Germany’s DLR aerospace research centre has completed ground vibration tests on its Deutsche Aircraft D328-based UpLift flying testbed (D-CUPL) ahead of future modifications of the twin-turboprop.
Lead by DLR’s Institute of Aeroelasticity in Gottingen, the tests ran for a two-week period earlier this summer at Deutsche Aircraft’s Oberpfaffenhofen site near Munich.
During the evaluations, the D328 was suspended on actively controlled air springs attached to its landing-gear axles to isolate it from the ground.
Its structure was then excited at more than 20 locations by electrodynamic shakers and 237 acceleration sensors captured the aircraft’s dynamic response to the inputs.
In all, three aircraft configurations were tested, accumulating a total of 45 hours of ‘excitation time’ and identifying 50 distinct vibration modes.
These show the specific frequency, amplitude and direction of a vibration, as well as the damping characteristics of the structure.
DLR says the results of the testing will be used to validate forecast models of flight behaviour and will enable modifications to the aircraft to be made more quickly.
“The ground vibration test has enabled us to reach a key milestone in the UpLift project,” says Julian Sinske from the DLR Institute of Aeroelasticity.
“We can now also evaluate upcoming modifications to the research aircraft in terms of their aeroelasticity.”
Ultimately, the project’s goal is the transformation of the UpLift aircraft into a flying laboratory for the wider industry to test new climate-friendly fuel and propulsion technologies under real-world conditions.
Future modifications include the installation of fuel tanks underneath the aircraft’s wing-tips.
“We have obtained a very valuable dataset from the ground vibration test,” says Stefan Schröder from the project management team at the DLR’s Flight Experiments department.
“On this basis, we can now proceed with the required external modifications to the wing and fuselage faster than expected.”
Previously, the DLR and Deutsche Aircraft have used the UpLift aircraft for in-flight measurements of fully synthetic aviation fuel.
