Session 5: Integration / certification
Authors: Wilson Thomas , Iorga Lucian , Stefes Bruno , Silvestre Flavio 
Published: October 2023

**Chair: Moti Karpel (Technion)**

Integrated Wing Design - an industry perspective

The talk will first give an overview of criteria and constraints on Wing development from an *industry insider* perspective, with a focus on the structural design.
The need for structural enablers for High Aspect Ratio Wings design will then be discussed and an overview of several HARW specific challenges will be presented.

The European UP Wing project: Developing and maturing technologies for an high aspect ratio wing

The short-medium range class is the largest contributor in terms of passenger and cargo kilometers to the commercial air transport emissions. As set out in the Green Deal of the European Commission, this transformation requires the development in this class of a new generation of aircraft with radically improved energy efficiency and capable of operating on 100% green fuel. A Clean Aviation Programme has been launched with the objective of developing disruptive new aircraft technologies to support the European Green Deal. At least 30% reduction of net greenhouse gas (GHG) compared to 2020 state-of-the-art is targeted for the next aircraft generation in the short-medium range segment of civil transport aircraft with an expected entry into service by the middle of the next decade and to replace 75% of the fleet by 2050.
A significant contribution to achieving these high ambitious goals is a breakthrough in the next generation wing design, as the wing component plays the dominant role for a further drastically drag and weight improved aircraft. The more the product concept may change the more the wing design concept has to be adapted. ^

The Ultra Performance Wing project (“UP wing”) will validate, down select, mature and demonstrate key technologies and provide the architectural integration of “ultra-performance wing” concepts for targeted ultra-efficient Short/Medium Range aircraft (SMR), i.e.  150-250 PAX and  1000-3700km ( 500-2000nm) range.
Two main challenges will be addressed covering most of the potential design space:

Configuration1 (SAF wing) - An aircraft equipped with a novel ultra-high performance wing using SAF (sustainable “kerosene-like” fuels) targeting TRL4 by end of UP Wing phase1 (Q2/2026)

Configuration2 (Dry wing) - An aircraft equipped with a novel ultra-high performance wing exploiting non-drop-in fuels such as hydrogen in cryogenic storage will be investigated, including different types of propulsions.

The high aspect ratio wing (AR>14) is a key contributor to significantly reducing the environmental footprint, aiming for fuel burn reduction thanks to reduced aerodynamic drag (induced drag), while the wing weight penalty needs to be minimized.
Key enablers to achieve this objective are the development of:
- Novel flight control systems for advanced active and passive loads control concepts for weight control
- Design and integration of multi-functional and multi-purpose movables (incl. systems) to support these functions on a very flexible and space constraint high-aspect-ratio wing.

An overall aircraft design (OAD) process is in the loop to quantify the benefits of the technologies at integrated aircraft level.
A series of demonstration lines are planned that consists of wind tunnel tests, ground-based demonstrators (GBD) for structural and functional demonstration as well as (virtual) flight tests.

TU-Flex: A Very-Flexible Flying Demonstrator with a Generic Transport Aircraft Configuration

In the continuous search to increase efficiency in fuel consumption and reduce environmental impact, the aeronautical industry is getting more interested in enabling and developing higher aspect ratio wings. However, the increase in flexibility tends to deteriorate flying qualities making it necessary to implement more complex controllers and to develop more complex numerical models to capture the real flight dynamics of the aircraft. Nevertheless, there are not enough demonstrators to provide validation data for such models. For these reasons, the Chair of Flight Mechanics, Flight Control, and Aeroelasticity of the TU-Berlin in cooperation with the DLR's Institute of Aeroelasticity is working on the development of TU-Flex, a remotely piloted vehicle designed to gather coupled flight and structural dynamics data to validate flexible/very flexible aircraft models with a typical transport aircraft configuration. This paper shows that it is feasible to attain the levels of deformations required to study the dynamics of flexible and very flexible aircraft in a low-cost scaled demonstrator. The aircraft was designed using an in-house development process that includes the use of DLR's ModGen/NASTRAN for dimensioning the main structural components, and the DLR's software Loads Kernel for the load analysis of the free-flying aircraft. The current geometry of the TU-Flex allows performing experiments in an available wind tunnel facility, and in flight test experiments for a gradual validation process. This demonstrator is capable to attain all main design requirements and it is in a detailed design process and construction. Time-domain simulations are in development with an in-house code for the flight dynamics of very flexible aircraft.