Flying Tourbillon – a whirling hour-hand

  • Hybris Mechanica tourbillon master
The Master Grande Tradition Grande Complication is the only high-end watch to use a flying tourbillon to indicate sidereal time. This extraordinary feature is controlled by a complex mechanism beneath the dial, which is itself divided in three different levels: the lowest is a disc turning once every 24 hours with a sun marking the hour at the outer end. On top of this circles a second blue lacquered disc depicting the star chart of the northern hemisphere, on which the flying tourbillon is mounted. In this construction, the flying tourbillon hovers above the movement with the sky-chart- – which itself is mounted on a ball-bearing mechanism and eight jewels to ensure smooth operation. In this construction, the flying tourbillon hovers above the movement with the sky-chart – which itself is mounted on a ball-bearing mechanism and eight jewels to ensure smooth operation. Contrary to traditional construction comprising both lower bridge and upper bridges, a flying tourbillon is fixed to the movement side only and thus features only one pivot. In all, the tourbillon of the Grande Complication comprises 73 parts, measures 12.42 millimetres in diameter and is 3.85 millimetres thick. Built of ultra-lightweight titanium, the cage is reduced to its bare functional essence, providing an unobstructed view at the escapement system and mounted on a lubricant-free ceramic ball bearing. The 10-millimetre monometallic balance-wheel with its regulation screws and its Breguet-type overcoil balance-spring has an inertia of 11.5 mg x cm2 and beats at a high frequency of 4 Hertz. The silicon parts of the escapement are therefore clearly visible, like the lever with its integrated pallets and the escape wheel. This latter features a completely new design for reasons of lightness and operating efficiency. The lever with integrated pallets has a straight shape for better aerodynamics. Using silicon parts that require no lubricants not only improves the long-term precision of the watch, but also reduces the inertia of the components by about a third in comparison to the classically used steel, yielding a 15 percent increase in the efficiency of the whole movement.