Tactical Unmanned Aerial Vehicle Research Articles

Fuselage Weight Estimation in Conceptual Design Phase for Tactical Unmanned Aerial Vehicles

Fuselage weight Estimation of an Unmanned Aerial Vehicle (UAV) during the conceptual design phase has been demonstrated to be an important challenge because of its unconventional configuration. Investigation of the development of a new suggested formula for fuselage weight estimation of UAV is done for UAVs having takeoff weight ranging from 100 to 500 kg, and which have similar characteristics. Based on statistical trends, obtained from analyzed existing UAVs, takeoff weight is estimated from mission specification, and it is derived for a tactical unmanned aerial vehicle (TUAV). Software tools are developed in MATLAB to facilitate takeoff and component weight calculations. The least square method is applied to analyze statistical data in order to develop trend functions which correlate TUAVs takeoff weight. Existing formulas, developed for general aviation, for fuselage and takeoff weight estimations are applied to TUAV and promising one are selected and adjusted to TUAV conceptual design phase. Fuselage weight estimation is related to geometrical parameters and takeoff weight of TUAVs.

Acquiring Precise Coordinates of Ground Targets through GCP Geometric Correction of Captured Images in UAS

Acquiring precise coordinates of ground targets can be regarded as the key mission of the tactical-level military UAS(Unmanned Aerial System) operations. The coordinates deviations for the ground targets estimated from UAV (Unmanned Aerial Vehicle) images may depend on the sensor specifications and slant ranges between UAV and ground targets. It has an order of several tens to hundreds of meters for typical tactical UAV mission scenarios. In this paper, we propose a scheme that precisely acquires target coordinates from UAS by mapping image pixels to geographical coordinates based on GCP(Ground Control Points). This scheme was implemented and tested from ground control station for UAS. We took images of targets of which exact location is known and acquired the target coordinates using our proposed scheme. The experimental results showed that errors of the acquired coordinates remained within an order of several meters and the coordinates accuracy was significantly improved.

Poletno-sletne performanse taktičke bespilotne letelice

The research presented in this paper focuses on take-off and landing performance of a single pusher-propelled Tactical unmanned aerial vehicle. The analysis presented includes flight test verification of estimated UAV characteristics. The study proposes a possible approximated method for estimating UAV characteristics. Flight test results have been conducted to verify the estimated results, and the calculated and measured results show good agreement.

Static Analysis and Design of Fixed-Wing Tactical Unmanned Aerial Vehicle (TUAV) Retractable Main Landing Gear

Bu çalışmada, insansız hava araçlarında iniş yüklerine dayanıklı ve maksimum hafifliğe sahip kompozit iniş takımı tasarlamak amaçlanmıştır. Bu kapsamda, iniş ve kalkış sırasında uçağın iniş takımlarının maruz kalacağı yüklerden yola çıkılarak iniş takımı tasarımı yapılmış ve üç boyutlu modelleme oluşturulmuştur. Tasarlanan katı model sonlu elemanlar yöntemi kullanılarak sayısal analizler yapılmıştır. Elde edilen verilerin belirtilen konfigürasyonda uçak iniş takımları üzerindeki yükleri herhangi bir kırılma olmaksızın karşılayabildiği gözlemlenmiştir. Çalışma sonunda elde edilen bulgular grafiklerle desteklenmiştir.

Mathematical model of inertial-optical autonomous navigation complex of unmanned aerial vehicle

In the article considers the possibility of implementing an autonomous mode in the navigation complex of a small-sized tactical unmanned aerial vehicle, including a strapdown inertial navigation system and an onboard vision system. Due to the fact that the accuracy of such navigation systems significantly depends on changes in the background-target environment and equipment failures, it is proposed to organize automatic adaptation of the system to changes in external conditions and internal factors by controlling the operating modes and parameters of the software that implements optimal estimation algorithms. For this purpose, a model of an onboard inertial-optical autonomous navigation system has been developed in the class of discrete dynamic systems with a random change in structure.

İnsansız Hava Aracında, Ataletsel Navigasyon Sistemine ait Yapısal Yerleşim Tasarımlarının Frekans Cevap Analizi ve Modal Test Metodları ile değerlendirilmesi

Inertial navigation systems are precise devices that are used to measure the orientation and accelerations of a platform they are integrated. Accuracy of the measured data is essential due to the critical role of these systems. The way that these devices are integrated to platform, directly affects the measured data accuracy. In this paper, a case study of alternative designs for Navigation device integration on a Tactical Unmanned Aerial Vehicle is presented. Mechanical behavior of the given alternative designs are evaluated with Finite Element Analyses and Modal Testing, hence the appropriate design is selected.

Quasi-3D Aerodynamic Analysis Method for Blended-Wing-Body UAV Configurations

The current study presents a low-fidelity, quasi-3D aerodynamic analysis method for Blended-Wing-Body (BWB) Unmanned Aerial Vehicle (UAV) configurations. A tactical BWB UAV experimental prototype is used as a reference platform. The method utilizes 2D panel method analyses and theoretical aerodynamic calculations to rapidly compute lift and pitching moment coefficients. The philosophy and the underlying theoretical and semi-empirical equations of the proposed method are extensively described. Corrections related to control surfaces deflection and ground effect are also suggested, so that the BWB pitching stability and trimming calculations can be supported. The method is validated against low-fidelity 3D aerodynamic analysis methods and high-fidelity, Computational Fluid Dynamics (CFD) results for various BWB configurations. The validation procedures show that the proposed method is considerably more accurate than existing low-fidelity ones, can provide predictions for both lift and pitching moment coefficients and requires far less computational resources and time when compared to CFD modeling. Hence, it can serve as a valuable aerodynamics and stability analysis tool for BWB UAV configurations.

Cooling system design for the internal combustion engine of a BWB UAV prototype

The current study presents an analytical design methodology for a compact thermal management system (cooling system) of a high-power density internal combustion rotary engine. The engine is installed on a fixed wing, tactical Blended-Wing-Body (BWB) Unmanned Aerial Vehicle (UAV) prototype that has been developed for the aerial delivery of cargo and lifesaving supplies. The design methodology is based mainly on a low-fidelity thermodynamic model and on high-fidelity Computational Fluid Dynamics (CFD) analyses. The results are validated against wind tunnel experiments for the cooling system of the engine. The overall methodology is divided into two distinct segments, the design of the heat exchanger (HEX) and the sizing of the cold-air inlet ducts. The low-fidelity thermodynamic model is based on 0D and 1D textbook methods and well-established formulae from the existing literature. The thermodynamic model is used for the calculation of the geometrical characteristics of the HEX. The high-fidelity CFD modeling is employed to yield a more detailed investigation of the flow field around the HEX and provide information about whether the airflow velocity requirements, for the 0D and 1D model, are met. Additionally, the detailed CFD computations assist the design of high-efficiency inlet ducts, in order to secure optimal airflow through the HEX and around the engine compartment. Using the proposed methodology, a functional HEX experimental prototype is designed and manufactured, as a proof of concept, in order to be thoroughly examined on a test rig in laboratory conditions. Multiple experiments are conducted in a variety of inlet temperatures and airflow velocities, for the validation and fine-tuning of the overall proposed design methodology. The study concludes with the final HEX design, as well as an analysis of its integration aspects on the tactical BWB UAV prototype.

Generative design case study of a CNC machined nose landing gear for an unmanned aerial vehicle

Generative design is a design method inspired by nature’s evolution, pushing the limits of the industry to new design solutions. Using minimum input requirements, the resulting designs can be structurally adequate, weight-optimised and almost production-ready. The main purpose of this paper is to present the different approaches of the standard engineering design and the generative design methods. This is achieved through the case study of a nose landing gear for a prototype tactical unmanned aerial vehicle, intended for low volume production. The first part of the paper outlines the conceptual design of the nose landing gear. Subsequently, during the preliminary phase, the stress distribution along the different parts is calculated, based on the classic Strength of Materials theory and therefore a design solution is produced. In the second part, a generative design study is carried out with a commercially available tool, based on the conceptual parameters previously chosen. Both concepts are studied with industry-standard finite element analysis tools in order to validate, from a theoretical standpoint, the strength requirements according to the STANAG 4671 regulation. The final structure will be manufactured with 3-axis CNC machining, while providing about 36% weight reduction without compromising the structural functionality.

Determining UAV Flight Trajectory for Target Recognition Using EO/IR and SAR.

The paper presents the concept of planning the optimal trajectory of fixed-wing unmanned aerial vehicle (UAV) of a short-range tactical class, whose task is to recognize a set of ground objects as a part of a reconnaissance mission. Tasks carried out by such systems are mainly associated with an aerial reconnaissance using Electro-Optical/Infrared (EO/IR) systems and Synthetic Aperture Radars (SARs) to support military operations. Execution of a professional reconnaissance of the indicated objects requires determining the UAV flight trajectory in the close neighborhood of the target, in order to collect as much interesting information as possible. The paper describes the algorithm for determining UAV flight trajectories, which is tasked with identifying the indicated objectives using the sensors specified in the order. The presence of UAV threatening objects is taken into account. The task of determining the UAV flight trajectory for recognition of the target is a component of the planning process of the tactical class UAV mission, which is also presented in the article. The problem of determining the optimal UAV trajectory has been decomposed into several subproblems: determining the reconnaissance flight method in the vicinity of the currently recognized target depending on the sensor used and the required parameters of the recognition product (photo, film, or SAR scan), determining the initial possible flight trajectory that takes into account potential UAV threats, and planning detailed flight trajectory considering the parameters of the air platform based on the maneuver planning algorithm designed for tactical class platforms. UAV route planning algorithms with time constraints imposed on the implementation of individual tasks were used to solve the task of determining UAV flight trajectories. The problem was formulated in the form of a Mixed Integer Linear Problem (MILP) model. For determining the flight path in the neighborhood of the target, the optimal control algorithm was also presented in the form of a MILP model. The determined trajectory is then corrected based on the construction algorithm for determining real UAV flight segments based on Dubin curves.

Model of the inertial and optical navigation system of the unmanned aerial vehicle

In article approaches to creation of the complex inertial and optical navigation system of the short-range tactical unmanned aerial vehicle are considered. Algorithms constant and periodic (in intermediate points of a route) are offered correction of the platformless onboard inertial navigation system. At integration of information on parameters of the movement of the unmanned aerial vehicle (received from the considered systems) the invariant loosely coupled scheme of data processing on the basis of the expanded filter of Kallman was used that allowed to lower significantly a systematic component of an error of the platformless inertial navigation system. Advantages of the complex inertial and optical navigation system when ensuring flight of the unmanned aerial vehicle in an area of coverage of means of radio-electronic fight of the opponent are shown. The results of modeling confirming a possibility of ensuring precision characteristics of the inertial and optical navigation system in the absence of signals of satellite radio navigational systems are presented.

Below the radar. Examining a small state’s usage of tactical unmanned aerial vehicles

ABSTRACT There is an extensive and rapidly growing body of literature on armed Unmanned Combat Aerial Vehicles (UCAVs) focused on the US War on Terror. However, smaller Unmanned Aerial Vehicles for military use, or what this paper refers to as tactical UAVs utilised by small states, have received much less scholarly attention ̶ despite their rapid proliferation in the last decade. In order to start rectifying this dual neglect of more limited UAVs employed by small states, the paper makes an empirical contribution to the study of tactical UAVs. Drawing on a substantial number of interviews and studies commissioned by the Swedish Armed Forces, the paper examines the Swedish UAV program, which is in certain ways representative of a smaller state’s efforts to incorporate UAVs into its armed forces. The paper argues that it is crucial to think in terms of systems rather than the UAV as a free-standing resource to be used on its own. If utilized along with other ISR assets, tactical UAVs may have a significant role to play in asymmetric conflicts.

Aerodynamics, Stability and Control Analysis of Tactical Solar Power UAV

This paper addresses the fundamental aerodynamics, stability, and control analysis of a solar power Unmanned Aerial Vehicle (UAV) as a part of the preliminary design stage. The tactical solar-powered UAV addressed in this paper is primarily developed for intelligence, surveillance, and reconnaissance (ISR) missions at low altitude. Moreover, such design also has a dual-use capability, which could be utilized in both military and civilian domains. The aerodynamic characteristics of the UAV are obtained from both computational fluid dynamics analysis technique and the wind-tunnel testing at the design operating Reynolds number ranging from 1x105 – 4.5x105. The fundamental aerodynamics coefficient consists of lift, drag, and pitching moment variations versus the angle of attack. The stability and control analysis was carried out based on the small disturbance theory in correlation with the XFLR5 software. The results show that the tactical solar power UAV design could achieve high aerodynamic efficiency at a 4-degree angle of attack which is corresponding to the lift-to-drag ratio of 20.05. Also, the analysis results confirm that the design possesses positive static and dynamic stability at the design cruise flight condition.

전술급 무인기 프로펠러의 형상변화에 따른 소음 수준 특성

Sound levels from the propeller of a tactical unmanned aerial vehicle (UAV) were computed using an acoustic analogy. The potential based panel method was used to obtain the pressure distribution on the blade surface. The blade geometry, pressure distribution on the blade surface, and operating conditions were used as input data for the thickness and loading noise analyses. A change of blade shape was adopted to investigate noise signals from the UAV propeller. Noise prediction for three rotating blade speeds (tip mach numbers of 0.4, 0.8, and 0.95) from the UH-1H rotor with and without the swept tip was also carried out, respectively. It was determined that meaningful noise level reduction cannot be expected except in the case of Mach number of 0.95. Sound levels generated from three different shapes, straight, forward-curved, and backward-curved blade shapes, were compared with each other with various tip Mach numbers.

Energy management-based design of a Wankel hybrid-electric UAV

PurposeThe purpose of this study is to investigate the optimization of design and energy management in a parallel hybrid-electric powertrain to replace the conventional engine of an existing tactical unmanned aerial vehicle (UAV) equipped with a Wankel engine with a pre-defined flight mission. The proposed powertrain can work in four different operating modes: electric, thermal, power-assist and charging.Design/methodology/approachThe power request at propeller axis of each flight segment is used as input for an in-house model that calculates the overall fuel consumption throughout the mission (Mfuel) and the maximum payload weight (Wpay) by means of an average-point analysis. These outputs depend on the energy management strategy that is expressed by the power-split ratio between engine and electric phase (Uphase) of each mission phase, according to which the components of the hybrid system are sized. The in-house model is integrated into an optimization framework to find the optimal set of Uphase and battery size that minimizes Mfuel and maximizes Wpay.FindingsIt was found a 3.24% saving of the fuel mass burned throughout the mission (or, alternative an improvement of endurance by 4.3%) with about the same maximum-payload mass (+0.2%) of the original configuration, or a smaller fuel saving with +11% more payload. The fuel saving of 3.24% corresponds to −3.25% in total emissions of CO2 and a 2.34% reduction of the cost-per-mission.Practical implicationsThis study demonstrates that environmental advantages, even if limited, can be already obtained from optimal design and management of the hybrid power system with today technologies while waiting for further benefits from the introduction of advanced technologies for batteries and electric machines.Originality/valueThe main novelties are the design of the powertrain on the basis of the energy management and the application of scalability and hybridization to Wankel engines.

An Application of the ECMS Strategy to a Wankel Hybrid Electric UAV

In a previous work, the authors optimized the hybrid electric power system for a tactical Unmanned Aerial Vehicle including a Wankel engine as thermal converter and a permanent magnet electric motor powered by lithium batteries. Startingfrom this optimal configuration, we address here the topic of a refined optimization of the energy management strategy, i.e. the contribution of the battery to the required power in each segment of the flight. The Equivalent Consumption Minimization Strategy (ECMS) was chosen with the goal of minimizing fuel consumption while fully depleting the energy stored in the battery from the beginning to the end of each mission.

Variance Constrained Vibration Control of Morphing Tactical Unmanned Aerial Vehicles (TUAVs)

In this study, using dynamic model of passive and active morphing featured Tactical Unmanned Aerial Vehicle (TUAV) called which is produced in Erciyes University, Faculty of Aeronautics and Astronautics, Model Aircraft Laboratory, under the TUBITAK ARDEB 1001 program and designing Output Constrained Variance Controller for aircraft tracking the desired trajectory achieved with minimal vibration and minimum energy consumption. For this purpose, using MATLAB, in the simulation environment, studies have been performed and closed loop responses have been obtained. Longitudinal motion is in primary interest, desired output is pitching angle of TUAV, and desired input is elevator angle.

Maximum lift/drag ratio improvement of TUAVs via small aerodynamic modifications

PurposeThe purpose of this study is to increase maximum lift/drag ratio (Emax) of tactical unmanned aerial vehicles (TUAVs) via applying novel small aerodynamic modifications.Design methodology/approachA TUAV is manufactured in Erciyes University, Faculty of Aeronautics and Astronautics, Model Aircraft Laboratory. It has both passive and active morphing capabilities. Its nosecone and tailcone shapes are redesigned to improve Emax. Moreover, active flow control is also built on its wing for improving Emax.FindingsUsing these novel small aerodynamic modifications, considerable improvement on Emax is obtained.Research limitations/implicationsPermission of Directorate General of Civil Aviation in Turkey is required for testing TUAVs in real-time applications.Practical implicationsSmall aerodynamic modifications such as nosecone-tailcone shape modifications and building active flow control on wing are very beneficial for improving Emax of TUAVs.Social implicationsSmall aerodynamic modifications satisfy confidence, high performance and easy utility demands of TUAV users.Originality/valueThe study will enable the creation of novel approaches to improve Emax value and therefore aerodynamic performance of TUAVs.

Design of Future UAV-Relay Tactical Data Link for Reliable UAV Control and Situational Awareness

Unmanned aerial vehicles (UAVs) have recently been widely used in the military and commercial domains. UAVs, especially in the military domain, were initially used for gathering intelligence, surveillance, and reconnaissance data, and sending them to a command center. Their use was then expanded to the tactical level to perform military operations with manned platforms. Operating a UAV as a relay node in the air has many advantages, including coverage, recovery from disconnection from a relay, clear communication channel, and easy deployment. Thus, the UAV-Relay tactical network can support more effective military operations. However, reliable UAV control and situational awareness must be guaranteed for the use of tactical UAVs. In other words, all tactical nodes must be able to send their location and status periodically under the dynamic and unexpected situation of a battlefield. However, a jamming attack from the enemy can make UAV control and situational awareness impossible. Thus, we need a robust tactical data link (TDL) to guarantee reliable UAV control and situational awareness under a jamming attack. In this article, we first explain the requirements for reliable UAV control and situational awareness. We then design a future UAV-relay TDL, called link-situational awareness and control (Link-SAC), which satisfies the requirements. We also deal with the spectrum allocation and management of Link-SAC because Link-SAC requires large bandwidth under the scarcity of spectrum resource. Thus, we consider spectrum sharing to allocate an X-Band uplink to Link-SAC. Based on the interference analysis in a prior study, we show that spectrum sharing is possible. We also show how Link-SAC can manage the spectrum. Lastly, we present our concluding remarks.

ESTIMATION OF WING WEIGHT IN CONCEPTUAL DESIGN PHASE FOR TACTICAL UNMANNED AERIAL VEHICLS

New formula for wing weight estimation, in conceptual design phase is derived for a tactical unmanned aerial vehicle (TUAV). Formula is derived by analyzing existing UAVs of the weighs from 100 to 500 kg, and which have similar characteristics. The materials suggested for UAV weight design are aluminum alloys and aluminum based composite materials. Software tools are developed in Matlab to facilitate takeoff and component weight calculations. The least square method is applied to analyze statistical data in order to develop trend functions which correlate TUAVs empty weight and takeoff weight. Existing formulas, developed for general aviation, for wing and takeoff weight estimations are applied to TUAV and promising one are selected and adjusted to TUAV conceptual design phase. Wing weight is related to geometrical parameters, maximum speed, and takeoff weight of the TUAVs. All existing and newly developed formulas are applied to typical TUAV example to validate it applicability.