Every pump-fed liquid rocket engine has to answer one question: what spins the turbopump? US11008977B1, granted to Firefly Aerospace on May 18, 2021, answers it with a tap-off cycle — a "liquid rocket engine tap-off power source" that bleeds hot gas from the main combustion chamber itself to drive the turbine.
The CPC is squarely in liquid-rocket territory: F02K 9/48 (feeding of propellants to combustion chambers), with F02K 9/42, 9/44, 9/46, 9/52, 9/62, and 9/64 spanning turbopump, gas-generator, and chamber arrangements. Naming inventor Thomas Markusic, Firefly's founder, on the patent underscores that this is core engine IP, not a peripheral.
The mechanism is the cycle itself. A gas-generator engine burns a little propellant in a separate small combustor to make turbine drive gas — extra hardware, extra plumbing. A staged-combustion engine runs a preburner at high pressure — efficient but complex and expensive. A tap-off cycle skips both: it takes already-burning gas from the main chamber, routes it through the turbine, and dumps it. You lose a little performance; you gain a much simpler, cheaper engine.
That trade is the dependent-claim story and the company story at once. Firefly is a low-cost-launch player, and the tap-off choice is a thesis about market position — cadence and unit cost over peak specific impulse. The cycle you pick is a statement about who you are trying to undercut.
The standard caveat applies: the tap-off cycle is old art in the abstract (the Space Shuttle Main Engine used a tap-off for one function), so the claim is necessarily about Firefly's specific implementation, not the concept. For an analyst, the value of the record is confirmation that Firefly's engine architecture is built around manufacturability — and that its founder put his name on the IP that encodes it.