20/07/2004 20/07/2004 EF Transonic Pitch Up Mitigation EF Transonic Pitch Up Mitigation and ALSR Concept and ALSR Concept 1 1 Eurofighter Transonic Eurofighter Transonic Pitch Up Mitigation Pitch Up Mitigation and and Auto Low Speed Auto Low Speed Recovery (ALSR) Recovery (ALSR) Concept Concept Heinz Spölgen, EADS Test Pilot
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20/07/200420/07/2004EF Transonic Pitch Up Mitigation EF Transonic Pitch Up Mitigation
and ALSR Conceptand ALSR Concept 11
Eurofighter Transonic Eurofighter Transonic Pitch Up MitigationPitch Up Mitigation
andand
Auto Low Speed Auto Low Speed Recovery (ALSR) Recovery (ALSR)
ConceptConceptHeinz Spölgen, EADS Test Pilot
20/07/200420/07/2004EF Transonic Pitch Up Mitigation EF Transonic Pitch Up Mitigation
and ALSR Conceptand ALSR Concept 22
Eurofighter Transonic Eurofighter Transonic Pitch Up MitigationPitch Up Mitigation
Heinz Spölgen, EADS Test Pilot
20/07/200420/07/2004EF Transonic Pitch Up Mitigation EF Transonic Pitch Up Mitigation
and ALSR Conceptand ALSR Concept 33
What happened?What happened?Transonic DecelerationTransonic Deceleration
offline simulationoffline simulation550 KEAS 550 KEAS worst case worst case
∆Nz ~4g
~1 sec
0.0 2.0 4.0 6.0 8.0
0.0
5.0
10.0
10.0
nz
nznz Auth.
Time (s)
Nz
M 0.98 M 0.95
20/07/200420/07/2004EF Transonic Pitch Up Mitigation EF Transonic Pitch Up Mitigation
and ALSR Conceptand ALSR Concept 44
ImpactsImpacts
• Handling Qualities
• Overstressing of aircraft structure
• non-compliant stability margin
• degraded performance and manoeuvring potential
• customer concerns
20/07/200420/07/2004EF Transonic Pitch Up Mitigation EF Transonic Pitch Up Mitigation
and ALSR Conceptand ALSR Concept 55
Problem Analysis Problem Analysis
M=0.9
M=0.95
M=0.975
M=1.05
M=1.1
10 20 300-20
0.08
0.06
0.04
0.02
0.00
-0.02
-0.04
-0.06
-0.08-10 40
AoA [deg]
CmCm
AOA [deg]
M 0.95, 6° AOA
M 0.975, 12° AOA
20/07/200420/07/2004EF Transonic Pitch Up Mitigation EF Transonic Pitch Up Mitigation
and ALSR Conceptand ALSR Concept 66
Problem Analysis (2)Problem Analysis (2)
4.006.00
C m
0.00
-0.01
-0.02
-0.03
0.01
0.02
0.03
0.9 1.0
Mach [-]
0.95 1.05 1.1
Cm
Mach
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and ALSR Conceptand ALSR Concept 77
Mitigation Options (1)Mitigation Options (1)
Basic Philsophies:
• Change Aerodynamics
• predictive technique
• based on airdatameasurements and prediction model
• technique based on detectionat „time of occurrence“
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20/07/200420/07/2004EF Transonic Pitch Up Mitigation EF Transonic Pitch Up Mitigation
and ALSR Conceptand ALSR Concept 1313
Asymmetric Stiffness (2)Asymmetric Stiffness (2)
ddt Gα
Gd
dt q
GA3AFADA
FQEA GQ5A ∫
Gα
GA1A
ddt
Gα
α
q
nzα(nz)
αc
-
PID-controller
Asymmetric stiffness AoA-feedback
GA5AGA5AFXDA
SI1A FIIA
compensatingpitch down motion
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and ALSR Conceptand ALSR Concept 1414
““Proof of Concept” Flight TestProof of Concept” Flight Test
• Experimental Software „on top of“ FCS Software• Dedicated flight test campaign• 6 flights (61 test points) in 4 days• 5 pilots (industry and Officials)• Comparison „G-Bucket“ / „Asymmetric Stiffness“
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and ALSR Conceptand ALSR Concept 1515
ResultsResults• predictions for „G-bucket“ and „asymmetric stiffness“
confirmed
• asymmetric stiffness preferred virtually full Nz-authority
• still some minor transonic pitch up
• aircraft behaviour benign and safe
• no exceedance of structural limits
9g7g
Mach
0.9 1.0
nz<9g
0.87 1.05
Nz
Mach
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and ALSR Conceptand ALSR Concept 1616
Lessons learntLessons learnt
•• Experimental SW and Experimental SW and „„proofproof of of conceptconcept“ “ flightflight test
EfficientEfficient Design Design ToolTool
test
•• AdequateAdequate ADS ADS accuracyaccuracy forfor a a „„predictivepredictive“ “ solution
DifficultDifficult to to achieveachievesolution
High potential High potential
Independent of ADS Independent of ADS accuracyaccuracy and and MachnumberMachnumber
•• AsymmetricAsymmetric StiffnessStiffness
20/07/200420/07/2004EF Transonic Pitch Up Mitigation EF Transonic Pitch Up Mitigation
and ALSR Conceptand ALSR Concept 1717
20/07/200420/07/2004EF Transonic Pitch Up Mitigation EF Transonic Pitch Up Mitigation
and ALSR Conceptand ALSR Concept 1818
Auto Low Speed Auto Low Speed Recovery (ALSR) Recovery (ALSR)
ConceptConcept
Heinz Spölgen, EADS Test Pilot
20/07/200420/07/2004EF Transonic Pitch Up Mitigation EF Transonic Pitch Up Mitigation
and ALSR Conceptand ALSR Concept 1919
FlightFlight MechanicsMechanics IssuesIssues
• unstable in pitch axis
•• AOA AOA measurementmeasurement unreliableunreliable < 50 < 50 ktskts EAS EAS AOA AOA protectionprotection isis lostlost
below 50 kts departurecannot be excluded 100%
AUTO Low Speed Recovery
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and ALSR Conceptand ALSR Concept 2020
General ALSR General ALSR PhilosophyPhilosophy
ALSR
• must ensure safe recovery fromall conditions ≥ 50 KEAS
• Robustness (gusts, Air Datameasurement tolerances etc.)
• must not be triggered too earlyduring air combat
• must not occur „by surprise“Pre - warning
20/07/200420/07/2004EF Transonic Pitch Up Mitigation EF Transonic Pitch Up Mitigation