24 May, 2001 Simulation Technology & Training 1

Aerodynamics Modeling and Dynamics Simulation at High Angles of Attack

M.Goman, A.Khramtsovsky and M.ShapiroCentral Aerohydrodynamic Institute (TsAGI), Zhukovsky, Russia

24 May, 2001 Simulation Technology & Training 2

Contents:

• Introduction• Closed-loop research & development cycle• General structure of the mathematical model• Aerodynamics modeling• Nonlinear dynamics analysis• Control laws design• Simulation & pilot training• Conclusion

24 May, 2001 Simulation Technology & Training 3

TsAGI Research/Training Simulators

24 May, 2001 Simulation Technology & Training 4

Research & Development Cycle

FlightTests

Simulation&

Stability&

DynamicsAnalysis

ControlLaws

Design

AerodynamicsModelling Pilot Training

24 May, 2001 Simulation Technology & Training 5

General Structure of Aircraft Mathematical Model

Equationsof motion

Undercarriagemodel

Aerodynamicforces and moments

model

Aerodynamiccharacteristics

database

Atmosphericturbulence

model

Engine model

Altitude-velocityengine characteristics

Cockpit

Control systemand actuator

models

Flight testssafety equipment

24 May, 2001 Simulation Technology & Training 6

Wide-Range Aerodynamics Model

AerodynamicsModel:

o

o

o

Static tests

Forced oscillation

tests

testsRotary balance

Flight testsFree spin tests(Vertical wind tunnel M=1:16)

Large-scalecontrolled models(flight tests M 1:4)

24 May, 2001 Simulation Technology & Training 7

Anti-Spin Parachute Model

a

a

b

b

XZ

Y

V

p

p

p

p

r

p

F

lp

V

V

V

p

p

p

p

p

p

p

= V0 + +

+

+

+

+

rp

pp

pp

p

p

p

p p

pl

l

dd t = -

[ ]

(r )

)F

F

= CD S S( 2

2

M = r

w

r

24 May, 2001 Simulation Technology & Training 8

Qualitative Analysis of Nonlinear Aircraft Dynamics

24 May, 2001 Simulation Technology & Training 9

Deep Stall and Unrecoverable Flat Spin Regimes

Pitc

h m

omen

t coe

ffici

ent

Pitc

h m

omen

t coe

ffici

ent

Full pitch-up control Full pitch-up control

Full pitch-down control

Full pitch-down control

Deep stalllock-inNormal flight regimes

(stable with FCS)

Deep stall regimes Unrecoverable flat spin regimes

Flat spin lock-in

CC

mm

Angle of Attack Angle of Attack

IIIxyz- sin2a2

inertia moment

Angle of Attack

Cn asym

Potential function analogy

Normal flight regimes

Critical regimes

Rocking control

p r

Yaw

mom

ent

Aerodynamicyaw asymmetry

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Aerodynamic Yaw Asymmetry (X-31)

Data range

-.10 -.05 0 .05 .1020

30

40

50

60

70

80

Ang

le o

f atta

ck (d

eg)

C n0

.06 .08

Flight Tests

24 May, 2001 Simulation Technology & Training 11

Flat Spin Due To Aerodynamic Asymmetry

24 May, 2001 Simulation Technology & Training 12

Pitch Rocking Control for Spin Recovery

Tim

e of

reco

very

(sec

)

0

10

20

30

40

50

0 0.05 0.10 0.15

with rocking

withoutrocking

Yaw asymmetry Cn0

Potential function analogy

Normal flight regimes

Critical regimes

Rocking control

24 May, 2001 Simulation Technology & Training 13

Spin Prevention & Recovery Control System

ConventionalControl Laws

Spin Prevention& RecoveryAlgorithms

Spin Entry& RecoveryIdentification

a,b,V,p,q,r

d

24 May, 2001 Simulation Technology & Training 14

Deep Stall Departure and Recovery

24 May, 2001 Simulation Technology & Training 15

Flat Spin Departure and Recovery

24 May, 2001 Simulation Technology & Training 16

Cobra Maneuver Simulation

24 May, 2001 Simulation Technology & Training 17

Unsteady Nonlinear Aerodynamic Modeling

24 May, 2001 Simulation Technology & Training 18

High Incidence Flight Simulation of a General Aviation Aircraft

24 May, 2001 Simulation Technology & Training 19

Canard Flow Separation & Pitch Self-Sustained Oscillations

Low angle of attack

High angle of attack

Attached flow

Canard separated

aq

q

X

X

e

thr

18

64

16

-3

3

0

(deg/s)

(deg)

24 May, 2001 Simulation Technology & Training 20

Concluding Remarks:

• Piloted simulation of an aircraft dynamics at high angles of attack is extremely important element of the aircraft development and sertification processes

• Piloted simulation helps in assessment of aerodynamic model, accompanying flight tests, and training of rank-and-file pilots

24 May, 2001 Simulation Technology & Training 21

Desktop Training Simulator

24 May, 2001 Simulation Technology & Training 22

Research & Training Flight Simulator

24 May, 2001 Simulation Technology & Training 23

Medium-Size Training Simulator