Flyfans SU‑57 Twin 70 mm EDF Jet Assembly Guide

This is the general ARF kit build procedure (always follow your printed paper manual first) Spec note: This SU‑57 uses two 70 mm ducted fans, recommended battery 6S 22.2V 5000mAh–5800mAh LiPo, EC5 battery connector.

Initial Control Surface & Setup Specs

Pre‑assembly checks

1. Unpack all foam fuselage, wing, tail parts, hardware bag, landing‑gear set, decal sheet.
2. Inspect foam for shipping cracks; repair small foam cracks with hot‑glue or foam‑safe CA.
3. Lay out servos, two ESCs, twin 70 mm EDF units, receiver before starting assembly.

Important: Do NOT use regular cyano super‑glue directly on EPO foam; use foam‑safe CA or hot glue.

Step 1: Install horizontal & vertical stabilizers

1. Locate the slots at rear fuselage for vertical fins. Slide each vertical stabilizer into the fuselage tail slots, secure with the provided self‑tapping M3 screws.
2. Fit the full‑flying horizontal stabilators. Insert the metal hinge pins first, then mount both left‑right horizontal stabs. Tighten the retaining screws gently — do not over‑tighten, they must pivot freely.
3. Attach the horizontal stabilator servo pushrods to the control horn ball‑links.
4. Power on your radio, set all sticks to neutral, then adjust pushrod length so horizontal stabilators sit perfectly level at neutral.

Step 2: Main wing assembly & carbon wing spar

1. Pass the thick carbon fibre wing spar through the fuselage spar tunnel.
2. Align left and right main wing onto the fuselage; push wings fully home onto the spar.
3. Secure wing roots to fuselage with M3 self‑tapping screws from the underside.
4. Connect the wing servo extension leads through the fuselage. Secure servo extension plugs with tape so they cannot rattle loose in flight.
5. Set aileron servos to radio neutral, adjust aileron pushrods so ailerons are flush with wing surface.

Step3: Twin 70 mm EDF & ESC installation (critical step)

1. Route ESC wires forward from the rear EDF bays toward the central battery compartment.
2. Slide each complete 70 mm EDF fan unit into its rear fuselage EDF cradle.
3. Before screwing fans down: test fan rotation!
   • Connect one ESC at a time to battery, give a tiny throttle blip. Both fans must spin the same direction (looking from rear, clockwise or both counter‑clockwise).
   • If one fan spins backwards, swap any two of the three motor‑ESC power wires to reverse rotation.
4. Once rotation direction confirmed, fasten both EDF units using the black M3 self‑tapping screws into the foam mounting formers. Fit the rear exhaust nozzle pieces.
5. Mount the two ESCs inside the fuselage side bays; leave small air gaps for ESC cooling. Secure ESCs with hook‑loop tape or zip‑ties.

💡 Twin ESCs: Program each ESC individually, set soft start, brake OFF. Do NOT mix ESC settings.

Step4: Landing gear installation (if retract version)

1. Fit metal landing‑gear struts into the designated mounting pockets in wings / nose bay.
2. Route retract servo wires forward toward receiver cavity.
3. Check gear cycles fully up & down by testing from your transmitter. Ensure no foam is blocking gear movement.

Step5: Receiver & wiring

1. Place your receiver inside the forward battery compartment, use double‑sided foam tape for vibration isolation. Keep receiver away from high‑current EDF power cables to avoid radio interference.
2. Connect all servos (aileron, stabilator, retracts) to receiver channels.
   • If using separate ESCs for each fan: throttle channel can use a Y‑harness to run both ESCs from one throttle output. Best practice: Some pilots use two separate throttle channels and radio mixing to sync twin EDFs.
3. Secure all loose wiring with zip‑ties, prevent wires from rubbing against moving control surfaces.

Step6: Canopy, pitot tube & decals

1. Install the cockpit canopy. This model’s canopy usually fits with small screws or magnetic retention.
2. Carefully insert the thin pitot tube into the nose tip.
3. Apply scale decals after airframe assembly is fully finished.

Step7: Centre of Gravity (CG setting — extremely important for first flight!)

Recommended CG for Flyfans SU‑57 twin‑70 mm: ~90‑96 mm back from the leading‑edge of wing root (confirm with your manual).

• Place battery forward / backward inside battery tray with hook‑loop strap to adjust CG.
• Balance the jet by supporting it at the CG points with your fingertips; nose should drop very slightly, not tail‑heavy. Tail‑heavy will cause violent pitch‑up on take‑off.

Step8: Final radio check before first flight

1. Transmitter ON first, then connect flight battery.
2. Check movement directions:
   • Aileron: right stick right → right aileron goes up.
   • Elevator: pull back stick → stabilators deflect upwards (nose up).
3. Slowly advance throttle, verify both EDF spool‑up smoothly together, no strange grinding noise.
4. Double‑check all screws (wing, tail, fans, landing gear) are secure.

Common build pitfalls for this SU‑57

Make both EDF spin same direction. Opposite rotation will create huge yaw on take‑off.

Do not over‑tighten foam screws — they will strip the EPO foam.

Prioritise correct CG; this large twin‑EDF jet is unforgiving if tail‑heavy.

Secure all servo leads, vibration can dislodge plugs during high‑speed flight.