This document summarizes the thesis submitted by Oleksandr Panasenko for a Master's degree on the design concept of a folding wingtip mechanism for civil aircraft. The thesis investigated folding wingtip designs to allow for larger wingspans while meeting airport space restrictions on the ground. Computational fluid dynamics, structural mechanics, and kinematic analyses were conducted using CAD and CAE tools to develop and test a folding wingtip design concept for a large passenger airliner with a 71.1 meter wingspan. The analyses showed the design concept was structurally sound and able to fold the wingtips to reduce the wingspan to 64.8 meters for ground operations while maintaining adequate aerodynamic and structural performance for flight.

1. The design concept of
folding wingtip mechanism
for a civil aircraft
Thesis for Master degree
Submitted by: Oleksandr Panasenko
Supervisor: XuYuanMing
School of Aeronautical Science and Engineering
Beijing, June 2014

2. Motivation
• Interesting research topic
• Complete design process
• Enough space for investigation
• Real application rather than virtual one
• Not “linear” neither planar problem
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3. Folding wingtip definition
• A folding wingtip (FWT) is a design feature of aircraft to save space in
the airfield, and is typical of naval aircraft that operate from the
limited deck space of aircraft carriers.
• Folding surfaces are rare among land-based designs, and are used on
aircraft that are tall or too wide to fit inside service hangars.
• The Boeing 777 twinjet wide-body airliner was offered with folding
wingtips for confined airports, but no airline purchased this option.
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4. Applications of FWT
Su-33 ASN-213
SUGAR Volt Boeing 777
• Military aircraft (both jets and propellers)
• Unmanned aerial vehicles (UAV)
• Ultragreen electric aircraft
• Civil jet airliners (777X, A320?)
• Others
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5. Wing performance
Aircraft with high AR wing needs less thrust
to produce enough lift force to fly and so it is
more efficient.
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6. Reducing fuel burn
• more than 3% of direct fuel savings from
increased wingspan
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7. Airport restrictions
• At the airport an aircraft has three main
operating phases in the following areas:
runway, taxi-way/taxilane and
gates/hangar.
• They have different purposes and
operational conditions depending on
airport size, more specifically Design code,
in accordance with ICAO or local CAA
recommendations.
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8. Geometrical
properties of FWT
• Number of hinges
• Type of cutting plane
• Direction and position of hinge axis
Different composition of these properties
can be seen among all kinds of aircraft. In
each particular case they define advantages
of the design solution necessary for flight
mission to be successful.
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9. Components of FWT
• Hinges
• Locks
• Actuators
Hinges allow the FWT to be folded by rotary
motion. Locks secure it in flight or on the
ground. Actuator creates enough moment
around hinge axis for folding tip section of
the wing.
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10. Wing tip devices
Wingtip devices are usually intended to
improve the efficiency of fixed-wing aircraft.
• Winglet
• Blended winglets
• Raked wingtip
Beechcraft Starship Model
2000 with common
winglet
Boeing 737 with blended
winglets
Boeing 787
Dreamliner showing raked
wingtip
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11. Raked wing tips pros
In testing by Boeing and NASA, raked
wingtips have been shown to reduce drag by
as much as 5.5%, as opposed to
improvements of 3.5% to 4.5% from
conventional winglets.
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12. Geometry of wingtips
• sweep angle of the leading edge
increases from between 25 to 45 in the
connection region up to 70 to 80 in the
tip
• chord may reduce from 100% in the
connection region to 10 to 20% in the tip
• local dihedral increases from about 0 to
10 in the connection region up to 45 to
60 in the tip
• height of the wing tip extension is 30 to
60% of the span of the wing tip
• Span of the wing tip extension is between
8 and 12% of the half-span of the wing
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13. Master aircraft data
The focus was given to big wingspan civil
airliners that are restricted by ICAO Code E.
It has been decided to follow Boeing’s new
project on 777x with FWT that will start
service operations in 2020.
Wingspan In-flight, m 71.1
Wingspan Folded (on the ground), m 64.8
Cruise Mach number 0.84
Cruise altitude, m 11000
Engine section, SC(2)-0410 [Ap. A] [6]
Wingtips section, SC(2)-0406 [Ap. B] [6]
Engine section inclination, deg 4
Wingtips section inclination, deg 1
Engine chord, m 8.45
Wing tips root chord, m 3
Dihedral (on the ground), deg 3.7
Leading edge sweep, deg 32.7
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14. Master aircraft data
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15. CAD model
• Purpose of Computer-aided design (CAD)
model is to capture knowledge about
physical representation of an object.
• This physical representation means not
only geometry but also geometrical
relations, materials, temporary elements
etc. that describe the object.
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16. CAD model
• Such model then has many uses
depending on necessities of a project,
including various analyses, manufacturing
processes and simulations.
• Additional features of the model: “design
intent” and “design in context” are of
benefit providing deeper flexibility when
an object is complex.
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17. Computational Fluid
Dynamics
• Computational Fluid Dynamics (CFD), is
used to generate flow simulations around
a body to solve Fluid Dynamics problems.
• CFD allows numerical simulation of fluid
flows, results for which are available for
study even after the analysis is over.
Airflow pattern in clearly shows a tendency
of developing spanwise flow in tip direction
potentially influencing loading conditions in
FWT region.
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18. Computational Fluid
Dynamics
• Pressure distribution over the wing
section in cruise conditions(Mach 0.84)
has indicated expected pattern without
artefacts observed.
• It was checked that Mach number does
not exceed 1 in cruise conditions all over
the analyzed section. In particular the
highest speed has been found near the
root of FWT
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19. Computational Fluid
Dynamics
• Using FloEFD tools the pressure
distribution has been transferred into
Excel file by creating 1000+ of sensors
over the surface of FWT.
• Total aerodynamic force acting on the
surface of FWT has been calculated
during CFD analysis is 13 065N.
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20. Computational
Structural Mechanics
• Finite Element model has been created in
CATIA Generative Structural Analysis
workbench on the basis of geometry in
assembly.
• Pressure has been exerted all over the
surface with CATIA tools.
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21. Computational
Structural Mechanics
• Additional structural member were
provided to reinforce skin and included in
FE model of FWT.
• Mesh size and other mesh parameters
has been selected by iterative process.
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22. Computational
Structural Mechanics
• Cross sectional area of structural
members has been set to be variable
decreasing from root to the tip.
• Spar caps were located to be
perpendicular to the surface of FWT.
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23. Computational
Structural Mechanics
• FE model has been clamped in hinges and
locks places.
• Maximum Von Mises stresses has been
found at the rear hinge to be 297 MPa
that doesn’t exceed 7075-T6 yield limit.
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24. Computational
Structural Mechanics
• Maximum displacement occurring at the
tip has been found of 56.5mm that seems
to be reasonable for the length of 3.150m.
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25. Kinematic analysis
• There has been introduced two actuators
located at each hinge location connected
to the locks.
• Each of actuators has twin–staged
schema due to limited space in the wing
section.
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26. Kinematic analysis
• It has been checked integrity of the
mechanism via simulation of motion and
its sizing has been confirmed.
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27. Conclusions
• In this project it has been proposed the design concept of FWT for big
wingspan passenger airliner in form of Digital Mock Up. It allows
further development of the mechanism on its basis by adding
additional components and detailing the system.
• It has been established and tested the development environment
consisting of Kinematic, CFD and Structural analysis tools on the basis
CATIA V5.
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28. OK了
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