Design and construction a flying wing unmanned aerial vehicles Vasile Prisacariu 1, Mircea Boscoianu 2 SUMMARY: Unmanned aerial vehicles (UAV) are starting to represent a larger importance in the aerospace sphere due to the fact that it can execute a wide range of missions. The ampleness of its development in the last years is due to its possibility to be also used in civil applications. The development of optic-electronics, nanotechnology and the use of smart materials make UAV projects innovative. In this paper we propose to approach a systematic scheme of a UAV concept with a presentation in steps of how we can realize a UAV type flying wing. Keywords: UAV, first person visual (FPV), flying wing Chapter 1 Introduction Unmanned aerial vehicles (UAV) are starting to represent a greater importance in the aerospace sphere. The development of optic-electronics, nanotechnology and the use of smart materials make UAV projects innovative. In the last years they have tried building smaller aerial vehicles dedicated for special missions. The flight widgets must transport sensors which will transmit information from interest zone (video, acoustic, chemical and biological); these widgets are called micro aerial vehicles. They became topicality due to the progress in miniaturization and use of unconventional materials. Aerial vectors must be capable to have sensors that transmit information from interest zones (video, acoustic, chemical and biological). Figure 1 Onboard sensor (video, acoustic, chemical and biological). The succession rate of mission depends on a series of factor like: meteorological conditions and operation restrictions; the performance of the sensors; the training level of the operators; the equipment level; the interoperability level with the other structures involved in the mission. 1 Vasile Prisacariu, Ph.D. student, Transilvania University, Colina Universităţii 1, Braşov, Romania, E-mail: aerosavelli73@yahoo.com 2 Mircea Boşcoianu, Prof. Ph.D. Faculty of Aeronautical Management, Henri Coandă Air Force Academy Mihai Viteazu 160 Braşov, Romania, E-mail: boscoianu.mircea@yahoo.com 1
In other words the succession rate of the mission is directly influenced by the aerial vector capabilities, the most important being: the vectors reliability, the correlation speeds with the stages of the mission, minimal print (radar, acoustic, and thermo). The main types of aerial vectors type flying wing are represented in table 1. Table 1. The aerial vectors type flying wing Micro UAS Mini UAS Close Range Black Wodow, USA Orbiter, USA Maxi 10, Franţa Short range Medium range Low altitude, long endurance Exodrone, USA Snowgoose, Canada Eaglescan, USA Lethal UAS Unmanned combat aircraft Cutlass, USA-Israel Corax, UK Chapter 2 The design and manufacturing a UAV type flying wing Design management The realization of an unmanned aerial vector must take in consideration a series of limits and requests for the aerial machines: geometry, aerodynamics, propulsion, technology and exploitation. These determine the characteristics and performance of the aerial product. 2
Fig.2 Design diagram The characteristics and performance of the aerial vector (geometry, aerodynamics, machines and propulsion) are defined after a series of laboratory tests (aerodynamic tunnels) in real situations (flight attempts). The proposition of a constructive solution The technical solution proposed by a flying wing (figure 3) can be found as a class of mini UAV, with a total weight of 1.6kg. The proposed concept has the purpose of fulfilling data acquiring missions (image and weather) out of the visual range of the unmanned aerial system operator. Fig. 3 The flying wing The proposed constructive configuration is flying wing (tailless) tricycle landing gear, the vector being equipped with the following systems: propulsion system (electric motor), flight control system, electric system, data acquiring system and flight parameters (video, FPV sensors-height, speed, altitude, GPS), terrestrial equipment (visual data, maintenance and transport). 2.1. Platform structure (airframe) Wing. The wing type is mono-strut (hard aluminum) composed of expanded polystyrene with extreme ribs from plywood (figure 3). It is composed of 2 semi-plans that are mounted on the central fuselage with a dihedral angel of 0. The main characteristics are pointed out in table 2. The aerodynamic profile picked by HS 522, for a easier manufacturing of the wing. The profile (figure 4) has the features as in table 3 and the polar as in figure 6 and 7, calculated using Profili software v.2.21. 3
Table 2.Wing characteristics Span (m) 2 Aspect ratio 6.96 Root chord (m) 0,4 Wight (g) 1800 Surface (m 2 ) 0,575 Wing load (kg/m 2 ) 1,730 Fig. 5 HS 522 airfoil Fig. 6 cl-alfa, cd-alfa Fig. 7 Cl/cd-alfa, cm-alfa Tabelul 3. HS 522 aifoil data The aero mechanic analysis of the flying wing is performed with the help of the XFLR5 v.6.06 software. According to figure 8 the wing develops portance marks, resistance for going forward and induced resistance using the VLM method (vortex lattice method), at 15 m/s and o incidence angel of 10 degrees. 4
Fig 8 Amprenta portanţei şi rezistenţei la înaintare 2.2. Board systems The propulsion systems are composed of a brushless electric motor equipped with a electronic regulator of 40A which can train a 12x6 bipal propeller (figure 9a). The flight control system is composed of: radio-control system necessary for flying the aerial vector at distance and composed of transmitter, receiver, four servo-mechanisms and a auto stabilization method on 3 axis (figure 9b). Data acquisition system (sensors) is composed of digital videocamera, temperature recorder/ ambient moisture. The electricity is assured by a LiPo 4000 ma accumulator with reduced weight. a b c Fig. 9 Onboard equipment (a. electric propulsion, b. radio control system, c battery ) 3. Performances and features Mass features and performances resulted from the banc tests and flight attempts are detailed according to table 4 and 5. The results are obtained following the compromise between the aerodynamic concept and the utility of the aerial vector. Table 4 Mass repartition Airframe weight (empty) Engine weight Equipments Total weight 1 kg 0,3 kg 0,5 kg 1,8 kg Table 5 Performances and features of the aerial vector Span Minimum /Maximum speed 2000 mm 42 / 90 km/h 5
Maximum ceiling Range Autonomy 2500 m 5 km 20 min Conclusions The vector in his current state is easy to be piloted and does not have extreme problems with the exploitation. The auto stabile behavior of the aerial vector was obtained due to the auto stabilization method used. The performance of the aerial systems can affect directly the quality of the mission with major influences regarding the acquisition capacity, dissemination and decision regarding data from interest zones. The global performances of an aerial vehicle directly depend on the boarded aerodynamic concept, board equipment, the exploitation method used by the human user which is on the ground and last but not least the weather conditions. Acknowledgment The authors wish to thank the Transilvania University of Braşov and "Henri Coandă" Air Force Academy of Braşov for supporting the research necessary for writing this article. References 1 UAS Yearbook, Unmanned aircraft systems The Global Perspective 2011/2012, Blyenburg & Co, june 2011, Paris, ISSN 1967-1709, p 216, URL:<www.uvsinfo.com>, [cit. 2012-09-02] 2 URL:<http://www.aerodesign.de/english/profile/profile_s.htm>,[cit. 2012-09-26] 3 URL:<http://www.profili2.com/eng/default.htm>, [cit. 2012-09-26] 4 Guidelines for XFLR5 v6.03, 2011, 71p., URL:<www.xflr5.com>, [cit. 2012-09-27] 5 URL:<http://www.sierra.ro/Motor-BL-Outrunner-FC-3536--06-p4705p.html>, [cit. 2012-11-25] 6 SANDRU, V., RADULESCU,, M., CIUFUDEAN, C., BOSCOIANU, E.C. Critical aspects regarding the integration of a low cost up-grade architecture in hightechnology assets for defense, in Advances in Applied Mathematics, Montreux, Dec. 2012. 7 GUNDLACH J., Designing unmanned aircraft systems, Virginia, USA, AIAA series, 2012, 805 p. 6