The Audemars Piguet Royal Oak Self-winding Flying Tourbillon Extra-Thin RD#3 Is The Next Evolution Of AP’s Automatic Tourbillons

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.

In order to fit the tourbillon cage into a Jumbo case, AP had to change several elements of the tourbillon cage from the classic version used in the caliber 2950 in the standard Royal Oak Selfwinding tourbillons. The caliber 2950 has an overcoil balance spring, while the newer caliber 2968 has a flat balance spring (most ultra-thin watches don’t have overcoil balance springs as the overcoil adds height). The balance in the 2968 has timing weights on the inside of the balance rim (in the 2950 they’re traditional weights on the outside of the rim) set flush with the rim. The balance arms have steps milled into them, which form a sort of recess that lets the balance spring sit closer to the balance – another height-saving measure.

One other notable difference is that while the 2950 uses conventional screws to fix the upper part of the tourbillon cage in place, the 2968 uses spline bolts, which usually take up less room than screws (although I’m not sure if this is the purpose here as I don’t have the dimensions for the bolts vs. the screws available). There are also cut-outs in the pillars of the tourbillon cage, which provide extra clearance for the balance rim, allowing AP to use a larger balance (this is also one of the benefits of the internal flat-rim weights). Finally, the tourbillon cage is driven via gear teeth on its outer edge. This is a so-called peripherally driven tourbillon. A traditional tourbillon carriage is driven via a pinion on the underside of the cage. Driving the cage directly from its edge produces a savings in height as well.

As we’ve said, the caliber 2968 is not the world’s flattest automatic tourbillon, but at 3.4mm thick, it’s pretty damned flat for a full rotor automatic tourbillon – to get any thinner than that you have to start using either a micro-rotor or a peripheral rotor. Before Bulgari’s Octo Finissimo automatic tourbillon came along, the thinnest automatic tourbillon (after the AP 2870) was the Breguet Classique Tourbillon Extra-Thin Automatic 5377, whose movement has a peripheral rotor and is 3mm thick (and again, it’s very wide at 36.10mm). Looked at in context, AP’s ability to make a full rotor automatic flying tourbillon which is only 0.4mm thicker than a much wider recent record-holder with a peripheral rotor starts to look a lot more interesting.

And aesthetically? What can I tell you, it’s a Jumbo, 39mm x 8.1mm, with that lovely Bleu Nuit, Nuage 50 dial. The only classic Jumbo element missing from the RD#3 Jumbo Tourbillon is the AP logo at six o’clock, but it seems a reasonable thing to lose if you’re going to have an open dial flying tourbillon. If you like the Jumbo, you’re probably going to like the Royal Oak Selfwinding Flying Tourbillon Extra-Thin RD#3, unless the idea of an open dial flying tourbillon is just not your brand of vodka. Comparing ultra-thin automatic tourbillons can be a little tricky – it helps to know the history of the complication and it also helps to understand that a full rotor movement compared to a peripheral rotor movement is fair on one hand, but on the other hand it’s also a little bit of an apples-to-oranges comparison. Seen from that perspective, RD#3 is a beautiful, very well-thought-out piece of contemporary watchmaking.