In-flight wing measurement using monocular photogrammetry

Actual wing shape, not just simulation

Wings change shape during flight. Aerodynamic lift and fuel level influence their deflection; on large commercial aircraft, the deflection at the wingtip can be several metres. A 3D model created for ground-based conditions therefore does not adequately represent these operational states. For realistic flow simulations and the development of aerodynamic aircraft modifications, geometric data captured under real flight conditions are required.

Monocular photogrammetry through the cabin window

The Fraunhofer IOSB has developed a photogrammetric measurement method that requires only a single camera in the aircraft cabin. Before the flight, measurement markers are attached to the wing and their positions are precisely determined whilst the aircraft is still on the ground in the hangar. During the flight, the camera then captures the markers in various flight conditions. During calibration, we also take into account the influence of the cabin window and reconstruct the spatial coordinates using a geometric model of wing deformation. This enables three-dimensional wing models to be generated even in situations where a conventional stereo camera system cannot be installed.

Tried and tested on long-haul flights

The method has been in use since 2016 on long-haul flights with wide-body aircraft. To install the fuel-saving AeroSHARK film developed by Lufthansa Technik and Surventis (formerly BASF Coatings), the wings of a Boeing 777-300ER and an Airbus A330, among others, were measured in flight (see also the press release ‘Wings measured in flight’). The geometric models generated serve as the basis for aerodynamic analyses.

Beyond aviation, the approach can be applied to specific measurement tasks where moving or deformed objects need to be captured under operational conditions and only a single camera viewpoint is available.