1. CH-53K Heavy Lift Helicopter A Survivability Focused Design
Kathy Russell
Vulnerability Analyst
NAVAIR
China Lake, California
Martin Krammer
Vulnerability Test Engineer
NAVAIR
China Lake, California
Richard Gardner
Survivability Lead
NAVAIR
Patuxent River, Maryland
Nicholas Gerstner
Survivability Analyst
SURVICE Engineering
Dayton, Ohio
Presented at the American Helicopter Society 67th Annual Forum
Virginia Beach, VA
May 3-5, 2011
This is a work of the U.S. Government and is not subject to copyright protection in the U.S.

2. Next Generation Heavy Lift Helicopter for the US Marine Corps
Introduction
Next Generation Heavy Lift Helicopter for the US Marine Corps
Operational
Requirements
Survivability
Key Performance
Parameters
Air Vehicle
Specification
More Survivable Design
CH-53E
CH-53K

4. Background Balanced Survivability Approach
Susceptibility - the inability of an aircraft to avoid being hit
Susceptibility Reduction - missile warning and missile jamming or decoying further enhance the survivability capabilities of the platform
Vulnerability - the inability of an aircraft to sustain damage once hit
Vulnerability Reduction – threat tolerant design
Susceptibility and Vulnerability Reduction Verification
• Analysis • Flight Test • Live Fire Test

5. Susceptibility Reduction
Threat Avoidance Susceptibility reduction for the CH-53K consists of an integrated Aircraft Survivability Equipment (ASE) suite
Radar Warning Receiver
AN/APR-39B(V)2 (RWR)/Electronic Warfare Management System
Directional Infrared Countermeasures System (DIRCM) AN/AAQ-24(V)
 Missile Warning System (MWS)
*update – Laser Detection incorporated with MWS
Countermeasure Dispenser System (CMDS)
AN/ALE-47

6. Susceptibility Verification
Susceptibility Analysis
Incorporates threat systems
Aircraft performance data
Various models and simulations
Moderate Transmittance (MODTRAN)
Modeling System for Advanced Investigation of
Countermeasures (MOSAIC)
Future Operational Combat Unified Simulation
(FOCUS)
Multi-Service Electro-Optics Signature
(MuSES)
Analysis and Flight Test will assess the ASE system effectiveness against AVS threats

8. Survivability Requirements
CH-53K Key Performance Parameters
Two of the seven system KPP’s are Survivability Requirements
Fly Away Capability – Ballistic Tolerant Design
Force Protection – Cockpit and Cabin Armor
Meeting the KPP requirements
Challenging yet achievable Air Vehicle Specification (AVS)
Continuous Survivability Analyses
Early Ballistic Tests
Early involvement and a coordinated survivability team

10. Vulnerability Reduction

11. Vulnerability Verification
Analysis and Test
MODEL
TEST

12. Vulnerability Verification
Vulnerability Analysis – Critical Data Sets
Geometry Conversion Techniques
SAC CATIA to BRL-CAD format
Streamlines the modeling effort
Ensures precise and accurate component representation
Traditional Data Sets
DMEA
Pd/h and Pk/d
FALT

13. Vulnerability Verification
Vulnerability Analysis – Critical Data Sets
Traditional Flight Regimes
Discrete Mission Points
Define specific flight conditions
Correlate to susceptibility analyses
Mission Points

14. Vulnerability Verification
Design Impact
Initial Assessment – Not compliant
Assessment Updates
Updated preliminary designs
Integrated CH-53E JLF results
Design Enhancements
MGB redundant lube system
Supplemental fuel feed system
Main rotor actuator redesign
Tail rotor drive shaft growth
Risk Reduction Testing
Identified components for testing to refine design and analysis
Tail rotor drive shaft and Flexbeam successfully tested
Additional items identified for testing

15. Vulnerability Verification
Assessment Progression Milestone Assessments – Compliant

16. Force Protection Verification
Design Impact
Initial and Milestone Assessments – Compliant
Assessment Progression
KPP requirements addressed cockpit and cabin occupant protection
Weight optimization studies conducted to minimize ineffective armor and maximize protection
Design changes assessed for impact on protection levels
CDR Cabin Armor
CDR Cockpit Armor

17. CH-53K Survivability Risk Reduction Tests Live Fire Tests
Tail Rotor Flex Beam
Tail Rotor Drive Shaft
Sponson Material - Fuel Cell Interaction
Fuel Line Leak Containment
Live Fire Tests

18. Test articles were able to maintain
Risk Reduction Test
Tail Rotor Flex Beam Test
Ballistic Impact
Test Conclusion
Test articles were able to maintain
the loads after damage
Test Damage

19. Tail Rotor Drive Shaft is tolerant to the AVS ballistic threat
Risk Reduction Test
Tail Rotor Drive Shaft Test
Ballistic Impact
Test Conclusion
Tail Rotor Drive Shaft is tolerant to the AVS ballistic threat
Test Damage
Test Set-up

20. Fuel Line Leak Containment
Risk Reduction Test
Sponson Material –
Fuel Cell Interaction
Fuel Line Leak Containment
Purpose to make sure interaction between fuel cell wall and back-up panel is not excessive damage due to hydrodynamic ram effects
Optimize weight by making panels light as possible – but still functional
Honeycomb construction test panels (and system panels) ramped down to solid laminate around periphery
Backing board (BBC8) for additional bladder support required to achieve self sealing
Hydrodynamic ram is observed when projectiles impact fluid filled tanks at high velocities. The hydrodynamic ram effect is characterized by the penetration of the projectile into the tank, and the propagation of shock waves through the fluid. A combination of these effects can lead to catastrophic failure of the tank and adjacent components. As the manufacture and test of tanks and alleviation mechanisms is expensive
The walls of the tank are pushed outwards as a result of the raised pressure in the tank. A spherical shock wave that is shown in green, proceeds ahead of the projectile and is reflected by the rear wall of the tank
Potential Hazards:
Strong ram: Catastrophic rupture of tank, Loss of fuel and loss of aircraft
Weak ram: Increase in size of penetration hole, Fuel leakage with potential for a fire
Demonstrates structural capability to respond to hydrodynamic ram
Sponson composite wall
construction
Self sealing performance of
candidate fuel bladder
Proposed solutions tested for leak mitigation / fire suppression initiated by ballistic impacts on fuel feed lines

21. LFT&E CH-53K is designated as a covered LFT&E system
U.S. Code Title 10, Section 2366 (10USC2366)
Alternative LFT&E (ALFT&E) strategy uses analysis to aid in
identification of critical components and viable test shots
Key Focus Areas
Collateral and cascading effects
Assess potential crew and passenger casualty
Assess CH-53K Battle Damage Assessment and Repair procedures
Provide survivability comparison of CH-53K with legacy CH-53E
What modifications can be made to reduce the vulnerability of the CH-53K?
Alternative means no requirement to use a full – up production acft for testing.
We’ll use the GTV
Not flight worthy or will not have a flight clearance for human occupants but it will be a fully functionable.
We will have the acft in a 3-4 inch captured hover.
So some representative flight loads will be distributed through the airframe , control and drive components.

22. Component Level Ballistic Tests
Stationary and Rotating Scissors
TR Pitch Beam
Pitch Control Link
Main and Tail Rotor Servos
MRGB
IGB & TGB
TR Drive Shaft
TR Flex Couplings
TR Disconnect
Couplings
TR Hangar Bearings &
Mounts
Stationary Scissors
Swash Plate
MR & TR Servos
Sponson structure & cell
TR Blade, Flex Beam
TR Pitch Link
TR Pitch Change Shaft
TR Shaft
TR Pitch Beam
Armor – Crew, Cabin
Propulsion – GE 38

23. GTV System Level Tests CH-53E • Drive System Tests Armor Tests–
MRGB Rear Module
TR Gearbox
Intermediate Gearbox
TR Drive Shaft
TR Flex Coupling
TR Disconnect Coupling
TR Hanger Bearing and
Bracket
NGB -
MRGB Shaft, Coupling
Hanger Bearing
Rotor Brake
NGB & Mounts
Armor Tests
Cabin floor / wall
Cockpit seat & wing
Structure Tests
Transition and Tail
Fire Tests
Engine Nacelle
Fire detection / ext. system
Fuel System
Sponson / SEFS
Feed (Engine)
Dump & Refuel
Fuel line Sleeves
Hydraulic System
Flight Control Tests
Control boxes & wiring
MR Servo Actuator
TR Servo Actuator
TR Blade
TR Hub
TR Pitch Beam
TR Control Link
TR Pitch Change Shaft
Swashplate
CH-53E
(mounted on a hover stand at WSL during JLF Tests)

24. ENSURES SURVIVABLE DESIGN
Model - Test - Model
Lessons learned from previous programs
e.g. CH-53E
MODEL
TEST
MS - C / OTRR
CDR Update
Trade Studies
Risk Reduction Test results
PDR Update
Trade Studies
Initial Assessment/
Model
Data from formal live fire test program
ENSURES SURVIVABLE DESIGN

25. Questions ?