Browse Topic: Data exchange
A quantitative understanding of the perceptual elements of handling qualities rating brings us to the heart of pilot control. In previous work it was shown that pilot induced oscillation ratings (PIORs) were a strong linear function of the closed loop dominant mode decay rate of the modeled pilot-vehicle system. While PIORs are based solely on the degree that oscillation degrades the task, the handling qualities rating (HQR) scale employs aggregate performance criteria and three apparently distinct sensations: workload, compensation, and controllability. However, in practice the pilot must modulate control in real time based on an instantaneous sense of performance. It is incumbent to model these four perceptions if the objective is to reproduce the manner and resolution with which the pilot assigns HQRs. The current work examines the same offset landing task that was conducted in two separate piloted studies: 1) Flight, using the Calspan variable stability NT-33A aircraft, and 2) Fixed and motion-based simulation, using the NASA Vertical Motion Simulator (VMS). The substantial difference in actual pilot ratings between the inflight and simulation studies was unexpected and hitherto could not be accounted for. The perception-based theory developed herein predicted pilot ratings that matched well the two studies’ ratings. It is demonstrated how acceleration washout (employed in most motion simulators) could impede the vestibular system from sensing decay rate and require the visual system to be used for primary control. A biomechanical feedback model is developed that computes dynamic limb tension from the neuromuscular system which is then integrated with the feel system to produce a stick force disturbance in response to aircraft motion. This model is flight-data-validated, and the neuromuscular mode’s decay rate was used as a metric to successfully predict the occurrence of roll ratchet (a higher frequency PIO phenomenon).
In this paper the time accurate coupling between the high fidelity CFD code FLOWer and the multi-body dynamics code SIMPACK is presented. To facilitate this coupling a socket-based data exchange was developed and used to exchange aerodynamic forces and kinematic data. Two flight states were investigated: a hover and a forward flight. To obtain a reasonable initial flight state a previously obtained, trimmed solution was taken as the base. This study shows the feasibility of the strong coupling approach with the direct influence of the helicopter motion on the flow field and vice-versa. As expected, the factor limiting the overall performance is the runtime of the CFD simulation. The effort of running the flight mechanics simulation and the data exchange necessary for the strong coupling is negligible compared to this runtime.
Rotorcraft continue to experience higher fatal accident rates compared to fixed-wing aircraft, primarily due to low altitude flight operations and reduced situational awareness in complex environments. A critical factor is the limited availability of accurate, up-to-date information on helipads and surrounding obstacles - such as trees, poles, and buildings - that pose significant risks during takeoff and landing. Existing resources, including the Federal Aviation Administration's heliport registry, are often outdated and incomplete, particularly for private or state-operated sites, and fail to report nearby obstacles. This lack of up-to-date data is largely due to privacy restrictions at certain locations and the high cost associated with comprehensive obstacle surveys. To address this challenge, we develop a deep learning (DL) framework that automatically detects helipads and nearby obstacles from high-resolution satellite imagery. Our approach combines Mask R-CNN for precise pixel-level helipad segmentation with Grounding DINO, a zero-shot vision-language model that identifies obstacles using flexible text prompts (e.g., "Pole", "Tree") without task-specific training. This text-guided, scalable detection method adapts to diverse and evolving operational settings. We validate our framework across helipads in the United States, and demonstrate strong performance in both helipad localization and obstacle detection. In addition, we build a web-based application that automates image processing, updates incorrect heliport coordinates, and provides obstacle reports. This work aims to enhance aviation safety, modernize infrastructure records, and deliver scalable tools to the aviation and machine learning communities.
The Main Gearbox of a helicopter is a crucial component that delivers the desired performance and ensures the highest possible level of safety of the aircraft; it includes several gears and bearings, which require to be continuously lubricated by a pressurized oil flow. Undesired circumstances may cause the oil to leak from the main circuit, hence reducing its pressure and consequently the oil flow rate targeted towards the rotating components; this modifies their friction coefficient, and subsequently leads to an overheating of the parts with the risk of degenerating in a catastrophic failure. During the design of a helicopter drive system, engineers need to take proper precautions and make sure that the MGB is fully equipped with the proper features to cope with a loss of lubrication event; specifically, the drive system is supposed to be able to run at least 30 minutes after the oil pressure drops to zero. A lot of effort has been put over the years at Leonardo Helicopters to find robust solutions to attain the longest performance of the drive system in no-oil conditions: the most important result is the certification of the AW189 for a 50-minutes “run dry” capability. Nevertheless, the dynamic environment typical of the rotorcraft industry pushes towards continuous innovation, and in the last few years the Transmissions Systems Design department of LH has been asked to investigate suitable ways to further augment the no-oil capabilities of the MGB: the main steps followed and entailed results are presented in this paper. The first part of the manuscript discusses the “state of the art” auxiliary lubrication system, currently flying on the AW189 drive system. The second part tackles the approach adopted to meet the novel requirements, unveiling both the methodology and the final design choice: the latter includes a metering element, able to tune the oil flow rate headed towards the component deemed the most critical in order to satisfy the requirement of longer no-oil performance. Numerical and experimental tools are exploited as complementary tools to properly crystallize the obtained results and corroborate the solution.
We present our ongoing efforts towards the development of crash-tolerant rotorcraft airframe structures through topology optimization, with the goal of enhancing energy absorption and occupant survival during vertical impact events. A high strain rate explicit dynamics solver has been developed, fully accelerated on GPUs, to enable rapid and accurate simulation of impact events critical to crashworthiness evaluation. In parallel, we have built a scalable three-dimensional topology optimization framework that enforces stiffness, weight, and frequency constraints simultaneously, driving structurally efficient and vibration-resistant designs. Benchmarking results demonstrate significant GPU-enabled speedups, facilitating high-fidelity crash simulations and large-scale optimization at practical turnaround times. This work establishes a computational foundation for future integration of crash-centric objectives and constraints into the optimization framework.
This paper investigates an output-based approach for predicting limit-cycle oscillations caused by freeplay, which can affect actuated structures of vertical lift vehicles. The proposed approach uses pre-critical time-history data to estimate the recovery rate to equilibrium following perturbations as a function of amplitude and a varying parameter. Recovery rate data points in the parameter-amplitude plane are fitted and extrapolated to predict limit-cycle oscillation solutions, corresponding to a recovery rate of zero. While previous work demonstrated this approach for systems with geometrical or polynomial stiffness nonlinearities, this study investigates its applicability to freeplay for the first time. The study uses time-history data from simulations of an analytical model of an idealized, elastically mounted tilting propeller in airplane mode, with freeplay in the tilting mechanism. The results highlight the promise of the proposed approach, paving the way for addressing more complex configurations.
This paper investigates an output-based approach for tiltrotor whirl flutter bifurcation analysis. The approach uses free decay output data for a quantity of interest at various forward speeds to estimate the system's recovery rate to equilibrium while capturing its variation with amplitude. The recovery rate is then extrapolated to predict the bifurcation diagram, which gives the limit-cycle oscillation amplitude for the quantity of interest as a function of the forward speed. The approach is demonstrated using output data from transient simulations of a notional tiltrotor model with polynomial structural nonlinearities. The approach accurately predicts the tiltrotor whirl flutter speed and limitcycle oscillation amplitudes while only requiring two free decays. This approach can facilitate whirl flutter bifurcation analyses of tiltrotor systems exhibiting nonlinear dynamics.
Prior to 1950, use of the helicopter for evacuation was extremely limited, as military top brass often considered it a worthless contraption; thus, rescue was uncertain at best for downed pilots and wounded soldiers stranded behind enemy lines. However, this all changed in Korea, where twelve U.S. Army helicopters from three detachments, working in tandem with seven, newly created Mobile Army Surgical Hospital (MASH) units, would fundamentally change the Army's medical-evacuation doctrine forever. Using several models of the Bell H-13, the Hiller H-23, and the Sikorsky H-5 and H-19, this small band of courageous pilots pushed themselves and their aircraft to their limits, transporting 21,212 critically wounded soldiers for life-saving surgery to various MASH units, cutting the fatality rate from World War II in half. Adopting the 3rd Air Rescue Squadron's motto, "That Others May Live," these pilots and their helicopters were affectionately known to the wounded as "Angels of Mercy."
A state-of-the-art emerging progressive damage failure analysis tool CDMat has been successfully applied to multiple material systems on open-hole tension and compression, and double shear bearing laminate coupons under static and fatigue loading including simulation to ultimate failure. CDMat also successfully demonstrated component-level strength/fatigue analysis under the Air Force Composite Airframe Life Extension (CALE) and the Fail-Safe Technologies for Bonded and Unitized Composite Structures (FASTBUCs) Programs. Building on the success of CDMat an integrated software solution for certification and sustainment of rotorcraft primary composite structures is being developed. A method and an algorithm for fatigue crack growth simulation in laminated structures are proposed to improve the accuracy of CDMat fatigue predictions. The method is based on using cohesive material model, tracking material points at the crack front, and calculating the pointwise energy release rate employing the J-integral. The algorithm was implemented as a set of user material subroutines developed within the framework of explicit finite element formulation for ABAQUS. The effectiveness of the method is demonstrated on several examples of Mode I and II fatigue crack growth.
The airframe digital twin analysis framework developed at the National Research of Canada is being transposed to safe life applications for rotorcraft components. A probabilistic safe life prediction approach, consisting of uncertain material property data and uncertain load spectra is used to calculate risk assessment metrics, such as the cumulative probability of failure, the hazard rate, and the average hazard rate as a function of time. A demonstration of this approach is presented for a CH-146 Griffon component, for which the uncertain loads are estimated from a model developed through machine learning. This preliminary assessment shows the feasibility of using digital twin concepts as a viable alternative to traditional deterministic life predictions, with the potential to reduce maintenance costs and increase aircraft availability.
This paper investigates a sliding-window matrix pencil method for predicting flutter points and limit-cycle oscillation amplitudes of nonlinear aeroelastic systems that experience whirl flutter. The approach applies the matrix pencil method to a short time window that slides along the free decay of a quantity of interest, quantifying the variation in the system's recovery rate to equilibrium with amplitude. The recovery rates at each amplitude and various forward speeds are extrapolated to predict the critical forward speed of zero recovery rate at those amplitudes. This process yields a set of limit-cycle oscillation solutions that can be visualized as a bifurcation diagram. The approach is demonstrated using output data from transient simulations of a propeller-nacelle test case with hardening structural nonlinearities. The impact of each parameter in the sliding-window matrix pencil method is first characterized via sensitivity analyses. Next, the bifurcation diagram is predicted using the recovery rates for the optimal parameter values. The results are compared with direct time marching and with the extrapolation of recovery rates estimated from envelope functions. The proposed method accurately captures the bifurcation diagram using two pre-flutter transient simulations with no need for envelope functions. This approach shows promise for output-based bifurcation analysis of nonlinear aeroelastic systems exhibiting limit-cycle oscillations associated with whirl flutter.
Safety professionals receive data from internal and external sources, then manually determine whether the issue constitutes a safety hazard. Many reports are received, and each report is reviewed, then investigated further, using a tedious, labor intensive, and possibly error prone process. In the course of reaching a decision, human bias is inevitable - any two humans could reach different conclusions, and the same individual human could draw different conclusions on different days. As technology has advanced, numerous approaches have been pursued, attempting to reduce human bias and improve both efficiency and effectiveness of the process. In recent years, moderate success was achieved, which provided accuracy rates near 85% but continued refinement did not achieve acceptable results. In early 2023, the challenge was given to a new team, and within a few months, state-of-the-art Artificial Intelligence/Machine Learning data analytics techniques were utilized to aid in safety data analysis efforts, which resulted in high accuracy and efficiency, with reduced human bias.
A piloted simulation experiment was conducted in the NASA Ames Vertical Motion Simulator to investigate the effects of bandwidth, phase delay, attitude quickness, and maximum achievable rate on yaw-axis handling qualities in hover and forward flight. Two different aircraft were tested, representative of advanced scout-class rotorcraft. Five target acquisition and tracking Mission Task Elements were used in the study. Two of the tasks were modified versions of tasks used to determine the ADS-33E target acquisition and tracking yaw attitude quickness boundaries. Two of the tasks were modified versions of attitude capture and hold and sum-of-sines tracking previously used to evaluate pitch and roll axis handling qualities. The final task was a forward flight target acquisition task developed for this study based on a ground attack or strafing maneuver. Eight Army pilots participated in the study and evaluated 60 yaw-axis configurations. The results of the study suggest that the current yaw-axis hover/low-speed and forward flight bandwidth and hover/low-speed attitude quickness requirements for target acquisition and tracking are too low. Updated boundaries for these requirements are recommended.
This paper documents the re-evaluation and updates to the previous Partial Regime Recognition Spectrum effort for the MH-47G using Structural Usage Monitoring System (SUMS). Further validation of the SUMS algorithm allowed for additions to the spectrum. These additions include more refined categorization of turn and partial power descent regimes based on angle of bank and descent rates, respectively; high load prorates for turns, partial power descents, level flight, and climbs based on the Cruise Guide Indicator; exceedances of maximum density altitude; and use of occurrences for Landing and Run-On Landing regimes. Additional years of flight data from 2013 to 2019 were included in this effort. The updated usage spectrum for the Army MH-47G aircraft has been delivered to the OEM (Original Equipment Manufacturer). The OEM calculated new fatigue lives and updated the "Fatigue Substantiation Report", which will soon be fielded.
A Common Open Data Exchange format for rotorcraft Health and Usage Monitoring Systems (CODEX-HUMS) would offer a more affordable, capable and effective Integrated Vehicle Health Management System. The Society of Automotive Engineers (SAE) HM-1R committee is developing a standard definition for the CODEX-HUMS open data format produced or used by an on-board or off-board system, SAE Aerospace Standard AS7140. The standard format benefits end users (e.g., operators, developers, suppliers, integrators, and maintainers) with the capability to more rapidly operationalize HUMS data. This HUMS open data format meets the intent of a Modular Open System Approach (MOSA) and provides a foundation for rapid realization of operational benefits from the point of maintenance and from the exchange of HUMS data with external enterprise systems.
Maintenance of spatial orientation (SO) is achieved primarily through visual information where the horizon and celestial reference cues or flight instruments are used by pilots to infer aircraft orientation. However, cross checking the instruments in degraded visual environments can be complicated by factors such as workload, distraction, and situations where the vestibular and proprioceptive systems may provide false and competing orientation information. We describe experiments measuring pilot performance using a flight simulator under challenging conditions where the sensory information was controlled. Reducing available visual instruments increased the task difficulty. A wearable vibrotactile array could provide concurrent, additional orientation information. Increasing the flying task segment difficulty increased the perceived workload and also corresponded to an increase in accidents. Adding tactile orientation information reduced the accident rate.
A key objective of this work was to develop a quantitative rationale to explains some aspects of pilot rating variability, as this would point to the fundamental principles driving pilot response that may not be observable if averaged ratings are used as a handling qualities metric. This paper hypothesizes that the factors affecting a pilot's ability to stabilize and control an aircraft following abrupt control motion is neither the damping nor the frequency of the ensuing oscillation, but rather the length of time that the oscillation remains large enough to interfere with the task (i.e., the product of damping and frequency). A handling qualities metric is introduced called the decay rate parameter that reflects the decay rate of the closed loop dominant mode. Closed loop pilot-vehicle oscillation decay rates were generated by a pilot model employing pitch (visual channel) and pitch rate (vestibular channel) tracking strategies. These decay rates were used to predict minimum and maximum handling qualities ratings and pilot induced oscillation (PIO) ratings which closely matched actual pilot ratings from an inflight PIO study using a variable stability NT-33A aircraft. PIO frequency prediction results were excellent. Predicted handling qualities and PIO ratings from a piloted NASA Vertical Motion Simulator study also closely matched the actual ratings. The results indicate that even with the highest fidelity motion simulation, pilot control relies primarily on the visual channel and is constrained by its inherent limitations. Conversely, the dominant control strategy appears to be the vestibular channel when pilots conduct a visual task that is anchored in the physical, out-the-window environment. The vestibular channel is shown to incur effectively no time delay.
ABSTRACT
ABSTRACT
The aerospace ecosystem is a complex system of systems comprising of many stakeholders in exchanging technical, design, development, certification, operational, and maintenance data across the different lifecycle stages of an aircraft from concept, engineering, manufacturing, operations, and maintenance to its disposal. Many standards have been developed to standardize and improve the effectiveness, efficiency, and security of the data transfer processes in the aerospace ecosystem. There are still challenges in data transfer due to the lack of standards in certain areas and lack of awareness and implementation of some standards. G-31 standards committee of SAE International has conducted a study on the available digital data standards in aircraft asset life cycle to understand the current and future landscapes of the needed digital data standards and identify gaps. This technical paper presents the study conducted by the G-31 technical committee. This paper reviews the data being exchanged between various stakeholders in the aerospace asset lifecycle and the availability of standards for the data transfer within the aerospace ecosystem. It identifies gaps based on the list of currently available data standards, and then creates a future landscape to address the needed digital data standards. This paper focuses on aircraft operations, maintenance, transfer, disposal processes, and post-build stage, and does not address the detailed interactions during the aircraft design, development and manufacturing phases. Its scope is also limited to key stakeholder interactions throughout the different stages of the aircraft operations, maintenance, and retirement.
An alternative approach to regime recognition that is based on the notion of motion primitives is developed. The algorithm developed is non-causal and leverages the ideas of maneuvers and trims as defined in a motion primitive context. The algorithm functions in three major steps. Given a state and control input time history obtained from flight data, the first step consists of classifying the state and control time history into trim and maneuver segments. The second step leverages the information in the trim state and control vectors to classify each trim segment into a particular trim condition based on conditional (if-else-if) logic. The third step entails the classification of each maneuver segment (flown between two trim segments) as a particular maneuver condition. Importantly, maneuver classification leverages dynamic time warping in order to compensate for rate and time duration variations. Accuracy of the proposed algorithm is evaluated using SH-60B simulated flight data. Operation of the algorithm is also demonstrated using real-world piloted flight test data from a generic utility helicopter.
An improved conditioning monitoring technique is provided for rotating components in gearboxes that account for gear system dynamics. A rotation rate for the component is generated from vibration data by estimating the rotation rate based on a tachometer measurement of another shaft and the shaft ratio. This estimated rotation rate is used, together with the known configuration of the component, to estimate a known gear mesh frequency of the component. By filtering for a range of frequencies around the gear mesh frequency based on variation in the shaft rate, the gear mesh frequency can be determined, and from that signal, an actual rotation rate for the component can be determined. The exact rate can then be used in deriving an analytic vibration spectrum for the component that is not degraded due to gear system dynamics effects. Further, this allows the calculation of the gearbox transfer function.
Military rotorcraft engines operating in harsh environments routinely ingest large quantities of mineral dust, which can degrade components and ultimately reduce operability. Time off-wing for unscheduled maintenance is a costly burden, both financially and operationally. Rapidly predicting engine deterioration rates as a function of the mission presents an opportunity to optimise flow of supplies, better manage fleets, and perform safety risk assessments when dust loading is expected to be particularly high. In the current contribution, we present our ongoing efforts in this field with a new methodology for assessing the effectiveness of inertial particle separators and quantifying the changes they impart to the inbound dust. We demonstrate that both the concentration reduction and the modification to the particle size distribution can be made on the basis of a single independent variable- a generalised Stokes number for inertial particle separators- and a single performance parameter- the corrected separation efficiency. To develop these parameters we conduct numerical simulations of the flow through a generic axi-symmetric inertial particle separator, over a range of five mass flow rates, three scavenge mass flow rates, and 16 particle diameters. In addition to this, a framework is presented to enable an estimation of the dust concentration at the engine intake. This is achieved by correlating the total wake strength to an existing dust landing trial dataset. A coupled rotorcraft-engine model is then used to combined the two methodologies to investigate the influence of engine mass flow rate on dust ingestion rate. A weak non-linear relationship is observed, which arises due to the simultaneous increase in wake strength with engine mass flow rate as rotor power requirements increase. The additional dust stirred up by the stronger wake leads causes this non-linearity. Finally, we show that an improvement in separation efficiency caused by higher engine mass flow rate is far outweighed by the associated increase in dust loading in this condition.
The serial introduction of passive and active anti-vibration means lead primarily to the reduction of the vibration levels at blade passage frequencies Nb/rev. Consequently, other- previously unnoticed- sources of vibration are perceived by rotorcraft occupants. Therefore, a comprehensive vibration assessment metric is required to characterize the impact of different vibration sources of helicopters regarding passenger comfort. Since the advance of industrial/military aerial transport machines, several vibration assessment metrics were developed such as the Intrusion Index (ADS-27A-SP), the overall ride value av (ISO2631-1) and the NASA DISC model. However, these metrics have deficiencies regarding the evaluation of complex rotorcraft vibrations, e.g. the Intrusion Index favors only the rotor harmonics in the vibration evaluation, the overall ride value av is based on uniaxial, sinusoidal oscillations at discrete frequencies and the NASA DISC model considers only vibration measurements on the floor and not on other vibration contact surfaces. Since the rotorcraft vibrations are characterized by the presence of triaxial, multiple vibration sources it is unclear whether one of these metrics is appropriate to assess the perceived discomfort. The work presented in this paper addresses this topic. The suitability of existing vibration evaluation metrics, especially av, regarding typical rotorcraft vibration patterns is investigated. For that purpose, a systematic whole-body vibration campaign was performed, in which human subjects were seated in a helicopter seat on a motion platform and exposed to helicopter specific vibration patterns of which specific frequencies were systematically attenuated or increased. Participants rated the perceived discomfort using magnitude estimation. The campaign reveals, that the overall ride value av is not well-suited to predict and to compare the discomfort of different vibration spectra. Especially in vertical direction, the application of av will significantly overestimate the discomfort. This implies that this metric is not appropriate for evaluation of helicopter specific vibrations and could be improved. The results in this paper are a first step in that direction but more comprehensive analyses of helicopter specific vibrations and their impact on passenger comfort are necessary.
The benefits of developing objective measures of handling qualities, more specifically pilot workload, are of great interest to the United States Navy. Several lines of research have been initiated to that end with this study focusing on inceptor activity. Potential pilot inceptor workload metrics were applied to a data set consisting of ten pilots conducting simulated approach and hover tasks to a DDG-class ship. Piloted handling qualities ratings were recorded for the tasks. Workload variation was induced by using different aircraft response types, varying degrees of ship motion, and the presence/absence of cueing. Using only pilot inceptor state data, potential workload metrics were evaluated and correlations with handling qualities ratings were examined. Methods to apply traditionally single-axis metrics to multi-axis tasks were explored, inconclusively. Predictive ability of the simple metrics improved by breaking tasks into pseudo-time invariant sub-tasks. A multi-axis metric from past research was shown to correlate best with workload ratings, but several more traditional workload measures show promise and correlation may improve if applied to a scale other than Cooper-Harper. A novel approach of treating the multi-axis problem as a metric itself is introduced and data presented to support adoption as a workload discriminator in and of itself.
This work examines the handling qualities (HQ) rating scale from a psychophysical perspective, characterizing workload as the response to a stimulus composed of input to the pilot and pilot outputs. Previous work by the author examining three different display tracking tasks indicated that pilot workload is effectively a logarithmic function of tracking error rate and control rate. This approach, called the Spare Capacity OPerations Estimator (SCOPE), is extended to flight and Handling Qualities data collected (109 runs) for the slalom Mission Task Element (MTE) using the U.S. Army’s JUH-60A RASCAL aircraft. Attitude and Rate Command response types as well as various forcefeel configurations were tested. Based on flight data observation a novel and intuitive action model is proposed for the slalom MTE whereby the pilot operates on the relative angle between the ground track and the upcoming cone’s location (effectively the cone’s location on the windscreen relative to the aircraft nose, assuming a no-wind environment). Proximity to an approaching cone determines which of two strategies is active: maintaining a constant relative angle or maintaining the relative angular rate constant. A method is proposed for mapping Handling Qualities (HQ) ratings to flight data performance and the workload estimate, offering the possibility for easing the requirement that a pilot trained in HQ evaluation fly test maneuvers. Applying this approach to the slalom maneuver produced good correlation between actual and estimated HQ ratings over the varying aircraft and inceptor feel system dynamics.
To achieve Level 1 Handling Qualities, Aeronautical Design Standard ADS-33E-PRF requires an Attitude Command Attitude Hold or Translational Rate Command response-type in Degraded Visual Environments while allowing a rate response in Good Visual Environments. The authors describe the design and analysis of a Blended Command Model that may offer the precision of the former and the aggressiveness of the latter. The command model, comprised of a single flexible transfer function and its parameter scheduling functions, produces attitude, rate, and blended responsetypes as functions of cyclic stick position. The authors explain the command model’s design considerations, test considerations, and its behavior through time domain and frequency domain perspectives. This effort precedes a handling qualities assessment aboard the U.S. Army’s JUH-60A RASCAL aircraft.
ABSTRACT Rotorcraft operations in arid environments can result in the ingestion of large quantities of dust particles into turboshaft engines, where they can melt and deposit on high pressure turbine nozzle guide vanes. This can result in reduced engine life-span and in worst case scenarios, in-flight engine failure. Predicting the extent and rate at which this damage occurs has proven difficult owing to the wide range of variables relating to the dust cloud, engine and most importantly, the properties of the particulate encountered. Whilst significant work has been carried out to model the particle deposition process for both volcanic ash and coal fly-ash, there is scarce similar work for the different types of mineral dusts rotorcraft encounter. In this contribution, we assess the suitability of two opposing numerical approaches for use in a generalised, reduced-order deposition model of individual mineral particles depositing on a vane. Both models are seen to be heavily reliant upon empirical inputs, be this the thermo-mechanical properties of the particles such as their yield strength, or currently unknown experimentally determined constants. An alternative approach is therefore proposed whereby the particle yield strength is correlated using existing relationships to the Vickers hardness of the grain, a property more amenable to empirical determination. The results obtained represent the current applicability limits of the two models based upon existing empirical data and thus highlight the need for further experimentation relating to both the thermo-mechanical properties and probabilities of adhesion for both individual mineral grains and mineral dust blends.
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