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Ladislav Smrcek





Students will work on a group aircraft preliminary design project. The conditions
under which the aircraft must meet the needs and any operational constraints that
apply to the design must be defined so that clearly stated performance
specifications can be drawn up. Several alternative concepts that may satisfy the
design requirements should be devised with `the group seeking an innovative
solution. The students form design groups and work on an aircraft preliminary
design study according to the technical specification of a new proposed aircraft.
Each design group will create a spreadsheet to demonstrate effect of change in
selected aircraft design parameters on required mission specification.


The aim is to give students experience in operating design processes in a group
design environment with application of fundamental engineering disciplines.
Other aims are to

Encourage teamwork

Develop a sense of individual and collective responsibility

Present importance of market forces and role of airworthiness requirements

Develop written and oral or poster presentation skills

Learning objectives:

To demonstrate knowledge of basic aircraft performance calculations related to
aircraft preliminary design; to analyse performance for take-off and landing,
rejected take-off, climb glide and cruise climb. To determine aircraft range by a
simple model (for example, Breguet range equation) to convey understanding of
aircraft behaviour and successful design as a careful synthesis of multi- and inter-
disciplinary topics.

At the end of the design project the students should be able to combine basic
aerospace disciplines for aircraft mission specification and corresponding
airworthiness requirements and have developed the necessary skills to apply them
to the preliminary stage of aircraft design.
Students will also have demonstrated the following:

An understanding of the necessary phases in the preliminary aircraft design phase

An understanding of the role of competitors and market forces

An understanding of the role of Civil Aviation Authorities and airworthiness

The ability to develop individual specialized skills

The ability to communicate aircraft preliminary design outcomes
The ability to use engineering charts for aircraft design assessment
The ability to work as an effective member of a small team
Project objectives:

Preliminary Design of Regional Aircraft

In terms of an aircraft, performance can be defined as a measure of the ability of the
aircraft to carry out a specific task. In this project (design group study), the expression
“performance” will be taken to refer to tasks relating to the flight path of the aircraft
rather than to those involving its stability, control or handling qualities.

The estimation of the performance of an aircraft requires calculations of quantities such
as rate of climb, maximum speed, distance travelled (range) while burning a given mass
of fuel and length of runway required for take-off and landing. It is clear that the
performance of an aircraft depends on its design and it follows that performance may
often be improved by changes in design.

This is a subject of great importance but the design of an aircraft involves an integration
of several different technologies, aerodynamics, structures, materials, power plants,
systems etc. and a proper consideration of any one of these in sufficient depth to reveal
its significance in relation to performance would be far beyond the scope of the Aircraft
Design 3 course. Thus the course is not on aircraft detail design it is on aircraft
preliminary design where the use of the overall characteristics mentioned earlier allows
some useful inferences to be drawn as to design changes that might be beneficial.
Spreadsheets will have to be created to allow fast calculations and demonstration of
different aircraft design modifications and show their effect on the proposed mission

This project is concerned with design issues that have to be considered when
redesigning/designing commercial aircrafts. Students have to propose a methodology,
which can be used as a guide to design an aircraft from basics. The methodology will
include information for basic weigh calculations, performance calculations and sizing to
various flying requirements as required by the FAR (Federal Aviation Regulations) or
CS (EU Aviation Regulations). Some of the main issues that have to be addressed

• Preliminary weight calculations

• Performance calculations

• Sizing to climb requirements

• Sizing the cruise speed requirements

• Sizing to stall speed requirements

• Sizing to take-off and landing requirements
In addition, group members would have to specialise individually on a specific aspect of
the aircraft; (e.g. wing, fuselage, propulsion, empennage, landing gear, control surfaces,
etc). Each student is expected to research the importance of the aircraft component and
the consequence of various configurations on the aerodynamics and operational
performance of the aircraft. This would be included in the write up of the final report.

Based in on the research done on the individual aircraft configuration as well as
information on sizing the aircraft and definition of sustainability, the students will then
have to redesign/design an aircraft. This is to be done as an illustration for the
steps/methods proposed by the students in sizing an aircraft.
Example of Evolution of a Mission
Specification and Its Relation to
Conceptual Sizing and Preliminary Design

Commercial Airplanes

Independent Customer
Market Survey Request

Initial De sign
and Trade Studies


Conceptual Sizing

Preliminary Design

If all is well Full
Scale De sign and

Step 1: Carefully review the mission specification, prepare a list of those items which
have a major impact on the design and produce the mission profile.

Step 2: Perform a comparative study of airplanes with similar mission performance.
Use statistical analysis, trend lines. Set design constraints for your plane.

Step 3: Select the type of configuration to be designed.

Step 4: Perform aircraft weight estimation and all other input data necessary for
preliminary aircraft sizing.

Step 5: Prepare a preliminary (scaled) drawing of the fuselage and cockpit layout.

Step 6: Decide which type of propulsion system is to be used.

Step 7: Decide which wing planform design parameters are to be used. Also decide
on the size and location of wing mounted lateral controls and the size and the
position of high lift devices.

Step 8: Decide on size and layout of the fuselage. Put special attention for the space
available for the payload and fuel.

Step 9: Decide on the layout of the empennage: size, planform geometry and
position. Also select the size and location of longitudinal and directional

Step 10: Decide which type of landing gear is to be used. Also: decide on the landing
gear disposition and determine the required number and size of tyres.

Step 11: Prepare a scaled preliminary arrangement drawing of the proposed
configuration and re-do (from point 4) a weight and balance analysis.

Step 12: Perform a drag polar analysis.

Step 13: Discuss stability and control analysis of the proposed configuration.

Step 14: Analyse the results and if necessary repeat the Steps 6 through 11.

Step 15: From the drag polars of Step 13, compute those L/D values which correspond
to the mission phases and to the sizing requirements considered in the
preliminary sizing process.

15.1 Tabulate the new and the old L/D values.

15.2 Determine the impact of any changes in L/D on W
, W
and W

15.3 Calculate performance for which the aircraft is designed for and check if
it fits into your design constraints.
Step 16: Prepare dimensions, fuselage cross section, three-view drawing which reflects
all the changes which were made as a result of the iterations involved in Steps
11 through 15.

Step 17: Prepare a report and presentation which documents the results obtained during
preliminary design sequence. Include the recommendations for change, for
further study or for research and development work which needs to be carried
out before the design can be frozen.

At this point, the first preliminary design sequence should be complete.


Each design lab should arrange themselves into groups of 5/6 students. The group leader
of the group will be responsible for day to day running of the project. Each
student will be a group member with special role in aircraft design for its
mission specification and performance (aerodynamics, propulsion, weights,
etc.) and sustainability. Each student is require to keep his/her logbook
updated. Design group should record the minutes of their meeting which will
form a part of the final report (Appendix).

Task 1 (group work)

Describe how you believe the original specification has been arrived at and identify the
customer‟s principal requirements.

• Identify any issues that need clarification.

• Describe the operational environment and identify the significant issues.

• Find references and supporting information that will be useful is subsequent
design phases.

• Identify your principal design strategy. How will this make your new aircraft
competitive with existing, established designs?

• Identify at least ten aircraft that fulfil a similar or adjacent role to the new design

• Gather information from Jane's and other sources (this may be arranged as sub-
group work if preferred).

• Identify any other relevant data.

• Discuss your findings with your design group.
Task 2 (group work)

This task relates to the classification and analysis of aircraft configurations. Choose
about the specimen aircraft from those you found in the previous task.

• Write a paragraph for each aircraft describing its configuration and identifying
any unusual aspects.

• In tabular form, list the strengths and weaknesses of the various aspects of the

• Propose at least one different form of configuration suitable for your concept

• Critically compare your concept design to existing configurations. Provide a
preliminary recommendation on the merits of the new configuration for further

• Discuss your findings with your design group

(Note: In the group work later in the course, it is preferable to have a variety of aircraft
concepts from the group members. Show at least one unusual configuration to be
studied further.)

Task 3 (group work)

This task relates to some simple analyses of significant parameters from your full aircraft
list produced in the previous tasks. The data generated below will guide you
in the conceptual phase of your individual design work.

In tabular form, present the following information:

• Geometrical information (e.g. span, length, wing area, aspect ratio, sweepback

• Mass and engine information (e.g. MTOW, operating empty, normal combat load,
max combat load, empty and operational mass, zero-fuel mass, installed static
thrust/power, SFC/fuel flow).

• Performance (e.g. max operating speed/Mach No., stall/approach speed,
range/combat radius, take-off and landing field lengths).

Using this data:

• Derive the following (depending on you aircraft list):

Empty weight ratio, useful load to MTOW, fuel load to MTOW, wing
loading, thrust or power loading, C
, etc.
• Plot at least two graphs illustrating trends in your derived data and comment.

• Using this data draw a neat sketch or a scale three-view general arrangement
drawing of your preferred initial „baseline‟ aircraft layout.

• Add textural data of your aircraft to the drawing.

Task 4 (group work)

At this point, you will have been formed into small groups to develop your ideas further.
The group will need to decide the configuration of their preferred design. This will be
formed from the sketches brought to the group by the various members (i.e. their work of
tasks 1, 2 and 3). Note the original „first report‟ will be available at the start of Task 4.
It is important that each member has a copy of their report (submitted after Task 3) to
show to the other group members.

This task expects the group to find the mass ratio, wing loading and thrust loading for
their chosen design option. From the specification:

• Draw a diagram of the mission.

• Tabulate the constraints and flight conditions on each phase of the mission.

• From the data on existing aircraft collected from the previous tasks, particularly
your specimen aircraft, determine estimates for the mass, aerodynamics and
propulsion values for your design.

• Using the required payload, estimate the take-off gross weight, and hence the
engine thrust and wing area.

• With the above data draw a scale three-view general arrangement drawing of your
preferred initial „baseline‟ design layout.

Part of the group working is to delegate (share fairly!) the work between members.

Task 5 (individual work)

The objective of this task is to produce a better estimate of the design take-off gross
weight and other characteristics related to the sustainability requirements.

• From available empirical models and data, determine a detailed mass breakdown
for your aircraft.

• Estimate values of TSFC, propulsive efficiency, aerodynamic coefficients, and
aircraft performance.

• Draw a mission diagram, with annotated segments.

• For each segment, compute the segment weight fraction.

• From these, determine the overall fuel fraction.
• Draw a constraint diagram. Consider each constraint and calculate the
appropriate curve (you may use a spreadsheet to speed things up). Check at least
one point on each curve by doing a manual calculation.

• Reconsider any of the critical design constraints to determine the „rigidity‟ of
these requirements.

• Identify any problems with the problem specification.

• If appropriate re-define your aircraft design point for wing loading and thrust

• Compare the results of the above calculations with the required specification and
decide what changes are necessary to your initial baseline layout.

• Draw a new three-view drawing (to scale) of your preferred design.

Task 6 (group work)

With knowledge of all the design options from the group members and an agreed full
understanding of the problem, devise a mechanism for making a decision on which
design should be selected as the group „baseline‟ configuration. This may be an
amalgam of several students‟ viewpoint or the adoption of a single student‟s
specification. To produce a consistent design it will often be necessary to rework some
of the design processes done in the earlier individual tasks.

Assign one member of the group to produce a working drawing of the baseline design
and to distribute copies to all group members to use in the next tasks.

Task 7 (group work)

The design team decides what type of analysis are required to develop the design, the
timescale and organisation of the work (project plan). This will involve the
allocation of specialist tasks to particular team members. A separate note indicates the
nature of these tasks to be undertaken in the second term. Some technical assistance will
be available to guide students in these decisions.

Task 8 (individual work)

This task is materially different for each member of the team. It involves the writing of a
technical report on each specialist task by the student(s) responsible for the work. The
reports will contain the outlines of the work that may be conducted in later phases of the
project. Students will be expected to report on their recommendations, in general terms,
at specified project meetings so that group design decisions on the synthesis of the
various (sometimes conflicting) issues can be taken.

Task 9 (group work)

In concluding the concept definition phase of the design process, it is necessary to set out
the detailed description of the aircraft. This task is intended to define the final, baseline
aircraft layout by:
• The production of three-view general arrangement drawing to scale (on A3 paper

• The tabulation of the geometrical data for your aircraft (sizes and areas).

• The production, to scale (on A3 paper max), of the inboard sectional view of the
aircraft fuselage showing the main components (cockpit arrangement, engine,
systems etc.).

• The tabulation of the aircraft component mass breakdown as used in the layout
process and the estimates of the aircraft centre of gravity positions.

• The production of reports on the technical analysis of the aircraft from each
specialist area.

Task 10 (group work)

This task completes the initial Conceptual Design Process.

• Produce an aircraft Type Specification to the level of detail available from the
specialised analysis and group decisions.

• Submit the final design team report where the contribution of individual members
of the design team will be clearly stated.

• Submit the log books..

• Project Presentation (interim and final)


Group Leaders (Managers) are responsible for co-ordinating and directing the activities
of the group throughout the duration of the project. They are NOT responsible for doing
all the work. They should make sure that the project workload is evenly distributed
amongst the group members. Failure by any member of the group to make a proper
contribution to the project, to keep up to date with the course material (e.g. handouts), or
to attend group meetings and tutorials regularly, must be taken up immediately by the
group leader with the project supervisor. Each group leader must make sure that all
project milestones are on time. Design sessions will be supervised by metors.

The project leaders make sure that; the design group is well organised (each member of
the group has his/her role and engineering specialistaion. An individual workbook
(logbook) must be kept from the outset of the project by each student. This must be a
full record of the work done by the individual, and should contain sketches, notes,
calculations, computer print outs, technical papers etc. The best idea is to keep all your
work in a binder, and add explanatory notes where appropriate. The workbook may be
reviewed from time to time, and must therefore be in English, but otherwise you may
choose your own format and presentation. The workbook must be submitted for
assessment at the end of the project as this forms a significant part in determining your
final mark. You should indicate what is your own personal work and what are copies of
other people‟s work, or collaborative group work. This is especially important with print
outs of work done on the computer. Do not forget to use references!!


Airplane Aerodynamics, Performance, Thrust and Power Characteristics covers the
methodology and decision-making involved in the process of analysing aircraft
performance covers a systematic progression of fundamentals: aerofoil theory; wing
theory; aircraft drag; aircraft propulsion systems; propeller theory; climb performance
and speed; take-off and landing performance; range and endurance; manoeuvres and
flight envelope. This specialisation also covers familiarisation and the following
fundamentals: methods for estimating aircraft drag with and without flaps; methods for
estimating aircraft lift with and without flaps; methods for estimating aircraft pitching
moment with and without flaps; methods for estimating installed thrust and power data;
methods for estimating installed thrust and power data; methods for estimating stability
derivatives; methods for estimating control derivatives; methods for estimating hinge-
moment derivatives.

Airplane Flight Dynamics and Automatic Flight Control covers a systematic
progression of fundamentals; general steady and perturbed state equations of motion for a
rigid aircraft; concepts and use of stability and control derivatives; physical and
mathematical explanations of stability and control derivatives; solutions and applications
of the steady state equations of motion from a view point of aircraft analysis and
emphasis on aircraft trim, take-off rotation and engine-out control; open-loop transfer
functions; analysis of fundamental dynamic modes; phugoid, short period, roll, spiral and
dutch roll; equivalent stability derivatives and the relation to automatic control of
unstable aircraft; flying qualities and the Cooper-Harper scale; civil and military
regulations; extensive numerical data on stability, control and hinge-moment derivatives.

Preliminary Sizing of Airplanes covers familiarisation with the following
fundamentals: estimating take-off gross weight, empty weight and mission fuel weight;
sensitivity studies and growth factors; estimating a wing area; take-off thrust and
maximum clean, take-off and landing lift; sizing to stall speed, take-off distance, landing
distance, climb, manoeuvring and cruise speed requirements; matching all performance
requirements via performance matching diagrams.

Preliminary Configuration Design and Integration of the Propulsion System covers
familiarisation with the following fundamentals: selection of the overall configuration,
design of cockpit and fuselage layouts; selection and integration of the propulsion
system; simplified method for wing planform design; simplified method for verifying
clean airplane maximum lift coefficient and for sizing high lift devices; simplified
method for empennage sizing and disposition, control surface sizing and disposition,
landing gear sizing and disposition, weight and balance analysis, stability and control
analysis and drag polar determination.

Layout Design of Cockpit Fuselage, Wing and Empennage covers familiarisation with
the following fundamentals: cockpit (or flight deck layout design); aerodynamic design
consideration for the fuselage layout; interior layout design of the fuselage; fuselage
structural design considerations; wing aerodynamic and operational design
considerations, wing structural design considerations; empennage aerodynamic and
operational design considerations; empennage structural and integration design
consideration; integration of propulsion system; preliminary structural arrangement,
material selection and manufacturing breakdown.

Layout Design of Landing Gear and Systems covers familiarisation with the following
fundamentals: methods for estimating aircraft drag with and without flaps; methods for
estimating aircraft lift with and without flaps; method for estimating aircraft pitching
moment with and without flaps; methods for estimating installed thrust and power data;
methods for estimating stability derivatives; methods for estimating control derivatives;
methods for estimating hinge-moment derivatives.

Component Weight Estimation covers familiarisation with the following fundamentals:
simplified method for estimating aircraft component weights; simplified method for
estimating aircraft moments of inertia; for detailed aircraft component and grouping
weights; V-n diagram methods; method for structure weight; method for powerplant
weight; method for fixed equipment weight; data and methods for centre of gravity
location of individual components; method for aircraft moments and products of inertia;
database for aircraft component weights; database for aircraft non-dimensional radii of

Stability, Control and Performance Characteristics: FAR and CS Requirements
covers familiarisation with the following fundamentals: controllability, manoeuvrability
and trim; static and dynamic stability; ride and comfort characteristics; performance
prediction methods; civil airworthiness regulations for aircraft performance and stability
and control; the airworthiness code and relationship between failure states and levels of

Aircraft Cost Esitmation: Design, Development, Manufacturing and Operating
covers familiarisation with the following fundamentals: cost definitions and concepts;
method for estimating research, development, test and evaluation cost; method for
estimating prototyping cost; method for estimating manufacturing and acquisition cost;
method for estimating operating cost; example of life cycle cost calculation; aircraft
design optimisation and design-to-cost considerations; factors in aircraft programme


Each group will be required to submit a group design project report on the work done
ten pages max per group member. The group leader will allocate each member of the
group a task. These job tasks and contributions of the individual members of the group
must be clearly stated in the group report. Each student will keep updated logbooks and
this logbook will be submitted with a group design project report. Minutes of the group
meeting will form part of the report (Appendix)


- Roskam "Aircraft Design" Books and Manuals

- Raymer "Aircraft Design: A Conceptual Approach" Book and Software

- "Jane's All The World Aircraft"

- Ira H. Abbott & Albert E. Von Doenhoff "Theory of wing sections"

- D. Stinton “The Design of the Aeroplane”

- D. Stinton “The Anatomy of the Aeroplane”

- D. Howe “Aircraft Loading and Structural Layout”

- Jenkinson “Civil Jet Aircraft Design”

- Course notes

- WWW resources:

UIUC Airfoil Database


MH Aerotools (JavaFoil)

Advanced Topics in Aerodynamics:

Some general webpages:

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