HM9 Flow Air EditionReference# 90.TL.AB
- Limited Edition: 33 pieces
- Case: Titanium
- Size: 57 x 47 x 23mm
- Movement: hand-wound in-house caliber
- Function: planetary differential transmits the average rate of the two independent regulators to the single gear train
- Power Reserve: approximately 45 hours
- Water Resistance: 30 m
- Dial: black
- Caseback: sapphire crystal
- Strap/Bracelet: hand-stitched brown calf-leather
Presenting Horological Machine No. 9 Flow, inspired by the dynamic profiles of automotive and aviation mid-century design.
Reminiscent of a jet engine, a highly complex titanium case in alternating polished and satin finishes encloses an equally complex manual winding movement, developed fully in house. Independent twin balance wheels beat at a leisurely 2.5Hz (18,000bph) on each flank of Horological Machine No. 9, visible under elongated domes of sapphire crystal. A third pane of sapphire crystal on the central body reveals the gearbox of the HM9 engine: a planetary differential that averages the output of both balance wheels to provide one stable reading of the time.
Sitting perpendicular to the rest of the HM9 engine is the dial indicating hours and minutes, driven by conical gears that ensure precise engagement even when motion is put through a 90-degree planar translation. The winding and setting crown is located on the rear of the central body, its deep fluting providing ergonomic grip as well as aesthetic coherence with the overall design.
Two satin-finished air scoops are mounted alongside the pods containing the oscillating balance wheels, evoking the raised vents that allow continuous airflow to high-performance motor engines.
HM9 Flow treads the path first opened by the HM4 Thunderbolt and subsequently by the HM6 Space Pirate, utilizing a geometrically complex combination of milled sapphire crystal and grade 5 titanium case elements. However, HM9 goes beyond its predecessors, redefining what was thought to be possible in case design – illustrated for example by a patented three-dimensional gasket ensuring water resistance.
About the HM9 Engine: The result of three years of development, the HM9 engine was created entirely in-house, with the accumulated experience that came with MB&F’s 13 years in existence (in 2018) and previous 14 different movements.
Long-time MB&F collectors and fans will recognize the mechanical pedigree of the HM9 engine. Its double-balance with differential is descended from the similar system in Legacy Machine No. 2, albeit in vastly different aesthetic form. Whereas LM2 emphasized design purity and the hallucinatory effect of its suspended oscillators, HM9 is exultant in its celebration of expressive design.
The twin balance wheels of the HM9 engine feed two sets of chronometric data to a central differential for an averaged reading. The balances are individually impulsed and spatially separated to ensure that they beat at their own independent cadences of 2.5Hz (18,000bph) each. This is important to ensure a meaningful average, just as how a statistically robust mathematical average should be derived from discrete points of information.
Two balances beating within the same movement will inevitably bring up discussions of resonance, the mechanical phenomenon that describes linked oscillators in a state of mutual harmonic excitation. As with the LM2 engine, HM9 deliberately avoids inducing the resonance effect. Its purpose in including two balance wheels is to obtain discrete sets of chronometric data that can be translated by a differential to produce one stable averaged reading. This purpose would be defeated by two balances oscillating perfectly in phase, giving the same chronometric data at every point.
HM9 further calls out the MB&F Legacy Machine collection with the curved arms anchoring its balances, their polished steel finish contrasting vividly with the movement bridges. There are two versions of the HM9 engine, one with a dark NAC coating and another in matte rose gold coating.
The Horological Machine N°9’Flow’ “Air” version with darkened movement was launched in limited titanium edition of 33 pieces.