An Unmanned Helicopter Energy Consumption Analysis

Aerodynamic interference between the main and tail rotor can have a strong negative influence on the flight mechanics of a conventional helicopter. Significant unsteadiness in the tail rotor loading is encountered under certain flight conditions, but the character of the unsteadiness can depend on the direction of rotation of the tail rotor. Numerical simulations, using Brown's vorticity transport model, of the aerodynamic interaction between the main and tail rotors of a helicopter are presented for a range of forward and lateral flight trajectories. Distinct differences are predicted in the behavior of the system in left and right sideward flight that are consistent with flight experience that the greatest fluctuations in loading or control input are required in left sideways flight (for a counterclockwise rotating main rotor). These fluctuations are generally more extreme for a system with tail rotor rotating top-forward than top-aft. Differences are also exposed in the character of the lateral excitation of the system as forward flight speed is varied. The observed behavior appears to originate in the disruption of the tail rotor wake that is induced by its entrainment into the wake of the main rotor. The extent of the disruption is dependent on flight condition, and the unsteadiness of the process depends on the direction of rotation of the tail rotor. In intermediate-speed forward flight and right sideward flight, the free stream delays the entrainment of the tail rotor wake far enough downstream for the perturbations to the rotor loading to be slight. Conversely, in left sideward and quartering flight, the free stream confines the entrainment process close to the rotors, where it causes significant unsteadiness in the loads produced by the system.

The paper deals with the possibilities of reducing the consumption of electrical energy of the impact screwdriver during the assembly of fixed threaded joints. The recommendations related to a decrease in electrical energy consumption would allow reducing product costs but so far there have been no such recommendations from the producers of the tool as to the effective operating regimes of the impact screwdrivers in relation to electrical energy consumption and necessary tightening moment of the nut. The aim of the study is to find out the economical operating mode of the electrical impact screwdriver when assembling fixed threaded joints. By varying the set speed of the rotor head and working time of the impact mechanism, there is an opportunity to determine electrical energy consumption of the tool for the given tightening moment. The results of the experiment show that at the same tightening moment obtained the electrical energy consumption of the impact screwdriver is less at a higher starting set speed of the rotor head but shorter operating time of the impact mechanism than at a lower speed of the rotor head and longer operating time of the impact mechanism.

The energy consumption of passenger vehicles is affected by the physical properties of the environment. The ambient temperature in particular has a significant impact on the operating energy consumption. To quantify the impact of a changed climate on vehicles with different drivetrain systems, we set up a model that calculates the change in energy demand with respect to multiple global warming levels. In particular, the effect of rising temperatures on the energy consumption of battery electric vehicles and vehicles with internal combustion engines was investigated. Our results indicate that climate change will likely lead to a rise in energy consumption of vehicles with an internal combustion engine. This is mostly due to the increase in cabin climatization needs caused by the higher ambient temperatures. At a global warming level (GWL) of 4.0 °C, the calculated annual energy consumption on average is 2.1% higher than without taking the climate-change-related changes in temperature into account. Battery electric vehicles, on the other hand, are expected to have a lower overall energy consumption (up to −2.4% at 4 °C GWL) in cold and moderate climate zones. They benefit from the lower heating needs during winter caused by global warming.

A high-fidelity engineering simulation model has been developed in FLIGHTLAB for a Sikorsky production helicopter to support future design modifications. The simulation model consists of major subsystems for main rotor, tail rotor, fuselage, empennage, landing gear, flight control system, and propulsion system. As the manufacturer, Sikorsky was able to provide a complete and validated set of model data and a large database of flight test records to ensure the model quality and fidelity. Although the model correlation with test data is satisfactory in most flight conditions including hover, low-speed flight, level flight, and vertical climb, some model-data discrepancies were seen in the forward climb/descent and autorotation test cases. An additional study was conducted at Sikorsky to investigate these discrepancies. Based on the study, a set of model enhancements were developed to improve the model correlation with test data in forward climb/descent and autorotation. These enhancements allow for adjustment of certain semi-empirical corrections to address model limitations at these challenging conditions such as fuselage characteristics and interference at high angles of attack and rotor inflow and interference at low collective settings and near 90-degree wake skew. These enhancements were carefully designed such that the effects were localized so that the model-data correlation was not adversely impacted in other flight conditions. The model-data correlation in forward climb/descent and autorotation were significantly improved by implementing these model enhancements with little to no impact on the other flight conditions resulting in a high-fidelity engineering simulation model validated in the entire flight envelope.

A high fidelity engineering simulation model has been developed in FLIGHTLAB for a Sikorsky production helicopter to support future design modifications. The simulation model consists of major subsystems for main rotor, tail rotor, fuselage, empennage, landing gear, flight control system, and propulsion system. As the manufacturer of the aircraft, Sikorsky is able to provide a complete and validated set of model data required for a high quality engineering model. A large database of flight test records was used to conduct a comprehensive validation effort to ensure the model quality and fidelity. The trim tests include hover (both in and out-of-ground effect), lateral and longitudinal low-speed flight, level flight, vertical climb, forward climb and descent, and autorotation. The dynamic response tests include longitudinal, lateral, collective, and pedal step and doublet control responses in both hover and cruise. The model predictions satisfactorily correlate with the test data in most of the test cases covering a broad range of configurations and flight conditions. For the most challenging low-speed flight regime, a set of customized modeling enhancements were implemented via the "user-defined subsystems" in FLIGHTLAB. These enhancements allow for more sophisticated adjustment of some semi-empirical corrections to address certain model limitations in the main rotor ground effect, the main rotor inflow and interference, and the tail rotor inflow and interference. The model-data correlation in low-speed flight was significantly improved by implementing these model enhancements, resulting in a high fidelity engineering simulation model.

Automatic flight control systems have become increasingly vital ever since the emergence of airplanes. Automatic systems are not subject to fatigue and emotions as compared to the human pilot. As such, the possibility of human errors in flight control is minimized. Current automatic Flight Control Systems are designed based on classical control theories using linear controllers that are complex and inefficient. Since an aircraft is naturally nonlinear in its behavior, it is intuitive to design a nonlinear controller that could cover a wide variety of possible `extreme' flight conditions. A novel controller utilizing the Nonlinear Energy Method was developed by Akmeliawati for the longitudinal dynamics of an aircraft, and has been proven to provide effective control and better performance when compared to an equivalent linear controller. The novel controller was designed using the Passivity-Based Control (PBC) technique. In this paper, a similar nonlinear controller was designed to direct the roll and yaw motion, which is part of the lateral dynamics of the aircraft. Simulations show that this PBC is able to stabilize both roll and yaw motion of the aircraft.

Purpose – The presented paper aims to describe the general idea, simulations and prototyping process of an assisting flight control system (FCS) for light sport aircraft (LSA). The proposed FCS framework is intended to simplify piloting, reduce pilot workload, and improve system's reliability and handling qualities of manual flying. Design/methodology/approach – Assisting flight control strategy integrates mechanical and digital FCS into a synergic platform, combining the high reliability of mechanical controls with the computation and actuation power introduced through a single line digital FCS. Concepts drawn from classical control theory along with flight envelope protection algorithms have been used throughout the design of the flight control laws. A prototype of the assisting FCS has been subjected to validation trials during series of hardware-in-the-loop simulations. Findings – Despite controversies between the pilots' perception of a modern aircraft and limitations imposed by the legacy airworthiness codes, it has been shown that a pilot assisting and workload reducing control system can be successfully implemented on board of a LSA while satisfying the expectations on a state-of-the-art equipment meeting required level of safety defined by the current legislation. Research limitations/implications – A transition between specific flight modes as well as nonlinearities in the FCS may lead to unfavorable and unpredictable forms of aircraft-pilot interactions. The number of accessible flight control modes should be therefore limited to the most significant ones. Practical implications – Sport aircraft are mostly flown by a single pilot, who could benefit from the pilot assisting FCS as the system has the potential to supervise the aircraft's safe operation in various flight conditions. Originality/value – Introducing an assisting FCS on board of a LSA through an innovative approach which utilizes hidden and unused resources of modern digital automatic FCSs while respecting the limitations imposed through the weight and cost sensitive nature of the LSA market.

This chapter introduces a number of the issues which must be addressed during the design and development of an automatic flight control system (AFCS). It does not make a comparison of potential system architectures nor does it suggest an optimum approach because each AFCS is different, depending upon the airframe and application. However, there is a common theme associated with an AFCS development programme that can be introduced and used to familiarise the reader with some of the concepts which must be addressed during the design evolution.

The ability to conduct an automatic landing maneuver is a key requirement for many unmanned aerial vehicles. By the example of the novel SAGITTA Demonstrator UAV, an autoland algorithm is presented as a modular extension to an automatic flight guidance and control system. At the Institute of Flight System Dynamics of the Technical University of Munich, a procedural definition of the automatic landing has been elaborated and implemented as a finite state machine. Based on this, existing guidance and control modules of the auto flight system are utilized to perform the landing maneuver. Particular attention has been paid to the design of transition conditions of the state machine, as these guide the temporal sequence of the maneuver and must reflect the high uncertainties that prevail concerning the performance of a novel aircraft configuration and its systems. Simulation testing and verification results in combination with ground testing of SAGITTA present a proof of concept of the design and give an outlook to its application during SAGITTA's maiden flight.

Access to electric energy is one of the drivers of wellbeing and universal access to energy has recently been identified as an important goal in the international community. A data-driven analysis of electric energy consumption and subjective wellbeing indicators is introduced to promote a broad conversation about relationships between energy poverty, global equity, subjective wellbeing measurements and good quality of life. The proposed approach directly focuses on the overall goal of attaining good and long lasting lives, the implications for future generations, the importance of ecosystems in enabling sustainable wellbeing and the needed capabilities in communities to flourish. Eventually, the proposed pathway should lead to a capabilities approach assessment for appropriate technologies. The results point out that although there is an important relationship between electric energy consumption and human wellbeing, a deeper look at electric energy access, subjective wellbeing indicators, local capabilities, and participatory decision making processes is needed to better prepare and implement long-term energy plans at local and global levels.

Analysis of electrical energy consumption of reusable active intraoperative warming pads compared with single-use warm water warming pads for cardiac surgery.

The paper analyzes electric energy consumption of three different refrigeration installations: cascade refrigeration system with R134a in the high temperature circuit and CO2 in the low temperature circuit, single stage refrigeration system operating with R404A and two-stage transcritical CO2 system. The indirect impact of the refrigeration system on global warming through electric energy consumption was examined. Thermodynamic cycles of these installations have been described and models have been developed to analyze the electric energy consumption required to drive the compressor as the largest consumer, for the cooling capacity of the evaporator 5,7 kW at evaporation temperature -30 °C for meteorological 2017, in the city of Belgrade. As a basis for comparative analysis, the existing cascade refrigeration system, which is located in the Laboratory for Thermal Science at the Faculty of Mechanical Engineering in Belgrade, was selected.

We measured electric energy consumption and estimated electric energy cost of a closed-type transplant production system to investigate how much we can reduce them toward a practical use of the closed-type transplant production system. Sweetpotato (Ipomoea batatas (L.) Lam. cv. Beniazuma) transplants were grown for 15 days under 31/42/68W m-2 (1-5/6-10/11-15 days after planting, respectively) photosynthetic active radiation with 16h d-1 photoperiod, 28°C air temperature, 75% relative humidity and 920μmol mol-1 CO2 concentration in the closed-type transplant production system. The amounts of electric energy consumption of lamps, air conditioners, fans and humidifiers during 15 days were 376, 118, 55 and 19 MJ m-2, respectively. The amount of increased chemical energy of transplants was 3 MJ m-2. The electric energy cost per tray of the closed-type transplant production system was estimated as 288 Yen. We estimated reductions of 50% of electric energy consumption of lamps, 20% of air conditioners, 40% of fans, 30% of humidifiers and 7% of electric energy cost without reducing the amount of increased chemical energy of transplants during 15 days by improving the efficiency of lighting, air cooling and circulating systems. From the above estimation, the amount of electric energy consumption and the electric energy cost per tray of the improved closed-type transplant production system will be 288MJ m-2 (50% reduction) and 132 Yen (54% reduction).

Novel compact ion exchange membranes through suppressing reverse permeation for high-efficiency recovery of inorganic acids

The prediction of energy consumption is the primary goal of an intelligent energy management system (IEMS). Based on the actual road–traffic conditions, the vehicle energy consumption on the whole planned path can be predicted online by road condition recognition or speed sequence prediction. Because the speed sequence prediction required by the latter cannot accurately reflect the real dynamic characteristics of vehicle speed such as acceleration and deceleration changes due to the random factors of traffic or human beings, which will greatly affect the predicting accuracy, especially on the urban road with complex working conditions. Therefore, based on the analysis of the cumulative relationship between vehicle speed characteristics and energy consumption, this study proposes a prediction method of vehicle driving energy consumption based on the statistical characteristics of vehicle speed, regardless of the accuracy of the prediction of vehicle speed sequence, including the establishment of a long‐term vehicle speed feature prediction model and energy consumption prediction model by BP and SVM algorithms. Finally, its rationality is validated based on the authentic data with an accuracy of about 95%, significantly improved compared with that based on long‐term vehicle speed prediction.