Aeroelastic Tailoring of a Composite Wing with Adaptive Control Surfaces for Optimal Aircraft Performance

Abstract

The ever-progressing air transport industry has always been challenged to improve aircraft efficiency. Although enhanced fuel burn metrics have been achieved over the last decades, increased
air travel demands, and the recent introduction of fuel efficiency and emission goals by industry
regulators, represent a major force opposing the required improvements imposed on the aviation
sector. These factors create a conflicting landscape, driving proposed new aircraft configurations
towards even more fuel efficient and emission-free designs. In this scenario, the aviation industry
has been evolving constantly and is anticipated that major and drastic improvements in aircraft
performance will only be possible by means of non-conventional or hybrid design approaches—for
instance, the combined use of composite materials with active/adaptive control of aerodynamic
surfaces. The expected outcome is the creation of designs that outperform those following solely
passive aeroelastic tailoring paradigms.

As a novelty, an investigation of the synergies and trade-offs between passive and adaptive
aeroelastic tailoring of a transport composite wing based on the NASA Common Research Model
is presented. The drivers, design interdependencies, and performance improvements of combining
composite thickness and stiffness tailoring with quasi-steady control surface scheduling, and jig-twist shape are assessed for improved fuel burn efficiency and its related disciplines: manoeuvre
load alleviation and cruise aerodynamic performance. The dependence of actuator weight on the
level of load alleviation is also quantified for different control surface topologies. Furthermore, in
addition to straight-fibre laminates, potential benefits and related design compromises of tow-steered laminates augmented by adaptive full-span control surface devices are correspondingly
investigated.

Relative to an all-metallic wing with undeflected control surfaces, it is shown that the
combined exploitation of composite stiffness tailoring with adaptive trailing-edge devices allows
for a remarkable 6.7% fuel burn saving. From the total noted fuel burn improvement, 69% of was
due to trailing-edge devices and the remaining 31% to the use of straight-fibre laminated skins.
Adding leading-edge flaps to the optimisation improved the fuel burn savings in ~ 0.25%, and
similarly, allowing the fibres to locally steer produced designs ~ 0.45% more fuel burn efficient
than straight-fibre counterparts. If compared to a baseline model with straight-fibre laminates
and undeflected control surfaces, 86.2% of the fuel burn improvement was due to trailing-edge
devices, 9.3% achieved due to tow steering and only 4.5% obtained via leading-edge devices.
Overall, the results found encourage intersecting two emerging and prospective aeroelastic
tailoring technologies for improved aircraft aerostructural performance: composite tailoring (both
straight-fibre or tow-steered laminates) and variable aerofoil camber.

Date of Award	7 May 2019
Original language	English
Awarding Institution	University of Bristol
Supervisor	Alberto Pirrera (Supervisor) & Jonathan E Cooper (Supervisor)