A Flying Tourbillon is a tourbillon whose cage is supported only from below, cantilevered from a single point rather than pinned between an upper and lower bridge. Alfred Helwig developed it in 1920 while teaching at the German School of Watchmaking in Glashütte. Doing away with the top bridge leaves the rotating balance and escapement completely open, so the cage appears to hover above the dial. Visually it is far more dramatic than a classic tourbillon, but it is harder to engineer, since a one-sided bearing has to carry all the weight and absorb every shock from a single anchor.
The purest modern example is the Bvlgari Octo Finissimo Tourbillon Automatic. Its BVL 288 calibre is just 1.95mm thick, with a peripheral rotor and a flying tourbillon riding on a ball bearing; the titanium version runs around £94,000 and the platinum considerably more. At Watches and Wonders 2025 Bvlgari pushed further with the 1.85mm Octo Finissimo Ultra Tourbillon, the world's thinnest, at 750,000 euros in a run of 20. Glashütte Original's Senator Tourbillon (for instance ref. 1-94-03-04-04-04) sits around £76,000 and carries the Helwig lineage directly. For a more attainable entry, the TAG Heuer Carrera Chronograph Tourbillon runs about £28,000 in a series of 200.
When buying, look first at how the cage is held: on a true flying tourbillon there is no visible upper bridge and the cage seems to rise off the dial. Quality shows in the ball-bearing system, the anglage along the cage's edges, and how steadily the balance keeps amplitude as the cage turns. These are engineering statements rather than ornaments, so expect involved servicing, slightly more shock sensitivity than a fixed escapement, and a price weighted toward what you can actually see. If thinness matters most, the Octo Finissimo wins; if balanced German finishing appeals, look to the Senator.
At the entry level, Chinese makers such as Sea-Gull offer their own in-house flying tourbillon calibres (the ST8007, turning at six o'clock, is one) from roughly a thousand pounds; the finishing trails Swiss work, but it is a sensible way to live with the mechanism. At the top, Breguet's Expérimentale 1 tests the limits of the type with a constant-force magnetic escapement and a flying tourbillon spinning at 10Hz.