One of my projects I enjoy working on is launching model rockets, both kit designs and 3D printed model rockets. A typical model rocket launch ignition system is a 9V battery connected directly to the motor igniter. I’d been thinking for a while about building a better launch controller. In 2018, tensions between the US and North Korea escalated and gave me inspiration for my launch controller.
My launch controller design is inspired by the nuclear football, the suitcase that allows the President of the US to launch a nuclear attack. It features a multistep ignition procedure:
- Turn on the nuclear football.
- Set mode to internal or external fire control circuit using switch.
- Set countdown time using rotary dial.
- Set arm switch to on.
- Set safety key switch to on.
- Enter the 4-digit authorisation code.
- Open cover and press the big red launch button!
After the arming sequence is complete, the countdown begins, and once it has been completed depending on the configuration, either a MOSFET allows current to flow through the igniter to activate the rocket engine, or a message can be sent via UART for future use with a rocket with its own board igniter system.
The system is designed around the Atmel ATmega328P microcontroller.
