[Paper Review] Measuring thrust and predicting trajectory in model rocketry

Michael Courtney, Amy N. Courtney|ArXiv.org|Mar 9, 2009

Experimental and Theoretical Physics Studies1 references3 citations

TL;DR

This paper presents a low-cost, accessible method for measuring rocket motor thrust using common force sensors and data acquisition systems, enabling accurate trajectory prediction through numerical integration in spreadsheets. The approach is validated in both college and high school physics settings, demonstrating practical application of dynamics and calculus principles in real-world model rocketry experiments.

ABSTRACT

Methods are presented for measuring thrust using common force sensors and data acquisition to construct a dynamic force plate. A spreadsheet can be used to compute trajectory by integrating the equations of motion numerically. These techniques can be used in college physics courses, and have also been used with high school students concurrently enrolled in algebra 2.

Motivation & Objective

• To develop an accessible, low-cost method for measuring thrust in model rocket motors using common laboratory equipment.
• To enable accurate trajectory prediction using numerical integration of equations of motion in a spreadsheet environment.
• To provide a hands-on educational tool for teaching physics concepts such as force, acceleration, and motion in high school and college classrooms.
• To bridge theoretical physics with practical experimentation by linking measured thrust data to predicted flight performance.
• To demonstrate the feasibility of using consumer-grade sensors and open-source tools for quantitative physics education.

Proposed method

• Thrust is measured using a dynamic force plate constructed from a common force sensor and data acquisition system.
• The force sensor records motor thrust over time, producing a thrust curve that is logged and analyzed.
• A spreadsheet is used to numerically integrate the equations of motion, accounting for thrust, gravity, and drag.
• The integration process computes velocity and altitude as functions of time, enabling trajectory prediction.
• The method incorporates drag estimation based on empirical data and standard aerodynamic models.
• The system is designed to be implemented using off-the-shelf components and accessible software, suitable for educational labs.

Experimental results

Research questions

• RQ1 How can thrust curves of model rocket motors be accurately measured using affordable, accessible equipment?
• RQ2 To what extent can trajectory predictions be improved by using measured thrust data instead of assumed constant thrust?
• RQ3 Can numerical integration of equations of motion be effectively taught and applied in high school and introductory college physics courses?
• RQ4 How does the inclusion of drag and variable thrust affect the accuracy of predicted apogee altitude?
• RQ5 What is the educational impact of hands-on thrust measurement and trajectory prediction in physics instruction?

Key findings

• The force sensor-based thrust measurement system provides reliable and repeatable thrust curves for standard model rocket motors.
• Trajectory predictions generated via spreadsheet-based numerical integration closely match observed flight performance when accurate thrust and drag data are used.
• The method is successfully implemented in both high school and college physics courses, demonstrating its pedagogical utility.
• Students gain practical experience in data acquisition, numerical methods, and physics modeling through direct experimentation.
• The approach enables meaningful engagement with calculus and physics principles without requiring advanced computational tools.
• The study confirms that even basic data acquisition systems can yield sufficient precision for educational trajectory prediction in model rocketry.