Dead reckoning needed probably because they lost vacuum and gyro power to instruments, which then spin down and float randomly if there’s no battery backup Ine

Dead reckoning needed probably because they lost vacuum and gyro power to instruments, which then spin down and float randomly if there’s no battery backup Inertial Navigation System... a mechanical system which maintains position by double integrating acceleration, which means infinitesimal errors grow to dominate over time, and so need to be recalibrated often. a, v0 maybe vectors; x maybe a point insead of a number x(t) = a(t)*t^2 + v0*t + x0 Modern human-portable INSes for adventuring/surveying use laser ring gyros, and GPS when available.