Boeing Airplane Research Paper
There are proper units used for design of airplanes - I expect USA measures to be used in Boeing airplanes, and Airbus be metric - Russian airplanes are metric as well (and fly in metric airspace - speeds and altitudes) .
You would be surprised how well pilots, mechanics (engineers) cope with different units .
and also when soviets copied the B-29 to produce Tu-4, "sheet aluminum in thicknesses matching the B-29's imperial measurements were unavailable. The corresponding metric-gauge metal was of different thicknesses. Alloys and other materials new to the Soviet Union had to be brought into production. Extensive re-engineering had to take place to compensate for the differences, and Soviet official strength margins had to be decreased
You would be surprised how well pilots, mechanics (engineers) cope with different units .
and also when soviets copied the B-29 to produce Tu-4, "sheet aluminum in thicknesses matching the B-29's imperial measurements were unavailable. The corresponding metric-gauge metal was of different thicknesses. Alloys and other materials new to the Soviet Union had to be brought into production. Extensive re-engineering had to take place to compensate for the differences, and Soviet official strength margins had to be decreased