Examining the stability derivatives of a compound helicopter

Some helicopter manufacturers are exploring the compound helicopter design as it could potentially satisfy the new emerging requirements placed on the next generation of rotorcraft. It is well understood that the main benefit of the compound helicopter is its ability to reach speeds that significantly surpass the conventional helicopter. However, it is possible that the introduction of compounding may lead to a vehicle with significantly different flight characteristics when compared to a conventional helicopter. One method to examine the flight dynamics of an aircraft is to create a linearised mathematical model of the aircraft and to investigate the stability derivatives of the vehicle. The aim of this paper is to examine the stability derivatives of a compound helicopter through a comparison with a conventional helicopter. By taking this approach, some stability, handling qualities and design issues associated with the compound helicopter can be identified. The paper features a conventional helicopter and a compound helicopter. The conventional helicopter is a standard design, featuring a main rotor and a tail-rotor. The compound helicopter configuration features both lift and thrust compounding. The wing offloads the main rotor at high speeds, whereas two propellers provide additional propulsive thrust as well as yaw control. The results highlight that the bare airframe compound helicopter would require a larger tailplane surface to ensure acceptable longitudinal handling qualities in forward flight. In addition, without increasing the size of the bare airframe compound helicopter’s vertical fin, the Dutch roll mode satisfies the ADS-33 level 1 handling qualities category for the majority of the flight envelope

Maneuverability assessment of a compound helicopter configuration

The compound helicopter design could potentially satisfy the new emerging requirements placed on the next generation of rotorcraft. The main benefit of the compound helicopter is its ability to reach speeds that significantly surpass those of the conventional helicopter. However, it is possible that the compound helicopter design can provide additional benefits in terms of maneuverability. The paper features a conventional helicopter and a compound helicopter. The conventional helicopter features a standard helicopter design with a main rotor providing the propulsive and lifting forces, while a tail rotor, mounted at the rear of the aircraft, provides the yaw control. The compound helicopter configuration features both lift and thrust compounding. The wing offloads the main rotor at high speeds, and two propellers provide additional axial thrust as well as yaw control. This study investigates the maneuverability of these two helicopter configurations using inverse simulation. The results predict that a compound helicopter configuration is capable of attaining greater load factors than its conventional counterpart, when flying a pullup–pushover maneuver. In terms of the accel–decel maneuver, the compound helicopter configuration is capable of completing the maneuver in a shorter time than the conventional helicopter, but at the expense of greater installed engine power. The addition of thrust compounding to the compound helicopter design reduces the pitch attitude required throughout the acceleration stage of the maneuver

Manoeuvrability assessment of a hybrid compound helicopter configuration

The compound helicopter design could potentially satisfy the new emerging requirements placed on the next generation of rotorcraft. The main benefit of the compound helicopter is its ability to reach speeds that significantly surpass the conventional helicopter. However, it is possible that the compound helicopter design can provide additional benefits in terms of manoeuvrability. The paper features a conventional helicopter and a hybrid compound helicopter. The conventional helicopter features a standard helicopter design with a main rotor providing the propulsive and lifting forces, whereas a tail rotor, mounted at the rear of the aircraft provides the yaw control. The compound helicopter configuration, known as the hybrid compound helicopter, features both wing and thrust compounding. The wing offloads the main rotor at high speeds whereas two propellers provide additional axial thrust as well as yaw control. This study investigates the manoeuvrability of these two helicopter configurations using inverse simulation. The results predict that a hybrid compound helicopter configuration is capable of attaining greater load factors than its conventional counterpart, when flying a Pullup-Pushover manoeuvre. In terms of the Accel-Decel man oeuvre, the two helicopter configurations are capable of completing the manoeuvre in comparable time-scales. However, the addition of thrust compounding to the compound helicopter design reduces the pitch attitude required throughout the acceleration stage of the manoeuvre

Investigation of a Compound Helicopter Flying the Depart and Abort Mission Task Element

The next generation of rotorcraft will have to satisfy the appropriate handling qualities requirements before entering service. Many of these vehicles will operate at significantly greater speeds than the conventional helicopter and will therefore have different capabilities than current helicopters. Due to the different capabilities of the compound helicopter, it is possible that new Mission Task Elements (MTEs) need to be developed to assess the handling qualities of this type of helicopter. It is also possible that existing MTEs may be suitable without modification. Overall, it seems necessary to review the US Army’s current handling qualities specification, ADS-33, and determine the suitability of the current MTEs for compound vehicles. The broad aim of the paper is to assess the performance of compound helicopter during manoeuvring flight. More specifically, a simulation study of a compound helicopter flying the Depart and Abort ADS-33 Mission Task Element. There are two objectives: firstly the capabilities of the compound vehicle is compared with those of a conventional helicopter, and secondly, the suitability of the current Depart and Abort MTE, for compound vehicles, is assessed. The results of the research study highlight the capability of compound helicopters in low speed acceleration manoeuvres. These results can be used to redefine low speed acceleration manoeuvres in the new update to the ADS-33 specification. The results also indicate some information about the potential design issues with the compound helicopter

An economic analysis of the effects of feeder calf characteristics on important feedlot and carcass characteristics

The identification of relationships between feeder calf characteristics and important feedlot and carcass characteristics would improve the efficiency of the marketing link between commercial cow-calf producers and stocker and feedlot operators. The feeder calf characteristics examined in this study were initial weight and fat thickness, breed, and subjective frame size and muscle thickness. A bioeconomic simulation model was utilized to examine the individual effects of those observable feeder calf characteristics on the length of the feeding process, final live weight and fat thickness, carcass yield grade and marbling score, feed cost, profitability of the feeding process, and derived value of the feeder animal. The bioeconomic simulation model was used to represent 78A animals individually during the feedlot finishing process. The set of mathematical equations included in the model described the individual purchase, feeding, growth and selling process for the Angus, Hereford, Charolais-cross, and Angus-Hereford-cross animals in the study. Regression analysis was utilized to generate coefficients for growth and development of the animal in terms of weight, fat thickness, feed consumption, yield and quality grades, and salable carcass weight. The analysis included separate results for maximizing net revenue to the animal and to the feedlot facility for differing cost-price scenarios. Net returns to the animal and to the feedlot facility were calculated every five days (from 100 to 3A0) on feed and the optimum selling point was determined. An individual animal\u27s important feedlot and carcass characteristics utilized in this study correspond to the animal\u27s optimum selling point. In order to examine the relationships between individual feeder calf and important feedlot and carcass characteristics, each feedlot and carcass characteristic was regressed on the set of feeder calf characteristics while accounting for the animal\u27s diet. Separate regressions were analyzed when maximizing net returns to the animal and to the feedlot facility for each cost-price condition. The general findings of this study indicated that initial weight was negatively related to days on feed, marbling score, and feed cost and positively related to final live weight. Initial fat thickness was negatively related to days on feed, final live weight, net returns from feeding, feed cost, and derived feeder animal value while initial fat thickness was positively related to final fat thickness and yield grade. As for breed effects, the general findings indicated that Angus was negatively related to final live weight, net returns from feeding, and derived feeder value. Charolais-cross was negatively related to final fat thickness and yield grade and positively related to days on feed. The results indicated that Angus-Hereford-cross was positively related to net returns from feeding and derived feeder value. Subjective frame size was negatively related to net returns from feeding and positively related to days on feed, final live weight, feed cost, and derived feeder value. Also, the results indicated that subjective muscle thickness was negatively related to net returns from the feeding process

Digital Surrealism: Visualizing Walt Disney Animation Studios

There are a number of fruitful digital humanities approaches to cinema and media studies, but most of them only pursue traditional forms of scholarship by extracting a single variable from the audiovisual text that is already legible to scholars. As an alternative, cinema and media studies should pursue a mostly-ignored digital surrealism that uses computer-based methods to transform film texts in radical ways not previously possible. This article describes one such method using the z-projection function of the scientific image analysis software ImageJ to sum film frames in order to create new composite images. Working with the fifty-five feature-length films from Walt Disney Animation Studios, I describe how this method allows for a unique understanding of a film corpus not otherwise available to cinema and media studies scholars

The Ascription of Mental Illness: Inside Societal Reaction

Mental illness is examined as a classification of deviance and as a social process. The labeling perspective provides preliminary concepts and problems for research. The goal of research is the examination of the process of ascribing the label mental illness to individuals and their behavior by significant others prior to their contact with official and organizational agents of treatment and control. An exploratory interview research design thin the Fan district of Richmond, Virginia was executed. Fifty residents were interviewed. Preliminary data suggest that the primarily white, female, well-educated, professional sample was unwilling to stereotype the mentally ill, and revealed typifications of mental illness which differed significantly from those in previous research. Mental illness was ascribed primarily to individuals who were known well and who were observed as acting abnormally for their personal biographical situation and unable to function over a continued period of time

On Variety: The Avant-Garde between Pornography and Narrative

This article analyzes Bette Gordon’s first feature film Variety (1983), reassessing how experimental novelist Kathy Acker’s contributions to the screenplay awkwardly positioned the film within contemporary cultural debates over pornography and the future of avant-garde filmmaking. While centered on an erotic thriller narrative concerning a woman’s entrée into the scuzzy world of New York City porno theaters, Gordon and Acker also take up in the film a series of three related representational problems for the 1980s: feminist approaches to pornography, narrative in an avant-garde tradition, and the role of speech and writing in film