BLiMS (Brake Line Manipulation System)

BLiMS, the Brake Line Manipulation System, is a parachute guidance system developed for the Cornell Rocketry Team’s 2025 rocket. By pulling on the brakelines of a square parafoil, BLiMS navigates the team’s 19 foot long, 150 lb rocket to a GPS waypoint as it a descends from a 10,000’ apogee.

System Overview

A detailed, 50-page technical report is availible at the bottom of this page going into every aspect of the design and validation of BLiMS. I recommend checking that out for further insight into the project.

BLiMS is basically a miniature skydiver. Onboard, it has a single high-power BLDC motor connected to a pair of counter-rotating spools to extend and retract the brakelines of our rocket’s square parafoil. When the brakelines are pulled, the shape of parafoil changes allowing for left and right turns. An onboard PID controller uses GPS and altimiter data to guide the rocket to a predetermined landing point. Given the weight of the rocket and extreme deceleration during parachute inflation, BLiMS was deisgned to withstand >4,500 lbs of loading while still retaining complete control over the parachute.

I designed the entire mechanical system, as well as simuluated and selected the motors, motor drivers, and battery systems. Other members of CRT wrote the firmware, controller, and machined the actual components.

BLiMS was designed in the spring and summer of 2024. It was revised that fall, after which it was manufactured and assembled. It flew succesfully for the first time in January 2025. A second validation flight was launched in March of 2025, after which it was handed over to the software team for guidance control. Its official (and final) flight took place at IREC 2025 in Texas, where it succesfully returned our rocket to the designated landing point. Photos and videos of BLiMS working are below.

Mechanical

BLiMS uses the following components:

• Motor: ODrive D6374 150KV BLDC
• Motor Driver: ODrive Pro
• Motor Encoder: 16384 CPR Absolute RS485 Encoder (AMT212B-V-OD)
• Batteries: 9x 18650 Molicel P28A Li-Ion Cells
• Gearing: 10:1 Worm Gear and Worm

Detailed descriptions for how the system works are availible in the Technical Report at the end. The system were designed in CAD (Fusion360 and Solidworks), simulated and verified with Ansys, manufactured on a mix of manual and CNC mills, and tested on several high powered sounding rockets.

Photos of System

Photo of the assembled BLiMS

CAD cross section of BLiMS

Custom python simulation of BLDC motor

BLiMS connected to the parachute

Photos from Test Launches

Installing BLiMS into the rocket

BLiMS loaded into the airframe

Carrying the rocket to the launch pad

Rocket on the rail prior to launch

Rocket launch

L3 Launch #1 GPS Data

L3 Launch #2 GPS Data

Technical Report

Below is a detailed technical report I wrote for BLiMS, which dives deeper into the simulation and mechanical/electrical design.