Department Loads Analysis and Design

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The Load Analysis and Aeroelastic Design department deals with issues that arise in the design of aircraft with regard to aeroelastic properties and aeroelastic requirements. Furthermore, developments in the topic of aircraft loads are performed globally (e.g. for design tasks) and with a focus on dynamic loads (e.g. due to gusts) in the department.

Aeroelastic modeling

When designing an aircraft, it must be ensured that aeroelastic requirements are met. These include sufficient control surface effectiveness and the avoidance of divergence and flutter in the flight envelope to be demonstrated. The Load Analysis and Aeroelastic Design department develops methods for building parametric, aeroelastic analysis models that represent aeroelastic properties of an aircraft configuration. The level of detail of the models depends on the design phase (conceptual, preliminary or detailed design). The modeling is used to analyze conventional configurations (e.g. commercial aircraft) and unconventional configurations (e.g. high-altitude research aircraft).

Load process and load analysis

Determining the loads acting on the aircraft is one of the main tasks in aircraft development. Determination of the loads is crucial for the design and layout of an aircraft, e.g. for sizing of the structure, predicting flight performance and for certification. The department is involved in both the definition of a comprehensive load process and the development of selected load analysis methods. The load process consists of the following steps: load assumptions (definition of load-relevant analysis cases and specific specifications for modeling), execution of load analyses (analysis and simulation) and processing of results, i.e. the evaluation and condensation of the extensive analysis results into relevant data. The load analysis methods developed in the department include both fast methods, which allow a large number of load cases to be analyzed in a short time, and very precise methods, e.g. CFD-based manoeuvre and gust load analyses.

Structural optimization and aeroelastic tailoring

Finally, the calculated loads are used in structural design and optimization procedures. The structural model generated in the parametric modeling is sized with selected load cases. In the sizing process, methods from structural optimization are applied, whereby the restrictions from the field of aeroelasticity (control surface effectiveness, flutter velocity, divergence velocity) are also considered. Special optimization methods are developed for sizing with fibre composite material. Methods are also being developed for an efficient selection of the relevant sizing load cases for the design. Furthermore, certification regulations (e.g. CS25) are taken into account.

Research topics of the department

Research topic

Aeroelastic Design

In the research topic of aeroelastic design, we deal with various design tasks in the context of the aeroelastic design of an aircraft, an aircraft component or a wind tunnel model. The development of methods ranges from conceptual design and preliminary design to detailed design for manufacturing, in particular for wind tunnel models.

Research topic

Loads Analysis

The computation of flight and ground loads acting on the aircraft structure is one of the main tasks in the design and certification process of an aircraft. The term loads comprises all steady and unsteady, internal and external forces and moments that do mechanical work on the aircraft structure.

Technical articles and news from the department

May 21, 2024

Conceptual design loads for aircraft configurations with novel technologies in overall aircraft design - EXACT

Realistic concept design loads in the early phase of the overall aircraft design for the mass estimation of fuselage and wing play an important role in the overall aircraft assessment for new aircraft configurations and propulsion technologies.

January 17, 2024

Preliminary Aeroelastic Stability Assessment of High Aspect Ratio Wing Aircraft

One concept to reduce an aircraft's fuel consumption is to increase wing aspect ratio, i.e. the ratio of wing span to wing chord. Although slender wings have low induced drag, a number of aeroelastic issues arise.

September 14, 2023

New wing concepts for transport aircraft - less CO2 through higher aspect ratios

The airplane is the most efficient means of transporting passengers over long distances. In view of man-made global warming, however, it is imperative that air travel also makes its contribution to reducing climate-impacting emissions - the goal is to fly in a climate-neutral manner. In the EU's Clean Aviation  funding program, which was launched at the beginning of 2023, this goal is being pursued in a series of projects that build on each other.

June 2, 2023

Model Order Reduction in Geometrically Nonlinear Analyses

In aircraft and aerospace structures, nonlinear structural phenomena can be observed under certain loading and boundary conditions. Traditional analysis techniques lead to undesirable deviations in the solutions of nonlinear systems. Dedicated nonlinear solution techniques can be utilized to improve the accuracy, however, they tend to be computationally expensive. Researchers at DLR in collaboration with TU Delft aim to develop and extend nonlinear solution techniques with model order reduction to improve computational efficiency while retaining the accuracy in the analyses.

March 8, 2023

Modern aircraft design - use of sandwich composites in aircraft wingbox

Composite sandwich materials are an interesting alternative to the use of conventional composite structures for aircraft components. Current research at DLR addresses the question, as to where sandwich composites can be beneficially employed in aircraft wingbox designs.

November 18, 2022

Earth observation - aeroelasticity for the design of the High Altitude Platform HAP

The High Altitude Platform (HAP) is a very light weight, high altitude and long endurance aircraft (HALE) designed to stay airborne and hold position for several days at an altitude between FL450 and FL800 (≈14 to 24 km, above normal air traffic). Carrying optical measurement equipment, this allows scientists to make observations of the earth continuously for a long period of time.

March 18, 2022

Aircraft Configurations with Distributed Propulsion – Effects on Loads, Structural Mass, and Aeroelasticity

The concept of distributed electric propulsion units has great potential on the track to zero-emission aircraft. Investigations raise expectations that distributed propulsion engines improve the aerodynamic performance, flight mechanical aspects as well as the aircraft loads. Reduced loads will lead to a reduction of the structural weight. Besides environmental aspects, the physics and technical based aircraft characteristics are of great importance.

January 13, 2022

How can an aircraft save weight and have a longer service life by deflecting the control surfaces?

In aircraft research, the reduction of the structural mass is a core aspect since it helps in decreasing the fuel consumption and thus the CO2 emission. The structure itself is designed to withstand the loads on the aircraft. Hence, if the loads can be reduced, the structure can be built lighter. However, in doing so, the requirements of the certification specifications still have to be fulfilled.

November 19, 2019

Super-efficient wings take off

Wings with longer spans and lower weight generate less drag – and are therefore more energy efficient. More efficient lift could reduce kerosene consumption and thus reduce emissions and costs. The limiting factor for the construction of such wings is the aerodynamic phenomenon of flutter.

Contact

Prof. Dr.-Ing. Wolf-Reiner Krüger

Head of Loads Analysis and Design
German Aerospace Center (DLR)
Institute of Aeroelasticity
Bunsenstraße 10, 37073 Göttingen
Germany