DRI

THE DEVELOPMENT OF DITCHING and THE DEVELOPMENT OF DITCHING and WATER IMPACT DESIGN LIMITSWATER IMPACT DESIGN LIMITS

PRESENTED AT INT’L CABIN SAFETY PRESENTED AT INT’L CABIN SAFETY CONFERENCECONFERENCE

NOVEMBER 15-17, 2004NOVEMBER 15-17, 2004

LISBON, PORTUGALLISBON, PORTUGAL

DYNAMIC RESPONSE INC. (DRI)DYNAMIC RESPONSE INC. (DRI)FEDERAL AVIATION ADMINISTRATIONFEDERAL AVIATION ADMINISTRATION(FAA-TC)(FAA-TC)

DRISBIR WATER IMPACT

PROGRAMPHASE I• Feasibility of Methodology

PHASE II• Perform Full Scale Tests, Model and Correlate• Model For Existing Scale Model Ditching test• Evaluate FAR27/29 Water/impact/Ditching Regulations & Compliance• Develop Preliminary Water impact Design Limits

PHASE III• Develop Military Helicopter KRASH Models• Evaluate Correlation Techniques/Procedures• Develop Design Envelopes (DLE) - Water Impact/Ditching• Develop DLE Procedures

--- Civil helicopters--- Military helicopters

DRI

IMPACT ENVELOPESIMPACT ENVELOPES

0

5

10

15

20

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45

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0 10 20 30 40 50 60 70 80 90 100 110

longitudinal velocity - ft/sec

vert

ical

vel

oci

ty -

ft/

sec

U.S. Navy Helicopters, Land, 95th % SurvivableU.S. Navy Helicopters, Water, 95th % SurvivableU.S. Army Helicopters, 95th % Design RequirementCivil Rotorcraft, 95th % Land & Water Range - upperCivil Rotorcraft, 95th % Land & Water Range - lowerSBIR Test S1 - UH-1HCRADA Test C2 - UH-1HSBIR Test S2 - UH-1HOsprey Ditching TestsFAA Civil Ditching RequirementsSeahawk analyses - Phase ILynx analyses - Phase IUH-1H Parametric Analysis CasesOsprey OEI analysis

up to 172 fps

DRI

SIGNIFICANT QUESTIONS

1. Can modeling simulate /represent the significant aspects of full-scale impact and scale model ditching tests?

2. Can analytical modeling be an effective tool in the development of crash design criteria?

DRIASPECTS OF WATER IMPACT ASPECTS OF WATER IMPACT

AND DITCHINGAND DITCHING• Kinematics BehaviorKinematics Behavior• Overall responseOverall response• Discrete location responseDiscrete location response• FailuresFailures• Design parametersDesign parameters• Seat-occupant performance/toleranceSeat-occupant performance/tolerance• Trends & relationshipsTrends & relationships

DRI

FULL SCALE WATER IMPACT TESTS 1998 - 1999 Tests of UH-1H

Test S126 fps vertical Test S2

28 fps vertical39 fps longitudinal

DRIOVERALL RESPONSES & KINEMATIC BEHAVIOR

OverallOverall S1 TestS1 Test S2 TestS2 Testcg vertical g ------------- 7 % 18 %avg. floor vertical g---- 10 % 19 %average panel psi ------ 8 % 4 % avg. floor longit. g -------- ----- 22 %

KinematicsKinematicscg velocity change------ 19 % -----cg vertical g ------------- 7 % 17.6 %cg longitudinal g ------- ----- 8.3 %water penetration -------- 8 % -------attitude ---------------------- flat pitch up

DRI

FLOOR ACCELERATION

a) FS 42

-20

-10

0

10

20

30

40

50

60

70

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08

time - sec

verti

cal a

ccel

erat

ion

- g

KR mass 31

test S1 ch 01

test S1 ch 04

b) FS 155

-10

-5

0

5

10

15

20

25

30

35

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08

time - sec

vert

ical

acc

eler

atio

n - g

KR mass 91

test S1 ch 16

test S1 ch 17

DRI

PRESSURE RESPONSE

a) S1 Pressures at FS 81

-10

0

10

20

30

40

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08

time - sec

KR mass 51test S1 ch 06

test S1 ch 10

b) S2 Pressures at FS 84.5

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5

10

15

20

25

0.000 0.020 0.040 0.060 0.080 0.100 0.120 0.140 0.160 0.180 0.200

time - sec

pres

sure

- ps

ig

lsn 6 mass 51

test ch 4test ch 6

DRI

FLOOR PULSE

S1 Test 26 fps vertical

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30

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50

60

0 0.01 0.02 0.03 0.04 0.05 0.06

time - seconds

ve

rtic

al

ac

ce

lera

tio

n -

g

TEST

DRI/KRASH

MSC/DYTRAN

DRIFLOOR VERTCAL PULSES – FLOOR VERTCAL PULSES –

GROUND, WATER, REGULATIONSGROUND, WATER, REGULATIONS

W

G

G

G

W

WW

W

W

W

G

W

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70

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1

time to peak - sec

pea

k ve

rtic

al a

ccel

erat

ion

- g

FAR 27/29 Part 27/29.562Military - cockpitMililtary - cabinUH-1H Ground Test 23 fps vert - 18 fps latUH-1H Water Test 26 fps vertUH-1H Water Analysis (DRI) 26 fps vertUH-1H Water Analysis (MSC) 26 fps vertUH-1H Water Test 28 fps vert - 39 fps longUH-1H Water Analysis (DRI) 28 fps vert - 39 fps longUH-1H Water Analysis (MSC) 28 fps vert - 39 fps longSeahawk Ground Analysis (DRI) 30 fps vertSeahawk Water Analysis (DRI) 30 fps vertwater - upper limitwater - lower limitground - upper limitground - lower limit

Envelope ofWater Conditions

Envelope ofGround Conditions

DRI

SIGNIFICANT QUESTIONS

1. Can modeling simulate /represent the significant aspects of full-scale impact and scale model ditching tests?

2. Can analytical modeling be an effective tool in the development of crash design criteria?

DRI

DESIGN CONSIDERATIONS-DESIGN CONSIDERATIONS-SEAT LOAD LIMITSEAT LOAD LIMIT

a) pilot floor, torso & dri responses without seat load limiter

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-10

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70

80

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.10

time - sec

vert

ical

acc

el (g

) & D

RI

DRI

lower torso & seat pan

avg of 4 floor pts

UP

DO

WN

b) pilot floor, torso & dri responses with 14.5 g seat load limiter

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-10

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80

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time - sec

vert

ical

acc

el (g

) & D

RI

DRI

lower torso & seat pan

avg of 4 floor pts

UP

DO

WN

26 FPS VERTICAL WATER IMPACT

NO SEAT LOAD LIMITNO SEAT LOAD LIMIT 14.5G SEAT LOAD LIMIT14.5G SEAT LOAD LIMIT

DRI

DESIGN CONSIDERATIONSDESIGN CONSIDERATIONS – – EA OLEO Vs. SKID TYPE GEAREA OLEO Vs. SKID TYPE GEAR

vehicle kinetic energy vs time

0.00E+00

2.00E+05

4.00E+05

6.00E+05

8.00E+05

1.00E+06

1.20E+06

1.40E+06

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16

time - sec

ener

gy -

in-lb

skid gear

oleo gear

average floor vertical accel at troop 8,9 FS 138 vs timevertical velocity = 26 fps

-30

-25

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-15

-10

-5

0

5

10

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16

time - sec

acce

l - g

skid gear

oleo gear

DO

WN

UP

E.A. oleo reduces: lumbar load 29.6% seat stroke 21.7% avg floor accel 17.0%

Floor pulse Kinetic energy

DRI

TRENDS –SEA STATE VS. CALM SEA

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18

calm 2.58 / 52 3.75 / 75 7.5 / 75

Sea State - ( wave height / wave length )

peak v

ert

ical accele

rati

on

- g

FS217 - analFS217 - testFS412 - analFS412 - testFS552 - analFS552 - test

analysis average

test average

DRI

S2/S1 Pressure Trend S2/S1 Pressure Trend Comparison; Analysis Vs. Test Comparison; Analysis Vs. Test

14%

33%

42%

6%

31%

34%

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

Class 60 Filter Class 180 Filter Unfiltered

S2

/ S1

% c

hang

e

analysistest

PRESSURES

DRI

DITCHING COMPLIANCE

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vertical impact velocity - ft/sec

pre

ss

ure

- p

sig

Osprey p-mean (R&M 2917)

UH-1H p-mean (R&M 2917)

UH-1H avg p-dyn

Osprey avg p-dyn

FAA static flotation (UH-1H)FAR 25.533c distr press (Vx=50 fps)

FAR 25.533b local press (Vx=50 fps)

Osprey max p-dyn

UH-1H max p-dyn

UH-1H sea state = 4' high, 40' long, wave vel = 0Osprey sea state = 3.75' high, 75' long, wave vel = 0 -12 fps

UH-1H avg p-dyn (sea state)

Osprey avg p-dyn (sea state)

longitudinal velocity = 50 fpspitch = 10 deg ANU

Bell 609 test peakat 5 fps / 8.6 psi

Osprey test p-dyn

DRIDITCHING COMPLIANCE

PROCEDURESDITCHING COMPLIANCE

PROCEDURES

• Scale Model Testing- rigid, deficient, misleading, costly

• Similarity to Existing Designs - questionable basis

• Pressure Calculations- static flotation analysis

• Vertical Load Factor Calculations- stall speed, no sink velocity

• Procedures- under-estimate pressure & acceleration

DRI

DLE for WATER IMPACTSDLE for WATER IMPACTS

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longitudinal velocity - ft/sec

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t/s

ec

Civil Rotorcraft, 95th % Land & Water - Upper Civil Rotorcraft, 95th % Land & Water - Lower

SPECIFIED:Configuration, % LiftPitch Attitude _ DegreeLanding Gear Extended/RetractedCriteria Seat Load Limit < _ g Seat Stroke < _ In. Interior Design Pressure, < _ psi Mass Item Limit; Vertical, Longitudinal, and Side < _ g

Engine > Criteria

Engine > Criteria

Mid Fuel > Criteria

Interior Bulkhead Pressure >Criteria

DRI

DLE-DITCHING APPLICATIONDLE-DITCHING APPLICATION

Preliminary Ditching Envelope - No Underside Panel Failure

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25

0 10 20 30 40 50 60 70 80

Inititial Longitudinal Velocity, ft/sec

Initi

al V

ertic

al V

eloc

ity, f

t/sec

No Lift Calm Sea

67% Lift Calm Sea

Ditching Criteria

OEI Points

Weight = 23500 pounds CG = FS 349 Pitch = 10 degPanel Failure = 70 psiGears Retracted

DRI

KRASHSOM-HIC RESULTS

KRASHSOM RESULTS - LONGITUDIAL PULSEHIC

0 500 1000 1500 2000 2500 3000 3500 4000

MIL STD

Military-WI

FAR27/29

Civil-WI

PU

LS

E

HIC value

EA Blkhd HIC

Stiff.Blkhd HIC

1.01 inch Penetration8.50 inch head travel

0.90 inch Penetration6.50 inch head travel

3.8 inch Penetration11.0 inch head travel

50th Percentile male

1.7 inch Penetration11.0 inch head travel

x

1.06 inch surface penetration 8.5 inch head travel

Lap Belt Restraint Only

DRI

DLE CONSIDERATIONSDLE CONSIDERATIONSCONSIDERATIONS DITCHING WATER IMPACT

Configurations Modeled GTOW GTOWMax Design Landing Max Design Landing

Amphibious/Float Amphibious/FloatAuxiliary Fuel Tank Auxiliary Fuel Tank

S1, S2 Test ArticleDesign Envelope FAR27/FAR29 Civil 95th Percentile -Upr

Civil 95th Percentile-LwrVertical Velocity Ft/Sec. 0 to 25 10 to 28 Longitudinal Velocity Ft/Sec. 0 to 75 0 to 60Pitch Attitude Degree 0, 5, 10 0, 4, 5, 10Roll, Yaw Degree 10 10Sea State Calm Calm Sea State 4 NoRigid seat Yes NoLoad Limit Seat g 12, 14.5 12, 14.5Criteria Seat Stroke limit In. 5 5 Lumbar Load Limit Lb. 1500 1500 Underside Panel Failure psi Design Design Interior Bulkhead Failure psi No 20 Head Injury HIC 1000 1000 Restraint Belt Load Lb. 1750-2000 1750-2000 Mass Item Restraint g 30/30/15 <1> 30/30/15 <1> Engine Transmission Fuel

<1> Vertical/Longitudinal/ Side

DRIAPPLICABILITY TO FAR 25;

TRANSPORT CATEGORY AIRCRAFT

FAR 25, FAR 27 and FAR 29 HAVE:

• Ditching Envelope

• Seat Dynamic Test Requirements

• Mass Item Retention

• Acceptance Criteria

• Compliance Procedures

• Different Levels but Many Similarities

DRI

SUMMARYSUMMARY

• SBIR Tests/Correlation and Applications- 2 Full Scale Water and 35 Scaled Ditching Tests- Aircraft Weights: 10,000 -20,000- 42600 lb. GTOW- Design Requirements & FAR Regulations

• Development of Civil Design Limit Envelopes –- Occupant –Seat Integrity- Structural and Mass Retention Integrity

• Development of Ditching and Water Impact Design Criteria and Procedures

• Utilization of DLE to Evaluate Design Strength, Operational Conditions, Acceptance Criteria, and New Designs

• Applicability of DLE Concept and Procedures to FAR25 Transport Category Airplanes