Search

Six rotary wing aviators were subjects in a continuous operation regimen involving some 12 hours of flying and 3.5 hours sleep daily for five days. Estimates of performance on a dynamic visual acuity (DVA) task were obtained several times each day during the study using target velocities of 25 deg. and 40 deg./sec. DVA performance varied significantly during the fatigue regimen when measurements were made with target velocities of 40 deg./sec; with lower velocity targets differences in DVA scores were not significant. This indicates the need to tax the oculomotor system to demonstrate fatigue effects. Fatigue effects were partially obscured by practice effects which are considerable in the DVA task. DVA scores correlated only modestly with subjective estimates of fatigue intensity and flying performance, and IP ratings of performance, but the cluster of correlations provided a consistent picture.

In recent years Initial Entry Rotary Wing Training (IERW) has had a relatively high attrition (washout) rate. While current figures show a reduction in the rate, losses still represent a large dollar investment in the student in training and in allocated but unused resources when the student washes out or resigns. In addition, setbacks, some of whom eventually wash out, add to training costs. A study of the causes of washouts and setbacks which identifies factors not currently incorporated in student selection and recruitment would provide the basis for improving student input. This improvement would increase throughput and reduce training cost per graduate. (Author)

Sound levels were measured in a neonatal intensive care nursery as well as during transport in ambulance, rotary wing, and fixed wing aircrafts. In the nursery, under usual conditions, the sound levels were between 58 and 70 dB; while in transit, they were invariably higher, particularly in rotary wing aircarft ( greater than 90 dB). The observations suggest that neonates in transit are exposed to potentially hazardous sound levels. Provision of means to attenuate the sound is desirable as a part of stabilization of infant during transport.

Subjective ratings of annoyance caused by helicopter noise relative to that caused by fixed-wing aircraft were obtained. Comparison of the subjective ratings with various physical predictors of annoyance indicated that the integrated A-weighted level (dBA) predicted as well as any of the predictors with the D2-weighted level and EPNL almost equivalent. The B-weighted level and C-weighted level did not predict as well. No correction factor for the impulsive character (blade slap) of the helicopter noise was required. No substantial penalty for helicopters compared to fixed-wing aircraft noise was required. (Author)

The activities associated with establishing a Center of Excellence in Rotary Wing Technology at Rensselaer Polytechnic Institute under a five year contract with the U.S. Army Research Office are reported here. These include measures taken to provide comprehensive and in-depth curricula at advanced levels in rotorcraft technology; attract and retain outstanding young people in these programs; perform basic research at the leading edge of technology in structures, structural dynamics, unsteady aerodynamics and aeroelasticity disciplines as applied to rotorcraft; developing useful new national research resources in these areas; and accomplishing technology transfer to the rotorcraft community beyond the Rensselaer campus. Descriptions, references and statistics are provided to allow assessment of the extent to which these goals have been realized. Keywords: Laminated plates, Composite materials, Helicopters, Rotorcraft, Aeronautical engineering education.

A literature review was conducted to examine helicopter external vision requirements and related visual display characteristics. Several articles are summarized in annotated bibliography format. A subsequent discussion section addresses the information contained in those articles as well as relevant information contained in other documents. Suggestions are made for future research. Keywords: Bibliographies; Rotary wing aircraft; External Vision; Field of view; Helmet-mounted display; Panel-mounted display; Resolution; Vision; Literature survey.

This report contains a description of the characteristics and test of two alternative inflight scoring procedures. These procedures were designed to meet the requirements of (1) minimal data collection, and (2) objective scores for Initial Entry Rotary Wing (IERW) student performance on Basic Instrument maneuvers. The procedures were criterion-referenced, employing different performance criteria, sampling techniques, and scoring algorithms. They were subjected to tests in the UH-1 simulator to assess the potential value of various characteristics within each procedure for meeting the requirements. Results of the tests provided general indications of those characteristics which best discriminated proficiency within and among students across training days. (Author)

This report contains the Executive Summary of the evaluation of minority (Black, Hispanic, Asian, American Indian) and Female performance in the Army's Initial Entry Rotary Wing flight training program. Each minority group was compared to a matched sample of majority students. The groups were matched on FAST score, GT score, educational level, age, rank, and source of entry. The performance of the two groups (each minority and its matched control group) was compared on the following criteria: Warrant Officer Candidate Military Development Course grades; Academic grades by phase of training; Flight performance grades by phase of training; Overall grade; Attrition experience during the Warrant Officer Development Course and; Attrition experience during the flight portion of training.

A study was conducted (1) to determine the feasibility of an unmanned, tethered, rotary-wing vehicle as an elevated platform for target detection sensors or other payloads and (2) to determine the best approach to implementing specified design and performance requirements. A review was made of current and past developments of tethered platforms, and a large number of rotary-wing lift concepts, rotor drive and long-endurance power concepts, and stabilization and control concepts were formulated for evaluation. Mathematical models were designed and a digital computer was used to generate quantitative data on air vehicle size, weight, horsepower, etc., for alternative systems. A turboshaft-driven synchropter, utilizing fuel pumped from the ground for long endurance, was recommended as the best overall approach for an unmanned tethered platform. The synchropter, with cyclic pitch controls, will provide a stable platform for mission sensors and can be operated, without attention from the ground, by a simple automatic flight control system.

Substantial progress has been made over the past two years in the technological status and production aspects of Stratified Charge Rotary Engines, a new propulsion technology for aircraft of the 1990’s. A 400 HP aircraft engine, designed in cooperation with Avco-Lycoming (during late 1986) is currently undergoing testing at John Deere’s Rotary Engine Division. Current status and design features are reported in this paper and related to overall research and technology enablement efforts toward several families of advanced liquid cooled, turbocharged and intercooled engines over a wide power range for commercial general aviation. Capabilities for high altitude, long endurance, military unmanned aircraft missions are examined. Application to fixed and rotary wing aircraft are planned.Copyright © 1988 by ASME

Under a five-year contract with the U.S. Army Research Office, a rotorcraft Center of Excellence was established in the Fall of 1982 at the University of Maryland. As one of the universities chosen for the program, Maryland had the responsibility to attract and involve a significant number of experienced faculty into the program; to develop and add to its graduate curriculum a number of specialized rotorcraft courses which cover the disciplines applicable to rotorcraft design; to attract the best and brightest students into the program and motivate them into rotorcraft as a career; to upgrade and develop experimental facilities which meet the specialized needs of rotorcraft research; to blend faculty, students and facilities into a research combination which concentrated on leading edge research areas; and finally, to disseminate widely the results of the research. The degree to which these responsibilities were met at the end of the contract period is summarized herein. Keywords: Helicopters, Rotorcraft, Aerospace, Education, Rotary wing aircraft, Rotor blades(Rotary wings).

Aircraft display technology has advanced to the state where the flight path display--an integrated format on which both the vertical and horizontal path are graphically represented--is feasible. This report researches efforts made to design flight paths for use in both fixed wing and rotary wing aircraft. Results from comparison evaluations of flight path and non-flight path displays are discussed and conclusions drawn with respect to desirable display symbology. An hypothetical flight path display designed as a result of the findings in the referenced studies is proposed for future testing and evaluation.

A workshop was conducted, dealing with the fundamentals of composite constituent materials and laminates as they influence applications to advanced rotorcraft developments. Included in the purview of the workshop were the theory, numerical analysis, fabrication, testing, and inspection of thermoset & thermoplastic resin matrix and metal matrix composites as they may have advantage for rotors, fixed airframe, drive system, controls, and engine 'cold section' components. Rotorcraft composite materials & structures; Rotary wing aircraft.

The field of helicopter rotor aerodynamics is basically the study of unsteady aerodynamic flows in a rotating and translating coordinate system. Current trends in this field are briefly reviewed by examining recent advances in lifting-surface theory, wake modeling, panel methods, and finite-difference models. Examples are used to illustrate selected current methods and some indications of promising future directions are highlighted.

The incidence of pilot disorientation in fixed and rotary wing aircraft has been previously investigated, but special orientation problems of naval helicopter pilots engaged in operations at sea and landing on moving platforms have not been previously reported. A questionnaire concerning disorientation was answered anonymously and individually by 104 active naval helicopter pilots. Fifty-six percent indicated one or more episodes of severe disorientation and 8.5 percent indicated having experienced severe disorientation five or more times while piloting helicopters. A number of factors conducive to disorientation were identified. Some precipitating factors appear to be specific to operations over water or over a moving deck, although some of these may well have their counterparts in special operations over land. Other factors are common to land- and sea-based operations and some are common to fixed-wing as well as rotary-wing aircraft. A number of potential countermeasures for various precipitating factors are discussed. (Author)

A study program was conducted for the U.S. Army AMRDL to define ice protection requirements for advanced rotary-wing aircraft. The study included investigations into the hazards of flying through ice, probability of icing, vehicle ice accretion rates, current ice protection system designs, operational limitations of current helicopters, and advanced deicing concepts.

Helicopter development, although relatively more recent than conventional aircraft development, very rapidly underlined the primary importance of fatigue problems, as the rotors are an important source of vibration which is transmitted not only to the components of the rotors but also to the aircraft structure itself. It follows that the static dimensional requirements usually taken into consideration for any type of construction are insufficient in the rotary wing aircraft field and that it was necessary to develop test and stress analysis methods capable of ensuring the safety of this type of aircraft. The problem of fuselage fatigue—little different from that of conventional aircraft structures, for which abundant technical data exist—will not be treated here, in order to concentrate on the study of mechanical parts subjected to fatigue occurring at very high numbers of cycles. This paper deals with the methods used to overcome fatigue problems: Laboratory tests, measurement of flight stresses, determination of fatigue life of critical parts and quality control in production. It also covers certain stress analysis methods used and compares them with practical experience gained.

Procedures were developed to enable training personnel systematically and objectively to determine the potential utility of training devices for teaching how to perform missions in operational equipment. The procedures allow comparison of operational task stimulus and response elements with corresponding elements in synthetic training equipment. On the basis of such information, training programs consistent with the psychological principles underlying transfer of training may be developed. The procedures, termed task commonality analysis, were developed in connection with an Army rotary wing instrument flight training program.

Fail-safe structural design has been the preferred method and an acceptable procedure (Ref. 1) for designing fixed wing commercial transports for some time. This has not been true in the rotary wing field. The reasons for this and the adherence to safe-life requirements with associated design and verification procedures will be discussed. The problems associated with rotary wing safe-life procedures are presented. Changes are required to existing regulations and procedures which have motivated the safe-life approach so that the structural designer is not constrained to thinking in terms of a service life or a fatigue life as he now is. Practical considerations involved in the design and test verification of both safe-life and fail-safe structures are described.

This report covers the design and structural requirements of a thinwall lightweight field and mobile shelter capable of transport by truck, cargo, 3/4 ton, 4 x 4, M-37, and by fixed or rotary wing aircraft.

Direct person-to-person speech communication is sometimes required in rotary-wing aircraft where high levels of noise make the use of hearing protective devices desirable. The question arises as to what effect earplugs would have on the intelligibility of speech in rotary-wing aircraft. Intelligibility test data obtained in flight as well as in a simulated flight situation indicate that the use of earplugs in rotary-wing aircraft will improve the reception of direct person-to-person speech communication. Moreover, their use will afford protection against the deafening, fatigue, and annoyance effects of the hazardous noise present in rotary-wing aircraft. (Author)

Noise levels measured within the cockpits of 126 fixed- and rotary- wing aircraft were tabulated and arranged into stereotyped sets of exposure envelopes. The noise data from which these envelopes were derived represent 'typical' unprotected exposures encountered within 12 different categories of fixed- and rotary-wing aircraft during conditions of 'normal cruise.' Extreme or unique noise exposures were deleted from the study.

Aerodynamic and structural aspects of rotary atmospheric entry aids, including high temperature rotor material selection, rotor blade design and drag and lift modulation problems

A study of problems related to vibration and dynamic loads in helicopter propulsion systems was made. It was found that engine vibration, shaft whirling, and dynamic instabilities seriously limit helicopter performance and reliability. It is recommended that studies be made to justify an intelligent standardization of engine vibration limit specifications for helicopters, that impedance-mobility methods be developed for optimizing engine/ airframe interface design, that research and development of helicopter power transmission shafts and couplings be carried out to solve whirling problems, and that new methods and hardware be developed to eliminate torsional instabilities in helicopter drive systems with automatic fuel control.

Results are presented of an effort to develop improved design, test, and acceptance criteria for all rotary wing aircraft transparent structures. Some of the criteria relate to all-weather capability, optical and structural quality, abrasion resistance, safety, and bird and ballistic resistance. The transparent structures, specifically windshields, made of the present glass laminate and 1/4 inch stretched acrylic do not have a strike resistance beyond 100 mph, when exposed to bird impact tests, whereas the use of polycarbonate achieves a resistance at a speed of at least 211 mph.

The purpose of the Rotary Wing Branch of the Flight Test Division is to investigate and determine flight characteristics of helicopters procured by the Navy and to evaluate such equipment and developments which might enhance the value of the helicopters for Naval use. Specifically, the Branch determines whether or not the Navy is getting what it has paid for by checking contract performance guarantees and flight handling characteristics, conducting Navy Preliminary Evaluations to evaluate the Naval aircraft in the early stages of development in order that major deficiencies can be corrected, witnessing contractor's demonstrations to check design criteria, etc.

As part of an analysis of the value of synthetic training at the U.S. Army Aviation School, costs associated with the conduct of flight and synthetic training in the instrument phase of the Army's Officer/Warrant Officer Rotary Wing Aviator Course were identified and computed separately for each type of training. It was found that, for the factors considered, the hourly cost of flight training at the time of this study (September 1966) was approximately six times as great as the corresponding cost of synthetic flight training. The report describes the sources for and the treatment of data, and the major assumptions made in allocating the costs.

Ground effect on rotary aircraft has been studied for many decades. Although a large body of research results is now available for conventional helicopters, this topic is just beginning to receive attention in the unmanned aerial vehicles community, particularly for small size UAVs. The objective of this papers is to assess the applicability on small rotary wing UAV of a widely-used ground effect model, developed in the middle of the last century by Cheeseman and Bennett, for predicting the ground effect on helicopters. Furthermore, other aerodynamics effects associated with flying close to surfaces or obstacles. Test stand has been designed to experiment with different configuration as walls, ceiling or combinations of them have been studied. A test stand has been designed for testing the aerodynamic effects with different configurations, and experiments with ground, ceiling and wall surfaces have been done. Also, experiments to assess the combined effect of ground+wall and the ground effect for a tandem rotor have been carried out. The experimental procedures and the implications on the obtained results is also included in the paper.

As one of the subsystems of advanced flight simulators, Control Loading System (CLS) enhances the realism of simulation by artificially producing the control forces that occur during the actual flight. In this study, an engineering flight simulator is realized for the purpose of CLS development. The simulator integrates the CLS with a flight dynamics model and a visual system to enable validation with piloted simulations. A linkage type CLS is designed with high torque electric motors, while paying special attention to reconfigurability. Data measured from the actual flight controls is transformed to be input to the CLS by using the proposed systematic procedure. Performance of the designed CLS is investigated, according to the requirements of the international certification standards, by comparing the measured flight control behavior of the simulator with that of the actual aircraft., Gelişmiş uçuş simülatörlerinin alt sistemlerinden biri olan Kumanda Yükleme Sistemi (KYS), uçuş sırasında oluşan kumanda kuvvetlerini simülasyon ortamında yapay olarak üreterek simülasyonun gerçekçiliğini arttırır. Bu çalışmada KYS geliştirmek amacıyla bir mühendislik uçuş simülatörü hayata geçirilmiş, uçuş dinamiği modeli, görüntüleme sistemi ve KYS entegre edilerek pilotlu doğrulama testlerinin de yapılabilmesine imkan sağlanmıştır. KYS’nin donanımsal tasarımında kolay uyarlanabilme özelliği ön planda tutularak, yüksek torklu elektrik motorlarıyla tahrik edilen eklemli yapıda bir tasarıma gidilmiştir. Simüle edilecek hava aracının kumandalarından ölçülen verilerin girdi olarak kullanılabilmesi için bir prosedür önerilmiştir. Geliştirilen KYS’nin başarımı, simulator kumandalarından ölçülen davranışın hava aracından ölçülenlerle karşılaştırılmasıyla, uluslararası standart sertifikasyon dokümanlarındaki isterler doğrultusunda incelenmiştir.

It can be argued that rotorcraft represent some of the most complex of flight vehicles, due to the strong aeroelastic interactions between highly flexible rotor blades and unsteady aerodynamic forces. The challenge of designing a helicopter with low vibration levels, enhanced safety and low acoustic signature remains significant. Moreover, predictive capability of helicopter aeroelastic analysis lags behind that of fixed wing aircraft, leading to higher levels of experiments and testing. Helicopters therefore remain costly to manufacture and maintain compared to fixed wing aircraft. However, because of their unique ability to fly vertically and slowly, helicopters have niche applications in search and rescue operations, reconnaissance, civil transport and military. Helicopters are useful for short distance travel in densely populated Asian countries, as has been already shown in Japan, and is increasingly happening in India and China. However, the use of helicopters is limited due to high costs which could be alleviated by spreading the science and technology of rotary wing flight internationally. For example, automobile technology has spread worldwide and has resulted in lower costs with increased innovation. Interestingly, substantial rotorcraft activity has occurred in India in the last two decades such as the development of indigenous helicopters and increasing contribution to basic research as measured by journal publications. This paper will cover the research activities on helicopters in India, with emphasis on the last 10 years. In this paper, the research will be divided into work done at three key institutions: (1) Indian Institute of Science, Bangalore, (2) Indian Institute of Technologies and (3) Hindustan Aeronautics Limited, Bangalore.

2016 IEEE International Conference on Robotics and Automation (ICRA), ISBN:978-1-4673-8026-3

Recently there has been an explosive growth in the use of helicopters and fixed wing aircraft for the transportation of patients who are ill and injured. Although using such methods of transport may result in faster access to health care centres, their ultimate role for the civilian population is unclear. Unfortunately, there are many problems associated with aeromedical transport, particularly with rotary wing aircraft, which have shown an alarming tendency to crash. The use of lighter than air vehicles (blimps, hot air balloons) might offer most of the advantages of conventional aieromedical transport, with an appreciable improvement in safety.