What was a major historical factor that delayed the widespread adoption of liquid methane as a primary launch propellant?

Answer

Established infrastructure, legacy knowledge, and the significant capital investment required to switch from mature $ ext{RP-1}$ systems.

The aerospace industry had decades of experience and supply chains built around $ ext{RP-1}$. Transitioning to cryogenic methane involved significant development risk and capital investment, slowing its adoption until newer, complex engine technologies matured.

What was a major historical factor that delayed the widespread adoption of liquid methane as a primary launch propellant?
fuelrocketpropellantcombustionMethane