DRI THE DEVELOPMENT OF DITCHING and WATER IMPACT DESIGN LIMITS PRESENTED AT INT’L CABIN SAFETY CONFERENCE NOVEMBER 17, 2004 LISBON, PORTUGAL DYNAMIC RESPONSE INC. (DRI) FEDERAL AVIATION ADMINISTRATION (FAA-TC)

DRI SBIR WATER IMPACT PROGRAM PHASE I Feasibility of Hybrid and FEM Methodology PHASE II Perform Full Scale Tests, Model and Correlate (KRASH and MSC/DYTRAN) KRASH Model For Existing Scale Model Ditching test Evaluate FAR27/29 Water/impact/Ditching Regulations & Compliance Develop Preliminary Water impact Design Limits With KRASH PHASE III Develop Military and Civil Helicopter KRASH Models Evaluate Correlation Techniques/Procedures Develop Design Criteria & Design Envelopes (DLE) & Procedures- Using KRASH --- Ditching and Water Impact --- Civil helicopters --- Military helicopters Recommend Ditching and Water Impact Design Criteria

DRI IMPACT ENVELOPES

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 ASPECTS OF WATER IMPACT AND 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 Tests of UH-1H Test S1 26 fps vertical Test S2 28 fps vertical 39 fps longitudinal

DRI OVERALL RESPONSES & KINEMATIC BEHAVIOR

DRI FLOOR ACCELERATION

DRI PRESSURE RESPONSE

DRI FLOOR PULSE

DRI FLOOR VERTCAL PULSES – GROUND, WATER, REGULATIONS

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- SEAT LOAD LIMIT 26 FPS VERTICAL WATER IMPACT NO SEAT LOAD LIMIT 14.5G SEAT LOAD LIMIT

DRI TRENDS – SEA STATE VS. CALM SEA

DRI S2/S1 Pressure Trend Comparison; Analysis Vs. Test Resultant Velocity S1 Test = 26 FPS S2 Test = 48 FPS S2/S1 Velocity Ratio 1.85 S2/S1 KE Ratio

DRI TRENDS Correlation Sea State Levels S2/S1 Test Levels -Pressure -Acceleration -Transfer Function (Accel. to Pressure) -Filter Levels Design Envelopes Panel Failure Floor Acceleration Mass Item Response Occupant-Seat Response VS. -Panel Strength -Pitch Attitude -Seat Load Limit -Velocity Profile -Sea State

DRI DITCHING COMPLIANCE

DRI DITCHING 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 What Exists – Relative to Ditching Assessment Capability Inadequate evaluation and compliance procedures KRASH modeling features that address significant issues, i.e. trends, sea state, nose-over, failures Analysis predictable within a level of acceptance Analysis simulation time efficient

DRI CURRENT DLE CONSIDERATIONS; TAKE INTO ACCOUNT

DRI CURRENT WATER IMPACT DLE CONCEPT

DRI DLE-DITCHING APPLICATION

DRI KRASH/SOMR-HIC RESULTS

DRI APPLICABILITY TO FAR 25; TRANSPORT CATEGORY AIRCRAFT FAR 25, FAR 27 and FAR 29 HAVE MANY SIMILARITIES: Ditching Envelope Seat Dynamic Test Requirements Mass Item Retention Acceptance Criteria Compliance Procedures

DRI SUMMARY Balanced Test, Analysis, Design SBIR - F/S WI and Scaled Ditching Tests - Civil and Military Rotorcraft Models/Correlation - FAR 27/29 and Military Design Specifications/Compliance Development of Ditching Criteria and Design Limit Envelopes Based On; - Occupant –Seat-Restraint System Integrity - Structural and Mass Retention Integrity - In Excess of 300 Simulations Performed Applicability of DLE to Evaluate Design Strength, Operational Conditions, Acceptance Criteria, New Designs, FAR 25, 27, 29 End Product Goal- Recommended Ditching and WI Design Criteria, DLE and Procedures

DRI