Longitudinal flight dynamics and stability of blended wing-body unmanned aerial vehicle with canard as control surface / Rizal Effendy Mohd Nasir

Blended wing-body (BWB) aircraft concept has its body „blended” with the wing in smooth transition. Unlike conventional aircraft design, BWB aircraft”s body produces lift force and this causes large impact on the flight dynamics and stability. This thesis focuses on flight dynamics of a small unmanned aerial vehicle (UAV) with BWB configuration incorporating a set of canard as longitudinal control surface. The objective is to predict the flight dynamics and stability behaviour of UiTM”s Blended Wing-Body (BWB) unmanned aerial vehicle (UAV) with canard as control surface, known as Baseline- II E-2, in longitudinal mode with classical-approach stability augmentation to achieve level 1 phugoid and short-period modes flying qualities (restricted to damping ratios) as stated in MIL-F-8785C standard. This study proposes simple scheduled feedback gains to the canard. Wind tunnel experiments, computational simulations and empirical estimations were conducted to characterize its aerodynamics and to come up with its aerodynamic mathematical model for flight dynamics derivatives calculation. The flight dynamics model was derived to become Model-N state-space representation and compared to established models. Transient response to a unit step canard input was simulated using these models for flight conditions inside the airplane operating flight envelope (OFE) within its allowed angle of attacks. It was found that the BWB airplane without SAS, despite being statically and dynamically stable, has poor flying qualities for both short-period and phugoid modes

Stability augmentation for longitudinal modes of a small blended wing-body aircraft with canard as control surface / Rizal Effendy Mohd Nasir and Wahyu Kuntjoro

Failure to achieve satisfactory level for transient response of an aircraft in longitudinal motion - short period mode and phugoid modes - would mean poor flying and handling qualities leading to unnecessary pilot workload. This study proposes a stability augmentation system in longitudinal fly ing modes for steady and level flight at all airspeeds and altitudes within Baseline-II E-2 BWB s OFF. The main controlling component of this stability augmentation system is a set of canard. It must be able to compensate Baseline-II E-2 BWB poor transient responses 'damping ratios so that good flying quality can be achieved. Observation from the transient responses of the unaugmented system signify high-frequency short-period oscillations with almost constant low damping ratio at an altitude, and low-frequency phugoid oscillation with varying damping ratio depending on airspeed. A conclusive behaviour of natural frequencies and damping ratios against dynamic pressure leads to the understanding on how dynamic pressure influences the flying qualities. Derivation of dynamic equations in terms of dynamic pressures enables one to design and device a feedback system to compensate poor flying qualities of the original unaugmented aircraft with conclusive relationship between important parameters and dynamic pressure are put in the overall dynamic equation. Two feedback gain systems, pitch attitude and pitch rate gains are scheduled based on dynamic pressure values and are combined into the aircraft longitudinal SAS. The proposed SAS has proven to be the suitable candidate for Baseline-II E-2 BWB as it is able to ensure Level 1 flying qualities, longitudinally

K-180 G Micro Gas Turbine Performance Evaluation / Mohamad Zulfazli Arief Abd Latif...[et al.]

The K-180 G jet turbine is categorized as turbojet engine. This paper studied and analyzed the performance of K-180 G micro jet turbine for Unmanned aerial Vehicle (UAV) at static condition. The project was done to study thrust and temperature behavior with respect to rpm for a turbojet engine using standard kerosene fuel. A theoretical thermodynamic model was derived to understand theoretical aspect behind the test and to ensure the validity of performance measured. Various sensors were integrated to the gas turbine and computed to record the performance parameters such as EGT, thrust, engine rpm and pump power. The engine was tested several times in order to obtain average reading. At maximum RPM, the average thrust recorded was 18.57 kg, the maximum temperature recorded was 523˚C and the maximum pump power was 293 W. The relationship between thrust against RPM and the thrust against pump power is third order polynomial and thrust against EGT is parabolic. The mass flow rate of fuel was obtained from the relationship of the RPM against pump power which is third order polynomial. The thermodynamic theoretical model validated the engine’s performance measured with the percentage error between 1 to 30%

An evaluation of cots-based radar for very small drone sense and avoid application

The use of very small unmanned aerial vehicles (UAVs) are increasingly common these days but its applications are limited to the pilot line-of-sight view. To extend its use beyond the pilot view, UAVs need to be equipped sense and avoid (SAA) system to avoid potential collisions. However, the development of SAA for very small drones is still in the infancy stage mainly due to the high cost of design and development for reliable range sensors. Recent developments of very small size and lightweight commercial off-the-shelf (COTS)-based radar systems may become a crucial element in very small drone applications. These types of radars are primarily developed for industrial sensing but can be adapted for applications such SAA. Thus, this paper contributes to the survey of a miniature and lightweight radar sensor to assist the SAA development. The focus of this paper is to analyse the eligibility of a COTS-based radar in detecting very small drones. For this purpose, we used a frequency-modulated continuous radar (FMCW) developed by Infineon Technologies. Field test results show the real-time capability of the radar sensor to detect the very small drones within ± 0.5 meters in static and dynamic conditions

The effect of centre-elevator on aerodynamics of UiTM baseline-1 blended wing body (BWB) unmanned aerial vehicle (UAV) at low subsonic speed / Rizal Effendy Mohd Nasir .. [et al.]

A group of researcher in Universiti Teknologi MARA (UiTM) has started a project on the development of future unmanned aerial vehicle based on BWB concept since 2005. A case study on the effect of centre-elevator deflection to aerodynamics of UiTM's Baseline-1 blended wing-body aircraft is presented in this paper. Elevator deflection in study is limited to ± 10 degrees. Analytical theory on possible contribution of elevator deflection to aerodynamic coefficients is highlighted. Aerodynamic parameters are computed via computational fluid dynamics method based on RANS to simulate low subsonic flight at Mach 0.3 sea level ISA. Discussions focus on the effect of elevator deflection to lift, drag and moment curves at small angles of attack within linear region ofCL-α curve. Results show significant change in lift and drag coefficients within + 10 degrees elevator deflection but no considerable change of moment that it is impossible to change trim angle of attack without shifting centre of gravity

Aerodynamic Analysis of Blended Wing Body - Unmanned Aerial Vehicle (BWB-UAV) Equipped with Horizontal Stabilizers

This paper presents an aerodynamic characteristic study in longitudinal direction of UiTM Blended Wing Body-Unmanned Aerial Vehicle Prototype (BWB-UAV Prototype) equipped with horizontal stabilizers. Flight tests have been conducted and as the result, BWB experienced overturning condition at certain angle of attack. Horizontal stabilizer was added at different location and size to overcome the issue during the flight test. Therefore, Computational Fluid Dynamics (CFD) analysis is performed at different configuration of horizontal stabilizer using Spalart - Allmaras as a turbulence model. CFD simulation of the aircraft is conducted at Mach number 0.06 or v = 20 m/s at various angle of attack, α. The data of lift coefficient (CL), drag coefficient (CD), and pitching moment coefficient (CM) is obtained from the simulations. The data is represented in curves against angle of attack to measure the performance of BWB prototype with horizontal stabilizer. From the simulation, configuration with far distance and large horizontal stabilizer gives steeper negative pitching moment slope indicating better static stability of the aircraft

Aerodynamic Analysis of Blended Wing Body - Unmanned Aerial Vehicle (BWB-UAV) Equipped with Horizontal Stabilizers

This paper presents an aerodynamic characteristic study in longitudinal direction of UiTM Blended Wing Body-Unmanned Aerial Vehicle Prototype (BWB-UAV Prototype) equipped with horizontal stabilizers. Flight tests have been conducted and as the result, BWB experienced overturning condition at certain angle of attack. Horizontal stabilizer was added at different location and size to overcome the issue during the flight test. Therefore, Computational Fluid Dynamics (CFD) analysis is performed at different configuration of horizontal stabilizer using Spalart - Allmaras as a turbulence model. CFD simulation of the aircraft is conducted at Mach number 0.06 or v = 20 m/s at various angle of attack, α. The data of lift coefficient (CL), drag coefficient (CD), and pitching moment coefficient (CM) is obtained from the simulations. The data is represented in curves against angle of attack to measure the performance of BWB prototype with horizontal stabilizer. From the simulation, configuration with far distance and large horizontal stabilizer gives steeper negative pitching moment slope indicating better static stability of the aircraft

Comparison on the aerodynamic coefficients obtained from three different size of wind tunnel model on Baseline V set at 45 degree sweep tail angle

This paper analyzes the aerodynamic coefficients of a blended wing body, Baseline V which is equipped with 45° sweep tail angle. Base-line V is one of the Universiti Teknologi MARA (UiTM) Shah Alam Flight Test Technology Centre's blended wing body designs that have unique configuration as it uses different NACA airfoil for its fuselage, body, wing root, midwing, wingtip, tail root, and tail tip. The intention of the comparison for three different size of wind tunnel model is to determine the similarity of the aerodynamics coefficients and the behaviour of the model itself. The wind tunnel experiments were conducted at three different wind tunnel locations: Universiti Teknologi Malaysia Skudai, UiTM Shah Alam and Universiti Pertahan Nasional Malaysia Kuala Lumpur, using 1:1 scale full model, 1:2 scale half model, and 2:7 scale half model, respectively. The data obtained are studied and plotted in term of lift coefficients, lift-to-drag ratio, and drag coefficients. The pitching angle for all experiments were varied between -10° to +17°. The blockage corrections have been applied to the data to obtain the actual performance of the aircraft. From the observations, the results show some similarity between those experiments, except for the lift-to-drag ratio of UPNM's data which are slightly higher compared to others