Stealth. If you look at any plane or boat designed with stealth in mind, they usually look to all intents and purposes anything but inconspicuous. And the stealthier they are, the more strikingly – radar excepted – obvious they are.

Inspiration and Realisation

A long childhood passion for assembling model aircraft had Maximilian Büsser’s walls, cupboards and ceiling covered in small aircraft of every description. Planes were what he saw last thing at night and then again first thing each morning.

Many boys sketch supercars and fast planes, but few have the drive and determination to make their dreams come true. Büsser created MB&F to do just that. HM4 was born of the child’s fantasy and the man’s tenacity.

Engine

HM4’s engine was entirely designed and developed by MB&F over three years of intensive work. Each of the 311 components was developed specifically; no off-the-shelf components could be used due to the extreme nature of its architecture.

Left: Maximilian Büsser - Right: HM4 Engine Double Movement

Two mainspring barrels connected in parallel provide 72 hours of energy and they transfer their power to the dual jet-turbine-like indication pods via vertical gear trains. Visible through a shaped sapphire display panel on the top of the case, a distinctive streamlined cock supports the balance, its centre cut away to reveal as much of the oscillating wheel as possible and validating the “kinetic” in MB&F’s “kinetic art”.

A work of art rewards when viewed from different angles and Horological Machine No4 is no exception. Turning the machine over reveals a panorama of meticulously finished micro-engineering through the sapphire sections. In a playful trompe l’oeil, what at first glance appears to be a micro-rotor in the form of MB&F’s iconic battle-axe is actually a bridge.

Indications

For a timepiece not developed specifically to tell the time, HM4 performs that role superbly. In fact, with its highly legible dials perpendicular to the wearer’s wrist, Horological Machine No4 might be described as the perfect pilot’s or driver’s watch.

HM4 Final Edition by MB&F

On the left pod, the power reserve is clearly indicated by a skeletonised hand echoing MB&F’s battle-axe motif. On the right, hours and minutes are displayed by bold, arrow-tipped Super-LumiNova filled hands. The two aviation instrument-styled instrument indications are directly controlled by their own crown: one to wind/re-fuel the tanks, the other to set the time.

Case

Inspired by aviation, the case of HM4 imparts speed, power, technology and refinement in equal measure. Visually, the case is composed of three parts: two streamlined jet-turbine-styled pods supported by a horizontal section housing the engine, which is clearly visible through transparent sapphire display panels and the central section of the case itself. Technically there are also three main sections, which include the dials and articulated front lugs; a central section in sapphire offering unprecedented 360° access to the superbly finished engine; and an aft section tapering down to the dual crowns.

More than 185 hours of intricate machining and meticulous polishing are required to turn an opaque solid block of sapphire crystal into the clear, light-filled atrium of the central case section, which reveals part of the HM4 engine and engineering details.

The contrasts of matte with highly polished surfaces under the black PVD, stealthy straight lines with seductive curves, and rigid forms with articulated arms, sets HM4 Final Edition apart from anything visible (or not) on land, sea, or air!

Source: MB&F

Video: MB&F on Vimeo