American Institute of Aeronautics and Astronautics1

The Use of Flight Simulation for Research and Teaching in Academia.

Mark D White* and Gareth D Padfield†

The University of Liverpool, Liverpool, L69 3GH, U.K.

The use of high fidelity flight simulation facilities for research has, until relativelyrecently, been limited to large Government and Industry research organizations and therehave been few opportunities to use such facilities for Engineering Education. However, withthe arrival of low-cost, high performance computing and PC based simulation technologies,the utilization of flight simulators has become viable within an academic environment tosupport both research and teaching activities in undergraduate Engineering degreeprograms. This paper describes the operation and activities carried out utilizing such asystem, HELIFLIGHT, at the University of Liverpool. The simulator combines a 6 degree offreedom motion platform, wide field of view visuals and programmable force-feel systemwith the FLIGHTLAB modeling environment, to produce a high fidelity research toolavailable to undergraduates. This enables the in-depth examination of flight vehicle handlingqualities and pilot-vehicle technology issues. Building on the modeling and simulationactivities carried out in industry related research activities, the facility is utilized as avaluable interactive teaching device in undergraduate degree programs and is central to thedevelopment of new problem-based-learning (PBL) modules. A novel approach to theteaching of Flight Handling Qualities to undergraduates using PBL, highlights fromundergraduate project work and the Royal Academy of Engineering HEADSTARTAerospace Focus summer school program, are drawn on to illustrate the operation ofHELIFLIGHT at Liverpool and the lessons learned during six years of operation.

Nomenclature∆φ = roll attitude change∆h = height changeδe = elevator deflection

pkh& = peak height rate

Q = attitude quicknessq = pitch ratew = downward velocity

I. Introductionith advances in aircraft and simulation technology, the relatively high cost of flight simulation facilitiesensured that their development and utilization was limited mainly to large training organizations andgovernment research agencies. More recently, PC hardware advances in processing chips and graphics cards

has resulted in the price of computing being halved every two years over the last twenty years1. This allows the levelof processing performance and image quality required for high fidelity flight simulations to be accessible to smallerinstitutions such as Academia who typically operate within a more limited financial regime. The primary role of anAcademic institution is the delivery of degree programs and this paper will primarily consider AerospaceEngineering degree programs in the U.K. and in particular at The University of Liverpool. It may be considered thatthe final product of an Aerospace Engineering degree program are capable graduates for the Aerospace Industry.Once committed to a degree program, students should be provided with the opportunity and environment to developtheir technical and inter-personal skills as fully as possible through challenging modules and exposure to active

* Flight Simulation Laboratory Manager, Flight Science & Technology Research Group, The University ofLiverpool† Professor of Aerospace Engineering, Head of Department of Engineering, The University of Liverpool

W

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learning methods. A key part of this learning environment are the tools available to instill the desire for self-improvement amongst the students. U.K. Universities have acquired a range of flight simulators to supportaerospace undergraduate teaching and research activities and this paper focuses on such a system, HELIFLIGHT,which has been in operation in the Flight Science and Technology Research Group at the University of Liverpool foralmost six years.

This paper presents the simulation facility’s capabilities and discusses the utilization of the facility forundergraduate teaching and research activities. The teaching aspect of HELIFLIGHT is highlighted via a newProblem Based Learning Module (PBL) on Flight Handling Qualities and the development of a more interactivelearning environment for other undergraduate modules such as Flight Control Systems. The PBL theme will befurther examined with a description of an aerospace summer school activity, HEADSTART, aimed at providing 17year old school students with an insight into University life prior to the formal application process.

A typical requirement for Aerospace Engineering programs is that undergraduates must complete a researchproject in either the final year of a Bachelors program or during the final two years of a Masters program. The scopeof these projects can be broad and varied and it would not be feasible to propose the projects without suitablefacilities to allow a realistic chance for the undergraduates to complete them. HELIFLIGHT provides this researchenvironment and the results from selected undergraduate research projects are presented.

The paper concludes with the lessons learned from the operation of a flight simulation facility to supportundergraduate teaching and research activities and offers some thoughts regarding the future development of thefacility and enhancements to the learning environment.

II. The HELIFLIGHT Simulation Facility

HELIFLIGHT is a relatively low-cost, turnkey and re-configurable flight simulator with five key components2:

1) selective fidelity, aircraft-specific, interchangeableflight dynamics modeling software, FLIGHTLAB3

with a real time interface (PilotStation)2) 6 degree of freedom motion platform (Maxcue),

(Figure 1)3) four axis dynamic control loading (Loadcue)4) a three channel collimated visual display for forward

view, plus two flat panel chin windows, providing awide field of view visual system (Optivision), eachchannel running a visual database

5) re-configurable, software-generated head-down andhead up display using Engenuity Technologies VAPSsoftware v6.3.1.

Typically, a simulation session is controlled from anadjacent control room which has a viewing window into thesimulator cockpit room. An authorized simulator operatorcontrols the real-time operation of the simulator from the mainhost PC running PilotStation in the control room and interactswith the pilot in the cockpit using a two-way communicationsystem. From this viewpoint, the operator can observe both the motion of the cockpit and also the visual displayswhich are duplicates of those present in the cockpit pod.

A. Modeling and Simulation Software Environment

The primary modeling package used to develop flight models for the system is Advanced RotorcraftTechnology’s FLIGHTLAB software. FLIGHTLAB provides a range of tools to assist in the rapid generation ofhighly complex, non-linear, multi-body models, reducing the effort required for computer coding that is typical ofmost flight simulation activities.

Figure 1. HELIFLIGHT 6-degree-of-freedom motion simulator

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To aid the generation and analysis offlight models, four graphical user interfaces(GUIs) are available: GSCOPE, ControlSystem Graphical Editor (CSGE),FLIGHTLAB Model Editor (FLME) andXanalysis. A schematic representation of thedesired model can be generated using acomponent-level editor called GSCOPE.Components are selected from a menu oficons, which are then interconnected toproduce the desired architecture and data isassigned to the component fields. When therepresentation is complete, the user selectsthe script generation option and a simulationscript in FLIGHTLAB's Scope language isautomatically generated from the schematic.CSGE provides a development environmentallowing a user to design and build controlsystem schematics and then integrate thecontrol system with FLME. FLME is a

subsystem model editor which allows a user to develop models from higher level primitives such as rotors andairframes (see Figure 2). Typically, a user will select and configure the subsystem of interest by inputting datavalues and selecting options that determine the level of sophistication. This approach provides a selective-fidelitymodeling capability, while maximizing computational efficiency. Models are created hierarchically, with a completevehicle model consisting of lower level subsystem models, which in turn are collections of primitive components.Prior to running a real-time simulation, the model generated using the above tools can be analyzed using Xanalysis.This GUI has a number of tools allowing a user to change model parameters and examine the dynamic response,static stability, performance and handling qualities characteristics of design alternatives. Hence the currentsimulation environment provides the ability to create models from physics-based components and the assembly oftree-like model structures, to assess trim, stability and handling qualities off-line, and conduct real-time piloted tests.This allows a wide range of pilot-vehicle problems to be investigated and taught. A user can adopt a number ofapproaches to the modeling and simulation of a desired aircraft e.g. a ‘Multi-body’ and ‘Multi-table lookup’ model.A companion paper examines the relative merits of these approaches in more detail4. Students have access toFLIGHLTAB modeling environment through a number of dedicated workstations.

Since its commissioning in 2000, the simulationenvironment has undergone a number of hardwareand software upgrades carried out in-house. Theseupgrades have primarily been driven by the researchneeds of industry related projects which in turn havebenefited the undergraduate activities. In particular,the implementation of BAE’s run-time environment,Landscape5, has allowed a user to more readilygenerate moving visual models or entities, apply arange of visual conditions at run-time (fog, cloudetc.) and display user defined Head Up Display(HUD) symbology and novel Head Down Displaypanels. HUDs and HDDs are built using EngenuityTechnologies’ VAPS tool suite and integrated intothe simulation environment once the prototypingprocess has been completed. The softwaredevelopment work has also increased the scope ofthe flight modeling activities. A new C++communication bridge (Figure 3) allows a user tointegrate Matlab/Simulink models or other flight models e.g. X-Plane, FlightGear into the simulation environment.In terms of undergraduate simulation activities, access to these lower cost simulation tools increases the scope for

C++ COMMS BRIDGE

xPC TARGET PC Real-Time application

xPC HOST PC(Simulink Model)

Motion baseControls &

SoundLandscape

Visuals

Figure 3. MATLAB-HELIFLIGHT Integration

Figure 2. FLME Representation of a Generic Rotorcraft

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introducing a modeling and simulation element into their learning and teaching environment at an earlier stage intheir studies.

B. Facility Utilization

HELIFLIGHT has been available for use in undergraduate teaching and research since 2000 and Figure 4 showsthe increase in simulator utilization for undergraduate and schools activities to year end 2005 (72 hours in 2001 toover 300 hours in 2005). This increase in facility utilization reflects not only the development and introduction ofPBL and interactive teaching concepts into undergraduate module specifications but also the growing interest fromschools and colleges to try and broaden the outlook of students when considering their choices for higher level

studies. Approximately one third of totalfacility utilization is dedicated toundergraduate and schools relatedactivities which are discussed in moredetail later in the paper. During itsoperation lifetime this share of the overallutilization has not changed significantlybut the overall number of hours dedicatedto schools and undergraduate activities hasincreased significantly. The hours showndo not include the more substantial timespent in off-line analysis and modeldevelopment. In the following sections anumber of simulator related undergraduateand schools teaching and researchactivities are detailed.

III. Undergraduate Teaching Activities

The University of Liverpool offers 10 undergraduate degree programs which have an aerospace theme, includingAerospace Engineering, Aerospace Engineering with Pilot Studies, Avionics and Avionics with Pilot Studies. Aspart of the ongoing teaching and learning developments within the Department of Engineering there is a drive toenable students to engage in all elements of the Conceive-Design-Implement-Operate (CDIO) cycle6. Hence anumber of undergraduate Aerospace engineering taught modules have been adapted, or new ones developed, toinclude an element of either problem based learning or interactive teaching utilizing the capabilities available withinthe HELIFLIGHT environment. In particular, four modules covering Introduction to Aerospace Engineering - FlightAwareness Exercise (Year 1 of study), Flight Control Systems (Year 3 of study), Rotorcraft Flight (Year 3 of study)and Flight Handling Qualities (Year 4 of study) have benefited from these developments. The following sectionsprovide an overview of each module, the manner of simulator utilization and the perceived benefits derived by theundergraduates.

C. Flight Handling Qualities – A Problem Based Learning Module

October 2002 saw the introduction of a new Problem Based Learning (PBL) core module into the M.EngAerospace undergraduate program, Flight Handling Qualities (FHQ)7. The aim of the module is to equip studentswith the skills and knowledge required to tackle handling qualities (HQ) and related whole system problems thatmay be experienced in Industry. The problems were examined using a combination of off-line desktop analysisusing FLIGHTLAB and piloted simulation trials using HELIFLIGHT. Access to the simulator was freely availablethroughout the module and the students were encouraged to carry out their own HQ trials in preparation for the mainsimulation trials flown by test pilots.

0

120

240

360

480

600

720

840

960

1080

UndergaduateActivities

UCAS/SchoolsVisits

Applied Research System Work CommercialVisits

Total

Hou

rs

20012002200320042005

UndergaduateActivities

25%

UCAS/SchoolsVisits 8%

Applied Research58%

System Work7%

Commercial Visits2%

Figure 4. Annual facility utilization

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Four themes underlie PBL:

1) Explore problems using background knowledge and experience2) Analyze problems and formulate hypotheses that might explain them3) Design and conduct experiments or perform theoretical analysis to test hypotheses4) Develop new understandings and formulate problem solutions.

In the Flight Handling Qualities module, the aircraft and its associated handling deficiencies become the focusfor knowledge acquisition. This method of learning helps the student to develop transferable, technical andinterpersonal skills that will serve them throughout their careers. The students are formed into 5 Teams of 3 or 4,depending on class size, and each team presented with a task of assessing and quantifying the HQs of a particularaircraft in a given role and developing fixes to any handling deficiencies identified. The students are provided with acomprehensive set of notes and attend a number of semi-formal lectures to help develop the knowledge of HandlingQualities theory and the intellectual capabilities to solve HQ problems and carry out the associated analyses,parameter calculations and evaluations to model, simulate and improve Flight Handling Qualities. This issupplemented with team building exercises and a number of workshops providing them with the practical andtransferable skills to enable them to use the software tools available and design their own experimentalarrangements. A “mentor” is assigned to each group to help facilitate the learning experience and regular meetingswith mentors are encouraged to assess progress and direct the group’s focus to solve any problems. The studentshave various deliverables during the course of the module including a personal learning journal (every 2 weeks), aninterim report and oral presentations for results from off-line analyses and simulation trials and associated test plansand planned improvements. A final presentation is made to a “customer” group derived from members of staff,another student team and visiting Industrialists, with the aim of demonstrating the ability of the modified aircraft tofulfill its role.

Test aircraft used in the module were the Bo-105 (to be upgraded for an anti-submarine warfare role ), theFLIGHTLAB generic rotorcraft similar to the UH-60 Blackhawk (assigned a tactical transport role), Grob G-115Tutor (required upgrading as an advanced combat trainer), the 1903 Wright Flyer (assigned role as an observationplatform) and the XV-15 (to be used for search and rescue missions). The specification of the roles assigned to eachaircraft can be changed from one year to the next. A snapshot of the work undertaken by the teams follows using theGrob team as an example.

The Grob Tutor team was presented with theproblem of carrying out design upgrades to allow thebasic training aircraft to fulfill a new aircraft role asan advanced combat trainer (ACT), the TutorPlus.An increase in maximum cruise speed at sea levelfrom 135 kts to 200 kts was specified, with acapability of sustaining a 3g turn and track a movingor fixed target at 200 kts. For the expandedoperational flight envelope mission task elements(MTEs) were designed to evaluate the effectivenessof the aircraft in different mission phases, theeffectiveness being measured in the form of CooperHarper handling qualities ratings8 using pilotedsimulation and analysis using MIL STD 1797criteria9.

Piloted simulation and offline analysis indicatedthat the basic aircraft had insufficient engine powerand roll control power and was poorly damped inpitch. To meet the requirements the span and chord of the ailerons were increased, a power plant upgrade wasimplemented and a longitudinal state feedback control system was designed (feeding back downward velocity, w,and pitch rate, q). The technical and economic viability of each modification was assessed. The effect of thesechanges on handling qualities performance in the roll axis may be seen in Figure 5 for a roll-step Mission TaskElement (MTE). During the roll-step MTE shown, the pilot is required to fly the maneuver at different speeds,crossing from one side of the runway to the other, flying a precise flight path through the gates. The higher thespeed, the less time available to cross the runway, hence the higher the required bank angle and turn rate. The pilotis required to fly to the desired and adequate performance standards, as defined in Figure 5. Throughout the task the

Figure 5. Improvements in Grob roll performance

Original Grob

Upgraded Grob

Adequate

Desired

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pilot has to monitor the speed and height constraints, whereas the remaining performance parameters (lateralposition, bank angle and heading) are only an issue between the gates along the runway edge. Through a number ofdesign changes, the pilot was able to achieve the desired performance for this task and the aircraft was able to satisfythe other requirements for its ACT role. A number of other MTEs were carried to examine the HQ in different axesand the TutorPlus design was found to have addressed the HQ deficiencies identified in the original aircraft.

A crucial resource utilized during the module was the students having access to test pilots. The simulation trials,designed and directed by the students, were flown by visiting former Test Pilots who were tutors at the UnitedKingdom’s Empire Test Pilot School. Access to the test pilots provided unique learning opportunities for thestudents especially with reviewing experimental design procedures, determining relevant mission task elements andperformance standards and aiding their understanding of the importance of flight handling qualities to operationaleffectiveness and flight safety. Ensuring the test pilots were adequately briefed and debriefed within a limited timeperiod added to the sense of responsibility experienced by the teams and instilled a professional outlook on theproceedings.

Other than the academic scores achieved by the students, the success of the module and the PBL approach takencan be measured by the feedback from the students. Whilst some students find the transition from a more traditional“chalk and talk” lecture arrangement to the PBL approach challenging at first, they do adapt and undergo asignificant amount of personal and academic development. Comments such as “I have found myself using my timemuch more constructively than ever before” and “Writing a learning journal has been a completely new skill that Ihave learned. I have found writing this journal very beneficial – gets me thinking more in depth about what I havejust been doing” are typical of the experiences garnered by the students. The students feel that the module provides afocal point for them to integrate the intellectual material they have collected throughout their academic studies.

D. Interactive Teaching Activities

The previous section detailed a module that was developed specifically along a PBL theme. Given the success ofthis approach, the challenge facing lecturers with existing modules is how to best update them to provide an elementof interactive teaching. Including the FHQ module, there are currently four undergraduate modules that now containsome form of interactive teaching, utilizing the flight simulation facilities at Liverpool to reinforce the materialdelivered in a traditional classroom environment.

Introduction to Aerospace Engineering is an undergraduate module taken by all Year 1 Aerospace Engineeringstudents. The aim of the module is to provide the students with a broad understanding of basic aerospaceengineering principles. The module includes a practical laboratory exercise in which the students are expected toutilize the technical material delivered within a class room session and then demonstrate a practical knowledge ofthe effects of a pilot’s controls on a fixed wing aircraft in flight, in this case by flying the Grob Tutor on thesimulator. Students attend the laboratory session and are briefed on the primary flight instruments which they willuse during their sorties. The students take off and climb to 2000ft where they are required to demonstrate theprimary and secondary effects of controls e.g. the primary effect of aileron is roll which generates a secondary effectof (adverse) yaw. Whilst the majority of students have some basic insight into the theory of aircraft performance, theconcepts can be new to them and an important part of flying that an engineer should understand. The studentscontinue with coordinated turns with rudder whilst holding height using the Vertical Speed Indicator before theyattempt more complex maneuvers such as stalling and spinning. The sortie finishes with a few circuits maintainingcorrect height and pattern. Throughout the session the students are asked to consider the underlying principlesinvolved and it is this combination of experiential and classroom learning that the students find beneficial indeveloping their intellectual capabilities.

Aerospace students entering their third year of study take a number of compulsory core modules and choose anumber of elective options. One of the options available is the Rotorcraft Flight module, the key aim of which is toprovide students with a firm grasp and understanding of the principles of rotorcraft flight mechanics. This is attainedthrough lectures and laboratory exercises using the flight simulator with FLIGHTLAB’s generic rotorcraft model(FGR), akin to the UH-60 Blackhawk. The module is designed to enable students to solve a wide range of rotorcraftproblems and through modeling and simulation allow them to investigate the roll and heave response characteristicsof the FGR. The latter involves laboratory session with a piloted assessment of different configurations by a testpilot. It allows the students to direct the focus of the investigation with regard to the roll and heave responsecharacteristics of the FGR to pilot control inputs, whilst performing a roll-step and bob-up MTE. The objective ofthe experiment is also to show how these relate to pilot perceived handling qualities when flying a test maneuver.Using reference material recommended for the course11, 12 students develop the necessary theoretical foundations

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and apply them to a practical evaluation of the test aircraft. A laboratory script is provided which suggests the openand closed loop tests to be carried out and the performance standards and assessment criteria which should beutilized during the sessions. In particular students are introduced to the concept of attitude quickness, Q, defined as:

φ∆= pkp

Q (1)

for the roll axis, where ppk is the peak roll rate achieved and ∆φ is the attitude change which resulted and for theheave axis:

h

hQ pk

∆=

&(2)

where pkh& is the peak height rate achieved and ∆h is the height change which resulted. A typical set of roll

quickness open loop results can be seen in Figure 6, along with the corresponding ADS-33 handling qualitiesboundaries. From such a starting point, the students are free to investigate a range of rotorcraft design issues such asthe effect of switching the Stability and Control Augmentation System (SCAS) off, an increase in vehicle all upweight due to operational requirements and main rotor design and assess their impact on the ability of the aircraft to

carry out its mission task. As with the FHQ module,an important asset in the delivery of this module isthe use of an experienced test pilot. The detailedfeedback provided by the pilot generates discussionpoints amongst the students. Guided by the requisitetheory available “live” from the module coordinatorduring a simulator session, it is possible to introduceand investigate a fundamental concept almost in realtime and generate sufficient simulation data to allowa more detailed analysis of the findings to beproduced at a later date. The interactive nature ofthe laboratory classes and the ability of the studentsto experience the complexities of rotorcraft flight byflying the simulation themselves instills anappreciation and understanding of the subject matterthat would not be available from a more“traditional” approach.

Over the years, undergraduates have expressed the opinion that at times they have almost become disconnectedfrom the learning outcomes that a module is designed to deliver. In this instance they go through the motions of apiece of work to gain the academic credits necessary for them to progress through their studies without necessarilybecoming fully engaged with the material. A continuous assessment in the Year 3 Flight Dynamics and Controlmodule provides this connection between key learning outcomes and a real world application. The aim of thismodule is to give the students a good understanding of Flight Dynamics/Flight Control Systems principles and toequip them to solve related problems. A real world problem relating to stability of a fixed wing aircraft wasformulated using the flight simulator to enable the students to apply their knowledge to the design and evaluation ofa feedback controller design. A linear model of the longitudinal dynamics of a fixed-wing aircraft using stabilityderivatives was produced and used as the test vehicle in the exercise. At a specified flight condition the aircraft isrequired to carry out a terrain following mission over undulating ground at a radar altitude of less than 250 ft. Thebaseline aircraft exhibits poor handling qualities in its assigned role due to the poor short period dynamics. Theobjective of the exercise is to design and implement a feedback flight control system to achieve Category A MIL-F-8785C terrain following requirements13. Prior to attending the simulator evaluation, students are required, using thetwo-degree of freedom short period approximate model, to determine a state-feedback control law and aproportional feedback controller feeding back pitch rate, q and downward velocity, w to elevator deflection, δe togive Level 1 flying qualities. Typically, students at the simulator session have carried out the paper controller design

Figure 6. FGR Roll quickness

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exercise with little appreciation for the impact their design can have on the handling qualities of an aircraft. Oncethey carry out an initial piloted evaluation of the test aircraft, both open and closed loop, their attention is soonfocused on the problem in hand. The aircraft is unstable in pitch and pilot induced oscillations are a key feature ofthe terrain following mission, for those students who are able to fly that far through the exercise. It is rare forstudents to arrive with similar design gains for the controllers and so the evaluation of all the designs and associateddamping ratios gives them the opportunity to evaluate a range of solutions. Generally a session begins following theapproach prescribed within the exercise guidance notes but soon develops into a more open “what if?” exercise thatgoes beyond the initial scope of the class; if the role of the aircraft is changed what gains would be required? Thispart of the session usually develops from discussions within the student groups with little or no prompting.

IV. Undergraduate Research Activities

HELIFLIGHT is extensively utilized as a research tool in a large number of undergraduate projects for bothfixed wing and rotary wing studies. Students entering their third year of study are required to undertake either a oneyear research project if following the B.Eng program or a two year project if enrolled on the M.Eng program.Research projects are typically proposed by members of the academic or research staff but undergraduates can alsosuggest their own areas of interest. Figure 7 shows the variety of the projects that have been undertaken by theundergraduate students in recent years. Ideally, projects are developed from ongoing research within the FS&Tresearch group which have an industrial relevance or are generated to provide tools and support for future researchand teaching developments. Having an active research group with an established research portfolio is an importantresource for the undergraduate students who can use the researchers as a sounding board for their ideas and asguides in their research projects.

In a typical project, students are required to research the problem, use the modeling and simulation toolsdescribed in Section II, design and conduct experiments and present their results to an assessment panel. The projectwork complements the teaching and learning activities that take place in the taught modules and supplies theframework from which they can attach and apply the knowledge gained during their studies. Examples ofundergraduate projects include:

1. Development and analysis of a Puma FLIGHTLAB rotary wing model, allowing a HQ assessment ofthe aircraft using ADS-33 metrics to be carried out. A control system was implemented which resultedin a significant improvement of the Dutch roll and phugoid behavior of the aircraft and a generalreduction in pilot workload during MTEs.

2. The development of a Boeing 747-100 FLIGHTLAB model and validation against a NASA simulationmodel. The eigenvalues and aerodynamic derivatives for various conditions were investigated andfound to be most accurate in the low speed and altitude ranges. One of the aims of the project that wasrealized was the production of a baseline model that can be utilized in future undergraduate andindustrially relevant research projects.

3. Pitch/ Flight Path Handling Qualities of Tilt Rotor Aircraft in Airplane Mode – the aim of the projectwas to contribute to the risk reduction studies for the flight control system of a future European civil tiltrotor aircraft that was undertaken by FS&T, Rotorcraft Handling Interactions and Load Predictions14.This undergraduate project focused on the pitch dynamics of a FLIGHLTAB XV-15 tilt rotor model inairplane mode at speeds of between 160-300kts. The undergraduate study also involved theimprovement of Handling Qualities (HQs) through the design of a stability and control augmentationsystem using a flight simulation model of the XV-15 tilt rotor.

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The following section highlights an example of one the undergraduate projects that have been undertakenrecently. One of the interesting aspects of this research project is that one of the deliverables of this project was theformulation of a new undergraduate PBL module focused on an aircraft accident investigation.

A. Diagnostic Tools for Aircraft Accident Investigations15

An engineer is often tasked with the design and development of a new system, with pre-defined operationalcriteria, which is then expected to enter service and function according to those specifications. Unfortunately,despite attempts to ensure that the probability of a failure within the system is acceptably small, systems do fail and“accidents do happen”. When accidents happen, they provide insightful learning opportunities for engineers. The

Rotary Wing• Tail rotor failures - control concepts• Simulating Helicopter Engine Off Landings• Helicopters in Steep Descent• Encounters with fixed-wing aircraft vortices• Puma helicopter development• Fairey Rotodyne development

Display Systems & Visual Perception• Investigation into How Peripheral Vision Affects Situation Awareness in Flight• Visual perception in fixed wing/rotary wing approaches

Fixed Wing• Model development:• Grob, B747• Space Shuttle• Bristol Boxkite• X-29• Jetstream• Centaur Seaplane

Tilt-rotor• Pitch/Flight Path Handling Qualities of Tilt Rotor Aircraft• High Altitude Assessment of Dutch Roll Stability• Actuator Failure Analysis with Turbulent Encounters• Lateral Handling Qualities of the XV-15 Tilt-rotor

Simulation Fidelity• Adaptive Pilot Model For Simulation Fidelity

Assessment – Yaw Axis Maneuvers,• Evaluation of Low Cost Flight Simulator

– Fixed and Rotary Wing

Figure 7. Undergraduate Aerospace Engineering Research Projects

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original design ethos can be examined and the mitigating factors that led to the failure determined. This newlyacquired knowledge can then be incorporated into the design of safer systems in the future.

Such a learning opportunity can be provided in the form of the investigation of an aircraft accident. Typically thecause of an accident can be attributed to one of or combinations of three categories; human factors, atmosphericconditions and mechanical/electrical/design failures. An investigator must examine the evidence in a systematicmanner, utilizing tools developed using engineering principles to work backwards from the catastrophic event todetermine the root cause(s) of the accident. The main objective of this research project was to develop a suite ofdiagnostic tools that could be used to support a new 2nd year undergraduate aerospace engineering PBL module thatallows a simulated aircraft accident investigation to be carried out.

In order to produce an effective scenario, the project student was required to draw on a range of academicdisciplines in order to “engineer” an exercise in which undergraduates could fully engage with the PBL process.Central to the learning outcomes of the new module is the method in which the underlying principles can bedelivered to the students. The input from an undergraduate student regarding the design of the knowledge deliveryprocess is key to ensuring students are presented with a constructive learning environment. The PBL scenario is setwith students being presented with black box data and they are expected to determine the cause of the accident usinga combination of piloted simulation trials and desktop analysis and simulation tools.

The project required the development and analysis of an existing FLIGHLTAB model of a Generic LargeTransport Aircraft GLTA (similar to a Boeing 707). A simulation was developed to replicate an accident in theapproach to landing phase of a flight, involving a rudder malfunction as experienced in United Airlines Flight 585and USAir Flight 42716, 17. For the PBL exercise, the test aircraft would be rolling out of a left bank in order to set upthe aircraft for landing. A cross wind was introduced whilst the aircraft was heading towards the runway. Thiswould require the pilot to use pedal inputs to maintain steady heading. At this point a rudder actuator malfunctionwould be initiated, resulting in a rudder hard-over. This would require additional pilot lateral stick activity but themodel is engineered such that there is insufficient roll power to overcome the rudder which results in loss of controlof the aircraft.

The GLTA model was modified to demonstrate the characteristics of a Boeing 737 aircraft via a re-design of thecontrol system and adjustment of the aerodynamic properties of control surfaces. A failure point was introduced intothe control system to affect a rudder hard over at a predefined point and realistic gust models developed to producean initial flight path disturbance.

To carry out the accident investigation students would be given 62 recorded flight parameters excluding thecontrol surface deflections as this information would readily indicate the rudder problem. The students would beprovided with a simple logic tree (Figure 8) and using desktop simulations would be able to explore the variousbranches of the tree using packaged tools for inverse simulation, system identification, trim and stability analysis todetermine the likely cause of the accident.

Throughout this project, and subsequent projects to follow, the research requires the integration of a number ofdisciplines and a systems approach to developing the PBL exercise. The production of this PBL exercise is a PBLexercise in itself and one in which the student’s academic knowledge and general transferable skills are given theopportunity to develop significantly. The research project to develop the PBL exercise has completed its first yearand has seen the development of an accident scenario and a desktop simulation environment that enables students tore-create the pilot inputs from data available from a virtual black box. Diagnostic tools have been proposed to allowstudents to investigate the accident and provide them with an interactive environment to successfully accomplish thetask of identifying the cause of the accident. It is anticipated that as the project completes it second year a newundergraduate PBL module will be available for introduction into the aerospace engineering degree program.

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V. Engineering Education and School Activities

A growing area of Engineering Education that the simulation facility has been utilized for has been the hostingof Secondary Schools and Higher Education college visits for students aged 11-18. The purpose of the visits is toexpose the students to the challenges still to be faced by the Aerospace Industry and the career opportunities that areavailable to them. One important role the visits play is to dispel the illusion that the majority of students have, if theyhave not taken a design and technology course, is that the main job of an engineer is to fix something, be it a car inthe case of a Mechanical Engineer or an aircraft in the case of an Aeronautical Engineer. Aerospace taster sessions,primarily utilizing the simulation facilities, allow the students to experience first hand what they may experience asan engineer. The HEADSTART program discussed in the next section details a significant commitment to thisprocess.

A. HEADSTART Summer School

HEADSTART is an activity of the Engineering Development Trust and forms part of the Royal Academy ofEngineering’s Best Program that aims to provide high quality Year 12 (Scottish Year 5) students normally aged 17,who are interested in science and engineering, an opportunity to spend up to a week at University, exploringappropriate degree courses prior to making their applications to the Universities of their choice. Applications forentry to a Higher education establishment are processed via a central organization, the Universities and CollegesAdministration Service (UCAS). The courses are designed to demonstrate what science and engineering is about,provide opportunities to meet university lecturers, recent graduates and engineering organizations and to show thatengineering is a worthwhile and dynamic career. Courses are either offered to demonstrate a wide range ofengineering disciplines or can be a Focus program, targeted at a particular branch of engineering e.g. Automotive,Civil.

Evaluate original atmospheric conditions. Did theaircraft encounter any atmospheric changes?

Re-simulate pilot inputs offline whilst includingatmospheric changes. Is data similar to black box?

Re-simulate pilot inputs offline. Isdata similar to black box?

Human Factorsand/or AtmosphericConditions and/or

Mechanical Failure

Human Factorsand/or Atmospheric

Conditions

Human Factorsand/or Mechanical

Failure

Human Factors

Did aircraft encounterany adverse conditionswhich would havecaused an accident?

Did aircraft encounterany adverse conditionswhich would havecaused an accident?

Human Factorsand/or Atmospheric

Conditions

Human Factors

Human Factorsand/or AtmosphericConditions and/or

Mechanical Failure

Human Factors and/orMechanical Failure

YES

YES YES

YES

YES NO

NO NO

NONO

Figure 8. Accident Logic Tree

American Institute of Aeronautics and Astronautics12

Since July 2003, students have been attending the Aerospace Focus program at Liverpool, which has had atheme celebrating the Wright brothers’ achievements in pioneering Aerospace engineering. HEADSTART atLiverpool is a four day residential course operated within the FS&T research group. A simulation of the Wrightbrothers 1903 Flyer had already been developed in the Flight Science and Technology Research Group10 and wasused as the baseline model for testing and development. The requirement for the program was for the students toevaluate the baseline 1903 Flyer model and, where necessary, carry out upgrades to produce a vehicle which couldbe used as a basic observation platform, flying circular flight paths over the ground in winds up to 10kts. In essence,the students are posed with the same problem as that given to the 4th year M.Eng FHQ students.

In order to accomplish this, the students were required to carry out a number of research activities to produce anaircraft with improved performance that was evaluated using the HELIFLIGHT simulator. In the latest version ofthe activity a group of 40 students operate in teams of six or seven and worked to tight deadlines in order to producea solution prior to presentations on the final day. The students are supported in this process by a team mentor, all ofwhom have either taken the FHQ module as an undergraduate or act as a group mentor for the FHQ module. Theprogram took the form of a number of lectures, laboratory sessions and simulation experiments:

1. Lectures on the Wright brothers achievements in the period up to 1905, aircraft performance andstability and control

2. Planning of flight tests – students split into their teams and using the information packages providedwere required to scope out a set of flight simulation tests that would highlight the handling qualitydeficiencies of the aircraft. Each group was required to design a flight test program and test pilot briefdetailing the performance standards to be used.

3. Control laboratory – although the Wright Brothers did not have access to modern control hardware, thedemonstration of the principles of flight control design for an inherently unstable aircraft was examinedusing desktop simulations

4. Wind tunnel tests – each group carried out lift/drag measurements on a Wright aerofoil section andcompared the results against wing sections fabricated by the students themselves.

5. Modeling and simulation tutorial – dedicated session to help inform the effect on the simulations of thedesign configurations under consideration.

Throughout the program the students had access to a test pilot, whose flight experience was invaluable to givethe initial piloted assessment to the complete student body as well as detailed group assessments based on the testprograms developed by individual groups. Significant support from members of the academic and research staff wasrequired during the program, especially with the implementation of model changes using FLIGHTLAB. Anevaluation of the modified aircraft was carried out with the test pilot on the afternoon of the third day. Students werethen required to present their results, acting as a potential supplier to a customer group consisting of the other teamsand members of the academic and research staff. This requirement to act as both customer and supplier during thefinal presentation session provided the students with contrasting perspectives regarding the performance of theirown designs and those produced by other teams and also introduced a significant element of competition into thecourse.

70 bhpengine

Mainwheels

Rudder

Tailwheel

Canard

70 bhpengine

Mainwheels

Rudder

Tailwheel

Canard

Moved forward 6ft

Moved back 3ft

Bigger by 25% Added tail plane

Figure 9. Proposed design solutions for the 2006 Flyer

American Institute of Aeronautics and Astronautics13

Although the students had not yet embarkedon an aerospace undergraduate program, theywere very adept at utilizing the resourcesavailable to correctly identify the majorhandling deficiencies of the 1903 Flyer, namelysideslip issues due to limited lateral directionalcontrol, lateral and longitudinal instability,asymmetric turning characteristics and adverseyaw problems. Figure 9 shows two examples ofconfigurations tested during HEADSTART2006. Whilst the main objective of the programis to demonstrate to the students the challengesfaced by engineers and that the final goal forthe exercise was to produce a “better” aircraft,

one of the most valuable learning experiences the students received was when the designs failed. The aircraft on theleft hand side of Figure 9 represents a successful design, illustrated in Figure 10 by the improvements in HQ ratingsobserved in the modern solution, the design on the right hand side of Figure 9 can only be categorized as a failure asthe modifications carried out only exacerbated the deficiencies inherent in the original 1903 design and produced asignificant degradation in HQ ratings. However the group gained a valuable learning experience from this result andin conjunction with the test pilot were able to gain a greater insight into the HQ deficiencies of the original aircraftand a more detailed understanding of the consequences of their design changes on the performance of the aircraft.This stood them in good stead during their role as customer during the final presentations as they could ask morediscerning questions relating to the modifications of other group’s aircraft.

VI. ConclusionThe use of flight simulation at the University of Liverpool is becoming more widespread as an undergraduate

teaching and research tool. The PBL approach to learning is a positive step forward in producing capable graduateswith the skills that are required by the aerospace industry and who can easily integrate into that environment. Thesimulation facilities at Liverpool provide the opportunity for students to engage with aerospace problems using aholistic systems approach in an area of study that is highly multi-disciplinary in nature. Interactive teaching and PBLmodules have been developed to provide undergraduates with a hands on experience drawing on intellectualmaterial accrued during their academic studies. Flight simulation and modeling provides academia with anaffordable method of delivering a design, test, build module with students taking responsibility for their ownlearning and knowledge development. It is anticipated that additional teaching modules will be developed having aflight simulation and PBL component and that there will be a closer integration of modules to ensure that studentscan benefit from the cross fertilization of learning outcomes.

Existing collaborations between academia and the Aerospace industry are important and a closer partnershipbetween the two groups will be desirable to both parties. Cheaper and faster simulation hardware will mean that thesimulation technology gap that exists between industry and academia will continue to close and it will become moreeconomical to use academia for research with their large resource pool and expertise. In return, academia will gainaccess to information and tools that will strengthen their simulation capabilities.

Academia is faced with a number of challenges and opportunities in the field of flight simulation and it is hopedthat this will inspire more students to consider a career in aerospace engineering.

Acknowledgments

The authors would like to acknowledge the help and enthusiasm of the undergraduate students who haveventured through the Aerospace degree programs at the University of Liverpool and whose work is presented in thispaper. In addition, authors would also like to acknowledge the commitment of numerous technical, clerical, researchstaff and test pilots who are involved in day-to-day operation of HELIFLIGHT and whose professionalism is greatlyappreciated. Sunith de Fonseka is specifically acknowledged for his research project reported in this paper.

References

02468

10Straight and level flight

Roll step

Climb

Descend

Left turn < 10°

Right turn <10°

Stall

Landing (Power on)

1903 Flyer

2006 Flyer

Figure 10. HQ ratings improvements for 2006 Flyer

American Institute of Aeronautics and Astronautics14

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