|Acquisition Program: ||PMS 502, CG(X) Program Office, ACAT 1|| Objective: ||Develop and demonstrate innovative algorithms that will provide the ability to analyze aircraft, ship, and environmental conditions to determine loads imparted on aircraft structure, securing equipment and traverse system components, as a function of aircraft limits associated with Dynamic Interface (DI) test and/or operational conditions. These advanced algorithms will aid in the determination of the appropriate type and/or method to enable the safe securing of aircraft on the flight deck of naval vessels in all environmental and operational conditions.
|| Description: ||The ability of an aircraft to remain on deck, in a controlled or restrained condition, depends on many factors such as ship motion, environmental conditions, as well as the size, shape, weight, configuration and operating condition of the aircraft. Current analysis tools used to determine aircraft securing, traversing and landing loads are not able to support dynamic interface flight operations. Current models that focus on helicopter/ship flight deck analysis include the Curtis Wright Controls Maritime Division Dynaface® simulation software and the Mechanical Dynamics, Inc. ADAMS® program. Dynaface is a special purpose 15 DOF model and ADAMS is based on non-linear dynamics and solves the equations of motion of complex systems. Although these programs can be used to calculate static loads, they are not able to account for helicopter rotor system aerodynamics or dynamic forces associated with rotor operations. These programs are not able to support Dynamic Interface (DI) testing involving helicopter Recovery, Assist, Secure and Traverse (RAST) or Aircraft Ship Integrated Secure and Traverse (ASIST) landings. These current tools do not support helicopter rotor modeling required for shipboard operations, and have no capability to support related real-time pilot-in-the-loop training.
Currently, aircraft manufacturers provide the Navy with tie-down/securing-chain patterns that are solely based on structural strength of the aircraft. Due to competing considerations associated with ship design process, these recommended patterns cannot always be duplicated in the design of the flight deck or applied during the construction of an air capable ship. The currently available analytical software tools do not take into consideration all necessary design factors when predicting loads on the aircraft, securing equipment or traverse system components. Additionally, chain-interference is caused when new or existing aircraft mission equipment requires a divergence from the contractor furnished tie-down patterns. As a result, aircraft are being secured with unknown loads on securing equipment/traverse system components and aircraft structures. The current solution to the uncertainties associated with unknown loads is to compensate by reducing the operational capability by reducing the total aircraft weight (i.e. fuel load, or payload) and/or restricting environmental conditions or sea states in which air capable ships may operate aircraft. To date, an analytic capability has not been developed that is sophisticated enough to enable the incorporation of multi-design factor variables, including aircraft rotor operations, to determine the optimal aircraft tie-down/securing-chain pattern configurations.
This topic seeks innovative and alternative approaches to the development of advanced algorithms that will improve the Navy’s ability to analyze the dynamics involved in aircraft securing by examining not only aircraft type and configuration (including fuel load and payload), but condition of operation, ship class, tie down configuration, ship motion and environmental conditions. The key challenge to DI modeling is being able to include all factors in the problem space. DI flight operations entails helicopter flight dynamics and trajectory, pilot feedback models relative to aircraft flight dynamics and trajectory, influence of ship air-wake and atmospheric turbulence, hydrodynamics of sea states, other human factors associated with ship deck crew, and influence of other environmental factors (i.e., temporal, weather conditions, etc.). Modeling of this magnitude requires a composable simulation environment that involves specialized platform models for the aircraft and sea-craft that can interact with hydrodynamics and aerodynamics models and can emulate the conditions of DI flight operations. Hydrodynamics models that represent various sea-state conditions are available, but the turbulence and air streams created by the influence of the ship superstructure will be a specialized model that is not currently available and a model of this complexity is extremely difficult to construct and validate. To determine loads and structural load limits, the platform configurations and structure designs will then need to be defined and analyzed against environmental scenarios. For the sake of demonstrating feasibility, proposers are encouraged to utilize aircraft data for the Multi-mission Helicopter MH-60R (references 6 and 7). Ship motion data should be obtained from modeling and simulation from the Arleigh Burke Class Destroyer (DDG 51) during the Phase II prototype demonstration phase. Once feasibility has been demonstrated, aircraft and ship specific data will be furnished by the Government POC identified for this topic. Utilizing data from the aircraft, ship and environment, the proposed algorithms are expected to be able to determine the loads sustained by existing aircraft/ship securing and traversing equipment, whether aircraft is static or operating rotor blades. The proposed algorithms shall also identify optimum locations for securing points on the flight deck, identify impacts of altering securing point locations and improve the capability to identify helicopter-traversing envelopes. Approaches should be designed to interface with, transfer data to and receive data from NAVSEA ship design tools such as the Leading Edge Architecture for Prototyping Systems (LEAPS) design software, as well as with other selected NAVSEA ship tools and/or NAVAIR Dynamic Interface support tools.
|| ||PHASE I: Demonstrate the feasibility of the development of innovative and alternative approaches that will improve the Navy’s ability to support DI testing and to analyze the dynamics involved in securing of aircraft by examining not only aircraft type and configuration (including rotor systems aerodynamics), but condition of operation, ship class, tie down configuration, ship motion and environmental conditions. Establish performance goals of the approach and software tool. Provide a Phase II development approach and schedule that contains discrete milestones for product development.
|| ||PHASE II: Develop, demonstrate and fabricate a prototype as identified in Phase I. In a laboratory environment, demonstrate that the prototype product meets the performance goals established during Phase I. Provide a detailed plan for software certification, validation, and method of implementation into a future aircraft/ship test and/or design environment. Prepare cost estimates, logistics data packages, and interface documents for use in both forward fit and retrofit ship programs.
|| ||PHASE III: Utilizing the software developed during Phase I and II, work with Navy and industry to certify and implement this software to existing and future Navy shipbuilding programs, including adapting the software to include multi-air assets.
PRIVATE SECTOR COMMERCIAL POTENTIAL/|| ||DUAL-USE APPLICATIONS: The advanced securing and positioning analytical tool can be utilized to improve the analysis of commercial cruise ships and other commercial air capable ships. The technology can also be used to support tie-down requirements for commercial helicopters and other equipment on offshore oilrigs.
|| References: ||
All available upon request:
1. Anon, Navy MIL-T-81259B, Requirements for Tie-Downs and Airframe Design, Naval Air Systems Command, 11 Oct 1991
2. Anon, MIL-R-85111A(AS), AMENDMENT 8, 15 Sep 1999
3. Wei, F. S., Baitis, E., and Meyers, B., Analytical Modeling of SH-2F Helicopter Shipboard Operations, Journal of Aircraft, Vol. 29, No. 5, Sep-Oct 1992
4. Langlois, R.G., LaRosa, M., Tadros, A.R., Parametric Investigation of the Sensitivity of Shipboard Helicopter Securing Requirements to Helicopter, Proceedings of the Canadian Society for Mechanical Engineers Forum 2992, Kingston, Ontario, CA, May 2002
5. Sikorsky website for MH-60R - MH-60R Overview, Attributes and Baseline Configuration
6. MH-60R Helo High Point Low Point Securing Configuration Drawing No. 627860
7. Carderock Tools Division Website - http://www.dt.navy.mil/tot-shi-sys/des-int-pro/des-too-dev/index.html
8. SMP 95 motion simulations data providing 6-DOF motion of a DDG 51 at the helicopter spot, helicopter hangar and pilot house for sea states 4, 5, and 6
|Keywords: ||tie downs; helicopter; aircraft/ship integration; ship design; aviation; software; algorithms|