Browse Topic: Rescue operations
An aspect of the ship-helicopter dynamic interface (DI) is the highly unsteady flow environment generated by ship-rotor aerodynamic interactions, which challenges safe launch and recovery operations. To investigate these interactions without the constraints of conventional rotor scaling, a novel airflow-and-blade-frequency (ABF) system was developed, decoupling rotor thrust from blade-passing frequency and enabling independent control of disk loading and periodic excitation. Mean-flow superposition and spectral analyses were used to assess the validity of linear-superposition approaches for DI modeling. While superposition reproduced portions of the interacting mean flow, it failed to capture key features such as superstructure sheltering. Spectral results showed that momentum injection and blade-passing frequency modified the interacting flow through distinct mechanisms. Across all operating conditions, the interacting flow exhibited elevated turbulent kinetic energy at pilot-relevant frequencies over a broader spatial extent than either the isolated airwake or the superposed field, indicating that nonlinear aerodynamic interactions generated flow features that super-positional models did not capture. The persistence of these trends across different ABF operating parameters suggested that correction-based approaches may approximate rotor-feedback effects without requiring fully resolved aerodynamic interactions between the ship and rotor (air)wakes.
Improving Slung Loads Operations for Rescue Operations
Helicopters' Vertical Take-Off and Landing (VTOL) capabilities are essential for maritime operations, especially for small-deck naval vessels. Unmanned Aerial Vehicles (UAVs) offer a cheaper, expendable, and efficient alternative for certain tasks, such as reducing pilot risk and lowering fuel consumption. While the procedures to approach and land on (moving) ships are standardized and bound to established operational limits in the case of crewed helicopters, UAVs lack such guidelines. This study investigates optimal rotary-wing UAV approach trajectories to a moving ship, for varying wind conditions and relative initial positions, and for different objectives. The goal is to provide preliminary guidelines for maritime UAV recovery operations, and a preliminary estimation of performance-based operational limits. The optimal trajectories are obtained using a global path-performance optimization framework based on Optimal Control Theory. The trajectories are compared to each other and to reference cases using the Longest Common SubSequence (LCSS) similarity measure, revealing how the unmanned helicopter adjusts its path to exploit the wind direction and profile for more efficient ground speeds. The violation of performance and/or geometric constraints is used to preliminarily indicate the presence of operational boundaries. The control effort and energy consumption are used to identify optimal starting positions for the helicopter approach phase for a given wind profile and intensity.
Refueling mid air is considered as important force multiplier for e.g. conducting search and rescue operations. Due to close proximity to the tanker, the refueling hose and drogue as well as the receiver can be strongly affected by the tanker's wake. Thus, the refueling drogue extended from the tanker by a hose is often oscillating from turbulence. Contact with the tanker has to be established by positioning the receiver's refueling probe within the tanker's drogue. During qualification training pilots are instructed to not focus on the drogue, due to its oscillations. This is done since chasing the drogue often leads to over-controlling and therefore mostly to a failed contact attempt. The presented research aims for improving today's Helicopter Air-to-Air Refueling (HAAR) as well as related training efficiency by a gain of understanding in this phenomenon. Therefore, the HAAR real-time simulation scenario at German Aerospace Center's (DLR) Air Vehicle Simulator (AVES) was extended with a multi body hose and a probe/drogue contact model to enable realistic contact initiation. During a piloted campaign, a total of six pilots with different levels of HAAR experience conducted the maneuver. This paper presents an analysis of obtained eye tracking data with regards to gaze entropy, total fixation duration on defined areas of interest and corresponding time history of control inputs. Potential links between gaze entropy and perceived workload that might be observed in the data are also discussed. Results show that the metrics can highlight differences in successful and unsuccessful attempts for contact of HAAR experienced and inexperienced pilots.
Advanced technology plays a vital role in search and rescue operations after natural disasters such as earthquakes. Thermal imaging equipment and sensitive listening devices are deployed to seek out signs of life. Small aerial drones could also survey otherwise inaccessible spaces, but the inherent fragility of current designs have limited their use.
National Institute of Standards and Technology, Gaithersburg, MD
The Royal Australian Navy completed a series of First of Class Flight Trials in 2015 to establish Ship Helicopter Operating Limitations for Australian Defence Force rotary wing aircraft to the Canberra Class Landing Helicopter Dock (LHD). A Risk Reduction Tool (RTT) was developed to understand the impact of LHD airflow behavior on rotary wing operations. Specifically, the tool combined a ship air wake, a flight dynamic and a Pilot Model to provide an indicative effect of the air wake on pilot controls throughout an MRH90 recovery evolution. A verification of this tool suggests that the RRT in isolation was not able to characterize the flight environment with sufficient fidelity to predict pilot workload during recovery operations to the LHD. However, the RRT improved upon the information provided through stand-alone ship air wake analysis and as such the tool is suitable as a risk reduction measure prior to flight testing.
Loads slung under aircraft can go into divergent oscillations coupling multiple degrees of freedom. Predicting the highest safe flight speed for a vehicle-load combination is a critical challenge, both for military missions over hostile areas, and for evacuation/rescue operations. The primary difficulty was that of obtaining well-resolved airload maps covering the arbitrary attitudes that a slung load may take. High speed rotorcraft using tilting rotors and co-axial rotors can fly at speeds that imply high dynamic pressure, making aerodynamic loads significant even on very dense loads such as armored vehicles, artillery weapons, and ammunition. The Continuous Rotation method demonstrated in our prior work enables routine prediction of divergence speeds. We build on prior work to explore the prediction of divergence speed for practical configurations such as military vehicles, which often have complex bluff body shapes. Results from simulations are presented for 3 vehicle shapes: one resembling a military truck, a Humvee, and a Sentinel Tactical Response Vehicle. Generic comparisons are shown where mass and sling length are held constant, across a variety of shapes. As expected, lower density causes a lower divergence speed. Between the vehicles, the flatter Humvee and the Sentinel show lower divergence speeds compared to the truck model. The results indicate that with specified inertia distributions, Froude scaling can be used to predict divergence speed for arbitrary configurations.
This paper describes the continuing development work being undertaken to establish Flying Qualities Requirements for Unmanned Aircraft Systems (UAS) that will be expected to operate in the Maritime Environment. A UAS Dynamics Model (UDM) has been developed to allow the rapid investigation of the aircraft dynamics required to conduct ship-deck launch and recovery operations. The process used to develop the UDM is described along with the method used to fix the UDM dynamics to ADS-33E-PRF style bandwidth criteria. Two turbulence model structures are described and a preliminary test of the model dynamics in the lateral axis is reported. The model has been initially configured to assess an SH-60B-class UAS operating from a Type 23 Frigate. These preliminary investigations show that the methods being pursued hold promise to achieve the project aims.
Solid chemical oxygen supplies of interest to aircraft operations are "chlorate candles" and potassium superoxide (KO2). Chlorate candles are used in passenger oxygen supply units and other emergency oxygen systems, such as submarines and escape devices. Potassium superoxide is not used in aircraft operations but is used in closed-cycle breathing apparatus. Characteristics and applications of both are discussed, with emphasis on chlorate candles.
ABSTRACT While helicopters are used for a myriad of purposes in rural and urban environments, their true potential can be measured by the support they can offer in extreme and remote areas. This paper describes a Northern Canadian operator, Universal Helicopters Newfoundland and Labrador LP, the equipment used, the tasks performed, the working conditions and the risks and challenges faced . The principal areas of operation include the Province of Newfoundland and Labrador, the Ungava Peninsula and Canada's high and eastern Arctic. The company operates 19 light and intermediate helicopters in one of the most challenging environments in the world. The aircraft are equipped with operational equipment and accessories for operation in temperature extremes which test not only the machinery but the crews that fly and maintain them. A Safety Management System is in place to properly identify and manage the unique risks of operating in the north as well as logistical support that recognizes associated added costs. The presence of multiple aircraft and their adjacency to remote communities often results in requests from authorities to assist in Search and Rescue operations. Despite challenges from wildlife, weather, topography and a long distance supply and communications chains, operators are able to conduct helicopter operations to support scientific research and natural resource development.
The eNOTIFY project defined an algorithm which allows the vehicle to recognize when an accident has occurred and what kind of accident has taken place (frontal, side, roll-over or rear-end collision). The innovative aspects of this methodology are basically that, for each type of accident and for each class of vehicle, a maximum and minimum level of vehicle accelerations (linear or angular) are defined for the severe accident, slight accident and no accident scenarios. A direct application of this algorithm could be to include it in an on-board unit on vehicles, and use it in emergency call applications. eCall devices have been developed to automatically notify emergency services in the event of an accident, in which a fast and efficient rescue operation can significantly increase the chances of survival of the severely injured. In order to reduce response time and improve the efficiency of the medical and technical services, fast and accurate accident identification is required. This on-board algorithm makes it possible to identify the type and severity of the accident allowing emergency services to respond accordingly; and as such could contribute to saving lives.
Solid chemical oxygen supplies of interest to aircraft operations are "chlorate candles" and potassium superoxide (KO2). Chlorate candles are used in passenger oxygen supply units and other emergency oxygen systems, such as submarines and escape devices. Potassium superoxide is not used in aircraft operations but is used in closed-cycle breathing apparatus. Characteristics and applications of both are discussed, with emphasis on chlorate candles.
Worldwide, 1.2 million people die in road crashes yearly; 43,000 in Europe alone. This implies a cost to European society of approximately 160 billion euros, and takes up 10% of all healthcare resources. To reduce these rates, safety technologies have been developed which help to minimize the severity of injuries to vehicle occupants. However, studies have shown that most deaths due to road accidents occur in the time between the accident and the arrival of medical care. Therefore, a fast and efficient rescue operation would significantly increase the injured person's probability of survival. The aim of this project was to define the On-Board Unit (OBU) hardware and software installed in all modern vehicles which could request medical and technical support after a road accident. This device, based on the information from the vehicle sensors, automatically decides whether the car has suffered a road accident or not, the severity of the accident and the kind of accident (impact area). Two kinds of communications were set up in parallel: the first one was an automatic call between the Service Answering Point and the vehicle and the another was the sending of a text message in order to give more detailed information about aspects related to the accident configuration, the vehicle and occupants' state after the impact, the road features and the weather conditions at the site of the accident. Apart from the design of this system, a protocol to test this kind of device was defined. This procedure is based on the accelerations and the rotation suffered by the vehicle due to the collision. Besides providing the accident location, the value of this system compared to other eCall devices is a greater amount of information which allows emergency services to arrive in less time with the suitable tools to properly treat the injured.
Although Portugal has a small continental area, two important factors contributed for the need to use helicopters: The first has to do with the expansion undertake by Portugal in the 14th -15th century. The second has to do with the climate. Because of this expansion Portugal became responsible for new areas, both land and maritime, for which there was recent need, even mandatory use of the helicopter, both in wartime and peacetime operations. The second has to do the hot and dry Mediterranean climate that originates very strong summer fires seasons. The first major use of helicopters was performed by the Portuguese Air Force, during the colonial war. Fighting guerrilla type warfare the helicopter was a fundamental asset. After the war and during peace time the helicopter was been used in maritime and land search and rescue operations, by both the Air Force and other government agencies. Fire-fighting operations are also extremely important and these involve not only the government agencies, but also civilian companies that supplement the some of the fire-fighting helicopter fleet. Portugal therefore has been using Helicopters for the past 50 years in a variety of roles creating a strong link to its use.
Helicopter shipboard launch and recovery operations can result in high pilot workload due to the unsteady, turbulent ship airwake. Successful gust response alleviation could improve safety and potentially expand operational envelopes. The results of a feasibility study of using active trailing edge flaps as gust alleviation mechanisms are presented in this paper. The benefits of on-blade actuation and previous swashplate-based gust alleviation control methods are combined, yielding a system that uses trailing edge flaps for gust disturbance rejection while the swashplate provides primary flight control. The controller is implemented in the GENHEL flight simulation model of the UH-60A Black Hawk with a CFD airwake solution for an LHA-class ship. Simulations are performed in hover. Results indicate that trailing edge flaps are capable of alleviating the magnitude of the vehicle angular gust response in the roll and pitch axes, including reduction in uncommanded roll rate of as much as ninety percent in specific wind-over-deck conditions and a reduction in uncommanded pitch rate of up to thirty-two percent. While achieving the performance of a similar swashplate-based controller, trailing edge flap deflection requirements can be kept below current actuation technology stroke and rate limits. The results of this study suggest that trailing edge flaps can be effective for shipboard gust alleviation.
Some of the most challenging and highest workload tasks for pilots performing maritime missions are shipboard launch and recovery operations. Pilots continuously need to compensate for gust disturbances due to both atmospheric turbulence and the turbulent air wake of the ship. Therefore this research concentrated on the development of an airwake compensator for the control laws which has the ability of reducing the pilot workload in the lateral, longitudinal and yaw axes. These airwake compensators were embedded into an already optimized and pilot-evaluated S-92-class fly-by-wire (FBW) rate command attitude hold (RCAH) control system. Using an extensively developed simulation model of a DDG-81 shipboard environment, which included a full CFD airwake model, and a Maritime mission task element (MTE) based on the visual cues found on the ship deck, a pilot evaluation of the airwake compensator control laws was performed. The piloted evaluation showed that by having a ship airwake degraded the Cooper-Harper handling quality ratings (HQRs) on average by 1.5. Implementing the airwake compensator showed an improvement of 0.4 HQRs for the 25 kts airwake. Similar improvements were also seen for the 40 kts airwake case as well. Power spectral densities (PSD) of the pilot’s cyclic stick and pedal inputs showed moderate improvement when the airwake compensator was activated.
The paper presents a methodology for the dispatching of helicopters in a large scale emergency, based on an iterative application of simulation and solution of linear assignment problems. Two examples of different complexity are shown, including sensitivity analyses. The sequential linear assignment problem methodology is especially suitable because it does not rely on the existence of a pre-existing network of routes, and can cope with highly dynamic situations. Because of the efficiency of the solution algorithms, the computation times are small and not a factor in the dispatching procedure. The computer times required for the solution of each LAP depend on the number of helicopters involved in the rescue, and the number of rescue locations, but not on the number of victims to be rescued (which, however, affects the time required for the entire solution). Through sensitivity analyses it is possible to study the effects of one or more design parameters, of one or more helicopters involved in the rescue, on the time required to complete the rescue. The problem proves nonlinear, at least in the design parameters considered in the study. The characteristics of the rescue operation, and the assumptions made in modeling the helicopters and the rescue operations themselves, play a major role.
The purpose of this project is to demonstrate the feasibility to automatically signal the initiation of UAV descent in a marine environment. The objective is to recover the UAV on-board a moving vessel within reasonable safety margins regardless of the seaway. Aircraft and flight deck availability calculations and improvements using Dynamic Interface (DI) flight simulators ahead of sea trials, are developed. The study, conducted in real-time, uses simulation techniques to represent several manned and unmanned VTOL (Vertical Take-Off and Landing) air vehicles landing on ships. Undercarriage deflection to encountered deck forces and aircraft stability were calculated with impacts on the proposed deck limits discussed and percentage of improvement for operational availability demonstrated. The use of flight simulator to forecast physical deck motion and deck motion limits, is discussed. A brief synopsis of the theory and calculation of the ship motion simulation and Energy Index programs are discussed. The Energy Index identifies quiescent periods to initiate aircraft descent based on aircraft deck limit definitions. Dynamic Interface simulation provides the physical information from which initial deck limits might be derived. Using Launch and Recovery “rondelles”, the deck limits at specific ship’s speeds may be identified. The results of this study are being applied to the realm of Simulation Based Design and Virtual Prototyping, potentially leading to NATO wide standards. The simulated flight test has five essential objectives: assess the capabilities of simulators to support or conduct helicopter-ship operational limits; demonstrate High Level Architecture (HLA) federation; evaluate recovery safety improvements offered by experimental systems, such as the LPD; and determine feasibility of applying these simulators in support of dynamic interface at sea testing.
Results from an ongoing investigation into a novel approach to provide a PC-based tool for the design and evaluation of Visual Landing Aids (VLAs) in supporting Naval aviation launch and recovery operations (often referred to as the Dynamic Interface (DI) problem) are to be presented. The software is based on the use of a suite of tools built around Virtual Reality Modeling Language (VRML) and X3D constructs. VRML, and its successor X3D, are both open 3D graphics standards supported by several free plug-in modules operating within standard Internet browser windows. The resulting cross-platform software will serve multiple roles for use in flight simulation, ship design, Navy operational doctrine development, and aviator and sailor training support.
The paper describes recent V-22 Integrated Test Team/NAVAIR full-scale downwash survey activity conducted as part of the V-22 Uncommanded Roll On-Deck test program. The objectives of the surveys were to quantify the aerodynamic disturbances driving the V-22’s on-deck uncommanded roll response experienced during recovery operations of upwind rotorcraft. Over 300 wake survey events were conducted aboard LHA and LHD class ships between October 2002 and November 2003, using an array of ultrasonic anemometers designed to measure the variation in wake induced velocities across the span of the V-22’s rotors. Data were recorded as various rotorcraft flew constant height and mission representative approaches, upwind hovers, departures, and air taxis past the array. Aircraft surveyed include the UH-1N, CH-46, and the CH-53E platforms. In addition to the anemometer data, the trajectory of the approaching aircraft was recorded using an IR tracking/laser ranging system. Ship motion and wind-over-deck data were also acquired, completing a comprehensive dataset.
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