Browse Topic: Evacuation and escape
Emergency evacuation slides (EVAC slides) are critical safety devices used on aircraft to enable rapid egress during emergencies. While these slides provide a quick and reliable escape route, communication between separated slides during evacuation remains a challenge. Often, during raft deployment over water, slides may drift apart impeding communication among evacuees and rescue personnel potentially compromising safety. Existing aircraft EVAC systems lack integrated wireless communication relying on visual or voice signals that are unreliable in chaotic conditions. This paper explores the integration of wireless IoT technology into EVAC slide systems to facilitate inter-slide communication and monitor critical parameters such as slide air pressure and the floating weight of stranded passengers through embedded sensors. It proposes the adoption of Long Range (LoRa) modulation technology for wireless communication chosen for its low-power, long-range performance and license-free operation in emergency evacuation scenarios. In addition, the usage of this proposed technology can be further extended to locate the aircraft when other existing locating mechanisms fail.
The Crashworthy and Escape Systems Branch at NAWCAD has been developing an integrated restraint harness concept for several years, with the intent of developing a novel method of providing improved occupant protection in a crash scenario. A series of tests was conducted on the Horizontal Accelerator at NAS Patuxent River to evaluate the performance of the prototype integrated-restraint system under MIL-STD-58095 conditions with the 50th percentile male Hybrid III Anthropomorphic Test Device (ATD). While occupant flail was the primary metric being analyzed in this effort, ATD instrumentation was also captured, showing that the integrated restraint system demonstrated a significant reduction in head flail compared to five-point restraints while maintaining injury criteria within acceptable levels.
In any human space flight program, safety of the crew is of utmost priority. In case of exigency in atmospheric flight, the crew is safely and quickly rescued from the launch vehicle using Crew Escape System (CES). CES is a critical part of the Human Space Flight which carries the crew module away from the ascending launch vehicle by firing its rocket motors (Pitch Motor (PM), Low altitude Escape Motor (LEM) and High altitude Escape Motor (HEM)). The structural loads experienced by the CES during the mission abort are severe as the propulsive, aerodynamic and inertial forces on the vehicle are significantly high. Since the mission abort can occur at anytime during the ascent phase of the launch vehicle, trajectory profiles are generated for abort at every one second interval of ascent flight period considering several combinations of dispersions on various propulsive parameters of abort motors and aero parameters. Depending on the time of abort, the ignition delay of PM, LEM and HEM are adjusted in order to minimize the lateral acceleration on the vehicle, at the same time meeting the horizontal range requirement. Aerodynamic load distributions on the vehicle and aero forces and moments on the Grid fin are generated for various Mach No., Angle of Attack (AoA) combinations for jet ON and jet OFF conditions of PM, LEM and HEM. In order to estimate the structural loads for CES during abort, inertia relief analyses are carried out for static load on a free-free finite element model at all the time instances in the abort trajectory as a time sweep simulation considering the appropriate aerodynamic forces, propulsive parameters (mass consumption and thrust) and trajectory parameters (Mach No., Dynamic Pressure and AoA) at each time instant in the trajectory. During abort at lower altitude along with LEM, Pitch Motor (PM) is fired perpendicular to the axis of the vehicle to turn the vehicle towards the sea thereby increasing the AoA and bending moment on the vehicle. The Pitch Motor thrust acting perpendicular to the vehicle excites the first bending mode and augments the Bending Moment. LEM thrust and HEM thrust acting along the vehicle axis also can excite the axial modes of the vehicle. Similarly the lateral aero dynamic forces on the vehicle excite the lateral dynamics of the vehicle whenever there is a sudden change in the AoA due to wind gust. To account for the flexible body dynamic forces, a load augmentation factor called Flexibility Factor is multiplied on the static loads to arrive at the limiting loads on the vehicle. This paper briefly explains the structural load estimation methodology for CES abort, various inputs required and different steps involved in it.
This SAE Aerospace Information Report (AIR) provides general information to aircraft engineers, regarding the types of Protective Breathing Equipment (PBE) configurations which are available, the intended functions of such equipment, and the technical approaches which may be used in accomplishing these functions. The term "PBE" or "Protective Breathing Equipment" has been used to refer to various types of equipment, which are used in a variety of applications. This way of using the terminology has been a source of confusion in the aviation industry. One objective of this AIR is to assist the reader in distinguishing between the types of PBE applications. A further objective is to assist in understanding the technical approaches which can be used in each of the major applications. Principles of PBE design are reviewed briefly. However, discussion of specific performance specifications and information regarding the details of manufacture and testing of such equipment is beyond the scope of this document.
This SAE Aerospace Recommended Practice (ARP) specifies criteria for the design, development, standardization, and comprehension testing of placards containing pictures, drawings, symbols, and/or written instructions for locating and operating aircraft emergency equipment. This ARP also provides guidance in the selection and implementation of warning placards intended to instruct occupants inside, and rescue personnel outside, the aircraft.
This document recommends criteria for standardizing flight deck interior doors and their operation to optimize their use under normal and emergency conditions.
Since flow separation causes increase of the drag on bluff bodies, its control method has been studied for many years. Active control methods are currently focused as an alternative to passive ones because they impose a larger drag penalty under certain conditions. Although the effectiveness of a steady jet using suction, blowing or pulsed jets has been demonstrated, it is difficult to obtain an effect commensurate with weight increase because the mechanism is complicated. One method of solving this problem is a synthetic jet. Synthetic jets are produced by periodic ejection and suction of fluid from an orifice induced by oscillation of a diaphragm inside a cavity. Small engine powered vehicles demand less drag, a compact package and light weight because the drivers expect fuel efficiency, load capacity and economy. Synthetic jets can supply them because they contribute drag reduction and require only simple components. In this study, the influence of synthetic jets on the drag of a simple bluff body representing a road vehicle is measured. Drag measurement was performed by varying synthetic jet parameters: jet location, reduced frequency, velocity ratio of jet flow and uniform flow. The vortex structure around the body was visualized by utilizing a smoke wire method. As a result, among the jet parameters, only reduced frequency had no effect on drag.
Ice protection is important for aero-engine induction system, such as the inlet vanes. For the ice protection of such parts manufactured with low thermal conductivity polymer-based composite material, the combined heating method using interior jet impingement and exterior ejection film has certain advantages. The simulation model coupling CFD with solid heat conduction was developed and solved with the anisotropic thermal conductivities model to investigate the heat transfer enhancement in the stagnation region of aero-engine inlet vanes due to ejection slot and anisotropic heat conduction, which is related to the curved geometry, ejection slots and anisotropic heat conduction. The temperature distribution and heat flux ratio between the stagnation region on outside surface and the impingement region inside were calculated and analyzed for the configuration with different ejection angle and different materials. The results show that ejection slots and anisotropic heat conduction plays important roles of the heat transfer process. For the same ejection angles, the larger the thermal conductivity, the higher the temperature at stagnation point and the better ice protection. For the same material property, the larger the ejection angle jet, the lower the temperature at stagnation point. The configuration with the ejection angle of 5 degree has the highest stagnation point temperature and have much bigger flux ratio than 1.0. This hints that the heat transfer through the slot surface in the direction of the fiber plane is dominant here. Besides that, the ratio of the composite material is almost six times higher than of the aluminum material. This research reveals some basic heat transfer process caused by the curved geometry, ejection slots and anisotropic heat conduction and will be helpful reference for the conceptual design of such ice protection systems.
Automotive liftgate latches have been subject to regulation for minimum strength and inertial resistance requirements since the late 1990’s in the US and globally since the early 2000’s, possibly due to liftgate ejections stemming from the first generation Chrysler minivans which employed latches that were not originally designed with this hazard in mind. Side door latches have been regulated since the 1960’s, and the regulation of liftgate, or back door latches, have been based largely on side door requirements, with the exception of the orthogonal test requirement that is liftgate specific. Based on benchmarking tests of liftgate latches, most global OEM’s design their latches to exceed the minimum regulatory requirements. Presumably, this is based on the need to keep doors closed during crashes and specifically to do so when subjected to industry standard tests. The focus of this paper is to understand the specific loads seen by center-mounted liftgate latches when exposed to various industry standard tests, as well as some foreseeable crash conditions currently not addressed by the standard tests. This paper explores the use of CAE analysis to understand the specific structural and inertial loads liftgate latches are exposed to in various rear and side crash tests, in order to better understand the design requirements for liftgate latches to ensure passenger compartment integrity and minimize the risk of occupant ejection through the liftgate closure. Various standard crash tests, vehicle body types and cargo load cases are explored as well. A methodology is presented which shows how the various load cases can be obtained and used for development of new liftgate latches. This paper does not deal with roll over load cases, which is a subject of ongoing research and will be presented in a subsequent paper.
This Aerospace Recommended Practice recommends general criteria for the development and installation of an aircraft emergency signal system to permit any crew member (flight or cabin) to inform all other crew members that an emergency evacuation situation exists and that an evacuation has been or should be immediately started.
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.
Flow control over aerodynamic shapes in order to achieve performance enhancements has been a lively research area for last two decades. Synthetic Jet Actuators (SJAs) are devices able to interact actively with the flow around their hosting structure by providing ejection and suction of fluid from the enclosed cavity containing a piezo-electric oscillating membrane through dedicated orifices. The research presented in this paper concerns the implementation of zero-net-mass-flux SJAs airflow control system on a NACA0015, low aspect ratio wing section prototype. Two arrays with each 10 custom-made SJAs, installed at 10% and 65% of the chord length, make up the actuation system. The sensing system consists of eleven acoustic pressure transducers distributed in the wing upper surface and on the flap, an accelerometer placed in proximity of the wing c.g. and a six-axis force balance for integral load measurement. A dSPACE™ hardware connected to the software environment Matlab/Simulink® and dSPACE Control-Desk® complete the test architecture. Wind tunnel experiments, on the uncontrolled wing (actuators off), are primarily performed for system identification purpose. The open-loop control operation (actuators on but no feedback) of the wing is implemented and tested, obtaining a stall delay of about 2.8 degrees of AOA. Furthermore, a closed-loop strategy, based on the wing upper surface mean pressure chord-wise distributions signature is adopted to characterize the forthcoming boundary layer detachment. This allows for triggering the controller in stall proximity only, for energy saving purpose. Pertinent results and discussion are provided along with concluding remarks and prospects for future research.
NHTSA issued the FMVSS 226 ruling in 2011. It established test procedures to evaluate countermeasures that can minimize the likelihood of a complete or partial ejection of vehicle occupants through the side windows during rollover or side impact events. One of the countermeasures that may be used for compliance of this safety ruling is the Side Airbag Inflatable Curtain (SABIC). This paper discusses how three key phases of the optimization strategy in the Design for Six Sigma (DFSS), namely, Identify; Optimize and Verify (I_OV), were implemented in CAE to develop an optimized concept SABIC with respect to the FMVSS 226 test requirements. The simulated SABIC is intended for a generic SUV and potentially also for a generic Truck type vehicle. The improved performance included: minimization of the test results variability and the optimization of the ejection mitigation performance of the SABIC. Results from this study show that for generic SUV and Truck type vehicles with hardware similar to that tested in this study; Beltline overlap, loft size and pressure account for 75% of the variability in performance of an ejection mitigation SABIC. These metrics may therefore be considered critical to the design of the SABIC. The identified key metrics may be used to define nominal ejection mitigation SABIC design best practice for the generic SUV and Truck. An associated investigation during this study showed that a SABIC may shrink significantly when fully inflated. This shrinkage has the potential to move SABIC lofts away from the intended impact location. The CAE based DFSS process has the potential to significantly reduce SABIC development time and may potentially enhance product speed to market using virtual tool versus empirically based SABIC development approach.
The Department of Transportation (DOT) National Highway Traffic Safety Administration (NHTSA) awarded a contract to Southwest Research Institute (SwRI) to conduct research and testing in the interest of motorcoach fire safety. The goal of this program was to develop and validate procedures and metrics to evaluate current and future detection, suppression, and exterior fire-hardening technologies that prevent or delay fire penetration into the passenger compartment of a motorcoach - in order to increase passenger evacuation time. The program was initiated with a literature review and characterization of the thermal environment of motorcoach fires and survey of engine compartments, firewalls, and wheel wells of motorcoaches currently in North American service. These characterizations assisted in the development of test methods and identification of the metrics for analysis. Test fixtures were designed and fabricated to simulate a representative engine compartment and wheel well. Fire scenarios were developed for each fixture, the current detection, suppression, and fire-hardening technologies were reviewed and a sample set selected to validate the test procedures developed during this program. Based on the results of testing and feedback from stakeholders, test methods and metrics were developed for evaluating wheel well warning systems, engine compartment detection and suppression systems, and fire-hardening systems. Detailed program conclusions and recommendations for areas of interest for further research and testing are also discussed.
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