With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Andrew Jackson was a United States president.
text_B: The staged combustion cycle is a power cycle of a bipropellant rocket engine .. power cycle. Liquid-propellant rocket#Engine cycles. bipropellant rocket. bipropellant rocket. engine. Rocket engine. In the staged combustion cycle , propellant flows through multiple combustion chambers , and is thus combusted in stages .. combustion chambers. Rocket engine#Combustion chamber. combusted. combustion. Also called topping cycle and preburner cycle , its main advantage relative to other rocket engine power cycles is high fuel efficiency , measured through specific impulse , while its main disadvantage is engineering complexity .. engine. Rocket engine. fuel efficiency. fuel efficiency. specific impulse. specific impulse. engineering complexity. reliability engineering. Typically , propellant flows through two kinds of combustion chambers ; the first called preburner and the second called main combustion chamber .. combustion chambers. Rocket engine#Combustion chamber. In the preburner , a small portion of propellant is combusted , and the over-pressure produced is used to drive the turbopumps that feed the engine with propellant .. engine. Rocket engine. combusted. combustion. turbopumps. turbopump. In the main combustion chamber , the propellants are combusted completely so to produce thrust .. combusted. combustion. thrust. rocket#Physics. The fuel efficiency of the staged combustion cycle is in part a result of all propellant ultimately flowing to the main combustion chamber ; contributing to thrust .. fuel efficiency. fuel efficiency. thrust. rocket#Physics. The staged combustion cycle is sometimes referred to as closed cycle , as opposed to the gas generator , or open , cycle where a portion of propellant never reaches the main combustion chamber .. The engineering complexity is partly a result of the preburner exhaust of hot and highly pressurized gas , particularly when oxidizer-rich , produces extremely harsh conditions for turbines and plumbing .. engineering complexity. reliability engineering
not_related.