1Rogers SmithRogers SmithConsultantConsultant

/ / NTPSNTPS

RoleRole

of Pilot of Pilot ModellingModelling

WithinWithin

HQHQ

EvaluationsEvaluationsManching, Germany, 11 Nov 2008Manching, Germany, 11 Nov 2008

Handling Qualities ReviewHandling Qualities Review……....

……

a Practical Perspectivea Practical Perspective

2

A PilotA Pilot--EngineerEngineer’’s Overview !s Overview !

3

AlternateAlternate

Title.....Title..... Evolution of Modern Evolution of Modern FlightFlight

ControlControl

SystemsSystems

….and My Pilot Modelling Exposure

4

•• Introduction Introduction ––

WhoWho

am I? am I? WhyWhy

am I am I herehere??

•• A Little A Little HistoryHistory--

Wright Brothers....Wright Brothers....

•• Pilot Pilot ModellingModelling

and and meme

!!

--

CriteriaCriteria

DevelopmentDevelopment

--

NealNeal--Smith Smith PerspectivePerspective

•• RealityReality: : PIOPIO‘‘ss

--

ExamplesExamples

•• PracticalPractical

PerspectivePerspective/ / CaseCase

HistoryHistory

•• Final Final CommentsComments

and a Little Musical Inspirationand a Little Musical Inspiration

Topics / Topics / PurposePurpose

5

•• Test Pilot/ Test Pilot/ EngineerEngineer

((manymany

decadesdecades

!)!)•• NRC (Canada) NRC (Canada) --

CAL(CalspanCAL(Calspan))

NASA (Langley / NASA (Langley / DrydenDryden))•• Projects:Projects:

--

(NRC / (NRC / CalspanCalspan))

> (VS > (VS HelicoptersHelicopters, X, X--22, NT22, NT--33)33)

--

(Neal(Neal--Smith)Smith)

--

(X(X--29, X29, X--31......)31......)

•• EADS / Eurofighter (FCS Team, EADS / Eurofighter (FCS Team, DirectorDirector

FlightFlight

Test)Test)

•• NTPSNTPS

((InstructorInstructor) )

MY BACKGROUNDMY BACKGROUND

NASANASA

AirborneAirborne

Simulators:Simulators:

HQHQ‘‘ss::

6

Why Look Back in History ?

“

What is Past is Prologue ”

“

Those

who

do not

learn

from

history

are

doomed

to repeat

it

″

“

The Future ”

* William Shakespeare

* George Santayana

7

A Little HistoryA Little History……the the Evolution BeginsEvolution Begins

8

Wright BrothersWright Brothers’’ EvolutionEvolution……19001900--19031903•• Longitudinal control with Longitudinal control with

““horizontal rudderhorizontal rudder””

forward forward of wingsof wings

•• CG coincident with ACCG coincident with AC•• PIOPIO’’s (Final TD~0.5 sec)s (Final TD~0.5 sec)19041904•• Moved elevator further Moved elevator further

forwardforward•• Moved CG aftMoved CG aft•• PIOPIO’’s (TD~0.4 sec)s (TD~0.4 sec)19051905•• Ballasted for more Ballasted for more forwardforward

CGCG•• Success (but still unstable) Success (but still unstable)

~1.0 s~1.0 s

9

Pilot Modelling and MePilot Modelling and Me

•• My History ~ 1970My History ~ 1970’’ss

--

““BirthBirth””

of Highlyof Highly--Augmented Designs (..YFAugmented Designs (..YF--16)16)--

Need for Suitable HQ CriteriaNeed for Suitable HQ Criteria

--

NTNT--33 Data Base (Specs no longer valid)33 Data Base (Specs no longer valid)--

Interest in Pilot Modelling (NRC/CAL) Interest in Pilot Modelling (NRC/CAL)

•• NealNeal--Smith Criterion Evolved (More Later)Smith Criterion Evolved (More Later)

•• Criteria Development Criteria Development ““ExplosionExplosion””

10

Other Criteria in Review (my list !)Other Criteria in Review (my list !)

•• Bandwidth (Roger Hoh)Bandwidth (Roger Hoh)•• Equivalent Systems (John Hodgkinson)Equivalent Systems (John Hodgkinson)•• Gibson (John Gibson) Gibson (John Gibson) ––Eclectic Approach!Eclectic Approach!•• PIO (Ralph Smith)PIO (Ralph Smith)•• Time Domain (Onstott)Time Domain (Onstott)•• Northrop (Nelson)Northrop (Nelson)•• ““Paper PilotPaper Pilot””

(Ron Anderson) (Ron Anderson) ––Famous LetterFamous Letter

•• Plus morePlus more……....

•• Evolution of Accurate Pilot Models Evolution of Accurate Pilot Models (Dr. Ron Hess)(Dr. Ron Hess)……....

11

Criteria Bottom LineCriteria Bottom Line

•• Overview ReferenceOverview Reference--

NASA Report (Radford et al, CR 163097, June NASA Report (Radford et al, CR 163097, June

1980)1980)Shows how to use NealShows how to use Neal--Smith effectively Smith effectively

•• Can use most as Design Tools and learn Can use most as Design Tools and learn somethingsomething

--

But need to use many to get guidanceBut need to use many to get guidance

•• Too Much Focus on Too Much Focus on ““Mine is BestMine is Best””

•• Strong Desire to do it all with ModellingStrong Desire to do it all with Modelling

12

Neal-Smith Pitch Attitude Model

Kp - pilot gain

p1 - pilot lead

p2 - lag

Time Delay = 0.3 sec

Kp e-0.3sτp1

τp 2

+ 1s+ 1s

θFs+

−

θc Fsθ e

“Pilot”Airframeplus FCSPitch Compensator

Standard of Performance

= Bandwidth (BW)τττ

MFCS:

13

NealNeal--Smith Criterion for Pitch DynamicsSmith Criterion for Pitch Dynamics

xX2

X3

X4

X5

F-16

X4

X3

X2

SpaceShuttle

Band Width

14

NealNeal--Smith Problems ??Smith Problems ??

•• Not Suitable for a Specification (Mil Spec)Not Suitable for a Specification (Mil Spec)--

Never agree on BandwidthsNever agree on Bandwidths

•• Huge debates about Huge debates about ““Pilot ModelPilot Model””

formform--

Not really the issueNot really the issue

--

Changed to Changed to ““Pitch CompensatorPitch Compensator””--

Still useful as a Still useful as a Design ToolDesign Tool

•• Let us look next at the Challenge of Modelling the Let us look next at the Challenge of Modelling the Pilot in a PIO eventPilot in a PIO event

15

Pilot Induced OscillationAnd the FAA

Or(Aircraft-Pilot Coupling) *

* was “in”

but now “out”

!!

16

Military/ NASA History

17

Rate Limited Surface Actuator Issue

Pilot Commanded Position

Actuator OutputPosition

Δtimedelay

20

10

-10

-20

1 2 3 4 5 6

SurfaceDeflection

~ degTime ~ seconds

18

Potential Causes of PIO

• Pilot controllers with ~Small displacement~Light forces~Equals, too sensitive (designed on ground

simulator)

19

Civil Issues

20

Transport Aircraft PIO Incidents

MDMD--11 Flight Number 583, 11 Flight Number 583, 19931993In cruise In cruise --inadvertent leading edge slats inadvertent leading edge slats deployment deployment Two passengers fatally injuredTwo passengers fatally injured. .

MD-11, Nagoya - June 08, 1997Autopilot disengaged resulting in a 15 sec period

of violent oscillations, One flight attendant killed; 3 passengers

seriously injured, 9 Minor Injuries

21

Necessary Conditions for PIO

•Pilot plus Aircraft,

• Attempting a High-Gain, Closed-Loop

Task,

• Critical BOUNDARY CONDITIONS,

• Latent HQ’s Deficiencies,

-

Time delay (Phase Lag)

-

Surface Rate Limiting

-

FCS or Aerodynamic Non-Linearities

-

High Control Sensitivities/ Poor Dynamics

• Must be a TRIGGER

to start the event

!!

22

But, The Testing Challenge is.......

•To Create SAFE, RELEVANT High-Gain Closed-Loop Tasks

•Remembering the Effect of BOUNDARY CONDITIONS, and.....

•Potential “TRIGGERS”

» Closed Loop Handling Qualities (CLHQ) testing

» IS Still Required !!

23

Pilot Modelling CommentsPilot Modelling Comments

•• Are we Going to Replace CLHQAre we Going to Replace CLHQ’’s Testing ?s Testing ?

--

No, the Pilot Situation (Triggers) and No, the Pilot Situation (Triggers) and Adaptability is Too Complex to Model perfectlyAdaptability is Too Complex to Model perfectly

•• Is Pilot Modelling a Useful Design/ Evaluation Is Pilot Modelling a Useful Design/ Evaluation Tool?Tool?

--

Yes Yes

•• A Case in Point is the NealA Case in Point is the Neal--Smith Criterion as a Smith Criterion as a

Design ToolDesign Tool

24

General General ModellingModelling

ExampleExample

•• PIO During Eurofighter InPIO During Eurofighter In--Flight Refueling Flight Refueling Development TestingDevelopment Testing

•• Reaction Reaction ––

““ItIt’’s the Pilot, he is not flying properly !s the Pilot, he is not flying properly !””

--

Design/Models Correct: A/C and Pilot Wrong !Design/Models Correct: A/C and Pilot Wrong !

•• Narrow Focus on Narrow Focus on ModellingModelling

not Flight Test plus not Flight Test plus Restricted Criteria UseRestricted Criteria Use

•• Lessons of the Past Finally Heard (Lessons of the Past Finally Heard (Use All the Use All the Tools)Tools)

•• Problem Easily Fixed in FBW Flight Control Problem Easily Fixed in FBW Flight Control SystemSystem

25

Summary Comments / Lessons To Be Summary Comments / Lessons To Be LearnedLearned

•• Our Goal is always a Our Goal is always a ““User Friendly DesignUser Friendly Design””

--

With FBW Technology With FBW Technology --

Should hit the Should hit the

““Sweet SpotSweet Spot””

EVERY time ! (EVERY time ! (Min CompensationMin Compensation))

•• Need to Use ALL the tools (Need to Use ALL the tools (““godgod’’ss””

Wind tunnel)Wind tunnel)

--

Include all available Criteria and PILOT Include all available Criteria and PILOT Models Models ––

BALANCED APPROACHBALANCED APPROACH

•• DonDon’’t Try to do it All with MODELLINGt Try to do it All with MODELLING

26

Music : Nicole Kidman

–

One

day

I’ll

fly

awayMusic : Nicole Music : Nicole KidmanKidman

––

OneOne

dayday

II’’llll

flyfly

awayaway

In the airIn the airIn the airTESTING........ Of More and More Complex Vehicles and Systems !!!

27

Including MODERN

FLIGHT

CONTROL

SYSTEMS

We Have Come a Long Way !!!

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Now to the Papers..... !

5353

Questions/ Comments ??

“May the Path You Walk

Light the Way for Those Who Follow”