Rocket Motors in Stick Rockets - Core Burner vs End Burner

Fireworks rockets (also known as stick rockets) typically use core-burning motors instead of end-burning motors because core-burning motors produce significantly higher thrust over a shorter duration, which is essential for the stable and efficient flight of the rocket. Here's why this design choice is preferred:

1. Higher Thrust for Lift-off

• Core-burning motors: These burn propellant along the length of a hollow core, exposing a larger surface area to combustion. This results in a higher burn rate and greater thrust.
• End-burning motors: These burn propellant only at the exposed end, resulting in a much slower burn rate and lower thrust over a longer duration.
• Reason for stick rockets: Stick rockets need an initial high thrust to overcome gravity and stabilize quickly during ascent. Core-burning motors provide the rapid acceleration required to achieve this.

2. Stability During Flight

• Initial boost: The high thrust generated by a core burner helps stabilize the rocket during the critical initial phase of the flight, minimizing the chance of tumbling or erratic behavior.
• Stick contribution: The stick acts as a passive stabilizer, and a fast lift-off ensures the aerodynamic forces stabilize the rocket more effectively.

3. Performance Efficiency

• Core-burning motors allow the rocket to reach higher altitudes in a shorter amount of time because of the rapid release of energy. Stick rockets are typically small and lightweight, so a short-duration, high-thrust motor is ideal for their design.

4. Practical Considerations

• Size and weight: End-burning motors would require a larger motor casing and more propellant to achieve the same altitude as a core burner, making the rocket heavier and more cumbersome.
• Cost-effectiveness: Core-burning motors use propellant more efficiently for achieving altitude and stability, which is beneficial in terms of material usage and performance.

By using a core-burning motor, stick rockets achieve the necessary thrust-to-weight ratio and stability for a successful launch, while also being lightweight and cost-effective to manufacture.

In a conversation with Fernando Macedo, from Macedo's Pirotecnia (Portugal), he told me that almost all stick rockets in Portugal use core burner motors, while the end burner motors are mostly used for set pieces fireworks (catherine wheels, etc).