The front page of the NY Times for 18 April 1957 has an article on inertial navigation. The previous day, Charles Stark Draper gave a talk describing the trip he made in 1953, Boston (Hanscom) to LA in a B-29 using inertial navigation. The article says the mechanism “simulates the Schuler pendulum”, the latter being a pendulum with length equal to Earth’s radius.
Never heard of that. Has the INS that’s been common in aircraft for decades ever done that?
(The article doesn’t say whether the mechanism controlled the plane itself, or just told the pilot where he was.)
ETA even today, AFAIK mechanical gyrocompasses have not completely disappeared from ships and 'planes, although I am not sure to what extent, so do not quote me on that. Of course, today you can get fiber-optic gyroscopes and laser velocity meters, but also various MEMS devices.
Inertial navigation systems have largely been supplanted by GPS.
The bizjet I fly has an Inertial Reference System (actually several, for redundancy), but these are laser devices, not a big box of spinning gyroscopes of years prior. Our IRS does a number of jobs, but navigation is a secondary function. It’s the primary source of attitude information, being much more sensitive than the old mechanical units.
I would assume our laser IRS units do something akin to Schuler Tuning, but that’s beyond my pay grade as a mere pilot.
I never heard of this before, but there’s a Wikipedia page on “Schuler tuning”
A pendulum the length of the Earth’s radius is impractical, so Schuler tuning doesn’t use physical pendulums. Instead, the electronic control system of the inertial navigation system is modified to make the platform behave as if it were attached to a pendulum.