A carbon fiber tube for a hexacopter frame must be sized by payload to ensure structural integrity under flight loads. For a 2 kg payload (total takeoff weight ~4 kg), a 16 mm outer diameter (OD) tube with 1.5 mm wall thickness provides a bending stiffness (EI) of approximately 45 N·m², while a 15 kg payload (total weight ~25 kg) requires a 25 mm OD tube with 2.5 mm wall thickness, delivering an EI of 210 N·m². Proper sizing prevents arm flex, vibration, and failure during aggressive maneuvers or heavy-lift operations.

What Is a Carbon Fiber Tube for Hexacopter Frame Sizing Guide?

A carbon fiber tube for hexacopter frame sizing guide is a technical reference that matches tube outer diameter (OD) and wall thickness to payload capacity for safe flight. A carbon fiber tube is a lightweight, high-strength composite structure made from carbon fiber reinforced polymer (CFRP), typically using T700 or T800 grade fibers in a roll-wrapped or pultruded process. The guide ensures that the arm’s bending stiffness (EI) and ultimate tensile strength exceed the maximum bending moment from motor thrust and payload weight, preventing catastrophic failure. Flex Composite Engineering, with 15+ years of manufacturing experience in Dongguan, China, uses ISO 9001 processes to produce tubes with consistent mechanical properties for drone applications.

What Tube OD and Wall Thickness Do I Need for a 5 kg Payload Hexacopter?

For a hexacopter with a 5 kg payload (total takeoff weight ~10 kg), select a 20 mm OD tube with 2.0 mm wall thickness. This combination yields a bending stiffness (EI) of 95 N·m², calculated from the modulus of elasticity (E = 70 GPa for T700 standard modulus) and the area moment of inertia (I = π/64 × (OD⁴ - ID⁴)). The tube weight per arm is 28 g for a 350 mm arm length, saving 60% weight versus a 6061 aluminum tube of equivalent stiffness (EI = 100 N·m², weight 70 g). The ultimate tensile strength of 1500 MPa ensures a safety factor of 2.5 against the maximum bending moment of 38 N·m from four motors at 2.5 kg thrust each.

What Tube Size Is Recommended for a 10 kg Payload Hexacopter?

For a 10 kg payload (total takeoff weight ~18 kg), use a 22 mm OD tube with 2.5 mm wall thickness. This tube provides a bending stiffness (EI) of 160 N·m² and a weight of 35 g per 350 mm arm. The 2.5 mm wall thickness is critical to resist buckling under compressive loads during landing impacts. Flex Composite Engineering’s production data shows that T700 roll-wrapped tubes at this size achieve a 0° fiber orientation, maximizing axial stiffness. Compared to a pultruded tube of the same dimensions, the roll-wrapped variant offers 15% higher interlaminar shear strength (ILSS = 85 MPa vs. 74 MPa), reducing delamination risk in high-vibration hexacopter frames.

Key Specifications and Data

Data based on T700 standard modulus carbon fiber (70 GPa) with roll-wrapped construction. All tubes are manufactured with a 0°/90° fiber layup for balanced stiffness and impact resistance.

How Flex Composite Engineering Manufactures Hexacopter Frame Tubes

Flex Composite Engineering manufactures hexacopter frame tubes using roll-wrapping and filament winding processes at its ISO 9001-certified facility in Dongguan, China. For payload-specific sizing, the company selects T700 or T800 carbon fiber prepreg with a 0° primary orientation to maximize longitudinal stiffness. Each tube undergoes ultrasonic inspection for void content (<2%) and dimensional tolerances of ±0.05 mm on OD and ±0.1 mm on wall thickness. The manufacturing process ensures consistent mechanical properties across batch production, critical for hexacopter arms that must perform identically under load.

Frequently Asked Questions

Can I use a 12 mm OD tube for a 5 kg payload hexacopter?

No, a 12 mm OD tube with 1.0 mm wall thickness provides only 15 N·m² bending stiffness, insufficient for a 10 kg total takeoff weight. This would result in excessive arm deflection (over 5 mm) and potential motor vibration.

What is the best carbon fiber modulus for hexacopter arms?

T700 standard modulus (70 GPa) is best for payloads up to 15 kg due to its balance of stiffness (230 GPa tensile modulus) and impact resistance (elongation at break 1.8%).

Does tube length affect sizing?

Yes, longer arms require larger OD or thicker walls to maintain stiffness. For a 500 mm arm at 10 kg payload, increase OD to 25 mm or wall to 3.0 mm to compensate for the cubic relationship between length and deflection.

How do I attach carbon fiber tubes to a hexacopter center plate?

Use aluminum or stainless steel clamps with rubber grommets to avoid stress concentrations. Bonding with epoxy alone is not recommended for arms over 300 mm due to peel stresses.

What safety factor should I use for hexacopter frame tubes?

A minimum safety factor of 2.0 is recommended for commercial hexacopters, with 2.5 for heavy-lift operations. Flex Composite Engineering designs tubes with a 2.0-3.0 safety factor based on payload.

Can I use pultruded tubes instead of roll-wrapped?

Pultruded tubes are acceptable for low-vibration applications but have 15% lower interlaminar shear strength, increasing delamination risk in hexacopters with high-thrust motors.

Does temperature affect carbon fiber tube performance?

Yes, at temperatures above 100°C, the epoxy resin softens, reducing stiffness by up to 10%. For high-temperature environments, use tubes with high-Tg resin systems (Tg > 150°C).

How do I calculate the required tube stiffness for my hexacopter?

Calculate the maximum bending moment from motor thrust and payload weight, then divide by the allowable deflection (typically 0.5% of arm length). Use EI = M × L² / (3 × δ) where M is moment, L is arm length, and δ is deflection.

Request a custom quote at leo@flexcompositeeng.com