Implementation of electrical rim driven fan technology to small unmanned aircraft

Aircraft propeller performance is significantly reduced when tip speeds become sonic causing the maximum attainable airspeed of the vehicle to be limited by the propeller diameter. There are also performance losses attributable to miniature Unmanned Aerial Vehicles as the propeller to hub diameter ratio is reduced. The research conducted indicated that re-arranging a Brushless DC Motor and propeller configuration, so that it becomes rim-driven rather than hub-driven, would provide some performance and operational advantages and could inspire the design of novel high-speed Unmanned Aerial Vehicle configurations powered by hub-less, multi-stage contra-rotating electrical fan-compressors. This investigation involved analysis, design and testing a prototype, low cost, concept demonstrator Rim Driven Fan device in order to assess the feasibility of applying this technology to Small Unmanned Aircraft. It was demonstrated that Rim Driven Fan technology could be successfully applied to lift and propel a Small Unmanned Aircraft. However, the performance testing of the Rim Driven Fan demonstrated that in its prototype configuration it would not be as efficient as a conventional Brushless DC motor and propeller

Curriculum development of undergraduate and post graduate courses on small unmanned aircraft

This paper describes the development of an undergraduate and a post graduate course on Small Unmanned Aircraft (SUA). Few emerging technologies provide the potential for such a diverse application of knowledge as SUA which are more commonly referred to as “Drones”. They are being used for civil purposes in a growth business sector predicted to be worth billions of pounds over the next 10 years. They are also revolutionising everything from agriculture to film-making and are increasingly being used to monitor, research and conduct data gathering missions in surveying, mining, forestry, ecology, archaeology virtual reality and computer gaming. The purpose of this paper is to present the ideas and the researched findings which informed the rationale used for the curriculum development of the first Bachelor of Engineering Degree in Drone Technology to be offered in the UK, and also that of an accompanying Master of Science Degree in Unmanned Aircraft System Technology

A review of electrical motor topologies for aircraft propulsion

This paper provides a review of the state-of-the art in aircraft electrical propulsion (AEP). Initially, the limitations of on-board energy storage devices are highlighted and contextualised. The definitions of useful measures for determining the suitability of motor design, namely specific power and motor torque per unit rotor volume (TRW), are discussed and relevant examples are provided. The classifications of motors used for terrestrial vehicle applications are reviewed and their limitations highlighted regarding their suitability to AEP applications. A discussion on motor configurations for aerospace applications is provided which includes: synchronous motor stator winding configurations; axial flux motor configurations and the causes of energy losses. Additionally, the topologies and performance characteristics of existing aerospace motor technologies are examined. It was concluded that electrical motors provide an ideal means for achieving aircraft propulsion and that higher motor speeds are likely to be required for future commercial aircraft motor designs

Review of electrically powered propulsion for aircraft

This paper presents a review of the state-of-the-art in aircraft electrical propulsion technology. A comparison is provided of differing propulsion mechanisms such as propellers, open fans, ducted fans, multi-stage rim driven fans and distributed thrust designs and their suitability to particular flight profiles and mission applications. Electrical motor architectures are also reviewed with particular attention being given to synchronous machines, such as Brushless Direct Current (BLDC) and Switched Reluctance Motor (SRM) technologies, and the recent advances that have been made in solid-state switching and High Temperature Superconducting (HTS) material applications. Present day electrical power generation, storage and control technologies are also reviewed including hybrid and fuel cell technologies and regeneration techniques. Electrical storage capabilities with regard to specific power and energy characteristics are discussed and the extent to which existing system technology can be integrated onto a Hybrid-electric and an All Electric Aircraft (AEA) is also investigated. Finally, a conclusion is provided highlighting the current technological challenges facing the development of commercial aircraft in terms of performance, airframe configuration and legislative and operational infrastructural requirements

Design of a Portable Drone for Educational Purposes

This paper discusses the design of a portable drone to be used by students for practical investigations of drone operating principles. The drone design is based on a Y6 frame module concept and takes into account the affordability and combinability of components which are widely available via the hobbyist drone manufacturing market. It is a foldable device and is protected against water ingress according standard DIN EN 60529 (IP01). The drone generates high thrust for a Maximum Take-off Mass (MTOM) of 5 kg and the propeller design has been investigated and analysed in detail to determine the optimum location required to provide maximum thrust

Analysis of the effects on the pitching, rolling and yawing rate of a v-tail configured quadcopter

Many different projects have been focused on multirotor aircraft, especially on quadcopters, but there are only a few papers relating to the dynamic effects on quadcopters with tilted motors. In this paper, a quadcopter has been modelled to allow flight simulation under differing motor tilt angle configurations. The simulation has also been validated by building a quadcopter of known physical attributes and with on-board instrumentation and telemetry to log its attitude and motor control inputs (PWM signals). The conversion from a PWM signal to the rpm was achieved by determining the relationship between the PWM signal and the thrust generated. Both of these parameters being recorded on a test bench. Thrust is calculated for each motor individually, since the angled motors generate different advance ratios and hence different thrust coefficients. The main focus of this research was on the effect of the different coefficients and the thrust components acting in the x-y plane of the quadcopter body frame

Review of unmanned aircraft system technologies to enable beyond visual line of sight (BVLOS) operations

The need to develop and deploy Beyond Visual Line of Sight (BVLOS) aerial vehicles has intensified over the last decade. As the demand for Unmanned Aircraft Systems (UAS) has increased, so too has the regulations that surrounds the industry. Strict regulations are currently in place but differ from country to country. Due to these regulations BVLOS innovators have been posed the task of exploring the means of operating flight missions with the UAV out of the sight of the pilot. Autonomous flight capability is not only fundamental to BVLOS operations for UAS but also likely to have a significant impact on the future development of passenger carrying autonomous aircraft. This review explores the technologies that have been developed to date that enable BVLOS applications. BVLOS flight operations have the potential to open a huge area of commercial opportunity however, there remain many concerns about the current capabilities of UAS to detect and avoid manned and unmanned airborne hazards that may pose a significant safety risk

Ultrasonic sensor for UAV flight navigation

Ultrasonic transducers were utilized for the design and development of an alternative method for flight instrumentation measurement of the velocity of unmanned air vehicles (UAVs). Current methods have been deemed to have significant shortcomings, such as the need for GPS thus leading to indoor UAV operations being incapable of velocity sensing. The proposed concept is developed from the utilization of ultrasonic transit-time flowmeters. A test bench has been produced to measure the accuracy and confirm the validity of the concept. Two key design variables were determined - the optimal transducer mounting configuration and the optimal angle of incidence for the transducer mountings. The mounting configurations were analyzed from common transit-time flowmeter sensor configurations and were tested using both CFD and acoustic simulations. The findings are presented and correlated based on these simulations and it was determined that a V-method configuration was the optimal choice. The correct angle of incidence was determined by an experimental methodology. The time-of-flight outputted from the transducers was compared to the calculated ideal value, and the findings revealed that an angle of 30° was the most accurate for the reflection of the emitted wave. The experimentation was conducted with a specially designed test bench and associated electronic hardware located in a wind tunnel. The test results have provided conclusive evidence that the overall design can produce accurate results comparable with current instrumentation sensors

Performance comparison between copper and aluminium windings in a rim driven fan for a small unmanned aircraft application

Rim Driven Fans (RDFs) are receiving increased attention amongst zero-emission aerospace technologists as they offer the potential for high Fan Pressure Ratios (FPR) to be efficiently generated and fan flow to be maximised compared with conventional (hub driven) electrical axial-flow fans. In other words; RDFs can provide higher thrust performance and exhaust air velocities than hub driven devices of the same intake area and also offer significant aerodynamic drag reductions. As such they are a feasible propulsion contender for fixed-wing, distributed-thrust, electrical aircraft designs. Thrust-to-weight ratio is a critical design parameter when considering aircraft propulsion devices and so design mass must be optimised accordingly. This paper presents an electromagnetic comparison of copper versus aluminium, slot-less, brushless DC motor (BLDC), stator-wiring architectures. The results of this study identify the performance benefits and limitations of these differing stator wiring materials in the context of a single rotor-stage RDF intended for the propulsion of a small unmanned aircraft

A Novel Extracellular Metallopeptidase Domain Shared by Animal Host-Associated Mutualistic and Pathogenic Microbes

The mucosal microbiota is recognised as an important factor for our health, with many disease states linked to imbalances in the normal community structure. Hence, there is considerable interest in identifying the molecular basis of human-microbe interactions. In this work we investigated the capacity of microbes to thrive on mucosal surfaces, either as mutualists, commensals or pathogens, using comparative genomics to identify co-occurring molecular traits. We identified a novel domain we named M60-like/PF13402 (new Pfam entry PF13402), which was detected mainly among proteins from animal host mucosa-associated prokaryotic and eukaryotic microbes ranging from mutualists to pathogens. Lateral gene transfers between distantly related microbes explained their shared M60-like/PF13402 domain. The novel domain is characterised by a zinc-metallopeptidase-like motif and is distantly related to known viral enhancin zinc-metallopeptidases. Signal peptides and/or cell surface anchoring features were detected in most microbial M60-like/PF13402 domain-containing proteins, indicating that these proteins target an extracellular substrate. A significant subset of these putative peptidases was further characterised by the presence of associated domains belonging to carbohydrate-binding module family 5/12, 32 and 51 and other glycan-binding domains, suggesting that these novel proteases are targeted to complex glycoproteins such as mucins. An in vitro mucinase assay demonstrated degradation of mammalian mucins by a recombinant form of an M60-like/PF13402-containing protein from the gut mutualist Bacteroides thetaiotaomicron. This study reveals that M60-like domains are peptidases targeting host glycoproteins. These peptidases likely play an important role in successful colonisation of both vertebrate mucosal surfaces and the invertebrate digestive tract by both mutualistic and pathogenic microbes. Moreover, 141 entries across various peptidase families described in the MEROPS database were also identified with carbohydrate-binding modules defining a new functional context for these glycan-binding domains and providing opportunities to engineer proteases targeting specific glycoproteins for both biomedical and industrial applications