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PENGARUH KETEBALAN DI TENGAH TABUNG MOTOR ROKET RX 122 YANG PANJANG (THE EFFECT OF THICKNESS IN THE MIDDLE OF RX 122 LONG ROCKET MOTOR TUBE)
No full textABSTRACTIn the calculation of rocket tube due to the effect of pressure and temperature, if the comparison of length and diameter is large, then the bending stress and bucking stress will occur because of the weight, shear force, and torsion of the tube. For this reason, the tube needs to be thickened on the middle part so the pressure in the middle part will be reduced but will not result a new bigger pressure. In-depth analysis of the tubes was conducted on a long tube which is 2000 mm long and having 122 mm diameter. The analysis was only regarding the effect of the pressure on the tube with same thickness and the tube with thickened middle part for the purpose of seeing the effect of thickening the middle part of the tube and how much thickness in the middle part is allowed, so the effect of bending and buckling stress can be neglected.ABSTRAKPada perhitungan tabung roket akibat pengaruh tekanan dan temperatur, bila perbandingan antara panjang dan diameter cukup besar, perlu memperhitungkan terjadinya tegangan bending akibat berat dan tegangan buckling akibat ketebalan. Untuk menghindari tegangan tersebut maka bagian tengah tabung harus lebih tebal agar tegangan bagian tengah berkurang, tetapi tidak menimbulkan tegangan yang lebih besar lagi. Analisis yang lebih mendalam tentang tabung dilakukan pada tabung yang cukup panjang yaitu 2000 mm dan diameter 122 mm. Analisis yang dilakukan hanya dari pengaruh tekanan saja pada tabung yang tebalnya sama dan tabung yang tengahnya dipertebal, dengan tujuan untuk melihat pengaruh penebalan bagian tengah tabung tersebut dan sampai ketebalan berapa tabung bagian tengah diizinkan sehingga akibat terjadinya bending dan buckling dapat diabaikan.Hlm. 143-15
VERIFICATION OF SCHRENK METHOD FOR WING LOADING ANALYSIS OF SMALL UNMANNED AIRCRAFT USING NAVIER- STOKES BASED CFD SIMULATION (VERIFIKASI METODE SCHRENK DENGAN SIMULASI CFD BERBASIS PERSAMAAN NAVIER-STOKES DALAM ANALISIS PEMBEBANAN SAYAP PESAWAT UDARA NIRAWAK KELAS RINGAN)
No full textABSTRACTPrediction of an aerodynamic load acting on a wing or usually called wing loading becomes an important stage for structural analysis. Several methods have been used in estimating the wing loading. Schrenk approximation method is commonly used to achieve the fast estimation of lift distribution along wingspan, but in order to achieve a high level accuracy of aerodynamic prediction, computational fluid dynamics (CFD) with Navier Stokes-based equation can be used. LAPAN Surveillance UAV (LSU series) has been chosen to represent an aerodynamics analysis on generic small unmanned aircraft with twin-boom vertical stabilizer configuration. This study was focused to verify the Schrenk approximation method using high accuracy numerical simulation (CFD). The goal of this study was to determine the lift distribution along wingspan and a number of errors between Schrenk approximation and CFD method. In this study, Schrenk approximation result showed similarity with the CFX simulation. So the two results have been verified in analysis of wing loading. Keywords: aerodynamic loads, CFD, unmanned aircraft ABSTRAK Prediksi dari beban aerodinamika yang terjadi pada sayap menjadi salah satu tahap yang penting dalam analisis struktur perancangan pesawat. Beberapa metode telah digunakan untuk mengestimasi besarnya beban aerodinamika pada sayap. Metode Schrenk umum digunakan untuk estimasi cepat perhitungan besar distribusi gaya angkat di sepanjang sayap. Guna mencapai tingkat akurasi yang tinggi dari prediksi aerodinamika, simulasi Computational Fluid Dynamics (CFD) dengan berbasis persamaan Navier-Stokes dapat digunakan. Pesawat nirawak LSU dipilih untuk merepresentasikan analisis aerodinamika pada pesawat nirawak dengan konfigurasi twin-tailboom pusher. Fokus dari studi yang dilakukan adalah untuk memverifikasi dari metode pendekatan dari Schrenk dengan menggunakan metode yang memiliki akurasi tinggi seperti simulasi CFD. Tujuan dari studi adalah untuk menghitung distribusi gaya angkat sepanjang sayap dan menentukan seberapa besar error dari kedua metode.?Hlm. 161-16
Increase Maneuver Performance of High Speed UAV
No full textFlight simulation of high speed UAV using autonomous control system related with auto take off and auto pilot by way points system had completed and succeeded using integrated HISS facility that had been developed previously. In this simulation, the ability of bank-to-turn control of the vehicle reached 30 deg within speed of 250 km/h. However, the flight Maneuver led to a rounding trajectory which was quite large and less effective. This research discusses the effort in maximizing control technology to gain the minimum time in reaching target, Which is by combining maneuver strategy and vehicle speed. The result is time reduction by 23.6% in reaching target, from 427 sec to 326 sec for 4 way points. Also, a very smooth maneuver and speed control in every flight condition reduce energy use significantly. Moreover, the maneuver successfully reaches the target accurately with target missing range below 80 m