Flywheels are typically made of steel and rotate on conventional bearings; these are generally limited to a revolution rate of a few thousand RPM. Some modern flywheels are made of carbon fiber materials and employ magnetic bearings, enabling them to revolve at speeds up to 60,000 RPM (1 kHz). Carbon-composite flywheel batteries have recently been manufactured and are proving to be viable in real-world tests on mainstream cars.
1925: The Tri-State Tornado. Indiana was one of three Midwest states in the path of the deadliest tornado in American history. On March 18, 1925, the Tri-State Tornado traveled a record 219 miles on the ground from Missouri through Illinois and into Indiana, where it struck Posey, Gibson and Pike counties.
Alabama No. 1 in F5 tornadoes and fatalities. The states with the most F5/EF5 tornadoes, the most violent, are, according to the Storm Prediction Center in Norman, Okla.: Alabama: 8 Oklahoma: 7 Iowa: 6 Kansas: 6 Texas: 6. The Top 10 states in the number of tornado deaths, using Storm Prediction Center records from 1953-2014, are: Alabama: 620 Texas: 530