Flex innovations FlexJet Pro 90 mm User manual

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 
Instruction Manual

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BEFORE CONTINUING WITH THIS INSTRUCTION MANUAL OR ASSEMBLY OF YOUR AIRCRAFT, PLEASE
VISIT OUR WIKI SUPPORT SITE FOR THE LATEST PRODUCT UPDATES, FEATURE CHANGES, MANUAL
ADDENDUMS AND FIRMWARE OR CONFIG FILE CHANGES FOR THE AURA PROFESSIONAL ADVANCED
FLIGHT CONTROL SYSTEM.
HTTP://wiki.flexinnovations.com/wiki/FlexJetPro90

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The FlexJet Pro 90 mm combines fast jet performance with modern aerodynamics. The stiff and clean airframe
excels at traditional jet aerobatics, while the modern aerodynamics with features such as Leading Edge Root
eXtensions (LERX’S), and Dog Tooth leading edges allow an extended angle of attack range.
The trailing-link landing gear is forgiving on takeoffs and landings. And the wing spar carries through the fuselage
making the aircraft stiff and strong.
The carefully engineered full flow ducting is efficient at high and low speeds
Specifications:
Wing Span 1127mm (44.4 in.)
Length 1486mm (58.5 in.)
Weight (without battery) 4.9kg (10lb 13oz) With 8S 6200 40C Battery
Radio Transmitter 6*-9 Channel
*Retracts (CH5) and Flaperons (CH6) are considered standard.
(4 Servos for LG Doors and Nose Wheel Steering and 3 Retracts with high quality trailing-link Struts and a
Sequencer are included.)
Non-Aura users can also program transmitter for dual elevators for a 7th channel. Optional Wheel Brakes are an
8th channel.
Aura users would typically use 7 transmitter channels (8 with wheel brakes).
*Aura users can fly with a 6 channel transmitter and put flaperons on a flight mode (and use the same transmitter
channel (6)/Tx Switch for Aura Flight Modes and Flaperons. Wheel brakes would not be practical with 6 channels.
Aura users need a minimum of a six channel receiver with working serial output. Receiver ports for Throttle and
Retract Landing Gear will be used, other flight controls can be plugged directly into Aura.
NOTE: the recommended 90mm EDF range is 8S and about 2800 to 3600 Watts. 6S setups are likely possible, but
have not been evaluated by Flex Innovations as of this writing. Higher Wattage setups have not been tested and
would void any and all actual or implied warrantees.
Required Equipment:
Transmitter: 6* channel (7-9+ channel preferred)
Receiver: 6*-9+ channel HV capable (8+ channel with serial output recommended)
Servos: 5 high performace mini servos: (2) Flaperons, (2) Stabs/Elevator, (1) Rudder
7-10kg/cm torque, metal gear, digital. (FPZDS11106BLHV recommended)
Receiver Battery: 2S LiPo 1400-2200 15C+. (FPZBR20002S55 recommended)
90mm EDF Unit: As chosen (FPMDFJP908S Flex 8S 90mm by JP - recommended)
ESC: As Required for your power system
(V-Good 120A HV –recommended (FPZEDFVG8S120BEC) -Disable BEC)
Power Battery: As chosen
8S 6200 mAh 40C –highly recommended (FPZB62008S40C)
8S 4000 mAh 75C –also works if you have available (FPZB40008S75C)
Miscellaneous:
(3) 24” servo extension leads (Elev, Elev, Rudd)

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(3) 12” servo extension leads , Rx Battery)
1/8” to 3/16” (3-5mm) Striping tape for fan to duct shimming
2-sided mounting tape
Hook and loop tape
Hook and loop straps
Clear vinyl tape
Recommended Optional Equipment:
Aura 8 AFCS 3-axis gyro (FPZAURA08 recommended)
Battery Charger ISDT T8 (ISDTT8)
Main Wheels with Brakes Includes brake controller (FPMWB55)
Tools:
Drill and Bits (1/16” or 1.5mm)
Hobby knife
Phillips Screwdriver
Hex Drivers: 2.5mm, 2mm
Sandpaper
Masking tape
Adhesives:
Thin CA
Medium CA
15 minute epoxy
USING THIS MANUAL
This manual is divided into sections to make the assembly of the airplane easier to follow. Note the boxes next to each
step to help you keep track of the steps that have been completed.
ATTENTION
Read the ENTIRE instruction manual to become familiar with the features of the product before operating. Failure to
assemble or operate the product correctly can result in damage to the product, personal property, and cause
serious or fatal injury.
All instructions, warranties and other collateral documents are subject to change at the sole discretion of Flex Innovations,
LLC. For up-to-date product literature, please visit our website at www.flexinnovations.com and click on the support tab for
this product.
WARNING
This is NOT a toy. This product is not intended for use by children under 14 years without direct adult supervision.
IMPORTANT INFORMATION REGARDING WARRANTY
Please read our Warranty and Liability section before building this product. If you as the Purchaser or user are not prepared
to accept the liability associated with the use of this product, you are advised to return this product
immediately in new and unused condition (in the original packaging) to the place of purchase.
SAFETY WARNINGS AND PRECAUTIONS
Protect yourself and others by following these basic safety guidelines.
1. This manual contains instructions for safety, operation and maintenance. It is essential to read and follow all the
instructions and warnings in the manual, prior to assembly, setup or use, in order to operate correctly and avoid
damage or serious injury.

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2. In some cases, the written instructions may differ slightly from the photos. In those instances, the written
instructions should be considered correct.
3. This model is not a toy, rather it is a sophisticated hobby product and must be operated with caution and common
sense. This product requires some basic mechanical ability. Failure to operate this product in a safe and responsible
manner could result in injury, or damage to the product, or other property.
4. This model must be assembled according to these instructions. Do not alter or modify the model outside of these
instructions provided by Flex Innovations, LLC, as doing so may render it unsafe and/or unflyable. You must take
time to build straight, true and strong. It is your responsibility to ensure the air worthiness of this product.
5. Use only compatible, appropriate components for the final assembly of this model. Ensure that the radio system is in
functional condition, that the engine is appropriately sized for the model, and that all other components are
appropriate for use in this model as specified in this instruction manual. All components must be installed correctly
such that they operate correctly both on the ground and in the air.
6. Inspect and check operation of the model and all its components before every flight.
7. If you are not an experienced pilot, or have not flown a high-performance model before, it is recommended that you
seek assistance from an experienced pilot in your R/C club for your first flights. If you're not a member of a club, the
Academy of Model Aeronautics (AMA) has information about clubs in your area whose membership includes
experienced pilots.
8. Keep the propeller area clear from such items as loose clothing, jewelry, long hair, or tools, as they can become
entangled. Keep your hands and body parts away from the propeller as injury can occur.
SPECIAL LANGUAGE DEFINITIONS
The following terms are used throughout the product literature to indicate various levels of potential harm when operating
the product.
NOTICE: Procedures, which if not properly followed, create a possibility of physical property damage AND a liable or
no possibility of injury.
CAUTION: Procedures, which if not properly followed, create a probability of physical property damage AND a
possibility of serious injury
WARNING: Procedures, which if not properly followed, create the probability of property damage, collateral
damage, and serious injury OR create a high probability of serious injury.
ATTENTION:
Before assembling your FlexJet Pro, please visit our WIKI Support
page for the latest information and documentation.
HTTP://wiki.flexinnovations.com/wiki/FlexJetPro90
Carefully unpack your FlexJet Pro and inspect the parts. Review the manual and gather the needed tools and
supplies.

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Wing and Rudder Assembly
NOTE: The ailerons can also be used as flaperons. We will refer to them as ailerons during the assembly process.
1. Use sandpaper to clean up the 3 horns and rough up the gluing area near the base.
2. Open the slots for the 3 control horn in the Ailerons and Rudder. Trial fit and use a sharp #11 hobby
knife to carefully remove the covering in the area around the horns as shown.
3. Glue the 3 horns into the 3 surfaces with 15 minute epoxy. Be sure to use a small stick to coat the
inside of the hole thoroughly, and apply a thin layer to the lower part of the horn. Form a small fillet
around the base of the horn.
4. Check the fit of the hinges and fit the ailerons to the wings. Make sure the hinges are centered fore
and aft. Check the fit of the wing to the fuselage and make sure the Ailerons are centered Left to Right
with a gap at each end.

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5. Use thin CA to carefully glue each hinge from each side of the wing. Make sure the glue wicks into
the slot. Use a tissue to blot away any excess glue.
6. After about 10 minutes re-apply a small amount of thin CA to each hinge and blot away any excess.
Let cure and give a good tug (about 8 pounds force) on each control surface to confirm it is secure.
7. Repeat steps 4 to 6 to install the Rudder onto the Fin. The gap at top between the fin and the rudder
balance tab is about 2mm.
8. Select arms for your aileron servos of about 18mm length hole to center. Center the servo and install
the arm. If your servo has a metal output gear, put a small amount of blue thread lock on the screw
threads, blot away any excess, and install the screw while avoiding getting thread lock on the plastic arm.

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9. Assemble three linkages as shown. Jam nuts are provided for the clevises. Use blue thread lock on all
metal to metal threaded joints to make them secure and to prevent play and thread wear over time.
10. Fit the servo to the servo hatch as shown noting the slot orientation above and just below. Use the
correct drill for your servo screws (typically about 1/16” or 1.5mm) to drill the servo mounting holes.
Screw the servo to the inside of the hatch using the screws provided with the servos.
11. Drill though the hatch into the wing mount with a 1.5mm (1/16”) bit. Secure the hatch with the
2mm x 6mm Philips washer head sheet metal screws.
12. Install the linkage and adjust so the control surface is centered.

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13. Connect a 600mm (24”) extension to the Rudder servo and run it through the tube in the fuselage. It
will soon be plugged into the Aura or receiver as configured. Tip: Use dental floss with several knots to
secure the servo lead to the extension.
14. Repeat steps 10 to 12 to install the Rudder linkage, noting the servo/hatch orientation. (Choose hole in
servo arm about 18mm from center.)
EXPERT TIP: After installing the servo hatches, remove them and put a little thin CA in the screw holes, then
re-install the hatches. This will form more secure and longer lasting threads.
15. Fit the missile rails to the wing tips. Secure them lightly with 3mm x 12mm socket head cap screws.
After fitting, you can disassemble it an apply thin CA to the screw’s hole in the rails wood to strengthen it.
The screw only needs to be snugged very lightly! The included optional missile rails are removeable for
transport.
Landing Gear:
The high quality electric landing gear installed in your FlexJet Pro is fully HV capable including the sequencer, the
retracts, and the door and steering servos. The optional wheel brakes work on HV (2S LiPo) as well.
The sequencer takes a receiver input (typically channel 5 is used) that simply provides switching. This input is does
not have any proportional requirement or function.

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1. Plug the sequencer can directly into your receivers Channel 5 port.
2. Program the transmitter’s channel 5 to a 2-position switch, and set the travel to about 110% to make
sure it passes the switching threshold (you can reverse later based on your preference).
3. With the receiver bound and functioning and the transmitter On, apply the Rx power. The retract
switch will need to be cycled once to arm the retracts each time the model is powered up. Cycle the
retracts to the UP position. Inspect the linkages. The linkage should pass very near the servo arm’s
‘center’. This keeps the servo from seeing any significant torque load when doors are up.
4. Adjust the linkage as needed ½ turn at a time until the doors are well closed, but without binding or
stalling. If any binding/stalling is suspected, power down, and disconnect the doors servo leads…
reinstall them one at a time while adjusting the linkage to prevent binding.
NOTE: Make sure the servos are not stalled. They will burn out over time if left in a stalled condition.
5. Lower the Landing gear. Check that the linkage is not binding and the servo is not stalled. Clear away
anything causing the door or linkage to bind so the door is open and free.
NOTE: If significant adjustments are needed, unplug the doors that are not being worked on to keep the
servos from a stalled condition.
NOTE: The nose gear door and the left main door are connected to the servo 1 port of the sequencer by Y-
harness. The right main door is connected directly to the sequencer’s servo 2 port. Servo ports 1 and 2 are
reversed in direction from each other.

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Equipment Installation:
1. Mount the retract sequencer with 2 sided tape or hook and loop tape. The location above the right air
intake is recommended.
2. Mount the receiver and antenna’s according to your manufacturer’s recommendations. We suggest
mounting the receiver with hook and loop tape. This will allow access later for installing additional items.
3. Temporarily install the removeable battery tray to aid in locating equipment.

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4. If you are using and Aura 8 AFCS, mount it now using the included mounting tape. Never use hook and
loop to mount a gyro system. It is not stable enough. The fixed platform at the back of the battery tray is
the recommended location. Make the required connections to your receiver. In the final assembly stages
you should further secure your Aura with a strap of hook and loop material.
Install the Elevator Servos
1. Connect the elevator servo leads to the 600mm (24”) servo extensions. Secure the junction so it
cannot be unplugged. TIP: Use dental floss to tie the servo lead/extension junction together.
2. Fit the elevator servos into the servo mounts in the aft fuselage as shown in steps below noting that in
most photos in the sequence the models is inverted in a stand.
3. Use a 1/16” (1.5mm) drill and a pin vise to drill/clean pilot holes.
4. Screw the servos in using the screws provided with the servos.
5. Run the extensions through the tube in the fuselage to the forward part of the model. Plug into the
Aura or receiver as configured. You can also plug the Rudder servo in at this time.
6. Assemble the Elevator linkages as shown. Jam nuts are provided.
7. Use blue thread lock on all metal to metal pushrod threads.

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Install the Stabs and Elevator Linkages
1. A servo arm hole of not longer than 15mm radius should be used. Install the linkages onto the servo
arms.
2. Center the servos and install the servo arm. (Do not install the arm center screws yet, as you can
remove the arms to adjust the length of the linkages. Be sure to secure the center screws once
adjustments are complete). Put threadlock on metal to metal connections ONLY. In the case of the center
servo screw with metal gear servos, put a very small amount of threadlock on screw and keep theadlock
away from the plastic arm.
3. Trial fit the Stab parts. Assemble the pivot axles into the stabs and lightly snug the 3mm x 8mm SHCSs.
Do not over-tighten as you could strip the threads.
4. Slide a circular shim over each stab axle.
5. Insert the stab assemblies into the bearings being careful not to dislodge the inner bearings. Install a
second circular shim over each stab axle.
6. Check the balance of the stab. It has leading edge weight applied at the factory. The stab should
balance level or pivot slightly to the nose/leading edge. If it needs weight in the nose, add weight such as
solder to the front corner and epoxy in place to make it balance as noted.
7. Fit the stab arms onto the splines. Connect the linkages to the outermost stab arm holes (25mm).
8. Power up the radio and carefully check the function of the stabs. Remove one of the arms and turn the
clevis and arm to adjust the length of the pushrods for correct perpendicular geometry. (Final very minor
tuning can be accomplished later with Aura sub-trim (or Tx sub-trim if not Aura equipped)
9. Remove the stabs from the aircraft and disassemble the axles from the stabs. Clean the axles with
isopropyl alcohol.
10. Put a couple of drops of 15 minute epoxy into the axle holes in the stabs, then twist the axles into
place. Put a small drop of epoxy into the screw holes then install and moderately snug the 3mm x 8mm
SHCS screws. This will permanently secure the axle into the stab.

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TIP: You can install the stab arm and ‘rotate’ the parts to the most vertical position possible while the glue
cures.
11. After the epoxy is cured, install the stab to the fuselage using the circular shims as before.
12. Use a toothpick to place three tiny drops of epoxy about the side of the head of a pin equally spaced
around the spline of the stab. Install the stab arm in the correct orientation and secure it very snuggly
with the provide socket head sheet metal screw using the provided 2mm hex wrench.
NOTE: The epoxy on the spline removes any possibility of rotary play in the arm assembly. The arm typically
can be removed later if desired by removing the screw and gently flexing the arm back and forth.
13. Connect the stab linkages making sure the length is properly adjusted. You can make any further
adjustments to the length by removing the servo arms from the servos. You do not need to disconnect the
clevises or stab arm.
14. Secure the servo arms to the servos with the screws provided with the servos. Tighten securely. (Put a
very small amount of blue thread lock on the metal to metal servo screw threads. Avoid getting
threadlock on the plastic)
15. Install the 1mm x 6mm x 65mm stab trimmer strip by gluing it to the trailing edge of the stab about
20mm from the root end. Top surface only. This mandatory strip helps by pre-loading the stab in high
speed flight.

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Prepare and install the ESC
1. Check the length of the ESC wire and make sure the length can reach from the ESC location to the fan
location. Adjust as needed.
2. Install the proper plug-in connectors between the ESC and the Motor. Flex used 4mm bullets on the
motor side on the prototypes, the JP supplied bullets are also good. Flex uses EC5 connectors for the
Battery to ESC connection.
3. If your ESC is equipped with a BEC, DISABLE it by removing and taping back the center red ‘+’ wire on the
ESC’s “throttle” lead. (A 2S LiPo will be used to power the receiver and accessories)
4. Assemble the included plywood ESC mounting parts.
5. Temporarily fit the plywood battery tray into the fuselage and Mark the location of the aft mount. This
will later allow you to attach the ESC mount furthest back, without interfering with the tray mounting.
6. Check the fit of the ESC and mount in the aircraft. Adjust the height of the mount if needed. The ESC
should be close to (4-6mm) the belly of the plane near the back side of the cooling air intake. You can add
extra 2-sided tape between the ESC and the mount if it is too far away.

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7. Glue the ESC Mount to the bottom of the battery tray.
8. Double-check that the wiring is sufficient to reach the Fan/Motor. Note that the V-Good 120A ESC is small
and can temporarily pass back through the former temporarily for wire connection.
9. Set the parts aside until after the Fan is installed.
Install the Aft Inlet Duct and Fan and ESC
1. Remove the fiberglass fuselage tail-cone by removing the (3) 3mm x 12mm SCHS and set the parts
aside.
2. Use sandpaper to clean rough edges on the aft inlet duct. Clean-up the front and back edges to allow
easier installation.
3. Remove the fans aft center body fairing and set aside. On the JP made fans this is a normal thread.
4. Remove the fans front ‘bell mouth’ if equipped and store it. (It is not used for the FlexJet’s full flow
ducting). On the JP made fans the bell mouth is a reverse thread.
5. Use some 1/8” to 3/16” (4 to 5mm) wide automotive striping tape to make several turns around the
front of the fan. Test fit to the duct till it fits close, but freely. It does not need to be tight. This feature
prevents wear on the fiberglass duct and allows different fans to be fitted.
NOTE: There is a NOTCH on the back portion of the fan mounting lug. This permits the tailpipe to slide
over that outside of the fan shroud.

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6. Install the Aft Duct through the very back of the fuselage. Sleeve the Aft Duct to the forward duct.
(final parts may vary slightly from photo)
7. Fit and install the fan with (2) 3mm x 12mm SHCS with 3mm washers. (Extra holes are provided to aid
in accommodating other fans.)
8. Plug the Motor and ESC wires together. The wire basically wraps around from the above (top) the duct
at the front, to below (bottom) the duct at the back.
9. Connect the radio and flight batteries and use the transmitter to carefully run the motor at high idle. If
the thrust does NOT come out the back of the model, remove the fan as needed and switch any 2 motor
wires.
10. Use quality vinyl tape to secure the aft duct to the fan, and the aft duct to the forward duct.

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11. We recommend gluing two-sided hook and loop strap to the mount as shown. Then apply thick two-sided
foam tape to the mount.
12. Attach the ESC to the mount/tape and secure with the hook and loop strap.
13. Bolt the battery tray into the model with (4) 3mm x 12mm SHCS and (4) 3mm washers.
Install the Tailpipe
1. Re-install the fan’s center body fairing (Some users prefer to save the weight and run without it.)
2. Fit the tailpipe over the OUTSIDE of the fan unit. Temporarily secure with a piece of masking tape.
NOTE: if the tailpipe is slightly loose on the fan, you can shim the inside of the tailpipe or outside of the
fan with a bit of striping tape
3. Install the fiberglass tail-cone using the (3) 3mm x 12mm SHCS’s that were removed earlier.

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4. Remove the temporary masking tap and adjust the tailpipe fore and aft until it is flush with the tail-
cone aft edge. Secure the tailpipe to the fan unit with quality vinyl tape.
Install the Ventral Fins and Fan Hatch
1. Test fit the ventral fins on the aircraft using the fixture parts provided.
2. Remove the fins. Use coarse sandpaper to aggressively scuff the sockets in the fuselage.
3. Rough up the corresponding covering on the fins with coarse sandpaper.
4. Perforate the covering in multiple places with a #11 knife.
5. Carefully wick thin CA into the perforations to strengthen the fin and the covering adhesion.
6. Apply 15 minute epoxy to the mating surfaces and assemble with the fixture. Let cure thoroughly.
7. You may optionally apply clear vinyl tape to the bottom of the fins, aft fuselage, and tail cone to
improve wear.
8. Secure the fan hatch with clear vinyl tape.
Attach the Wings
1. Install (2) 12 inch extensions for the Flaperons (Ailerons).
2. Slide the carbon spar through the fuselage.
3. Install the wing panels and secure with (2) 3mm x 12mm SHCS and 3mm washers.
Assemble the Cockpit
1. Apply the instrument panel to the cockpit deck.
2. If you are adding a pilot figure of your choice, you can install it at this now.
3. Install the cockpit deck into the canopy. If there is any interference, remove the deck and clear the
interfering part of the deck away.

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Center of Gravity and Receiver Battery Install
1. The CG is located 105mm aft of the front corner of the wing. You can apply a piece of masking tape to
the model and mark it on both sides of the fuselage for the balancing process. After first flights, pilots can
adjust the CG fore and aft up to 6mm per their preference.
2. Temporarily install your plywood receiver battery mount.
3. With the model completely assembled and the gear down, place your motor battery in the model in a
convenient location.