BIG RED

Design

Big Red 1 was originally designed and built in 2022 by the Founding Leads of Illinois Tech Rocketry. It was meant to fly at Mojave that summer, but the launch failed due to avionics issues. After that, the rocket was basically abandoned. In Fall 2023, I decided to take over the project. 

At first, this was one of the hardest projects I’ve worked on. My background was always in solid propulsion and motor design, not electronics — and definitely not dual-stage design or simulation. On top of that, there was little to no documentation for the rocket, so I had to figure things out myself: how to design and simulate a dual-stage rockets, how to set up avionics, and how to make it safe and reliable.

When I took over Big Red 1, there were a lot of constraints I had to work with. The motor was already selected and loaded — a less-than-ideal choice for a booster motor with a regressive thrust curve and a thrust-to-weight ratio of only ~7:1. Since I couldn’t change the motor, I had to optimize everything else. 

• Sanded down old layup and shorten the sustainer by removing 3ft of payload tube. 

  • Improved aerodynamic stability (the old design was overstable) 

  • Reduced mass, increase altitude, TWR and off-rail velocity

• Sanded down and refinished the existing composite layup to reduce unnecessary weight and drag

• Redesigned the avionics bay. The sustainer avionics handle sustainer ignition, and the booster handles stage separation. This eliminated the need to run ignition wires between stages, preventing hot-staging.

• Eliminated inter-stage wiring by routing the sustainer igniter internally via JST connectors between the motor and body tubes, all the way up to the avionics bay

These changes helped bring the rocket closer to its optimal flight profile, improving both stability and thrust-to-weight ratio — making the most out of a current motor selection.

Avionics

The avionics bay was completely redesigned. Instead of running ignition wires between booster and sustainer (which risked hot staging), I let sustainer avionics handle sustainer ignition and booster avionics handle stage separation. The sustainer igniter runs from the motor nozzle through the motor mount up to the avionics bay via a JST connector. 

Both the sustainer and booster avionics bay carry two flight computers for redundancy: 

• TeleMega V5 – Main flight computer. Chosen for GPS capability, live telemetry, and multiple sensors (accelerometer, barometer, gyroscope). 

• Blue Raven – Backup flight computer. No GPS, but it has Bluetooth for ground testing and gyros for tilt-angle lockout (most small flight computers only have baro + accel). 

Both computers run on completely separate batteries, wiring, and switches. If TeleMega fails at any point — separation, ignition, or parachute deployment — Blue Raven takes over immediately. 

For switches, I switched to pull pins instead of rotary switches for safety and convenience. I also used a 5-pull-pin arming sequence to isolate power, pyro, and ignition circuits. This allows full system checks before arming charges or igniters, minimizing the chance of accidental ignition.

• Power: TeleMega, Blue Raven 

• Pyro: TeleMega only (separated from power to allow safe functionality checks) 

• Igniter: TeleMega and Blue Raven

When arming, I always connect the e-match first, power up the flight computer to confirm continuity, and then load the black powder. That way, we don’t risk loading charges into a dead channel. 

Sustainer Ignition Safety Locks 

For sustainer ingitions, there are several lockout conditions to prevent premature or unsafe ignitions. 

• Altitude lockout: 70% of predicted ignition altitude (prevents premature ignition and/or igniting on the pad). 

• Velocity lockout: 400 ft/s (about 4× off-rail velocity, ensures the rocket has enough momentum). 

• Tilt lockout: 30° (a bit more lenient since sustainer ignites above 10,000 ft). 

• Timer: 17 seconds after the launch

In flight, with an N2000W booster, the rocket would leave the rail at ~87 ft/s. About 16 seconds in, 8 seconds after booster burnout, the sustainer separates at ~14,000 ft. One second later, TeleMega ignites the sustainer. If TeleMega fails, Blue Raven ignites it 0.5s later. The reason for the quick handoff is to keep momentum; waiting too long/extra coast  would cause the sustainer to lose speed and tilt over. 

These parameters ensure ignition only occurs under stable and safe flight conditions, minimizing the risk of failure or off-nominal behavior.

LAUNCH

Despite my best effort to fix Big Red 1, I made one critical mistake: I didn’t double-check the rail button placement. For some reason, the rail buttons on sustainer and booster didnt align, meaning their fin set were also misaligned. 

On December 13th, 2023, Big Red 1 launched in Mojave, CA. Due to a misaligned rail button, a few seconds into the flight, the rocket spun off the pad and hit the tilt lockout immediately. Fortunately, all lockouts and safety systemsworked as intended. The rocket was fully recovered without damage. While the design wasn’t perfect, Big Red 1 taught us invaluable lessons to design Big Red 2.

Launch Setup