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

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

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

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 Investigation of the Perception of Professional Development among Mississippi\u27s Secondary Welding Teachers

This research study originated as a result of a paucity of information available regarding how secondary welding teachers in Mississippi perceive the value of professional development they have received within the previous two years. The purpose of this study was to examine the perceptions of Mississippi’s secondary welding teachers regarding how professional development had affected their teaching methods and collaboration with peers. Also, this study sought to determine whether the teachers had positive motivation in attending professional development activities, and how motivated they were to pursue their own professional development, other than school-mandated activities. Finally, the study examined the barriers teachers perceived to hinder them from pursuing their own professional development. The findings in this study revealed that Mississippi’s secondary welding teachers had a positive perception regarding how current professional development had changed their teaching methodology, student expectation, content comprehension, and confidence in teaching. Furthermore, respondents indicated that they had experienced enhanced collaboration with other welding teachers within the state as a result of professional development sessions; however, data revealed that collaboration between their academic counterparts was nearly nonexistent. Financial incentives and improving their teaching skill were found to be positive motivators for teachers. Personal costs, distance traveled to professional development sessions, and perceived value of professional development were determined to be barriers to attending professional development opportunities. It was recommended that future studies should include determining if welding teachers with welding certifications outperform teachers who do not have welding certifications, determine the consistency of laboratory equipment among school districts, whether the laboratory equipment in the local schools match those found in the actual employment environment, determine whether the teachers have the most up-to-date skills needed to match those skills found in industrial employment and investigate the perception of local businesses and industries about the quality of the student they have hired who graduated from Mississippi secondary welding programs. Lastly, it is recommended that administrators consider including academic teachers, career and technical teachers, and industry representatives in professional development activities to increase collaboration between stakeholders

Supervision in the Clinic Setting: what we Really Want Students to Learn

This paper focuses on certain key elements of student supervision in Community Legal Services at Western University in London, Canada. Our clinic offers a very broad range of legal services, ranging from criminal law to wills, and consumer law to housing, with 125-150 students taking part in 800-1,000 files per year.The first part of this paper will examine compliance with the supervision requirements of the profession’s governing body. Clinic supervision in a clinic must start with compliance with the regulator. The supervision requirements of the Law Society of Ontario are set out to demonstrate the standards Community Legal Services must meet.This paper will then discuss the classroom component consisting of lectures and simulation exercises where we deal with professional identity, ethical issues, sensitization to the lives of our clients, awareness of the importance of access to justice, and the capacity of legal processes.I will discuss our online materials for the classroom, including our Caseworker Manual which provides guidance in substantive law, court/tribunal rules, and clinic policies and procedures

A new North American noctuid of the genus Anomogyna (Insecta, Lepitdoptera)

A comparative study of the North American species formerly referred to Anomogyna sincera H.-S. and of essentially typical sincera from Sweden has revealed a number of dissimilarities…

A revision of the moths of the subfamily Geometrinae of America North of Mexico (Insecta, Lepidoptera)

A new classification of the Geometrinae of the United States and Canada is presented, based largely on original investigations of male and female genitalia and larval characters….https://elischolar.library.yale.edu/peabody_museum_natural_history_bulletin/1028/thumbnail.jp