rc3Dprint ER-2 User manual

J
PRINTING AND
ASSEMBLY
INSTRUCTION
BOOK
ER-2

THANK YOU
Thank you for downloading this ER-2. These models take many hours of work to make
available to you so please don’t share the STL files with others. Send them to
www.rc3print.com where they can download the models themselves. This enables me to
continue to develop new models to make them available for download.
This document aims to help you print and assemble your aircraft. Our designs are made to
be simple, this model is designed explicitly with LW-PLA in mind, so it incorporates carbon
tube spars. If you print it from regular PLA it will obviously be heavier and you should take
this into account.
3D printers often have many differences so you may need to tweak settings to get the best
results.
Included in the document you will find Cura profiles and layouts for each part and assembly
instructions. Many of the components in the design are solid bodies, this has some advantages
over hollow bodies in that you can adjust some settings such as wall thickness, infill
percentage, etc. As such we recommend using Cura to slice the files. The walls of these solid
bodies are single line 0.4mm thickness to reduce weight. As you are printing and
assembling the model yourself we take no liability for damage or loss resulting from your
use of these files. Please fly responsibly and follow all local laws.
Share your results on Instagram, Facebook, or by email and tag @rc3dprint for discount
codes on future orders.

PARTS LIST
REQUIRED
EDF ChangeSun 90mm and Motor (TURNIGY SK3 FANDRIVE - 3659-1900KV (90MM
EDF - or similar). 6S
6 - Channel radio kit minimum.
8 x 9g Micro Servo
2 x Metal Servoless Gear Retracts - Non steerable version (Link)
Pultruded carbon tubes: 8mm, 6mm, 4mm and 2mm. The carbon tubes need to nest inside
each other: Check before you buy! See carbon schematics below for lengths required.
Piano Wire for Elevator and Rudder push rods
CA glue
Hot glue (for securing Servos)
2 x 25mm x 8mm x 2mm N35 Magnets for hatch - https://amzn.to/35GtsmC

INCLUDED STL. FILES
FUSELAGE
WING

EMPENNAGE
GEAR PARTS

CARBON TUBES

SPEED BRAKE PARTS

SPECIFICATIONS
Wing Span & Area
2020mm - 39.33dm2
Flying Weight
(2200mAh 4S): 2000g
Wing Loading
50.9 g/dm216.6 oz/sq.ft
Wing Cube Loading
8.1
Channels
6 Channel Minimum
Centre of Gravity
10 cm Behind of Leading Edge
2018
1309.16

PRINTING PROFILES
A handful of parts are printed in PLA and TPU, these can be printed using standard settings.
LW-PLA PROFILE
This model is designed to be printed in LW-PLA.
All printers are different, it is advisable to follow the calibration instructions given by
Colorfabb to get the best from this material.
Below are the settings I use on a Creality Ender 5. Listed are the changes made to the
generic ‘Low Quality’ PLA profile. I use these settings for all part, unless otherwise stated in
the Cura Placement pages.
A WORD ON RETRACTIONS
Layer height
0.24mm
Wall Thickness
0.4mm
Wall line count
1
Top/Bottom Pattern
Lines
Infill Density
3%
Infill Pattern
Cubic
Flow
50%
Printing Temperature
245C*
Build Plate Temperature
60C (optional)
Fan Speed
20% Maximum
Generate Support
No
Build Plate Adhesion
Brim

With regular PLA a common problem is under extrusion at layer change - to fix this change
the setting extra prime amount in Cura to +1-3mm.
With LW-PLA it is recommended to switch retractions OFF since trying to retract the
foaming filament can cause problems. If you need to fix under extrusion you can still use the
method above but will need to turn retractions ON and set the retraction distance to 0mm.
A big thing is made of ‘retraction free’ LW-PLA models. You don’t need retractions on if you
print his model however having retractions on but with a value of Zero means you can use
the retraction extra prime amount setting if you are offering from any under extrusion. You
should print the parts one at a time. You may need to clean up some parts with a craft knife
or sand paper to remove some stringing after printing.
Before and after cleaning up.
ASSEMBLY

FUSELAGE
Assemble the fuselage from the back forwards. Here is a recommended sequence:
1. Fuselage 7 and 8 glued together. With each Fuselage piece added you should run the piano
wire elevator and rudder push rods through the Bowden (which may need opening up
with a craft knife) to make sure it is lined up correctly.
2. Assemble the speed brake parts together and glue the CF tube hinge into Fuselage 6.
3. Glue the Fuselage 6 and speed brake assembly to Fuselage 7/8.
4. Attach your speed brake piano wire pushrods to the speed brakes, then glue on Fuselage
5 to Fuselage 6/7/8. Now you can attach 2 servos to the bottom of Fuselage 5 to actuate the
speed brakes. I usually attach the servos with a drop of hot glue.
5. Fuselage 4 has a lot of parts. You need to sit the EDF in place. You will need to clear out
any stringing with a craft knife. Secure the EDF in place with a thin bead of hot glue on
the left and right side. This also provides rigidity to the part. Servos need to be put in
place with the wires fed into the fuselage centre, the servo horns should face inwards. If
using the retractable undercarriage the servo less retract should be set into the bottom
of Fuselage 4. The CF tubes, inside which the wing spars nest, should also be put in place.
6. You can now glue Fuselage 4 to Fuselage 5/6/7/8. Be sure to run the servo wires up
through the fuselage belly.
7. Now glue on the Horizontal and Vertical stabilisers. The rudder can be assembled with the
Vertical Stab Top glued on after the rudder and CF hinge have been installed.
8. The Elevator is a little more complex and uses a torque tube system. The larger CF tube
connect the two elevators together and rotates around the spar. Once the two elevators
are aligned together and glued to the torque tube the spar can be passed inside the
torque tube and the Horizontal Stab Ends glued on to finish the tail assembly

9. The wings are assembled around 3 CF
Spars. When gluing the pieces together
it is advisable to build around these
spars as it ensures correct alignment.
Often the ends of the 3D printed spar holes will require a little cleaning up with a craft
knife. The flaps use a torque tube system similar to the tail. Assemble the Inner and
Outer Flaps, and Wing 2 around the torque tube first. The flaps should be aligned to each
other and glued to the torque tube. The long Aileron and Flap Hinge Spar then passes all
the way through the wing. You
can build the rest of the wing up
in any order after this, ensuring
that no glue is applied to the
ailerons, and they are free to
rotate around the hinge. Position
the Aileron control horns so that
the hot end if over the hinge.
The Flap horns should be placed
2cm further Aft, i.e, these
shouldn’t line up with the hinge
line.
10. At this stage it is a good idea to
assemble all the parts together,
running the servo wires and extensions forwards to make sure they are long enough.
11. Glue Fuselage 3 into position. You can now feed all the wire bundles forward making sure
they are out of the way either side of the gear retract cutout.
12. If using the retractable gear assemble these pieces together as per the images earlier in
this document. It is highly recommended that you use a strong filament for these pieces.
ALWAYS check the pieces for fit in the fuselage to make sure you get them in the right

position before gluing them on to the retract leg. The FWD Gear uses some pieces of
4mm Carbon Tubes to assemble.
13. The rest of the fuselage can now be glued in place. The Canopy sections are glued to
gather and use a small magnet to connect to the fuselage - make sure when gluing the
magnets in place that you check the polarity!
14. The wings are connected to the fuselage by inserting the wing CF tubes inside their
fuselage counterparts. To ensure a strong connection the underside of the wings have
four holes. Use small drill bit to drill a hole through both the wing and fuselage CF -
with the wings connected and firmly in place. Small servo size screws can no be put in
place to hold the wings (CAUTION: After drilling out the holes the wings may be
difficult to slide away from the fuselage - don’t press to hard on the wings to pull them
as they will break, instead use a wide prying tool to gently prise the wing away from the
fuselage.)
15. Set up the elevator and rudder servos with piano wire push rods. The EDF Hatch will be
glued into place so double check everything works before doing so.
FURTHER NOTES
• The model comes with parts for a launch dolly, the assembly of which is pretty self
explanatory. Wheels are not included as these will be dependent upon the surface you
plan to launch from. It requires 2 x 8mm OD Carbon Tubes and 1 x 6mm OD Carbon
Tubes.
•
• The wings have slots available, just inside of the ailerons for “POGO’s” to be installed.
On the full size aircraft these are installed after landing for taxiing. In our case you can
you piano wire inserted in these slots and bent as required.
• The CAD files for Wing 2 are included in the download. This is so that you have the
platform to design your own wing pods. The ER-2 was used as a flying laboratory with all
kinds of sensors housed here. I look forward to seeing what people add!

CURA COMPONENT PLACEMENT
FUSELAGE 1

FUSELAGE 2
FUSELAGE 3
FUSELAGE 4
Set the infill to 5%

FUSELAGE 5
FUSELAGE 6
FUSELAGE 7
FUSELAGE 7 HATCH

FUSELAGE 8
EDF HATCH
WING 1
WING 2

WING 3
WING 4
WING 5
WING 6A

WING 6B
INNER FLAP
OUTER FLAP
INNER AILERON

OUTER AILERON
VERTICAL STAB
HORIZONTAL STAB