Black-Magic Speedster on the Horizon

Founded, owned, and funded by brothers Ryley, River, and Keegan Karl—a trio of University of Wisconsin graduates with respective degrees in aerospace, computer/electrical, and mechanical engineering—DarkAero is the embodiment of a shared familial aspiration to develop a kit aircraft of surpassing speed, range, and efficiency.

The aircraft to which the brothers Karl have plied their considerable expertise and energies is the DarkAero-1, a single-reciprocating-engine, low-wing, retractable-tricycle-undercarriage, normal category airplane—the claimed performance of which beggars belief.

February 2023 found the DarkAero team focused on the sleek aircraft’s landing gear actuation hardware and flight test planning.

The gearboxes by which the DarkAero-1’s main landing gear are retracted and extended were built in February. To facilitate parallel manufacturing and optimize the project timeline, several components germane to the gearboxes were outsourced to Xometry, a Derwood, Maryland-based on-demand industrial parts consortium. The outsourcing process, though convenient, required the drafting of concise engineering drawings which, in addition to ensuring requisite dimensional tolerances were met, helped guarantee the outsourced components would fit together during assembly and subsequently function to specifications. The completed gearboxes are currently undergoing installation in the prototype DarkAero-1 airframe.

Each gearbox contains a clutch mechanism by which the corresponding drive motor—in the event of system failure—is disengaged from the gear strut. This architecture allows the DarkAero-1’s struts to extend under gravity with the assistance of gas springs that overcome aerodynamic loads and force the struts into their down and locked position.

Initial testing of the system was performed with off-the-shelf gas springs. However, a set of custom gas springs that better meet the specific requirements for force, stroke length, and damping was ultimately ordered.

The DarkAero-1’s landing gear actuation motors are controlled by a module that contains a motor speed controller, relay, and logic board. Previously, the electrical hardware components in the control module were validated through bench tests. Currently, the components are being arranged onto a mounting frame capable of being installed adjacent to each of the airplane’s gear struts.

Discussions with an FAA Designated Airworthiness Representative (DAR) are underway that will lead, ostensibly, to the issuance of an airworthiness certificate for the prototype DarkAero-1 and the commencement of flight-testing. The DarkAero team has also been working with test pilot Sean VanHatten to refine the airplane’s flight-testing itinerary—which includes reviews of the DarkAero-1’s center of gravity envelope, critical V-speeds, and airports of interest in the flight testing area.

Installation and testing of the DarkAero-1’s main landing gear actuation system will continue throughout March 2023. A number of miscellaneous tasks pertaining to the aircraft’s control system and cabin also remain to be completed.

It is not until one contemplates the DarkAero-1’s 240-knot (TAS) cruise speed, 1,477-nautical-mile range (at 240-knots!), and FL200 service ceiling that the diminutive aircraft’s potency becomes apparent. Equally remarkable is the fact that a bit of throttle-restraint will see the DarkAero-1 cover an astounding 1,912-nautical-miles (with a thirty-minute VFR reserve, no less) at a jaunty 222-knot economy cruise speed.

The DarkAero-1’s 61-knot stall-speed is commensurate with an aircraft of its speed-optimized wing planform and fuselage design, as is the machine’s 2,500-foot-per-minute climb-rate. Of lesser orthodoxy is the Hollow Grid structure of the DarkAero-1’s wings. “Hollow Grid” denotes an arrangement of CNC-cut carbon-fiber and honeycomb-sandwich panel-ribs and shear-webs. By design, the entirety of in-flight compressive, tensional, and torsional loading acting upon the DarkAero-1 is borne by the wings’ outer skin, while the Hollow Grid keeps the skin’s shape and prevents buckling. Wings of Hollow Grid design and construction are stronger and lighter than those deriving of conventional aluminum, rib, and spar architectures.

Home-building the DarkAero-1 requires neither complex jigs nor fixtures—only simple shop tools. The aircraft’s carbon-fiber composite airframe is fashioned in-factory by dint of computer-designed, precision CNC-machined tooling. The process produces smooth, accurate parts that fit together with minimal sanding.

The DarkAero-1 kit includes: airframe, canopy, engine-mount, landing gear, control hardware, and fittings and fasteners. Separately purchased components include: UL Power 520iS engine, avionics, propeller, wheels and brakes, and paint. The aircraft’s estimated completed cost is $200,000.

FMI: www.darkaero.com