Frame Material: Carbon Fibre and Fibreglass

Carbon fiber and Fiberglass are two popular materials for quadcopter frames. The choice between carbon fiber and fiberglass depends on many factors, in this article we will look into some of the most important aspects and differences between these materials

Weight

Carbon fiber is lighter than fiberglass, it’s 70% lighter than steel, 40% lighter than Aluminum. The nature of carbon fiber is low in weight, rigid, and strong. This is why most weight-critical performance products use carbon fiber, and it’s a far more popular choice of material for mini quad frames.

Strength vs Rigidity

Rigidity is also known as stiffness. Carbon fiber and fiberglass are both very strong, but Carbon fiber is more rigid. Carbon fiber is about 3 times stiffer than steel and aluminum for a given weight.

In applications where a small amount of flexibility is allowed, carbon fiber is a top choice. Fiberglass is better suited to extreme flex patterns, while carbon fiber has a relatively small flex window.

Toughness

The shape of Carbon fiber doesn’t deteriorate over time. That means the shape of carbon fibre doesn’t change when consistent and constant force is applied on it.

Fibreglass however being more flexible, it means that glass-fiber typically has a higher ultimate breaking point than a similarly shaped carbon fiber product, therefore having higher strength-to-weight ratio. In general it is a “tougher” material. The incredible rigidity of carbon makes it less capable of enduring certain abuses than fiberglass. I guess therefore you could say CF “more brittle”

Thermal and Electrical Characteristics

As opposed to most other materials, carbon fiber has a negative coefficient of thermal expansion which means they don’t expand or shrink as much as fibreglass when the temperature changes. This is a desirable quality for applications that have to operate in a wide range of temperatures .

Fiberglass composites are insulators, which means they do not respond to an electric field and resist the flow of electric charge. Fiberglass composites are very radiolucent, which means they allow radiation to pass through it freely. This makes fiberglass rods a useful material for antennas. CF is conductive and it’s a problem for mini quad frames.

Price

Fiberglass is more cost effective. Long strands of carbon fibers are very difficult and expensive to manufacture, while fiberglass processes much easier. As a result, fiberglass is considerably less expensive than carbon fiber. Fiberglass composites are less expensive than carbon composites in most cases.

More on Carbon Fiber Specification

3K, 6K?

These numbers indicate how many carbon strands per tow are in the weave. Lower the number “K” in carbon sheet the thicker and stronger the weave. To simplify it, 3K is stronger than 6K, 1K is stronger than 3K etc. However, 3K is pretty much the standard weave people use for general applications so if you pick up some random carbon it will most likely be 3K.

Twill Carbon fiber?

Some argue mini quad frame parts should be cut in twill pattern (diagonal shaped pattern), and that could maximize the strength. While others argue it just looks different but still provide the same strength properties. This remains a myth until someone can provide some scientific proof.

5 thoughts on “Frame Material: Carbon Fibre and Fibreglass

  1. Awal Muhammad

    Good morning.
    I feel much pleasure to find this web while I was searching for which material I have to choose for structuring body for for electric car. I have manage the electric motor and other parts.
    I will be more thankful if you let me know whether I have to choose Carbon Fiber or Fiberglass including its specifications.
    Let me know if you can guide me for other materials for mould as different adhesive, resin, tool and CSM and weight etc for carbon fiber / glassfibe.

    Thanks
    Awal Muhammad
    Engineer

    Reply
  2. SamXu

    Hi Oscar Im considering buying some 5045 HQ props that exist in two versions. Glass Fiber Mix (Glass Fiber & Plastic) and Carbon Fiber Mix (Carbon Fiber and Plastic). The price is the same! Wich of them would you recommend?

    Reply
  3. willer

    Still stick to GF rod for my drone arm instead of CF.
    much flexible, cheaper and survival rate higher then CB after crash!!

    Reply

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