ATDA Commercial Transport Airframe Part 4.pdf

Mr. Geoffrey Allen Wardle. MSc. MSc. ATDA Airframe Design Study 2012-2020
ATDA STUDY PRESENTATION PART: - 4 (ATDA EMPENNAGE DESIGN,
STRUCTURAL LAYOUT, MANUFACTURING ASSEMBLY).
By Mr. GEOFFREY ALLEN WARDLE. MSc. MSc. MRAeS. CEng. Snr MAIAA.
ATDA HT internal structural layout.
ATDA VT internal key datum layout.

This presentation has been created, for the sole purpose of private study and is not the work of a
company or government organisation it entirely the work of the author using resources in the public
domain. The final paper will be submitted for peer - review to the American Institute of Aeronautics
and Astronautics, Design Engineering Technical Committee, and the RAeS Structures and
Materials Group, for pre submission assessment. Readers must be aware that the work contained
may not be necessarily 100% correct, and caution should be exercised if this project or the data it
contains is being used for future work. If in doubt, please refer to the AIAA, Design Engineering
Technical Committee and the author.
All of the views and material contained within this document are the sole research of the author and
are not meant to directly imply the intentions of the Boeing Company, Airbus Group, GKN
Aerospace, or any contractor thereof, or any third party at this date. Although the USAF and NASA
have awarded contracts for studies into stitched composite transport aircraft structures, this work is
not the product of their results or any part of their body of research, and should not be considered
as such.
This document contains no material what so ever generated or conceived by myself or others
during my employment with BAE SYSTEMS (PLC), or that is governed by ITAR restrictions. This
work is solely my own creation and is based on my own academic studies and literature research
and the distribution of all information contained within this document is unlimited public release and
has been approved through the AIAA. This document and any part thereof cannot be reproduced
by any means in any format or used for any other research project without consultation with AIAA
Design Engineering Technical Committee or the author.
2
Presentation “Health” Warning.
.

3
This is an overview covering my current private design trade studies into the incorporation of new
structural technologies and manufacturing processes into a future transport airframe design, and
the incorporation of mission adaptive wing (MAW) technology for per review through the AIAA
This study has been undertaken after my 13 years at BAE SYSTEMS MA&I, in airframe design
development as a Senior Design Engineer, and my Cranfield University MSc in Aircraft Engineering
completed in 2007(part-time), and was commenced in 2012 and I aim to complete it at the end of
2020. This utilises knowledge and skills bases developed throughout my career in aerospace,
academic studies and new research material I have studied, to produce a report and paper
exploring the limits to which an airframe research project can be perused using a virtual tool set,
and how the results can be presented for future research and manufacturing. The toolsets used are
Catia V5.R20 for design / analysis / kinematics / manufacturing simulation: PATRAN / NASTRAN for
analysis of composite structures: AeroDYNAMIC™ for analysis of aircraft OML / Structural Loads /
performance. This work will also form the basis for a PhD study, it is the product of my own
research, and has not in any part been produced or conceptualised during my employment with
BAE SYSTEMS or any company which is any part thereof.
About this presentation:-
This presentation is Part 4 of a series of 5 presentation Parts which cover the airframe major
structural component development and engine and landing gear integration, and assembly
manufacturing technologies. The contents of this presentation are given in the following slide.
Overview of my current research activities in aircraft design for the ATDA paper.

 Section 1:- The general design, structural layout of the ATDA Empennage:
 Section 2:- The design, structural layout and detail part material selection and manufacturing requirements of
the ATDA Horizontal Tail:
 Section 2:- Manufacture / Assembly of PRSUES aircraft Horizontal Tail Torsion Box skin structure:
 Section 3:- Manufacture / Assembly of PRSUES aircraft Horizontal Tail Torsion Box internal sub-structure:
 Section 4:- Manufacture / Assembly of PRSUES aircraft Horizontal Tail Carry Through Box skins:
 Section 5:- Manufacture / Assembly of PRSUES aircraft Horizontal Tail Carry Through Box internal sub-
structure:
 Section 6:- Robotic assembly in the development of the Baseline Horizontal Tail (also Robotic Kinematic for
ATDA airframe Study LinkedIn presentation) (in work):
 Section 7:- Horizontal tail systems and elevator integration, and integration with aft Fuselage Sections 19 and
19.1 (in work):
 Section 8:- The design, structural layout and detail part material selection and manufacturing requirements of
the ATDA Vertical Tail:
 Section 9:- Manufacture / Assembly of PRSUES aircraft Vertical Tail Torsion Box skin structure:
 Section 10:- Manufacture / Assembly of PRSUES aircraft Vertical Tail Torsion Box internal sub-structure:
 Section 11:- Robotic assembly in the development of the Baseline Horizontal Tail (also Robotic Kinematic for
ATDA airframe Study LinkedIn presentation) (in work):
 Section 12:- Vertical tail systems and rudder integration, and integration with Fuselage Sections 19 and 19.1
(in work):
ONLY WORK FROM REFERENCED STUDIES MAY BE REPRODUCED WITHOUT EXPRESS PERMISSION
OF MYSELF AND THE AIAA. 4
Contents of this ATDA study overview presentation.

ATDA Baseline Vertical tail design.
The vertical tail presents a set of design issues which are different from those of the wing, or
horizontal tail and these are be itemised below:-
a) It is not unusual for the vertical tail of a large transport to be integrally attached to (but still
removable from) the rear fuselage, the leading and trailing edge spars of the vertical tail being
attached to dedicated fuselage frames. A root integration plate is built into the vertical tail to
coincide with the upper surface of the fuselage and is used to transmit the vertical tail root skin
shear loads directly into the fuselage skin, this is the case with the Boeing 787 and 777 CFC
vertical tails which use a tension fitting plate to interface with the fuselage with attachment to
this plate at the VT torsion box leading and trailing edge spars. Vertical tail span-wise bending
results in a fuselage torsion. In some cases it is logical to incline the rear spar bulkhead to
continue the line of the rear spar of the vertical tail torsion box, as this is usually at the end of
the fuselage well aft of the rear pressure bulkhead, although no current airliner produced by
either Airbus or Boeing has adopted this layout. All of the current large Airbus and Boeing
passenger aircraft, based on published data from literature surveys and examination of aircraft
cutaways attaching the rear spar to perpendicular frames. The front spar and any intermediate
attachments to frames are also made to perpendicular frame stations within the aft fuselage,
with the transition being made at the Vertical Tail root rib or integration plate in the case of the
B-777 , and B-787, shown in figure 1(a)ii The structural layout is generally the same format as
the wing with front and rear spars and ribs forming the vertical tail torsion box, with additional
rudder hinge ribs and auxiliary front spar to support de-icing equipment and other systems in
the vertical tail leading edge fairing. 5
Section 1:- The general design and structural layout of ATDA empennage.

6
Figure 1(a):- ATDA Vertical tail showing fuselage attachment design philosophy.
Figure 1(a)i:- Airbus A350 XWB Vertical tail to
fuselage attachment philosophy i.e. leading edge,
trailing edge spar, and intermediate attachment lugs
into fuselage clevis fittings (Flight International and
Airbus gallery). Rudder is CFC and Nomex
honeycomb skins with aluminium ribs.
Figure 1(a)ii:- Boeing 777 and 787 Vertical tail to fuselage
attachment philosophy i.e. Tension fixtures and integration
plate (Flight International and Boeing gallery). Rubber is CFC
and Nomex honeycomb skins with aluminium ribs.

b) Alternatively the vertical tail is designed to be readily detached as in the case of fighter aircraft
and modern large transports, in this case attachment is through a system of lugs attached to
the leading edge and trailing edge spars and intermediate lugs as shown for the Airbus A350 in
figure 1(a)i. The vertical attachment lugs are arranged in both lateral and fore and aft directions
so that in addition to vertical loads they react side and drag loads. The normal layout being that
the lugs attached to the leading edge spar arranged laterally and react the vertical and drag
loads, and the lugs attached to the trailing edge spar are arranged in the fore and aft direction
and react the vertical and side loads. This lug attachment philosophy was selected for the
ATDA vertical tail which is attached at the leading edge and trailing edge spars with lateral and
fore and aft lugs to perpendicular fuselage frames.
c) The rudder attachment to the vertical tail is invariably supported by a number of discrete hinges
and number and location of these hinges depends on the length and weight of the rudder, and
the other major points to consider in rudder attachment design are as follows:-
i. The bending distortion of the control surface relative to the fixed vertical tail must be limited
so that the nose of the control does not foul the fixed shroud:
ii. The control hinge loads and the resulting shear forces and bending moments should be
equalized as far as possible:
iii. Structural failure of a single hinge should be tolerated unless each hinge is of fail-safe
design and can tolerate cracking in one load path.
7
The design and structural layout of ATDA empennage (continued).

8
Figure 1(b):- ATDA Vertical tail showing internal structural layout key datum positions.
Fwd Attachment Frame interface:- two
lateral lugs the Leading Edge spar root.
Aft Fuselage
barrel section.
Mid Attachment Frame interface:- two Fore
and Aft lugs on the Mid spar root.
Aft Attachment Frame interface:- two Fore
and Aft lugs on the Trailing Edge spar root.
Triplex rudder
EHA actuators.
CFC Stringers.
CFC Leading Edge Spar.
CFC Vertical Tail Leading
Edge box with Al/Li Ribs.
CFC Mid (Intermediate) Spar.
CFC Trailing Edge Spar.
Al/Li alloy all Ribs.
Rudder CFC Honeycomb
skins with Al/Li ribs .
Figure 1(b)i:- VT / Frame interface.
FWD
Figure 1(b)ii:- VT internal layout Port
skin and stringers removed.
UP
CFC Skins.
Vertical Tail Pf Area = 35.36m²
Rudder Pf Area = 15.00m²

These points suggest the use of a relatively large number of discrete hinges but there are
issues associated with this solution. There is the obvious issues of high assembly complexity
and maintenance, and hinge alignment difficulties. Additionally the loads likely to be induced in
the rudder by the distortion under load of the vertical tail to which it is attached may be
significant. These problems do not arise if only two hinge points are used as any span-wise
distortion or misalignment can be accommodated by designing one of the hinges so that it can
rotate about a vertical axis a so called „floating‟ hinge. When more than two hinges are used
this „floating‟ hinge concept cannot fully overcome the problems. However it is possible to
design the control surface so that it is flexible in bending and indeed the more hinges there are
the easier this is to accomplish. One hinge must always be capable of reacting side loads in the
plane of the control surface, the hinges being supported near to the aft extremities of the
vertical tail ribs. For the initial internal structural layout concept the ATDA Baseline Vertical Tail
the rudder attachment layout of the Airbus A330 was used as a starting point for analysis using
AeroDYNAMIC™ of loads and detailed structural analysis.
ATDA Baseline Horizontal tail design.
When the horizontal tail is constructed as a single component across the centreline of the aircraft
the basic structural requirements are the very similar to the wing see above. Therefore to address
this the concept structure was designed as two spar multi rib torsion box, with two actuator
positions for the elevator on the Port and Stbd Horizontal Tail Planes figure 2(b), this is similar to
the Airbus A350 WXB, and A330. The Boeing 787 takes a different approach with the horizontal tail
torsion box being multi spar construction. The all moving ATDA horizontal tail is attached to the
fuselage by the fwd Screw Jack actuator fitting and aft pivot lugs figure 2(a). 9
The design and structural layout of ATDA empennage (continued).

10
Figure 2(a):- ATDA Horizontal tail showing internal and interface design philosophy.
Figure 2(a):- Airbus A350 XWB Horizontal tail to fuselage attachment philosophy i.e. stiffened centre box is attached to
the screw jack actuator at the front, and at trailing edge is attachment with two pivot outer lugs. The same basic layout is
used by Boeing (Flight International and Airbus gallery). Elevators are constructed of CFC skinned Nomex honeycomb
skin panels with aluminium ribs, and mesh instead of electrical bonding straps.
Port Lug
Stbd Lug
HT Composite leading edge spars.

11
Figure 2(b):- ATDA Horizontal tail showing internal structure layout.
Jack Screw actuator
attachment fitting
Elevators CFC Honeycomb
skins with Al/Li ribs
HT pivot lugs
Fixed CFC LE /TE spars
CFC Torsion Box Skins
CFC Ribs attached to Stitched Skin Cleats
Al/Li Topologically
Stiffened AM Ribs
Al/Li Topologically
Stiffened AM Ribs
PRSEUS Skin Stringers
Al/Li Machined Ribs
Ti Ribs to Spar Cleats
Ti Machined
Removable LE Spar
Ti Machined
Removable Ribs
Ti Machined Tip Rib
Ti Machined Root Ribs
FWD
UP
PORT
Top cover skins, splices and
stringers removed for clarity.

12
Figure 3:- ATDA HT Port / Stbd Top Cover Skin With PRSEUS Stringers.
Top Port cover skin, laid up on female tool in dry state,
preform stringers are mounted in position using soft
tooling. The stringers are then stitched by robot arm to
the cover skin. This is followed by covering the internal
surface with permeable membrane, and vacuum
bagging of the assembly.
This assembly is then positioned in a walk in oven and the inlet and exit feed
tubes are connected being positioned with main feed tubes at the root and
main vacuum tubes at the tip. The oven is heated to 60ºC, during injection the
permeable material results in a combination of in-plane and through thickness
flow reducing infusion times. Following injection cured at 93ºC, for 5 hours,
and finally with vacuum bag removed post cured at 176ºC for two hours. This
is followed by CNC machining to remove excess material.

13
Figure 4:- ATDA HT Port / Stbd Bottom Cover Skin With PRSEUS Stringers and Cleats.
Bottom Port cover skin, laid up on female tool in dry state, preform
stringers are mounted in position using soft tooling. The stringers
are then stitched by robot arm to the cover skin. The CFC Rib
cleats are then mounted over the stringers and stitched in place
using the stringers as determinate assembly aids. This is followed
by covering the internal surface with permeable membrane, and
vacuum bagging of the assembly.

14
Figure 5:- ATDA HT Port / Stbd Internal Structural Layout.
CFC Resin Infused Rib
with integral fwd cleats.
CFC Resin Infused Rib
with integral fwd cleats.
CFC Resin Infused Rib.
CFC Resin Infused Rib.
Al/Li Single Sided Topologically
Stiffened EB wire AM formed Ribs
Al/Li Standard Single
Sided Machined Ribs
Ti Standard Double Sided
Machined Tip Rib
CFC Fibre Placed TE Spar.
CFC Resin Infused TE Spar
with tip integral cleat.
CFC Resin
Infused Stub
Ribs Integral
stiffeners.
Ti Machined Cleats.
Ti Standard Single Sided Machined
removable spar and ribs.

15
Figure 6:- ATDA HT Carry Through Box Top Cover Skin With PRSEUS Stringers.
Top HT Carry Through Box Top cover skin, laid up on
female tool in dry state, preform stringers are mounted
in position using soft tooling. The stringers are then
stitched by robot arm to the cover skin. This is followed
by covering the internal surface with permeable
membrane, and vacuum bagging of the assembly.

16
Figure 7:- ATDA HT Carry Through Box Bottom Cover Skin With PRSEUS Stringers.
Top HT Carry Through Box Bottom cover skin, laid up
on female tool in dry state, preform stringers are
mounted in position using soft tooling. The stringers are
then stitched by robot arm to the cover skin. This is
followed by covering the internal surface with
permeable membrane, and vacuum bagging of the
assembly.

17
Figure 8:- ATDA HT Carry Through Box Internal Structural Layout.
Machined Root Rib
Machined Root Rib
Ti Spar to Root Rib
Fwd Splice Plates
Ti Spar to Root Rib
Fwd Splice Plates
Ti Spar to Root Rib
Aft Splice Plates
Ti Spar to Root Rib
Aft Splice Plates
Al/Li Double Sided Topologically
Stiffened EB wire AM formed Ribs
CFC Fibre Placed TE Spar.
CFC Fibre Placed LE Spar.
Jack Screw actuator
attachment fitting
Jack Screw over
run Stop Rod lug.
Jack Screw over run
Stop Rod lug.
HT pivot lugs.

18
WORK IN PROGRESS DRAFT NOT FOR ISSUE
AIAA.

ATDA Commercial Transport Airframe Part 4.pdf

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ATDA Commercial Transport Airframe Part 4.pdf