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THE DEVELOPMENT OF DITCHING and WATER IMPACT DESIGN LIMITS

THE DEVELOPMENT OF DITCHING and WATER IMPACT DESIGN LIMITS. PRESENTED AT INT’L CABIN SAFETY CONFERENCE NOVEMBER 15-17, 2004 LISBON, PORTUGAL DYNAMIC RESPONSE INC. (DRI) FEDERAL AVIATION ADMINISTRATION (FAA-TC). SBIR WATER IMPACT PROGRAM. PHASE I Feasibility of Methodology PHASE II

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THE DEVELOPMENT OF DITCHING and WATER IMPACT DESIGN LIMITS

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  1. THE DEVELOPMENT OF DITCHING and WATER IMPACT DESIGN LIMITS PRESENTED AT INT’L CABIN SAFETY CONFERENCE NOVEMBER 15-17, 2004 LISBON, PORTUGAL DYNAMIC RESPONSE INC. (DRI) FEDERAL AVIATION ADMINISTRATION (FAA-TC)

  2. SBIR WATER IMPACT PROGRAM PHASE 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

  3. IMPACT ENVELOPES

  4. SIGNIFICANT QUESTIONS • Can modeling simulate /represent the significant aspects of full-scale impact and scale model ditching tests? • Can analytical modeling be an effective tool in the development of crash design criteria?

  5. ASPECTS OF WATER IMPACT AND DITCHING • Kinematics Behavior • Overall response • Discrete location response • Failures • Design parameters • Seat-occupant performance/tolerance • Trends & relationships

  6. FULL SCALE WATER IMPACT TESTS 1998 - 1999 Tests of UH-1H Test S1 26 fps vertical Test S2 28 fps vertical 39 fps longitudinal

  7. OVERALL RESPONSES & KINEMATIC BEHAVIOR

  8. FLOOR ACCELERATION

  9. PRESSURE RESPONSE

  10. FLOOR PULSE

  11. FLOOR VERTCAL PULSES – GROUND, WATER, REGULATIONS

  12. SIGNIFICANT QUESTIONS • Can modeling simulate /represent the significant aspects of full-scale impact and scale model ditching tests? • Can analytical modeling be an effective tool in the development of crash design criteria?

  13. DESIGN CONSIDERATIONS-SEAT LOAD LIMIT NO SEAT LOAD LIMIT 14.5G SEAT LOAD LIMIT 26 FPS VERTICAL WATER IMPACT

  14. DESIGN CONSIDERATIONS – EA OLEO Vs. SKID TYPE GEAR Kinetic energy Floor pulse

  15. TRENDS –SEA STATE VS. CALM SEA

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

  17. DITCHING COMPLIANCE

  18. 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

  19. DLE for WATER IMPACTS

  20. DLE-DITCHING APPLICATION

  21. KRASHSOM-HIC RESULTS

  22. DLE CONSIDERATIONS

  23. APPLICABILITY 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

  24. SUMMARY • 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

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