Composite Motor Development

The CU Boulder Sounding Rocket Laboratory’s Composite Motor Development team brings together our expertise in solid rocket propulsion and composite manufacturing to create custom solid rocket motors at an unprecedented scale for a student team. We’ve accumulated a wealth of knowledge over the past three years of the program, and have static fired upwards of two dozen composite motors, ranging in diameter from 1 inch to 10 inches.

O class motor static fire 1/16/2021

Current Projects

6″ 1 Grain motor

6″ 6 Grain “Mamba” Flight motor

10″ Spaceshot Flight motor

R Class Motor Dev

Since the beginning, Composite Motor Development has had one end goal: an inexpensive and lightweight motor capable of getting us to space. The R motor is a 10-inch diameter, all carbon fiber casing beast with 250 pounds of propellant capable of producing over 10,000lbf thrust, accelerating the SpaceShot vehicle to 35 Gs at liftoff. SRL completed and static fired our first R class motor in February 2020, in hopes of securing an FAA waiver to fly SpaceShot soon after. However, propellant deficiencies and inadequate adhesion of the thermal protection system led to an overpressure event and loss of the motor. After this test, SRL decided to step back and take a more stepped approach to everything that goes into making an R motor, including its materials, design, propellant manufacturing, and all fabrication methods. Currently, SRL is in the process of scaling up to 6″ motors and then later this year static firing our 10″ R motor again

R Motor Faliure 2/08/2020

What We Do

The composite motor team is responsible for designing, manufacturing, and testing the propulsion systems that power all of SRL’s solid-fueled motors. Our long-term goal is to create low-cost and lightweight carbon fiber motors to enable frequent research flights from the CU community. We work with new materials such as carbon fiber, kevlar, ceramics, and more to develop casing and nozzle designs as we improve motor technology. Composite motor rapidly designs, builds, tests motors to scale up to the R class booster powering Spaceshot.

98mm Test and Dev Motors

The first solid motors SRL ever produced and tested were with 38mm diameter propellant grains in an aluminum casing, producing 25 lbf thrust for just over 2 seconds. Although the team quickly grew out of these into much larger motors.

Consistent and reliable propellant performance has been a struggle of SRL from our first motors, but this past year with the help of some of our sponsors we have identified and eliminated all of the things causing problems with our propellant and completed a vigorous 15-motor characterization campaign in our 1 Grain 98mm aluminum casing before moving up to a 3-grain motor, then a 6-grain 60% scale test of our Mamba flight motor!

98mm 1-grain characterization motor Feb 2023
60% scale of our Mamba Flight motor (48″ Length) April 2023