The Audemars Piguet Royal Oak Selfwinding Flying Tourbillon Extra-Thin RD#3, reference 26670ST.OO.1240ST.01 (if you can keep 20-character alphanumeric reference numbers in short- and long-term memory, bless you, because I can’t) landed with maybe a little less impact than it deserved when it launched last April. There are probably several reasons why. First of all, I think a lot of us were still suffering from a bit of Royal Oak overload from the announcement of the ref. 16202 Jumbo when it launched in January, along with several other models (including a non-Jumbo flying tourbillon). Secondly, the Jumbo Tourbillon RD#3 appeared in the context of a larger world in which Bulgari more or less owns the community mindshare of ultra-thin self-winding tourbillons. As astonishing as that might have been a couple of decades ago, there is little doubt that in 2022, it’s tough to make a splash with an ultra-thin tourbillon unless you have managed to unseat Bulgari. And not only is no brand challenging them, nobody even seems inclined to try. It’s telling, though, that to set their record, Bulgari had to unseat Audemars Piguet, and moreover, an AP watch that dropped back in 1986: The AP caliber 2870 self-winding tourbillon, which reigned as the undisputed champion of ultra-thin automatic tourbillons for over three decades until Bulgari came out with the Octo Finissimo Tourbillon Automatic, in 2018. While there’s no gainsaying Bulgari’s technical achievements, AP’s new Royal Oak Tourbillon does represent what is probably the single longest lineage in horology of automatic tourbillon wristwatches. For many years, Audemars Piguet has been using basically the same tourbillon – that is, the same cage, balance, and escapement, as well as the same upper tourbillon bridge – in all of its tourbillon watches. The bridge has a distinctive, inverted “V” shape, and the cage has three arms, with a free sprung balance fitted with poising and timing screws on its outer edge. Minus the upper bridge, this is the same tourbillon used as recently as the Royal Oak Flying Tourbillon 26730, launched in January of this year. It’s also the tourbillon used in the Code 11.59 collection’s automatic flying tourbillon chronograph. The new Audemars Piguet Royal Oak Selfwinding Flying Tourbillon Extra-Thin RD#3, on the other hand, uses a new configuration for its tourbillon, and moreover places a flying tourbillon, for the first time, in a Jumbo case. The RD#3 has exactly the same dimensions as the Jumbo – 39mm x 8.1mm. To get a flying tourbillon into the Jumbo case, AP had to develop a new tourbillon movement. The Royal Oak Flying Tourbillons introduced earlier this year use the AP caliber 2950, which is 31.5mm x 6.24mm, and it has a larger case than RD#3, at 41mm x 10.6mm. The RD#3, on the other hand, uses the caliber 2968 – a smaller movement, at 29.6mm x 3.4mm, which is considerably flatter than the 2950. For comparison, Bulgari’s caliber BVL 288, used in the Octo Finissimo Tourbillon Automatic, is 1.95mm thick, but it’s also larger in diameter than AP’s caliber 2968, at 36.60mm which is getting into smaller pocket watch caliber territory. It’s sort of like squishing a jelly donut – you can flatten it but it’s going to spread out at the same time. This means that Bulgari’s Octo Finissimo Tourbillon Automatic has to be a little larger in diameter, at 41mm. The AP caliber 2968 isn’t the flattest automatic tourbillon in the world, but you do have to bear in mind that unlike the BVL 288, it’s not a peripheral rotor caliber. Instead, it’s a full rotor movement, and it’s almost exactly the same size as the caliber 7121 used in the new 16202 Royal Oak, which is 29.6mm x 3.2mm. In fact, the caliber 2968 looks quite a lot like a re-engineered 7121, including the arrangement of the automatic winding train and the position and configuration of the mainspring barrel.