Simple propeller for indoor rubber powered models (living room flyer)

11 February 2025

Propeller Blades

Discardable Plastic Cups. I don't know what plastic is used for the clear discardable plastic cups. It is transparent, it could be polystyrene or propylene. It's not important, I just know it would make good propeller blades.

Propeller Spars

Don't need spars if the blades are glued to the propeller hubs.

If propeller hubs are made from thin tubes, with the idea of being able to adjust the blades' angle, then thin carbon fibre rods 1mm in diameter is suitable.

Wire shafts and propeller Hubs

Making propellers with these as motor shafts:

 

DIY Propeller Shafts for Indoor Model Aircraft

These pre-shaped steel wires, originally intended for fishing lures, offer a surprisingly effective solution for creating robust propeller shafts for small rubber-powered model aircraft, including indoor flyers like Living-Room-Flyers (LRFs). Their strength and pre-formed hook make them ideal for this purpose.

Features:

• Pre-formed Motor Hook: The integrated hook simplifies motor attachment or winding.
• High-Strength Steel: The 0.7mm diameter steel wire provides excellent strength and resists bending, even in collisions.
• Ideal for LRFs: The lightweight yet strong wire is perfect for the small, light propellers used in indoor models.
• Cost-Effective: A pack of 20 wires provides ample material for multiple propellers.

Specifications:

• Material: Metal steel wire
• Wire Diameter: 0.7mm
• Length: 65-75mm (Suitable for small propellers)
• Loop Diameter: 4mm
• Quantity: 20 pcs

Construction Notes:

These wires are exceptionally strong and require heavy-duty cutting tools. Standard side cutters may be damaged by the 0.7mm wire. A rotary tool with a cutting disc is recommended but they are noisy.

Propeller Hub Options:

Several hub designs can be used with these wires:

1. Balsa Strip Hub: A traditional method using a 1/8" x 1/8" (or larger) balsa strip (or bamboo or other wood) with chamfered sides for the propeller blades and a central hole for the wire. Secure the wire with a 90-degree bend, thread wrapping, and superglue. For added strength, consider using a thicker balsa strip (e.g., 1/4") to increase the gluing surface for the blades.

2. Balsa Dowel Hub: A more robust option using a 6mm diameter balsa dowel with a hole drilled for the wire. Propeller blades are attached to diametrically opposing saw cuts in the dowel. This design offers superior strength, is easier to drill straight holes in, and readily accommodates three or more blades.

3. Integrated Winding Hook: The pre-formed hook can also be used as a winding hook. Thread the wire through the hub components from the propeller side towards the tail, and then bend the motor hook to the desired shape (e.g., reverse-S, diamond, or round). For this method, create a 0.7mm slot in the balsa strip or dowel to securely position the wire and expose the winding hook.

Important Considerations:

• Cutting the Wire: Standard side cutters are not recommended. Use a rotary tool with a cutting disc for clean cuts. It will be noisy!
• Propeller Material: Lightweight materials are essential for LRF propellers. Avoid using heavy plastic propellers. 
• Hub Strength: Ensure the hub is strong enough to withstand the forces of the rubber motor. The balsa dowel method offers increased durability.

Conclusion:

These pre-shaped wires offer a simple and effective way to create durable propeller shafts for small rubber-powered model aircraft. Their strength, pre-formed hook, and compatibility with various hub designs make them a valuable resource for model builders. Just remember to use appropriate cutting tools and consider the strength requirements of your specific model.