The Flying Tourbillon was the major alteration to the complication. A tourbillon design is mounted using a support system such as a bridge or a prick. Meanwhile, a flying tourbillon is cantilevered. To put it differently, it's supported on just 1 side.
Alfred Helwig, a teacher at the School of Watchmaking created it, in 1920.
The Double-Axis Tourbillon was devised by Anthony Randall in 1977. On the other hand, Richard Good created the initial example a year.