The Answer is Blowing in the Wind

On 28 March 2023, Archer Aviation, the California-based designer of electric vertical takeoff and landing (eVTOL) aircraft, announced that its eVTOL, dubbed Midnight, had recently completed a six-week series of tests in RUAG’s Large Subsonic Wind Tunnel in Emmen, Switzerland.

Archer stated that the tests had covered a range of data germane to the aircraft’s performance, stability, and control characteristics, as well as its resilience to icing. A representative of the San Jose aerospace concern asserted the tests were part of a validation process that was “on pace for Midnight’s upcoming flight test program.”

Known throughout the aviation industry for its wind tunnel testing capabilities, Rüstungs Unternehmen Aktiengesellschaft (RUAG) is a Swiss company specializing in aerospace and defense industry engineering. The company’s facilities are capable of validating aircraft designs from initial concepts through final production versions.

Currently, Archer is testing a 27.6-percent scale model of its Midnight eVTOL with a wingspan of just over 13-feet. The company set forth that the model’s dimensions  allow engineers to gather maximal data while still fitting properly within the wind tunnel.

The RUAG tests focused on the aerodynamic characteristics of the Midnight airframe without its propellers deployed. Archer disclosed that the tests included a process of essentially assembling the aircraft piece by piece while making assessments at each stage—a vetting protocol to which engineers refer as an airframe component build-up. Starting with a bare wing and fuselage, test personnel added Midnight’s booms, landing gear, empennage, and additional components.

Archer averred: “This build-up approach allowed us to investigate and clearly understand the incremental effects of each airframe component.”

Archer further reported the wind tunnel tests significantly boosted overall confidence in elements of the Midnight design—including the size and deflection of the eVTOL’s control surfaces and predictions pertaining to aerodynamic loads. Upcoming tests will evaluate the effects of Midnight’s propulsion system on its gross aerodynamics.

Archer stated: “Altogether, these learnings, and those still being mined from the rich dataset we collected, allow us to take a significant step forward in the development and certification of Midnight.”

Though vastly larger and more capable than its Maker forebear, Midnight retains the latter aircraft’s 12-total/tilt-6 rotor configuration. Archer CEO Adam Goldstein remarked: “We’re still using a lot of those same philosophies that we validated with Maker.”

Notwithstanding the fact that Midnight’s design targets a one-hundred-mile-per-charge range, Archer’s strategy for the aircraft’s deployment is predicated primarily upon twenty-mile back-to-back routes conducted in rapid succession.

Mr. Goldstein explained: “A typical route would be airport to city center for passengers in and around urban environments.”

For initial urban air mobility (UAM) operations, Archer will rely on existing infrastructure, such as the Manhattan heliport, which anchors a route to and from Newark, and Vertiport Chicago, a facility that will presently serve as the hub for an air taxi route between the Midwestern metropolis’s famed downtown Loop and O’Hare International Airport (ORD).

Mr. Goldstein concluded: “Over time, we will build more infrastructure or work with companies to build more infrastructure.”

Archer’s development schedule calls for flight-testing of its Midnight eVTOL to commence in mid-2023. Currently, the company is completing a full-scale Midnight prototype that will be utilized in preliminary intra-company ground and flight-testing in advance of FAA evaluation and type-certification.

FMI: www.archer.com