Take-off Weight Research Articles

A Multi-Criteria Solution Approach for UAV Engine Selection in Terms of Technical Specification

Unmanned Aerial Vehicles are electronic systems that are used extensively in every field today and that develop and change very quickly with technology. UAVs are used extensively in many areas, especially in logistics processes, search and rescue activities, military operations, fight to forest fires, photography, monitoring and inspection of agricultural processes. Furthermore, considering their hobby use, it is understood that UAVs have a large commercial market and a high economic value. UAV systems contain many electronic and mechanical systems and many performance criteria can be found for UAV systems. The main ones of these performances are stabilization and engine power. The most important system affecting these performance criteria is the engine. In this study, engine alternatives available in the market for UAVs with take-off weights of 750 to 800 grams were evaluated in terms of mechanical and physical criteria of engine systems, and as a result, the ideal engine model was determined by Analytical Hierarchy method for maximum stabilization and velocity purposes. The article is the first in the literature in terms of the problem obtained and the application of the AHP method to this problem. Thanks to the study, it is aimed to create a Decision Support System for both UAV manufacturers and UAV users so that they can choose the ideal models in engine selection processes.

Approach to the Selection of Optimal Characteristics for Low Pressure Turbines Using a Single Gas Generator

An approach to the conceptual design of the low pressure turbine for the aviation turbopropeller engine has been shown. The engine is created on the basis of the single gas generator for the two-engine power plant intended for the average transport aircraft. This approach is of great interest because in addition to the efficiency factor, the mass of the designed turbine, the fuel mass and the number of aerodynamic profile were used as optimal design criteria. The designed turbine includes the two stages and the interturbine transition channel of a diffuser type arranged in front of them. Consideration was given to the four flow parts of the turbine that differ by the diameter and the height selected in the preset limitation range. The gas dynamic efficiency of the interturbine transition channel, gas dynamic efficiency of the after-turbine channel, the strength of the turbine blade of the last stage were taken as the limitations. The dependences of the efficiency factor, the turbine mass and the number of turbine blades on the turbine aerodynamic load factor were obtained for the four turbine options. The turbine efficiency factor was determined using our own method of one-dimensional gas-dynamic computation. The fuel flow rate was determined using the mathematical engine model. The turbine mass was determined using the parametric method as a function of the aerodynamic load factor and the turbine flow rate factor. The number of aerodynamic profiles was defined using the Zweifel parameter. It was shown that the use of heavy loaded and less loaded low pressure turbines can reduce the take-off weight of the aircraft in spite of an increased fuel flow rate.

Microdrones in field-based structural geology: a photogrammetry and fracture quantification case study from the North Mountain Basalt, Nova Scotia, Canada

Drone use in geoscience research and teaching is becoming widespread, with diverse applications documented. Many studies favour consumer-level drones, however, recent developments in so-called “microdrones” (takeoff weight < 250 g) necessitate further investigation to determine possible benefits, limitations, and future developments. Microdrone deployment is often advantageous in numerous jurisdictions due to fewer regulations, lower cost, and simple transportation. In this study, we deployed a DJI Mini 2 microdrone to study the ca. 201 Ma North Mountain Basalt (NMB) exposed in coastal outcrops along the Bay of Fundy, Nova Scotia, Canada. We report benefits of the microdrone as a field aid with three related approaches: (1) general site location and characterisation, (2) drone-based photogrammetry using ArcGIS Drone2Map, and (3) quantitative fracture mapping using FracPaQ. Application of these methods showed that microdrone-acquired imagery from the NMB exposures provides a valuable resource for interpretation post-fieldwork. The microdrone-derived data show two near-perpendicular fracture sets in the NMB: ∼NNE–SSW and ∼ESE–WNW, with some variation along the coastline. Overall, we determined that microdrones offer field-based geoscientists a valuable tool due to quick deployment, a simple image capture process and relatively straightforward data processing, and thus predict that this approach to enhancing fieldwork will continue to advance.

Flying Cars and eVTOLs—Technology Advancements, Powertrain Architectures, and Design

Flying cars and electric vertical takeoff and landing (eVTOL) aircraft could become the future of personal transportation and taxis, which would significantly reduce greenhouse gas emissions. Presently, over 250 companies are developing flying cars and eVTOLs, and at least a few vehicles are expected to be commercialized soon. This article presents the current trends and technology of VTOL flight mechanisms and identifies the vehicles in each category to evaluate their advantages and limitations. Most of the flying cars that are being developed do not have VTOL capability because of the requirement for high power during takeoff/landing for a roadworthy vehicle. This article proposes the powertrain architectures for incorporating VTOL capability for flying cars based on dual power sources, such as fuel cells and batteries. Besides, possibilities of using a single propulsion system for both drive and flight modes are explored. General design guidelines are presented for the proposed powertrain architecture to estimate the maximum takeoff weight (MTOW), power/energy demands, and source capacities. Furthermore, the technologies of the powertrain components, such as electric motors and power converters, are also discussed in this article.

Identification of Urban Air Logistics Distribution Network Concepts

This study attempts to identify urban air logistics (UAL) operational concepts by synthesizing the urban freight transport (UFT) network configurations and urban air mobility (UAM) characteristics. UAL is gaining popularity as a quick and safe mode that has the potential to address several logistics challenges. This study has reviewed scientific papers identified using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) framework to understand the features of existing UFT distribution networks, unmanned aerial systems (UAS), and UAM. The cross analysis considered UFT features such as the parcel’s weight, delivery type (time sensitivity, customer-to-customer, business-to-consumer, or business-to-business), and UFT distribution network types and compared them against the features of UAS such as maximum take-off weight, range, and infrastructure requirements (drone ports). The analysis identified three types of UAL operational concepts: door-to-door direct (D2DD), hybrid, and multimodal. Lightweight deliveries can be operated using D2DD and hybrid through point-to-point (P-P) and extended P-P network concepts. The hybrid concept uses an intermediate drop-off location to deliver goods. Hub-and-spoke (H-S), extended H-S, and trunk line with collecting/distribution network designs can be used for heavyweight cargo operations. D2DD versus hybrid/multimodal concepts were compared based on six thematic clusters (societal implications, safety and security, ethics, environmental issues, public acceptance, and urban planning and infrastructure). This study identified that technological development and innovation could reduce social implications and ethical challenges. Furthermore, public willingness and economic feasibility will determine the success of the operational concepts. The identified UAL operational concepts, network designs, and challenges will help to conduct further research in this subject area.

Models of early stages of design of trunk-route passenger airplanes with taking families into account

There is a tight connection between the Pre-Design (development of requirements for the designed airplane) and Conceptual Design stages while creating a new aircraft. Taking this connection into account would result in the design of more optimal aircraft that would have the appropriate advantage during operation. Previously when the ability to take such interconnections into the account was lacking the designers were forced to allocate certain reserves in the project based on previous design experience. The advancement of design, modeling and manufacturing methods allowed transitioning from allocating these reserves as means for possible error compensation to their planning or management. In particular, such planned reserves should be allocated in wing and landing gear at the Conceptual Design stage for the creation of passenger airplane families. The values of these reserves should be substantiated based on the evaluation of future functioning of the whole created airplane family within the airline fleet. This requires solving a problem of Pre-Design and requirements creation. Thus, the reserves become new design variables. The values of these new variables should be optimized together with the values of the existing “traditional” variables during airplane design. A model, which takes management of the aforementioned reserves into the account during airplane design, was constructed. The presented model is intended for usage within the framework of the models, which solve the problem of creation of a passenger airplane fleet at Pre-Design stage with taking the presence of an airplane family within this fleet into the account as well as optimization of this passenger airplane family. The model calculation results were verified for the trunk-route passenger airplanes of all main types with taking the existence of the appropriate families into the account. During verification the wing of each considered passenger airplane was sized for the appropriate family version with the maximum take-off weight. After that this wing was “fixed” and processed as initial data for the family version, statistics on which was used for checking the model calculation results. The verification demonstrated good correlation between the model calculation results and the available statistics. It also showed that the presented model can be used for the design of individual trunk-route passenger airplanes and families of all main types (short-, medium- and long-range).

Modeling and Simulation of Flight Profile and Power Spectrum for Near-Space Solar-Powered UAV

Currently, several solar-powered unmanned aerial vehicles (UAVs) have achieved 24 h uninterrupted cruise. However, models that can cruise for weeks or even months without interruption are in the minority. The technological progress requires the improvement of subsystems and also depends on the accurate planning of flight profile and power spectrum in a long working cycle. Combined with the test data obtained during the development of a solar-powered UAV, this paper establishes systematic mathematical and physical models of aerodynamic, energy, and propulsion systems, which can reflect the change in performance parameters with flight conditions and the performance attenuation with time. Further, a track control strategy based on the principle of maximum energy utilization is proposed, and the energy balance model of each flight stage is established. On the basis of the strategy, the typical flight profile and power spectrum of a solar-powered UAV are analyzed. Finally, the input parameters are decomposed into task parameters (takeoff time window, flight season, flight latitude, takeoff weight) and performance parameters (lift–drag ratio, secondary battery density), and their effects on mission feasibility are studied respectively. The research methods and conclusions of this paper have reference significance for the mission and track planning of solar-powered UAVs.

Multidisciplinary Analysis and Optimization Method for Conceptually Designing of Electric Flying-Wing Unmanned Aerial Vehicles

Current unmanned aerial vehicles have been designed by applying the traditional approach to aircraft conceptual design which has drawbacks in terms of the individual analysis of each discipline involved in the conception of new aircraft, the reliance on the designer’s experience and intuition, and the inability of evaluating all possible design solutions. Multidisciplinary analysis and optimization focus on solving these problems, by synthesizing all the disciplines involved and accounting for their mutual interaction. This study presents a multidisciplinary analysis and optimization method for conceptually designing electrical flying-wing micro-unmanned aerial vehicles. The conceptual design task was formulated as a non-linear mathematical programming problem. The method considers the trimming of the UAV during each mission profile phase, consisting of the climb, cruise, and descent. We used two algorithms, one for design space exploration and another for optimization. Typical examples of solving conceptual design problems were considered in the work: the modernization of an existing UAV; the effect of the change of the payload and endurance change on the takeoff weight; and the influence of different static margins on aerodynamic characteristics. The advantages of using this design method are the remotion of additional internal cycles to solve the sizing equation at each optimization step, and the possibility of not only obtaining a unique optimal solution but also a vector of optimal solutions.

Conceptual Aircraft Empennage Design Based on Multidisciplinary Design Optimization Approach

Within a conventional aircraft design process, the horizontal tail and vertical tail are generally sized via volume coefficient methods. In this manuscript, an improved method for conceptual aircraft tail design based on multidisciplinary design optimization (MDO) approach with stability and control constraints has been developed. To develop this method, first, the tail design requirements have been derived from the regulations and the fundamental functionalities of tail plans. Then, the empennage design is formulated as an MDO problem. Eventually the design optimization of horizontal and vertical tail is combined with the design optimization of the aircraft wing. A test case is presented for concurrent wing and tail plane design, which resulted in more than 9% reduction in aircraft block fuel weight and more than 3% reduction in aircraft maximal takeoff weight, which indicates a great potential for fuel burn and carbon reductions with empennage design optimization at conceptual aircraft design phase.

Feasibility of Extremely Heavy Lift Hot Air Balloons and Airships

State of the art airships and aerostats (air vehicles) use hydrogen and helium as lifting gases. Hydrogen is extremely flammable, while helium is rare and expensive. In the present work, feasibility of air vehicles using hot air, hot nitrogen, and/or hot mixture as lifting gases is demonstrated. Thermal power requirements for air vehicles using hot lifting gases are calculated. 1) It is shown that for extremely heavy aerial vehicles, whose gross takeoff mass exceeding 3,000 tons, required thermal power is proportional to 1/3 Mvehicle where Mvehicle is an air vehicle mass. 2) For lighter aerial vehicles, whose gross takeoff mass is below 100 tons, required thermal power is proportional to 2/3 Mvehicle . Specific thermal power requirement is low for extremely heavy vehicles and high for light vehicles (For 1000 ton gross takeoff weight, specific thermal power requirements are from is 41 W/ kg to 52 W/kg). 3) Using hot nitrogen and/or nitrogenhydrogen mixture decreases thermal power requirements by 10% to 24%.

A Novel 3-D Printed Air-Cooled Fuel Cooler Heat Exchanger for Aviation Industry

Unmanned aerial vehicles are expected to complete their missions even in adverse weather conditions. Overheating in the engine area may occur, particularly at high speeds due to using the full engine throttle. Another design factor that affects endurance duration and maximum take-off weight is the weight of the unmanned aerial vehicle heat exchanger. In this paper, a new type of air-cooled fuel cooler heat exchanger is proposed to reduce the total weight of the heat exchanger by increasing cooling performance through the design flexibility offered by additive manufacturing. The printed circuit heat exchanger has a circular cross-section to prevent dead bends in the heat transfer surfaces and feed coolant air directly onto the fins and circulation pipes. Twisted fins and piping structure were adjusted so they could be produced without any support, generate turbulence, and reduce total weight. The fluid flow and heat transfer characteristics of novel and conventional heat exchangers were simulated in 3-D. The flow physics of both exchangers were studied to determine how the new design enhances heat transfer. Numerical results showed that the new heat exchanger has 55.6% more cooling capacity than the conventional one. The heat exchanger weight was decreased from 774g to 263g.

SytaB: A Class of Smooth-Transition Hybrid Terrestrial/Aerial Bicopters

This work details the design, modeling and control of SytaB, a vehicle capable of hybrid terrestrial/aerial mobility with smooth transition, where the structure embedding a bicopter is adopted for the first time. In contrast to previous hybrid terrestrial/aerial vehicles with a quadrotor embedded, SytaB not only requires less energy for the same takeoff weight, but also regulates its attitude less frequently to restrain the vibration of sensors. Three modes, the terrestrial/aerial/transitional modes, are considered <styled-content style="color:black" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">for the vehicle</styled-content> , and the dynamics modeling and controller design of each mode are <styled-content style="color:black" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">carried out</styled-content> . The transition between terrestrial and aerial locomotions is smooth compared with the case of non-inclusion <styled-content style="color:black" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">of</styled-content> transitional mode such that the bounce and shake of the vehicle are alleviated. The energy efficiency is compared between the terrestrial and aerial modes, and between the energy-saving and high-maneuverability paradigms (a choice enabled in the terrestrial mode of SytaB). Experimental results are presented to demonstrate the potential of SytaB, the effectiveness of the designed controllers, and the necessity of considering the transition process.

MALE UAV selection in interval Type-2 fuzzy sets environment

Unmanned Aerial Vehicles (UAVs) are increasingly used in the military field. Especially in recent years, UAVs have been a very effective instrument in gaining airspace superiority and military success. Many countries compete with each other to develop better UAV technology or improve the technical features of UAVs. Therefore, it is critical to determine which UAV has the best performance, considering technical and operational characteristics, because the vehicles with more advanced performance can provide countries with strategic superiority. The purpose of this study is to investigate the technical, cost, and operational performance of Medium Altitude Long Endurance UAVs (MALE UAVs). In the study, as a result of a wide literature review, we determined a performance criterion for this type of vehicle. The model presented here uses an Interval Type-2 Fuzzy Analytical Hierarch Process (IT2FAHP) and an Interval Type-2 Fuzzy Technique for Order of Preference by Similarity to an Ideal Solution (IT2FTOPSIS) hybrid method. The findings indicate that some MALE UAVs have superior technical and operational performance over others and demonstrate that range, max take-off weight, and payload are important criteria in determining the performance and superiority of these vehicles.

Topical issues of personnel training in the field of unmanned aircraft systems

The legal regulation, and hence, the training system in the field of unmanned aircraft systems (UAS) in the Russian Federation, the European Union and the United States is based on the unmanned aerial vehicles (UAV) rating with respect to UAS maximum take-off weight (MTOW) and their purpose (method of use). In this regard, small-unmanned aircraft (sUAS) are identified – in our country up to 30 kg, in the EU and the USA up to 55 lbs (25 kg) and UAV with larger weight. In the USA and Europe, the training of remote pilots for sUAS is differentiated based on the degree of risk that UAV can represent for public safety. Thus, the training of remote pilots to use UAVs with MTOW less than 25 kg (55 lbs) in a sparsely populated area during daylight hours under the conditions of visual range is conducted in the online format, the result of which is taking tests. In the United States and Europe, the UAV application with MTOW more than 25 kg (55 lbs) or performing UAV operations, presenting a potential risk for public safety, requires more comprehensive and long-term training of remote pilots. In the Russian Federation, UAS personnel training is conducted in educational organizations according to different programs, which vary significantly depending on a specific type of aviation UAVs refers to: State, Civil or Experimental. UAS personnel training programs for various aviation types are not harmonized, which leads to the failure to credit previously received education in training to perform activities in another aviation type. The article describes the analysis results of the international and national experience, perspectives for the development of the UAS personnel training system, as well as formulates the proposals concerning further development of the national system for UAS specialists training.

Conceptual Assessment of the Possibility of Using Cryogenic Fuel on Unmanned Aerial Vehicles

The study is devoted to the creation of modern unmanned aerial vehicles (UAV), the most efficient from economic and environmental points of view. In connection with the vital need to switch to environmentally friendly vehicles, this research analyzes the possibility of using a cryogenic fuel (CF) for UAVs with piston or gas turbine engines. The numerical studies’ analyses of the takeoff weight of the currently widely used UAV MQ-9 Reaper show the practical impossibility of using liquefied hydrogen and the low efficiency of using liquefied natural gas (LNG) as fuel for similar UAV with takeoff weight up to 5 tons.

Aircraft conceptual design using metaheuristic-based reliability optimisation

The reliability optimisation methodology is developed to solve a conceptual design problem of a fixed-wing Unmanned Aerial Vehicle (UAV). The reliability quantification is based on the most probable point (MPP) concept, leading to a double-loop optimisation problem. The design problem is formulated as an outer-loop multiobjective optimisation for the main design problem and an inner-loop optimisation for estimating a reliability index (β) of a design solution. The goal of the outer-loop optimisation is to minimise the aircraft take-off weight, and simultaneously maximise β. The aerodynamic and stability properties of an aircraft solution are calculated by a vortex lattice method (VLM), while various types of empirical weight methods are obtained. The design problem is set up to have uncertainties in calculating aircraft empty weight and aerodynamic coefficients and derivatives. For the inner loop optimisation, the MPP is used for approximating the reliability index and probability of failure (pf). Multiobjective Meta-heuristic with Iterative Parameter Distribution Estimation (MMIPDE) and Success-History based Adaptive Differential Evolution (SHADE) are used for solving the outer- and inner-loop optimisations respectively. Four parameters setting strategies for running metaheuristics are proposed for use with the proposed metaheuristic-based reliability optimisation. The comparative results reveal that the best dynamic parameter setting from this study can reduce runtime by 22.5% compared to the traditional metaheuristic run while maintaining competitive results.

Integration and Flight Test of a 7 kW Turboelectric Vertical Take-Off and Landing Unmanned Aircraft

This paper evaluates the performance and practical challenges associated with fabricating and flight testing an unmanned aircraft powered by a turboelectric system based on a 7 kW turbine engine. Emerging hybrid gas-electric aircraft concepts have been the subject of numerous design studies and analytical evaluations; however, there is a critical need to identify and assess practical issues associated with integrating a hybrid turboelectric power system into an aircraft. The purpose of this study, relevant to emerging hybrid-powered aircraft, is to evaluate and retrofit a prototype turboelectric power system to an existing 391 N gross take-off weight unmanned airframe. The representative 7 kW turboelectric system was installed to identify challenges and to formulate data-driven recommendations for general application to urban air mobility. This work addresses performance, power and thermal management, vibration, and acoustic emissions. Results include a weight breakdown with the turboelectric system making up 21% of the total aircraft weight, in-flight voltage and current measurements with maximum loads observed during a dive pull-out, temperature measurements, accelerometer measurements, and far field sound pressure level measurements. Practical recommendations from this study are applicable to power system reliability, electronic component selection, cooling requirements, and peak power behavior, informing the design of future hybrid gas–electric aircraft.

Development of a novel supervisory controller on a parallel-hybrid powertrain for small unmanned aerial systems

PurposeA hybrid-electric unmanned aerial vehicle (HE-UAV) model has been developed to address the problem of low endurance of a small electric UAV. Electric-powered UAVs are not capable of achieving a high range and endurance due to the low energy density of its batteries. Alternatively, conventional UAVs (cUAVs) using fuel with an internal combustion engine (ICE) produces more noise and thermal signatures which is undesirable, especially if the air vehicle is required to patrol at low altitudes and remain undetected by ground patrols. This paper aims to investigate the impact of implementing hybrid propulsion technology to improve on the endurance of the UAV (based on a 13.6 kg UAV).Design/methodology/approachA HE-UAV model is developed to analyze the fuel consumption of the UAV for given mission profiles which were then compared to a cUAV. Although, this UAV size was used as reference case study, it can potentially be used to analyze the fuel consumption of any fixed wing UAV of similar take-off weight. The model was developed in a Matlab-Simulink environment using Simulink built-in functionalities, including all the subsystem of the hybrid powertrain. That is, the ICE, electric motor, battery, DC-DC converter, fuel system and propeller system as well as the aerodynamic system of the UAV. In addition, a ruled-based supervisory controlled strategy was implemented to characterize the split between the two propulsive components (ICE and electric motor) during the UAV mission. Finally, an electrification scheme was implemented to account for the hybridization of the UAV during certain stages of flight. The electrification scheme was then varied by changing the time duration of the UAV during certain stages of flight.FindingsBased on simulation, it was observed a HE-UAV could achieve a fuel saving of 33% compared to the cUAV. A validation study showed a predicted improved fuel consumption of 9.5% for the Aerosonde UAV.Originality/valueThe novelty of this work comes with the implementation of a rule-based supervisory controller to characterize the split between the two propulsive components during the UAV mission. Also, the model was created by considering steady flight during cruise, but not during the climb and descend segment of the mission.

From a Battery-Based to a PEM Fuel Cell-Based Propulsion Architecture on a Lightweight Full Electric Aircraft: A Comparative Numerical Study

The aviation sector is firmly committed to reducing harmful emissions and electric propulsion promises to tackle both pollution and noise at the same time. More Electric Aircrafts are progressively giving way to full electric aircraft that are expected to represent the next revolution in aviation. As is known, electric propulsion can be based on different electrochemical sources; nowadays, the widely used systems are developed on lithium battery packs, especially in automotive, where requirements in terms of gravimetric and volumetric energy densities are not so stringent compared to the aeronautical sector. Systems based on hydrogen fuel cells exhibit better performance in terms of range and endurance. In this article, a numerical study is presented on a lightweight electric aircraft, whose battery-based architecture is converted to a fuel cell-based architecture with the contribution of a battery pack that essentially intervenes in the take-off phase and, in addition, of a pack of ultracapacitors to prevent high discharge rate of the battery. The final intent is to explore the range extension without an increase in maximum take-off weight. The lumped parameter numerical models of the two propulsion systems have been developed in Simcenter Amesim where a set of simulations has been launched. It is shown that even under the constraint on the maximum take-off weight a significant extension of the range is obtained when adopting an electric propulsion system based on hydrogen fuel cells.

The Overall Design of Variable Diameter Ducted Fan in the Aircraft

Variable diameter rotor can improve the flight performance of the aircraft both in hovering and forward flying and a duct can improve the rotor performance further both in force and efficiency. In previous studies, those two parts are always studied in the one-factor-at-a-time method, and the duct is lack diameter change so that it cannot cooperate with the variable diameter rotor. In this paper, the Chinese utility helicopter Z9 is taken as the prototype, and the structural parameters of the variable diameter ducted fan (VDDF) are selected by an orthogonal experiment method. Based on the momentum-element theory, the aerodynamic theoretical model of the disk is established, and the structural parameters that can achieve the best efficiency in hover/propulsion and the best lift/thrust force ratio under different modes are obtained in the orthogonal range by computational fluid dynamics method. The structural parameters of the VDDF under the set working conditions are obtained by a technique for order of preference by similarity to ideal solution (TOPSIS) evaluation and the flight performance of the aircraft equipped with the VDDF is superior to the prototype: The max takeoff weight raises 25%; the hover ceiling raises 90%; the cruise altitude raises 11%; the cruise speed raises 23% and the max speed raises further. However, a better engine may be needed to provide greater power.