Rocket 4 is a two-stage liquid fueled rocket. The first stage is powered by two licensed Firefly Reaver engines, and the second stage is powered by a single Hadley Ursa Major engine. The first flight is scheduled for late 2023.

For it to count as a launch the rocket needs to complete the countdown sequence and the holdown clamps need to release. A scrub won't count as a launch. Achieve orbit means the rocket reaches orbital velocity.