Introducing: The Aquanaut Travel Time Ref. 5650G “Patek Philippe Advanced Research”

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One of the most interesting technical presentations this year came from Patek Philippe, whose Advanced Research Program announced two new innovations. This is the sort of thing that, unfairly or not, tends to take a back seat to more quickly graspable hot news. However, it’s something worth paying attention to. The two innovations announced aren’t necessarily super sexy at first glance, but they offer, on the one hand, a new system for activating a complication that uses no conventional pivots; and as well, a new method of forming a balance spring that allows Patek to offer shockingly good rate stability: just -1/+2 per day, in general production watches. That’s news.

The Patek Advanced Research Program

The Patek Advanced Research Program is part of a much larger story, which is the development of silicon components for use in watchmaking. Much of the original research into silicon components took place at the Centre Suisse d’Electronique et Microtechnique (CSEM) and was underwritten by a consortium that included Rolex, Patek Philippe, and the Swatch Group (all of which have in subsequent years adopted the technology for production watches). The Advanced Research Program at Patek Philippe is essentially an outgrowth of its participation in the CSEM group, and the very first practical expression of that program was announced in 2005, when the first Patek silicon component – an escape wheel in a proprietary silicon dioxide formulation known as Silinvar – was announced, along with a Silinvar escape wheel. These components are cut from silicon wafers with a fabrication process known as DRIE (Deep Reactive Ion Etching). 

silicon wafer watch components

The advantages of silicon are well known – its surface hardness (twice that of steel) and smoothness means it’s possible to manufacture interacting mechanical watch components that don’t require oils, and which can be fabricated with extreme precision as well. This was also the year that Patek released its first Advanced Research Project watch: the ref. 5250 Annual Calendar, in which the Silinvar escape wheel was first used. 

The ref. 5250 Annual Calendar, with Silinvar balance and escape wheel, from 2005.
The first Advanced Research movement, caliber 315 S IRM QA LU.
The first Patek Philippe silicon component: a Silinvar escape wheel.

Though silicon is sensitive to temperature changes, it’s possible to produce formulations that don’t have that property; Silinvar is one such formulation. The word has some deep roots in watchmaking, by the way; it’s related to the name Invar, which is the term for a special nickel-iron alloy with a very low tendency to expand when heated. ("Invar" is from "invariable," as in, invariable dimensions regardless of temperature.) It was invented in 1896 by Charles Guillaume, who would win the Nobel Prize for it in 1920; Invar went on to be widely used in scientific instruments and in watch and clockmaking (high precision pendulum regulators often had Invar pendulums). 

However, probably the the single biggest news in the entire story arc was the introduction of the Spiromax balance spring the next year. Made of Silinvar, the Spiromax balance spring was formed in such a way as to give the advantages of a conventional Breguet or Phillips overcoil balance spring – basically, better isochronism than that obtainable from a flat spring – but with less height; all other things being equal, a Spiromax balance is one third the height of an overcoil balance spring. Spiromax springs are unaffected by magnetism, and with a mass much lower than Nivarox, less affected by external shocks, or gravity. The Spiromax balance spring was first released in a limited edition of 300 pieces in the ref. 5350 Annual Calendar but it’s now widely used by Patek Philippe, in virtually all its watches other than high complications.

The Annual Calendar ref. 5350.
The Spiromax balance spring.

The reason I say "biggest news" is because the balance spring has such an enormous impact on timekeeping. The introduction of the balance spring to watchmaking, by Christiaan Huygens, in the late 17th century, was really what made precision portable horology possible after all and watchmakers have been chasing improvements ever since. If you look at the Spiromax, by the way, you’ll see a slightly thickened region at the outer terminal coil; this "boss" as Patek calls it, is what gives the outer coil a geometry that’s functionally equivalent to an overcoil.

In 2008, Patek added a silicon lever to its repertoire; the combination of a silicon balance spring, silicon lever, and silicon escape wheel was dubbed the Pulsomax escapement, which was launched in a limited edition of 300 watches: the ref. 5450 Annual Calendar, with caliber 324 S QA LU.

The ref. 5450 Annual Calendar, with Pulsomax escapement.
Patek Philippe caliber 324 S QA LU.

The last installment from the Advanced Research program, prior to this year, was the 2011 ref. 5550 Perpetual Calendar. This was also a limited edition of 300 watches, and featured, in addition to the Pulsomax escapement and Spiromax balance spring, a silicon balance wheel. The entire assembly of silicon regulating organs – escape wheel, lever, balance spring, and balance – was referred to as the Oscillomax "ensemble" by Patek Philippe."

The ref. 5550 Perpetual Calendar.
Patek Philippe Caliber 240 Q SI.
The "GyromaxSi" balance, with gold infill and Gyromax balance screws.

"These parts must be used as machined … which works for an industrial approach, but excludes any hand-finishing — which is an integral part of high-end watchmaking."

Stephen Forsey, the New York Times, 2010

Up until this point, the Advanced Research Program had been technically innovative, but in a fairly narrow (albeit critical) way; all silicon innovations, and all related to the regulating organs. The watches had also been stylistically conservative, perhaps to allay doubts Patek fans might have about the degree to which Patek remained committed to traditional watchmaking. After all, adopting silicon means some performance improvements, but it also means abandoning traditional adjusting and finishing techniques. Max Büsser and Stephen Forsey (of MB&F and Greubel Forsey) framed the problem in an interview with the New York Times, in 2010: 

"’As soon as you have silicium components, they necessitate high-tech wafer technology,’ Mr. Büsser said. Such pieces ‘not only cannot be redone, if you do not have the technology and exact plans, but as the technology will evolve, the parts made today will probably not be reproducible in the future.’"

"Mr. Forsey agrees: ‘These parts must be used as machined,’ he said, ‘which works for an industrial approach, but excludes any hand-finishing — which is an integral part of high-end watchmaking.’"

To put things a bit in context, a modern luxury watch, with much of its finishing automated or semi-automated, and with a Nivarox balance spring and Glucydur balance, is not exactly the kind of thing that a watchmaker working by hand with traditional materials can reproduce either. Like it or not, modern watches, even without silicon, are not hand-made from scratch; virtually all are produced with computer guided milling machines and involve, increasingly, other high tech manufacturing techniques like LIGA as well. The point remains, however, that silicon does exclude hand finishing by its very nature, and the very exactness with which parts can be reproduced, while a dream for watchmaking for centuries, is also at odds with the element of hand-craft; the real question, then, is if the improvements in performance justify the trade-off. Patek clearly believes this is the case, and, of course, there is still a significant amount of hand-finishing elsewhere in the movement.

After 2011, the Advanced Research program at Patek Philippe went dark, and six years were to pass before the next Advanced Research watch.

2017: The Aquanaut Travel Time Ref. 5650G "Patek Philippe Advanced Research"

The Advanced Research Travel Time is an obvious departure from previous Advanced Research watches. It is, first of all, the first Advanced Research watch to not be an annual or perpetual calendar; it is the first not in a round case; and moreover it’s pretty resolutely non-traditional in styling. In addition, it’s the first Advanced Research watch to present an innovation in a material other than silicon.

The ref. 5650G Aquanaut Travel Time Advanced Research.

The first, and most obvious, innovation is the "compliant (flexible) mechanism in steel." This is the mechanism for adjusting the GMT indication forwards and backwards. 

Patek caliber 324 S C FUS.

You can see the "compliant mechanism" on the left, and it’s a pretty piece of work. It’s all in steel; there are no exotic materials used, and while Patek says it required considerable computer time, as well as high tech manufacturing methods (the press release isn’t specific but electric spark erosion is a reasonable candidate) it’s still, strictly speaking, traditional watchmaking with traditional materials. It is fun to think, given its appearance, that it might have been nicknamed "the Crab" at Patek.

The "compliant" (flexible) steel mechanism in the ref. 5650G for re-setting the GMT indication.

The level of precision required probably could not be achieved with classical methods – the clearance between the leaf springs, where they form an "x," is only 150 microns – but the whole thing is hand-finished (which must have been, given the configuration of the mechanism, and to put it colloquially, a royal pain in the ass for whomever had to do it) and it looks very cool as well. It has a kind of intuitive appeal; almost no one could imagine such a thing but the basic principle, and construction, seem obvious and self-evident when you see it working. The easiest way to understand how it works is to watch this little short from Patek Philippe.

The Crab (if I may coin a nickname) has a lot of advantages over the usual GMT switching mechanism used by Patek – lower parts count (12 parts for the whole assembly, as opposed to 37 in the standard mechanism) and, just as significantly, no gears or pivots. That means no need for conventional lubricants, no friction anywhere in the mechanism, and very probably, much better durability and general functionality. The only downside I can see to it, is that it doesn’t seem repairable; if there’s damage or wear, you’d have to swap out the entire mechanism for a new one – the shell would molt the Crab, instead of the other way ’round. It’s damned clever, anyway.

The other innovation is the addition of a new inner terminal curve, on the Spiromax balance spring. Let’s look at the old and new versions, side by side.

Spiromax balance spring, 2017 edition.

If you look very closely, you’ll see that the innermost coil of the new version has a slight swelling in the coil, similar to the one in the outermost terminal curve. Just as the geometry of the outermost coil duplicates many of the advantages of the Breguet overcoil, so the new geometry of the inner coil duplicates that of a balance spring with a properly formed inner terminal curve. The basic idea behind all this, is to set up the balance spring so that the center of gravity of the spring always coincides with the exact center of gravity of the balance – this is the basic precondition for isochronism. With the addition of the new inner terminal curve, Patek’s been able to get pretty fantastic rate stability out of the watch – as we mentioned up top, the spec is just -1/+2 seconds per day.

By the way, there is an analogous technique with traditional balance springs. Just as the outermost coil geometry of the Spiromax duplicates the effect of a Breguet/Phillips overcoil, so the inner geometry of the 2017 Spiromax duplicates the effect of a mathematically correct inner terminal curve. One such curve is known as a Lossier curve and it was widely used by the American watch company, Waltham, in its high grade railroad watches.

The Aquanaut Travel Time Ref. 5650G "Patek Philippe Advanced Research" lifestyle image
The Aquanaut Travel Time Ref. 5650G "Patek Philippe Advanced Research" dial closeup

The Aquanaut Travel Time Ref. 5650G "Patek Philippe Advanced Research" sits right in the middle of some very strong and interesting debates – the role of silicon in watchmaking is a big one, and the jury is still very much out on whether it has a place in high end watchmaking, although in the entry to medium range, the issue is already settled. It’s well on the way to becoming ubiquitous, as least for many major brands (Omega is the most prominent example). 

It’s also a watch that raises the question of how Patek Philippe sees itself evolving in the next decade. Style-wise, this is a polarizing watch; it doesn’t have the easy to like classic configurations of the earlier Advanced Research watches, which are a sort of Trojan horse for silicon. The open dial and the fact that it’s an Aquanaut have raised some hackles amongst the Patek faithful, which I understand (in general, I can’t stand open dials either). With the 5650G, though, I get the logic – this is something of a demonstration model, and it makes sense to make the mechanism visible. Certainly, there’s quite a lot more fun in seeing it in action, than there would be in watching a silicon escapement do its thing. It’s worth bearing in mind as well that this is a limited edition specifically designed to showcase new tech, and as a limited run concept piece with that tech, the design makes sense even if it’s not to everyone’s taste.

It has to be said as well that these are both extremely interesting innovations and if nothing else, I think that in addition to being pretty cool on their own, they both offer real technical advantages (albeit there are tradeoffs in any engineering solution). Maybe most importantly, though, both add tremendously to the general conversation on modern mechanical horology, and where it’s going to go in years to come.

The Aquanaut Travel Time Ref. 5650G "Patek Philippe Advanced Research" is a limited edition of 500 watches. Price, $58,970. Movement, caliber 324 S C FUS, 31mm, self-winding, with 45 hour maximum power reserve, running at 28,800 vph in 29 jewels; Patek Philippe Seal, rated to -1/+2 seconds maximum daily rate deviation. Dual time zone, with compliant steel flexible mechanism for time zone setting. Case, 18k white gold; overall length lug to lug, 47.6mm; diameter from 9 to 3 o’clock including crown, 45.24mm; thickness, 11mm. Inter-lug distance, 21mm. Water resistance 12 bar/120 meters. Strap, water resistant composite with 18k gold foldover clasp.

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