How Lend-Lease joined British technology to American scale

British designs could shorten American research and development, while American factories could turn mature designs into mass-produced equipment faster than Britain could alone. The arrangement therefore exchanged development time as well as finished equipment. Packard-built Merlin engines show American industry absorbing a British powerplant and producing it at scale. American use of Spitfires, Mosquitos, and other British aircraft illustrates that technical knowledge flowed west even while weapons and industrial capacity flowed east.