Heavy Line F421 21” Carbon Fiber FPV Drone Frame

The Heavy Line F421 21” carbon fiber FPV drone frame is engineered for large-scale builds using propellers up to 21 inches. An 830mm wheelbase paired with a 4-arm True-X layout forms the foundation for a high-power FPV platform.

The structural core is manufactured from 3K carbon fiber, featuring full-length reinforced arms. An arm thickness of 10 mm combined with robust carbon profiling handles extreme torque and thrust forces from heavy-duty motors and oversized props.

Reinforced arms preserve structural geometry during high vibrations and sudden load fluctuations. Carbon motor mounts prevent arm flex during aggressive maneuvers, minimizing the risk of propeller-to-frame strike.

The central section is also reinforced with an expanded surface area of 180 × 180 mm. It serves as a mounting deck for main power components, battery packs, or specialized payloads. With assembled dimensions of 630 × 630 × 65 mm, the frame provides ample working room. Total frame weight is 1100 g, a crucial consideration during component selection.

The Heavy Line F421 carbon frame is tailored for surveillance platforms, radio communications relays, and signal repeaters requiring extended hover endurance. Additionally, it suits long-range delivery drones capable of carrying payloads up to 8 kg.

Flight stack mounting uses a standard 30.5 × 30.5 mm (M3) pattern. The frame is designed for 42xx and 60xx size motors, with motor installation secured via a Ø25–Ø32 mm pattern with four M4 screws.

Package Includes:

• Top plate IP27 F415-F421, 3 mm — 1 pc.
• Bottom plate IP27 F415-F421, 3 mm — 1 pc.
• Cover plate F421, 3 mm — 1 pc.
• Bottom X-brace F421, 5 mm (with press nuts) — 1 pc.
• Top X-brace F421, 5 mm (with press nuts) — 1 pc.
• X-brace F421, 5 mm — 2 pcs.
• Arm F421 21″, 10 mm — 4 pcs.
• Plate with press nut, 3 mm — 4 pcs.
• Spacer shim, 10 mm — 4 pcs.
• M3×8 Flat head screw — 8 pcs.
• M3×8 Button head screw — 2 pcs.
• M3×8 Socket head cap screw — 2 pcs.
• M3×10 Button head screw — 4 pcs.
• M3×26 Socket head cap screw — 1 pc.
• M3×30 Socket head cap screw — 4 pcs.
• M4×30 Socket head cap screw — 4 pcs.
• M4×25 Socket head cap screw — 20 pcs.
• M3×50 Socket head cap screw — 4 pcs.
• M2.5×6 Button head screw — 2 pcs.
• M2×4 Button head screw — 4 pcs.
• M2×8 Button head screw — 2 pcs.
• M3×14 Button head screw — 2 pcs.
• M3×18 Socket head cap screw — 2 pcs.
• M3 DIN934 Nylon lock nut — 12 pcs.
• DIN934 Metal nut — 4 pcs.
• Black aluminum standoff, 20 mm — 4 pcs.
• Black aluminum standoff, 32 mm — 6 pcs.
• Video Transmitter (VTX) Bracket — 1 pc.
• Quick-release VTX Mount — 1 pc.
• Left Camera Front Standoff — 1 pc.
• Right Camera Front Standoff — 1 pc.
• Left Camera Damper — 1 pc.
• Right Camera Damper — 1 pc.
• Left Control Antenna Mount — 1 pc.
• Right Control Antenna Mount — 1 pc.
• Rubber Pad Set — 1 set

For orders of 1000+ units, pricing is negotiated individually. Please contact us for a custom quote.

• Frame Class (Propeller Size): 21″ (compatible with props up to 21 × 6.5″)
• Wheelbase (Motor-to-Motor): 830 mm
• Geometry: True-X (4 arms)
• Material: Carbon Fiber (3K pressed, directional fibers)
• Arm Thickness: 10 mm
• Plate Thickness: 3 mm (bottom), 3 mm (top)
• Central Section Size: 250 × 45 mm
• Stack Mounting Pattern (FC/ESC): 30.5 × 30.5 mm (M3)
• Motor Mounting Pattern: Ø25–Ø32 mm (4 × M4)
• Motor Compatibility: 42xx, 60xx
• Assembled Dimensions: 630 × 630 × 65 mm
• Weight: 1100 g