8x6 mm 442 mm4
Front alignment carbon spar ⌀ 4x3 mm 985 mm2
Rear alignment carbon spar ⌀ 2x1 mm 809 mm2
Wing section 2:
Tertiary main carbon spar ⌀ 6x4 mm 404 mm4
Secondary front alignment carbon spar ⌀ 3x2 mm 230 mm2
Secondary rear alignment carbon spar ⌀ 2x1 mm 660 mm2
Wing tip:
Wing tip front carbon spar ⌀ 2x1 mm 193 mm2
Wing tip middle carbon spar ⌀ 3x2 mm 266 mm2
Wing tip rear carbon spar ⌀ 2x1 mm 218 mm2
Wing surfaces:
Aileron carbon spar ⌀ 2x1 mm 587 mm2
Flap carbon spar ⌀ 3x2 mm 680 mm2
Fuselage:
Fuse top carbon spar ⌀ 2x1 mm 518 mm2
Fuse bottom carbon spar ⌀ 2x1 mm 535 mm2
Fuse pod carbon spar ⌀ 2x1 mm 68 mm2
Fuse servo plate carbon spar rear ⌀ 2x1 mm 45 mm1
Fuse servo plate carbon spar front ⌀ 2x1 mm 48 mm1
Carbon woven boom ⌀ 14x12 mm 785 mm1
Wing alignment joiner ⌀ 3x2 mm 75 mm1
Wing joiner carbon tube front ⌀ 8x6 mm 515 mm1
Wing joiner carbon tube back ⌀ 8x6 mm 485 mm1
Tail:
Tail main carbon spar ⌀ 4x3 mm 374 mm4
Tail mov carbon spar ⌀ 2x1 mm 362 mm2
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TIP: How to cut carbon spars. Wrap masking tape around
carbon spar and mark cut position. Use rotary tool or X-
ACTO fine saw to cut the spar.
Work outside or in room with good ventilation. Use
breathing mask to avoid inhaling carbon dust! After cutting
wipe out carbon dust from the spars using wet tissue.
TIP: Carbon wing joiner tubes on the fuselage
should fit into spars in the wing. Sometimes the
fit is too tight or you cannot insert joiner tubes
into wing spars at all. You can use drill and wet
sandpaper to make joiner tubes thinner. Use
breathing mask to avoid inhaling carbon dust!
Remove support legs from all parts. Also sand all sharp edges and
printing imperfections to avoid covering foil damage.
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Assembly
This assembly guide will describe always left side of the plane when it comes to symmetric parts. I
recommended to use medium viscosity CA glue. You can use CA glue accelerator for faster curing
time. Dry fit all the parts before gluing them together. Wing parts in assembly drawings have
printing support legs visible, please ignore it, these legs should be removed before plane assembly.
Wing section 1
Assembly first section of left wing as sketched above. Main spars
(10x8_745) and front alignment spar (4x3_985) should be aligned flush
with base of wing_root_endcap_L part. Rear alignment spar (2x1_809)
should protrude 1 cm from wing_root_endcap_L part.
Before adding wing_L_7, prolong main spars by inserting secondary main
spars into main spars 8 cm deep and secure the spars in place with CA
glue.
When all the parts are in their position, put glue on contact points where
carbon spars are touching printed parts.
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When assembling flap servo mounts, notice that screws are screwed in from bottom side of the
wing. It is strongly recommended to pre-drill the screw holes. Servo has to be glued to
flap_servo_mount_L_F_glue_on and flap_servo_mount_L_B_glue_on parts.
Wing section 2
Assembly second section of left wing as sketched
above. Before adding wing_L_11, prolong
secondary main spars by inserting tertiary main
spars into secondary main spars 8 cm deep and
secure the spars in place with CA glue.
On the left picture you can see detail of aileron
servo installation.
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Wing tip
Assembly left wing tip as sketched above. When all the parts are in their position, put glue on
contact points where carbon spars are touching printed parts.
Aileron
Assembly left aileron as sketched above. Don't forget to insert ail_horn_L part between ail_L_2 and
ail_L_3. Aileron horn should stick out from the top side of the wing. When all the parts are in their
position, put glue on contact points where carbon spars are touching printed parts. Put also a bit of
glue on trailing edge where all the aileron sections are touching each other.
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