saab 2000 (aew&c)

Saab 2000 (AEW&C)Certification for flight in icing conditions

Wim Willemse

October 19, 2010

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Introduction

Platform Description – external changes

Effect of ice accretion on external changes

Definition of the artificial ice shapes

Flight test

Acknowledgments

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INTRODUCTIONAirborne Early Warning and ControlLatest generation of the ERIEYE radar and Mission SystemSelf Protection SystemIdentification Friend or Foe

The Saab 2000 (AEW&C) should full-fill the same civil certification requirements as the Saab 2000 airliner:

To operate into known icing conditions, the aircraft must be certified in accordance with the criteria of FAR/JAR Part 25, Appendix C.

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Saab 2000 (AEW&C)

PLATFORM DESCRIPTION

DOU

MAW/LWS

Towed decoy

WT pods Chaff/Flare

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EFFECT OF ICE ACCRETION

Wing Tip Pods – Unprotected Effect of Ice accretion

- Increased drag

- Possible effect on aileron aerodynamics

Has been investigated by flight test with

artificial ice shape.

Towed decoy – Unprotected Effect of Ice accretion

- Increased drag

Has been investigated by flight test with

artificial ice shape.

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DOU Struts – Protected Clean struts decrease directional stability and

increase the drag.

(Verified by CFD analysis and Wind tunnel tests)

Effect of Ice accretion

- Increased drag – Requires protection

- Decreased strut lift (side force) – Less negative effect on directional stability

Saab 2000 (AEW&C) Aft strut - 45 minutes holding

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-0.4 -0.2 0 0.2 0.4 0.6 0.8 1x/c

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-20 C

-12 C

-7 C

-5 C

-4 C

-3 C

No ice

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Vertical tail extension (30 inches) - Unprotected Effect of the 3 inch double horn ice tested in the wind tunnel.

- Increased drag

- Slightly increased directional stability

- Slightly increased rudder efficiency

Investigated by flight test with artificial ice shape.

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MAW/LWS sensors – Unprotected

No significant effect of ice accretion on pitot-tubes and angle of attack vanes

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DEFINITION OF ARTIFICIAL ICE SHAPES

ONERA Ice code

Code produced by Onera

Icing code used for Saab 2000 artificial ice shapes

Accepted by FAA and EASA

2-dimensional code

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Icing conditions

Requirement FAR/JAR:

Appendix C

For unprotected parts: 45 minutes holding in Continuous Maximum

pinnacle length up to 3 inch

Droplet size: 20 μm

LWC as function of temperature – according to Appendix C

.

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Artificial ice shape on wing tip pod

The ice shape is defined by two shapes: one top view and one side view. The thick red line is the selected shape for flight test. The ice shapes are made dimensionless with the “chord length”: 2.14mRoughness has been added up to 10 % length of the wing tip pod:

(a) roughness height: 3 mm(b) particle density: 8 to 10/cm2

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Saab 2000 AEW&C Ice accretion on wing tip pod - top view

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-20 C

-12 C

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-7 C

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No ice

flight test shape

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Saab 2000 AEW&C Ice accretion on wing tip pod - side view

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-20 C-12 C-11 C-10 C-9 C-8 C-7 C-6 C-5 C-4 C-3 C-2 CNo iceflight test shape

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Artificial ice shape on towed decoy

The ice shape is defined by two shapes: one top view and one side view. The thick line (-6 C) is the selected shape for flight test. The ice shapes are made dimensionless with the “chord length”: 1.454mRoughness has been added up to 10 % length of the wing tip pod:

(a) roughness height: 3 mm(b) particle density: 8 to 10/cm2


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Saab 2000 AEW&C Ice accretion on towed decoy - top view

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-2 C

-3 C

-4 C

-5 C

-6 C

-7 C

-8 C

-9 C

-10 C

-11 C

-12 C

-20 C

No ice

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Saab 2000 AEW&C Ice accretion on towed decoy - side view

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-0.05 0.00 0.05 0.10 0.15 0.20

-2 C

-3 C

-4 C

-5 C

-6 C

-7 C

-8 C

-9 C

-10 C

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-20 C

No ice

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Vertical tail extension - Ice shape at c = 1.370 m45 minutes holding

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-0.10 -0.08 -0.06 -0.04 -0.02 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14

x/c

y/c

clean profile-9 C-8C-7 C-6 C-5 C-5 C; 3 inch ice shape; selected for flight test-10C-9C-8C-7C-6C-5.5C-5C-5.5 C; 3 inch ice shape; selected for flight test

Artificial ice shape on vertical tail extension

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Saab 2000 (AEW&C) FLIGHT TEST

Flight in natural icing• boots on DOU struts

Dry-air flight test with artificial ice shapes• Effect on flying qualities• Aircraft performance

#1B-AEW Approach ice. 0.5” on protected, 3” unprotected#5-AEW Left Upper Wing failure case. 1.5” on failed surface.

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Saab 2000 (AEW&C) Dry-air flight tests Flying Qualities tests

Test\Ice 1B 5

Stall Characteristics X X

Push Over to 0 g X

Directional Control X

Lateral Control X

Steady Heading Sideslip X X

Dutch Roll X

Vibration and Buffeting X

Landings X X

Selected Flying Qualities tests, artificial ice configuration and flight conditions are ”worst case” from the Saab 2000 certification.

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Acknowledgments

Nenad Jankovic – Manager applied aerodynamics

Per Weinerfelt – Specialist Mathematical and numerical modeling

Henrik Åslund – Senior Research Engineer Aerodynamics

Karl-Erik Eklund – Advanced Design Engineer

Ronny Gyllensten – Advanced Design Engineer

saab 2000 (aew&c)

Documents

negative effect

foethe saab

known icing conditions

external changesdefinition

clean struts

directional stabilitychart1

erieye radar

controllatest generation