Flex innovations Twin Otter 80E User manual

Thank you for purchasing the Flex Innovations Twin Otter 80E!
Flex Innovations airplanes are now shipping with digital manuals. This ensures that you always have
the most up-to-date information, including any future modifications, upgrades or even future product
generations. It also makes your assembly and flying experience as accurate and enjoyable as possible.
You can find the most updated version of the manual at the link shown below or simply by scanning
the QR code with your phone. If you would like a printed version of the manual and did not order one
with your airplane you can also find information on how to order
one at the same location.
If you have experience assembling Flex Innovations Super PNP
aircraft then this quick assembly guide is for you. Inside you
will find general assembly sequence recommendations, radio
setup details and everything you need pre-flight. This
assembly guide is not comprehensive and assumes a certain
level of familiarity and comfort with the process.
For full details on how to put together your Twin Otter 80E, for
any last minute updates, for additional details such as parts
lists please follow the link or the QR code for the complete
manual.
Quick Assembly Guide
https://www.flexinnovations.com/product/twin-otter-80e-super-pnp/
DESIGNE
D BY:

2
Introduction
The Flex Innovations Twin Otter 80E offers something incredible for everyone. At first glance, it is a forgiving general
twin engine aviation aircraft with rough field capabilities but take a deeper look into the heart of the Twin Otter, and
you’ll find its expansive capability. From wild 3D aerobatics to gentle touch and goes on land or water, this incredible
aircraft offers a perfectly balanced airframe for all flying styles.
Completion Items
You will need the following to complete your Twin Otter 80E:
•5200-6200mAh 6S 22.2V 40C+ Li-Po (6200mAh, FPZB62006S40 recommended)
•Minimum 8 channel transmitter
•Serial capable receiver to match your transmitter, e.g. Spektrum 4651T or Futaba R2001SB. For a current list off
compatible receivers visit: https://wiki.flexinnovations.com/wiki/Aura
General Tips for this Quick Assembly Guide
This guide will go through a recommended sequence of assembly, including most pertinent information for each
step, but without any major details. It will include a small quantity of pictures wherever necessary to clarify or
illustrate these steps.
This information should be enough to put the Twin Otter 80E together but if you have any doubts please
download and reference the full manual.
Note: Do not use thread locker when attaching plastic parts, the parts will soften and fail.
Note: If you have the night version of the Twin Otter 80E we recommend that you dry assemble the
airframe and test all the lights before bonding anything permanently in place.
Assembly Sequence
Landing Gear
Main Gear
1. Insert the wire landing gear into the slot in the fuselage. Insert the landing gear mount cover and secure
using four M3x12mm self tapping screws.
2. Mount the wheels to the end of the landing gear with a wheel collet on each side of each wheel. Use thread
locker on all the set screws.
3. Glue the foam fairings to the landing gear wire leaving a 1-2mm gap to the fuselage to allow for landing
gear wire movement. We recommend using 15 minute Epoxy.
Nose gear
4. Mount the wheel to the end of the nose gear strut with a wheel collet on each
side of the wheel. Use thread locker on all the set screws.
5. Install the nose gear strut to the airplane with a wheel collet in the middle of each
of the mounts. The steering arm goes on top of the assembly. Use thread locker
on all set screws. View picture to the right for assembly details.
6. Install the servo arm and push-rod after the airplane is powered on, note that the
push-rod needs to be crossed over as in the picture to the right. Connect the
servo lead to the Y-harness on port S8 of the Aura (rudder).
Tail
The tail assembly uses the short carbon fiber rod for reinforcement.
1. Dry fit the tail assembly and reinforcement rod to the fuselage.
2. Once everything fits correctly, remove the carbon fiber rod and lightly scuffit with 220 grit sandpaper to aid
in adhesion. Clean all surfaces with rubbing alcohol before bonding.
3. If you have the night version first connect the LEDs. Bond the tail assembly to the fuselage using 30-minute
epoxy. Ensure that you get adhesive on all the mating surfaces as well as both ends of the carbon fiber rod.
4. Insert the horizontal stab tube and the wing tube into the airplane, ensure that they are parallel before
taping the tail section to the fuselage, this step is critical or the airplane will not end up straight.
5. Tape the assembly in place while the adhesive dries. Note: Do not apply tape directly to any painted part
as this will strip the paint offthe part, place the tape only on the white areas.

3
Assembly Sequence Continued
Horizontal Stabilizer
1. Insert and roughly center the carbon fiber horizontal stabilizer tube in the fuselage.
2. Insert both halves of the horizontal stabilizer onto the tube. Ensure that the control horn faces the bottom
of the fuselage and that the elevator jointer tabs line up properly.
3. If you have the night version, connect the LED power connectors.
4. Once both halves of the horizontal stabilizer are seated in place secure them using four M3x8mm self
tapping screws.
Rudder and Elevator Linkages
Install the rudder and elevator linkages now, but after setup you may need to re-center servo arms and ensure
that the pushrods are the correct length to center the control surfaces.
1. Using M3x6mm screws, Install the servo arms on the servos so that they are perpendicular to the servos and
face towards the top of the airplane for the elevator and towards the ground for the rudder. Once radio
setup is complete, remove these screws and re-install them with thread locker.
2. Install the linkages between the servos and the control surfaces using the following hardware sequence:
M2x10mm Machine Screw →M2 Washer →Ball Link →Servo Arm or Control Horn →M2 Lock Nut.
3. The following diagram shows the positions of the linkages:
Motor Installation
1. Install the prop adapters on the front of the motors using the provided socket head hex screws and thread
locker.
2. Install the x-braces on the back of the motors using four M4x6mm flat head screws and thread locker.
3. Mount the motors to the nacelles using four M4x22mm button head screws and thread locker.
4. Temporarily remove the ESC covers and connect the the three motor leads to the ESC leads inside the
nacelles (when you test the motors, if they spins in the wrong direction you can reverse the direction of
rotation by swapping any two leads).
5. Note: Do not install the motor cowlings or the propellers at this point, these will be installed after
radio setup and testing is complete.
Wing Installation
1. Remove the hatch from the fuselage.
2. Install and secure the wing struts on the nacelles using a pin keeper.
3. Insert and roughly center the carbon fiber wing tube in the fuselage.
4. Slide the left and right wing panels onto the tube. Ensure the servos orient to the bottom of the fuselage.
5. Connect the single wing connector from each wing panel to the provided wing harnesses and connect the
wing harnesses to the Aura as specified on page 5 of this guide.
6. Run the motor power lead (with the EC3 connector) into the fuselage and connect each wing to one end of
the provided power lead Y-harness (2 EC3 connectors and 1 EC5 connector).
7. If you have the night version, connect the LED power connectors.
8. Seat the wings completely in the wing saddles and secure the wings using the thumb screws through the
aluminum tabs. Before flight tighten the screws using a Phillips screwdriver.
9. Fasten the wing struts to the fuselage using the retaining pins and pin keepers.
Note: Do not use thread locker on
the bolts holding the push rods to
the servos or the control horns!
Using thread locker will weaken the
plastic, void your warranty and
cause your airplane to crash!
Control Horns
Elevator Rudder
Servo Arms
Elevator Rudder

4
Radio Configuration
The following shows the pre-configured Aura flight modes in the Twin Otter 80E.
Twin Otter 80E Aura Profile
Flight Mode 1: Sport (Gyro Off)
• For safety only.
• Rates and Expos are tuned for general flying.
• Gyro is set to off.
Flight Mode 2: Sport (Gyro On)
• For sport flying.
• Rates and expos are tuned for sport flying.
• Gyro is set to low.
Flight Mode 3: Advanced (Gyro On)
• For advanced aerobatic flight.
• Rates are highest and expos are tuned for 3D flight.
• Differential thrust is used (if enabled via switch).
• Gyro is set to moderately high.
In all flight modes the flaps are coupled with the ailerons for maximum roll rate and authority.
The following table shows the radio configuration required for the Twin Otter 80E:
* The default Aura program has Crow disabled, see the full manual for instructions on using Quick Set to enable Crow.
Connect your serial receiver to the Aura and bind it to your transmitter. Once this is complete proceed with final
configuration.
For more details on compatible receivers, on connecting and binding different receivers, flight modes and radio
configuration download the complete Twin Otter 80E manual (link on the cover page) or visit the Aura Wiki at:
https://wiki.flexinnovations.com/wiki/Aura
Spektrum, Futaba,
JR & Graupner
FrSky
Jeti (EX-Bus)
Wing/Tail Type
1 Aileron, 1 Elevator, 1
Rudder
1 Aileron, 1 Elevator, 1
Rudder
1 Aileron, 1 Elevator, 1
Rudder
End Points
(Travel Adjust or ATV)
Ail/Ele/Rud – 125%
Ail/Ele/Rud – 100%
Aileron/Ele/Rud – 100%
Thro/CH5/CH6 – 100%
Thro/CH5/CH6 – 84%
Thro/CH5/CH6 – 80%
Reversing
Not Allowed
Sub-Trim
Verify at Zero, NOT ALLOWED
Trim Levers
Verify at Zero
CH5 (Gear) – Flight Mode
Assign to a 3 Position Switch
CH6 (Aux 1) – Flaps
Assign to a 3 Position Switch
(Do NOT use Transmitter Flap System)
CH7 (Aux 2) – Differential
Thrust On/Off
Assign to a 2 Position Switch
(We recommend that you use the same switch as you use for throttle cut)
CH8(Aux 3) – Crow*
Assign to a 2 Position Switch
First Flight Timer
For your first flight, set to 4:30

5
Aura Configuration
Aura 8 Auto-Detect
Once your receiver is bound, powered, and connected to the Aura, the Aura will begin the Auto-Detect process to
learn what type of receiver you are using and set itself up for that specific system. Auto-Detect is indicated by a
series of sweeping LEDs of various colors. After Auto-Detect is completed, verify that Aura is on and receiving
data from your receiver by looking at the LEDs on the Aura.
Connecting Battery and Arming ESCs
1. Turn on the transmitter. Lower the throttle stick AND throttle trim to their lowest settings.
2. Ensure the aileron, elevator and rudder gimbals are centered.
3. With the airplane on a solid surface, connect the battery to the ESCs and wait. The ESCs will make the
motors emit a series of audible tones during their initialization process.
4. The ESCs will make the motors emit a short, final tone sequence indicating that the ESCs are now armed
and that the motors will spin in response to throttle stick movement.
ESC Throttle Calibration
In order to map the full range of the ESCs output to your throttle stick motion you will have to perform an ESC
throttle calibration. Both ESCs will calibrate simultaneously so you only need to calibrate once. NOTE: Execute
ESC throttle calibration with the propellers and spinners removed.
1. Power on your transmitter, DISABLE any throttle hold or throttle kill
switches, completely lower the throttle trim and set the stick to
full throttle.
2. Connect the flight pack to your Twin Otter 80E.
3. Listen for the tones coming from the ESCs through the motors, after
about 2 seconds you should hear two tones.
4. Pull your throttle stick back to idle.
5. Listen for the ESC arming tones from the motors.
6. Unplug the flight battery to complete calibration.
Final Radio Setup
Take this moment to finalize the position of the servo arms and pushrod lengths on your elevator, rudder and
nose gear steering and ensure that the motors are spinning in the correct direction, left motor is CCW and right
motor is CW when viewed from the tail of the airplane (swap any 2 wires to reverse motor rotation). Make any
final control surface adjustments as necessary either mechanically or in the Aura, do not use trim or sub-trim.
DEFAULT AURA CONNECTIONS
S1 – Left Throttle
S2 - Right Throttle
S3 – Left Aileron
S4 – Right Aileron
S5 – Elevator
S6 – Rudder
S7 – Left Flap
S8 – Right Flap
Port B – Serial Receiver Input
Mini Port A&B – Remote Receiver Inputs
Mini Port A
Mini Port B
Micro USB Port
Port B
Ready-To-Fly:
Solid Orange LED: Aura On and
Calibrated
Solid Green LED: Aura receiving Valid
receiver data
Possible Errors:
Flashing Orange LED: Aura Moved
During Power Up
No Green LED: Aura NOT receiving
receiver data
Note: After throttle calibration
is complete it is necessary to
reset the failsafe (see your radio
documentation, this may
require a re-bind).

6
Control Direction Test
Refer to the chart below to determine the proper control surface directions, test these in Flight Mode 3. To test
differential thrust, PROPELLERS MUST BE REMOVED and channel 7 must be active (typically throttle hold off).
If any controls are reversed, including the nose gear steering, DO NOT REVERSE CONTROLS IN YOUR
TRANSMITTER OR IN THE AURA CONFIG TOOL. Email us at support@flexinnovations.com for corrective
action. Note that BOTH the Transmitter Control Direction Test AND the Flight Controller Sensor Direction
Test MUST BE PASSED! IF EITHER ONE DOES NOT PASS, DO NOT FLY!
NOTE: There is pre-configured rudder to aileron and rudder to elevator mixing programmed into the Aura.
Simultaneous movement of these control surfaces with rudder input is intentional and completely NORMAL.
Additionally: Aura has a built-in flap system that moves the flaps at a slower speed. There is also flap to elevator
mixing configured in the Aura Flap System. This speed and mixing is intentional and completely NORMAL.
Transmitter
Command
Proper Control
Surface Deflection
Stick Left
Stick Right
Stick Forward
Stick Aft
Stick Left
Stick Right
RUDDER
ELEVATOR
AILERON

7
Aura Sensor Direction Test
Perform a test of the gyro system to verify the corrections made for a given movement are correct. If
any of the tests do not result in the correct reaction from the airplane's gyro system, including
the nose gear steering, DO NOT FLY THE AIRPLANE, and contact us via email at
support@flexinnovations.com
The flight control system activates with RF broadcast. Perform these tests in Flight Mode 3 (higher
gain) for better visibility and then in the remaining Flight Modes. Control surface deflections are
exaggerated in the pictures below for clarity. Please note that the control surfaces will move ONLY
while the aircraft is being ROTATED. To test differential thrust, PROPELLERS MUST BE REMOVED
and channel 7 must be active (typically throttle hold off).
Aircraft
Movement
Proper Control
Surface Deflection
RUDDER
ELEVATOR
AILERON

© 2023 Flex Innovations, LLC. All rights reserved.
Potenza™ is a trademarks of Flex Innovations LLC
DSM®, DSM2™, and DSMX™ are trademarks of Horizon Hobby, Inc.
Futaba is a registered trademark of Futaba Denshi Kogyo Kabushiki Kaisha Corporation of Japan.
Jeti, UDI, and Jeti Model are trademarks or registered trademarks of Jelen, Ing. Stanislav of Czech Republic
HoTT is a registered trademark of SJ, Inc.
Rev. A
Created 07/2023
Completion and Flight Readiness
Once your radio and Aura 8 configuration is complete there are only a few steps left to get your Twin Otter 80E in
the air:
1. Add thread locker to all servo arm screws on all servos (including nose gear steering and wing servos).
2. Install the nose cone using three M2X7mm self tapping screws.
3. Install the cowlings to the motor nacelles using two M2X13mm self tapping screws. Glue the exhaust to
each side of the nacelles using CA or Epoxy.
4. Install the propellers to the motors using the provided washer and nut, note that they are labeled L and R.
5. Install the spinners to the prop adapters using the provided
M3X10mm screw (don’t use thread locker).
6. Move the battery back and forth as necessary to achieve the
desired CG (shown to the right).
Center of Gravity Verification
The Twin Otter 80E does not fly like your typical acrobatic or 3D
model, for that reason it is important that you do not stray from
the recommended CG. Flex has done extensive flight testing to
arrive with this range. In particular, DO NOT fly the airplane more
tail heavy than recommended, it will not perform as expected.
The CG is located between 3-5/16 and 3-3/4 inches (85 and
95mm) from the leading edge of the wing.
First Flight and Quick Trim
We recommend that you fly the maiden flight using Flight Mode 2. Trim the airplane until you achieve straight
and level flight. Once you land execute the below Quick Trim procedure ensuring that you keep Flight Mode 2
selected.
1. Power offthe Twin Otter 80E. Insert a bind plug into Aura Port S3 (you will need to remove the servo lead
that is currently in S3). Check that the transmitter is powered on and re-power the Aura to enter Quick Trim.
2. Wait 5 seconds for the Aura to completely initialize. Confirm Quick Trim mode is active by checking the Blue
LED is slowly flashing.
3. Remove the bind plug to save your trim settings, the Blue LED will now flash quickly indicating the new trim
values have been stored successfully. Power offthe Twin Otter 80E and re-install the servo into port S3.
4. Center all control surface trims on the transmitter.
5. Re-power the Twin Otter 80E, the control surfaces should be unchanged and new trims have been applied.
www. f l e x inno v a tio n s . c o m
Recommended CG
3-5/16 in. - 3-3/4 in.
(85mm - 95mm)
DIFFERENTIAL THRUST WARNING!
The Twin Otter 80E implements differential thrust when in Flight Mode 3, this means that one of the motors can
spool up whenever rudder input is provided or the airplane is rotated. For this reason please follow these
recommendations:
•Never activate Flight Mode 3 until you are ready to take off, this includes taxiing to and from the runway.
•If the battery is plugged in, always handle and carry the airplane with all body parts clear of the propellers.
•We recommend that you assign the differential thrust disable switch to your throttle hold and only
engage throttle when you have cleared the airplane and are ready to taxi and take off.