Flying tourbillon

The flying tourbillon differs from the classic tourbillon in one precise constructional detail: the cage is anchored on one side only, without the upper closing bridge. The technique was perfected in 1920 by the German watchmaker Alfred Helwig, and since then it has remained one of the most copied and most misunderstood solutions in high watchmaking.

In the traditional tourbillon, the cage is held between two bridges, one lower and one upper: a solid, geometrically stable structure that nonetheless obstructs the view of the mechanism. Removing the upper bridge frees the view completely, but introduces a genuine engineering challenge: the cage's upper pivot must bear alone the stresses that, in a balanced system, are distributed across two points. The solution lies in tighter tolerances, lighter materials and, often, cages in titanium or exotic alloys that reduce the rotating mass.

From the bench, I have seen this construction have two immediate effects: on the aesthetic side, the cage appears suspended in mid-air, an effect that works best on open or skeletonised dials; on the technical side, reducing the cage's mass lowers the moment of inertia and can favour thinner movements. The Bianchet Rotondo UltraFino reaches a height of 3,85 mm partly thanks to this choice. Piaget, which I know well from my years working on those ultra-thin calibres in the Seventies, used this logic systematically.

The flying tourbillon can be fixed in position, as in the Audemars Piguet Code 11.59 at 6 o'clock, or orbiting: in the Jaeger-LeCoultre Master Grande Tradition calibre 948 it travels across the entire dial in 24 hours, becoming itself a time indicator. There is also the inclined variant, as in the David Candaux DC7, where the cage is tilted by 30° relative to the dial plane to compensate for the effects of gravity across multiple wearing positions.

A related but distinct concept is the flying governor, the speed regulator of minute repeaters: a similar name, a completely different function. It controls the rhythm of the chimes, not the precision of the balance wheel. The flying carousel in Ulysse Nardin's Freak also takes up the idea of a structure without an upper bridge, but applies it to an entire segment of the movement that acts as a hand.

Be careful with terminology in catalogues: «flying tourbillon» and «tourbillon volant» always indicate the same thing; «orbital tourbillon» adds the rotating motion around the dial, which is a further, separate complication.