Flight Qualification Research Articles

An Interactive Design System of Free‐Formed Bamboo‐Copters

AbstractWe present an interactive design system for designing free‐formed bamboo‐copters, where novices can easily design free‐formed, even asymmetric bamboo‐copters that successfully fly. The designed bamboo‐copters can be fabricated using digital fabrication equipment, such as a laser cutter. Our system provides two useful functions for facilitating this design activity. First, it visualizes a simulated flight trajectory of the current bamboo‐copter design, which is updated in real time during the user's editing. Second, it provides an optimization function that automatically tweaks the current bamboo‐copter design such that the spin quality—how stably it spins—and the flight quality—how high and long it flies—are enhanced. To enable these functions, we present non‐trivial extensions over existing techniques for designing free‐formed model airplanes [UKSI14], including a wing discretization method tailored to free‐formed bamboo‐copters and an optimization scheme for achieving stable bamboo‐copters considering both spin and flight qualities.

UAV route planning for aerial photography under interval uncertainties

Aerial photography refers to capturing photographs from the ground through an elevated camera, which is usually not supported by a ground-based structure. Unmanned aerial vehicles (UAVs) have been rapidly developed as a platform for collecting such hyper-spatial resolution visual data. Herein, UAV route planning is a critical issue that influences aerial photography quality, especially when uncertainties exist in the concerned aerial photography scheme. This work proposes a hierarchical optimization framework for UAV aerial photography route planning problems when real-world interval uncertainties in the scenario are taken into account. Specifically, in evaluating a candidate flight route, the interval uncertainties that associated with the concerned flight route would make the flight quality range in an interval (known as an interval response); a criterion is proposed to evaluate the quality of all the available interval responses so as to sort the very interval response associated with satisfactory flight route efficiency and robustness; the sorting process is carried out using stochastic fractal search algorithm.

Method for Improving the Natural Lateral-Directional Stability of Flying Wings

AbstractPoor lateral-directional flight quality is a critical technical problem in flying wing aircraft design. This paper proposes an approach to achieve lateral-directional dynamic stability of flying wing aircraft. This approach is different from general methods such as installing a wingtip vertical stabilizer or depending on a stability augmentation system. Through directly including the judgment of aircraft dynamic stability into the aerodynamic configuration design, sufficient lateral-directional stability can be guaranteed without relying on other systems. A lateral-directional dynamic stability satisfaction judgment function was built based on MIL-F-8785C. The lateral-directional dynamic stability was improved using only the adjustment of the spanwise dihedral layout. To validate the feasibility of this design method, this study selected a flying wing aircraft with a high aspect ratio as the object. Two optimized configurations with different aerodynamic shape but similar stability characters were...

Equilibrium characteristics and stability analysis of helicopter slung-load system

Based on rigid-body slung-load hypothesis, a nonlinear dynamical model of the helicopter and slung-load system is presented. As for helicopter and slung-load system, the introduction of the rigid-body slung-load results in several extra degrees of freedom and constraints, and this makes the nonlinear equations of helicopter and slung-load motion transfer from 9 orders to 19 orders. The nonlinear equations are linearized by small perturbation hypothesis for stability analysis and they are trimmed by the continuation method. First, the simulation trimmed results are compared with the helicopter flight test data without slung-load and the calculation results of helicopter with mass-point slung-load in the literature. Then, the differences among trimmed states of the helicopter with a rigid-body slung-load, a mass-point slung-load, and without slung-load are studied. The motion modes of helicopter with rigid-body slung-load are calculated in different cases, and the effects of extra slung-load to the helicopter stability are analyzed at the same time. Results showed that the rigid-body slung-load added five new motion modes to the whole helicopter and slung-load system, two of which concerning cable swinging motion are stable, while the others concerning slung-load attitude motion are unstable. At the same time, the introduction of rigid-body slung-load makes the short-period mode and the roll mode of helicopter unstable, which has a strong impact on the flight quality of helicopter.

Development of Digital Flight Motion Methodology Based on Aerodynamic Derivatives Approximation

[abstFig src='/00280002/12.jpg' width=""300"" text='3D contour views of Cz [-0.4—1.05],Mach:0.6-1.4, Alpha:0°-30°' ]The accuracy of efficient flight simulation depends on the quality of the aerodynamic data used to simulate aircraft dynamic motion. The accuracy of such data prediction depends strongly on motion variables, aerodynamic derivatives, and the coefficients used when the complete global aerodynamic database is being building. A surrogate model applied as a prediction method based on several measured points (exact function) used to predict unknown points of interest helps reduce time taken by the experiment or computation. Latin hypercube sampling searches the solution space for aerodynamic data to optimize the experimental design, so the key objective is to develop an aircraft's efficient digital flight motion by solving equations of motion and predicting aerodynamic data using a surrogate model. To realize these goals, we use sample surrogate model data, acquired from empirical model USAF Stability and Control DATCOM. The database was built for two main variables, the angle of attack and the Mach number, along the longitudinal and lateral axes. Exact and predicted functions were compared by calculating the mean squared error (MSE). The digital flight was validated through mode motion analysis and a flight quality scale to prove flight mission capabilities. A comparison between results predicted by the surrogate model and the exact function showed that flight simulation analysis and prediction ability of the surrogate model are useful in future analyses.

A Monte Carlo Analysis for Collision Risk Assessment on Vega Launcher Payloads and LARES Satellite

Abstract This work has been developed in the framework of the LARES mission of the Italian Space Agency (ASI). The LARES satellite has been built to test, with high accuracy, the frame–dragging effect predicted by the theory of General Relativity, specifically the Lense–Thirring drag of its node. LARES was the main payload in the qualification flight of the European Space Agency launcher VEGA. A concern arose about the possibility of an impact between the eight secondary payloads among themselves, with LARES and with the last stage of the launcher (AVUM). An impact would have caused failure on the payloads and the production of debris in violation of the space debris mitigation measures established internationally. As an additional contribution, this study allowed the effect of the payload release on the final manoeuvers of the AVUM to be understood.

Development and flight qualification of the C–SiC thermal protection systems for the IXV

The Intermediate experimental Vehicle (IXV) atmospheric re-entry demonstrator, developed within the FLPP (Future Launcher Preparatory Programme) and funded by ESA, aimed at developing a demonstration vehicle that gave Europe a unique opportunity to increase its knowledge in the field of advanced atmospheric re-entry technologies. A key technology that has been demonstrated in real conditions through the flight of this ambitious vehicle is the thermal protection system (TPS) of the Vehicle. Within this programme, HERAKLES, Safran Group, has been in charge of the TPS of the windward and nose assemblies of the vehicle, and has developed and manufactured SepcarbInox® ceramic matrix composite (CMC) protection systems that provided a high temperature resistant non ablative outer mould line (OML) for enhanced aerodynamic control. The design and flight justification of these TPS has been achieved through extensive analysis and testing:●Mechanical, Dynamical and thermo-mechanical analysis.●Coupons and technological tests.●Sub-scale tests specifically made to assess the behaviour of the TPS during re-entry.●Full scale qualification tests that addresses the flight envelope of the vehicle:•Sine, Random and shock tests on nose and windward.•Thermal test of the nose.•Mechanical tests of nose and windward.This paper describes the Flight Model TPS design, as well as the development activities, tests and results that lead to the qualification of the nose and windward TPS assemblies.

LADRC-based attitude decoupling control for helicopter and parameters tuning

To meet the ADS-33E-PRF flight quality and effectively overcome the influence of external disturbance,an attitude control strategy based on a linear active disturbance rejection control( LADRC) is proposed for helicopter. Flight dynamics model of UH-60 A and the wind model were established. UH-60 A was trimmed for verifying accuracy of dynamic model and trim algorithm. Helicopter attitude decoupling control loop based on the single input / single output second-order LADRC controller was set up with stabilization feedback loop. The controller parameter tuning problem was transformed into constrained optimization problem in time and frequency domain according to quality requirement of ADS-33E-PRF. Combining H-infinity synthesis algorithm and steepest descent algorithm,the optimization of parameters was calculated. Quality assessment of attitude control was made and the control loop was applied to the attitude hold control simulation in atmospheric disturbance. The results of simulation and quality evaluation show that the attitude control system based on LADRC has good decoupling performance and capability of anti-disturbance.

원격조종항공기조종사 적성검사에 관한 연구 (적성검사 항목선정을 중심으로)

Recently, the need of RPA(Remotely Piloted Aircraft) pilots is increasing rapidly with many requirements in order to be a beginner RPA pilot, including basic flight training, instrument flight qualification training, and aircraft type switching training. When RPA pilot gets disqualified, there will be generated much waste of efforts and expenses of trainees those pilots who are disqualified. Therefore, the methodology of pre-verifying those pilots who are not proper as RPA pilots through various scientific methods will save time and expenses with pre-reducing the pilots who will get disqualified later on. The methodology of aptitude test of RPA pilots is laid out as a consideration of pre-study of RPA pilots work analysis, and select types of aptitude test. A suitability of aptitude test is verified. In order to diagnose the flight aptitude precisely, it requires to be developed. Flight aptitude test tools might be connected with training program which could foster piloting aptitude with pre-diagnosing RPA pilot trainee selecting process. For that reason, we made an experiment in order to verify credibility and suitability of these selected programs with developing RPA pilot aptitude test tools. And also, we analyzed relationships among characteristics, analysis of data, and variables to verify the efficiency of data from prior experiment. Through this thesis, we expect to raise efficiency of flight training by providing pre-flight aptitude test information of RPA pilots.

Research on Control Augmentation System for a Flying Wing Aircraft

Requirements of the longitudinal control augmentation system are presented through studying the 25thChina Civil Aviation Regulations and C* flight quality evaluation criterion; The C* control augmentation scheme commonly used in modern large airliners is adopted to design the control augmentation system due to the stability and handling problems for the flying wing aircraft; The particle swarm optimization algorithm is proposed due to the parameter-scheduling difficulties in the designed control augmentation system. Numerical simulation shows that the designed C* control augmentation scheme is feasible.

Method for inspection of frame digital aerial photographic quality

At present,the aerial photographic quality inspection still uses the traditional method to check the digital frame images' quality,which prints the digital images on paper first and then checks them manually. The method greatly limits the advantages of digital aerial photography. This paper presents a fully digital aerial photographic quality inspection method,whose whole process is fully completed on computer. Firstly,index images are used to complete the image quality inspection,Then the aerial photography flight quality inspection software and airborne POS( position and orientation system) data are employed to check such quality factors as overlap,swing angle,strip deformation,and flying height,Finally,relevant documentation is collated and prepared according to the results. In order to verify the reliability and scientificalness of this method,the authors selected the manual quality inspection results of Hengyang area in Hunan Province to make comparison and analysis. The results show that this method can actually reflect the flight quality of aerial photography,is in good consistency with manual results,and has some other advantages such as simple operation,high efficiency and low cost.

Dihedral influence on lateral–directional dynamic stability on large aspect ratio tailless flying wing aircraft

The influence of dihedral layout on lateral–directional dynamic stability of the tailless flying wing aircraft is discussed in this paper. A tailless flying wing aircraft with a large aspect ratio is selected as the object of study, and the dihedral angle along the spanwise sections is divided into three segments. The influence of dihedral layouts is studied. Based on the stability derivatives calculated by the vortex lattice method code, the linearized small-disturbance equations of the lateral modes are used to determine the mode dynamic characteristics. By comparing 7056 configurations with different dihedral angle layouts, two groups of stability optimized dihedral layout concepts are created. Flight quality close to Level 2 requirements is achieved in these optimized concepts without any electric stability augmentation system.

Investigation on Aerodynamic Configuration of Monitoring Long Endurance UAV

In recent years, monitoring long endurance UAV is widely used in civil fields such as earthquake relief, it has certain particularities in comparison with conventional UAV; this paper studied and summarized its key technologies in aerodynamic configuration. The research of aerodynamic configuration is based on a general scheme, research indicates that: (1) monitoring long endurance UAV has the characteristics of low-Reynolds number, so laminar airfoil is needed to increase lift-drag ratio; induced drag can be reduced by optimizing wing twist angle; (2) subsection control surface and new design method on flight-quality would improve control reliability and flight quality, which are indispensable for the UAV to guarantee safety in bad weather condition; (3) take-off/landing/taxiing performance should be considered in order to improve the runway adaptability of the UAV.

Design and pre-flight testing of the electrical power system for the ESTCube-1 nanosatellite

Received 21 August 2013, revised 21 April 2014, accepted 22 April 2014, available online 23 May 2014 Abstract. This work describes the final design and implementation of the electrical power system for ESTCube-1, a 1-unit CubeSat tasked with testing the electrostatic tether concept and associated technologies for the electric solar wind sail in polar low Earth orbit. The mission required an efficient and reliable power system to be designed that could efficiently handle highly variable power requirements and protect the satellite from damage caused by malfunctions in its individual subsystems, while using only commercial-off-the-shelf components. The system was developed from scratch and includes a novel redundant stand- alone nearly 90% efficient maximum power point tracking system, based on a commercially available integrated circuit, a lithium- ion battery based fault-tolerant power storage solution, a highly controllable and monitorable power distribution system, capable of sustaining loads of up to 10 W, and an AVR microcontroller based control solution, heavily utilizing non-volatile ferroelectric random access memories. The electrical power system was finalized in January 2013 and was launched into orbit on 7th of May, 2013. In this paper, we describe the requirements for the subsystem, the design of the subsystem, pre-flight testing, and flight qualification.

Relative Status Determination for Spacecraft Relative Motion Based on Dual Quaternion

For the two-satellite formation, the relative motion and attitude determination algorithm is a key component that affects the flight quality and mission efficiency. The relative status determination algorithm is proposed based on the Extended Kalman Filter (EKF) and the system state optimal estimate linearization. Aiming at the relative motion of the spacecraft formation navigation problem, the spacecraft relative kinematics and dynamics model are derived from the dual quaternion in the algorithm. Then taking advantage of EKF technique, combining with the dual quaternion integrated dynamic models, considering the navigation algorithm using the fusion measurement by the gyroscope and star sensors, the relative status determination algorithm is designed. At last the simulation is done to verify the feasibility of the algorithm. The simulation results show that the EKF algorithm has faster convergence speed and higher accuracy.

BIOLAB on the International Space Station (ISS): Facility and Experiments

The BIOLAB is a multi-user facility of the European Space Agency ESA, accommodated in the European COLUMBUS Module of the International Space Station. The BIOLAB flight facility enables biological and biomedical experiments investigating the effects of weightlessness and/or space radiation on microorganisms, cell cultures of various origins, lower organisms and small plants and animals. The proposals for Life Sciences experiments are selected by an ESA peer group. The BIOLAB facility consists of an automated left part and a right part which is manually operated by the astronauts on orbit. The biological and biomedical samples are accommodated in experiment-specific containers, dedicated to each individual experiment. Sample preparation can be performed in the Bioglovebox, storage of biosamples in a cooler/freezer. On-orbit analyses can be performed by means of a microscope. The incubator as the heart piece of BIOLAB includes a life support system and two rotor platforms. Furthermore the video camera system mounted on the rotor platforms enables a regular control of the biosamples via telescience from/to ground. The BIOLAB facility is controlled and monitored by the Microgravity User Support Center (MUSC) as Facility Responsible Center (FRC) at DLR, Cologne, Germany, on behalf of the European Space Agency. MUSC is interfacing with the astronauts on orbit and the partners of the ISS ground segment, space hardware developers and the COLUMBUS Control Center. Main MUSC tasks for BIOLAB are increment preparation, experiment optimization and flight qualification, on-orbit operations via telescience, as well as post-increment evaluation. BIOLAB ground models - complemented by hyper-g and µg simulation devices - are available for experiments. DLR MUSC is supported by the specific expertise of BIOTESC (Lucerne, Switzerland). This review encompasses a description of the BIOLAB facility and exemplarily some experiments hitherto flown.

Towards a Failsafe Flight Envelope Protection: The Recovery Shield

Stall is an Inherent unsafe flight state that has caused catastrophes in civil aviation. Solutions were gradually introduced, such as aerodynamic devices, pilot training, stick shakers and stall warnings. These mitigating, stand alone solutions seemed to have solved the problem to an acceptable level. However, stall as a phenomenon has recurred in a new form, due to changes in operating conditions, flight envelope protection, cockpit automation and crew competence qualifications. Stall accidents, as unintentional loss of pitch control, deal with the malfunctioning of primary flight control surfaces, automation mismanagement and hostile environmental influences during all weather operations.As pitch control is the only primary flight control that has no design redundancy, a new control recovery approach is proposed, introducing new and uncorrupted aerodynamic forces by combining a technical recovery device with enhancing diagnostic abilities for the crew. In designing such a device, synchronizing time required and time available for flight control recovery is a critical design dimension. This contribution elaborates on a control recovery device as an integrated system, consisting of a technical design device, computerized flight control and crew qualifications. A practical application of such a device focuses on stall recovery, as a specific category of flight control recovery.

BIOLAB on the International Space Station (ISS): Facility and Experiments

The BIOLAB is a multi-user facility of the European Space Agency ESA, accommodated in the European COLUMBUS Module of the International Space Station. The BIOLAB flight facility enables biological and biomedical experiments investigating the effects of weightlessness and/or space radiation on microorganisms, cell cultures of various origins, lower organisms and small plants and animals. The proposals for Life Sciences experiments are selected by an ESA peer group. The BIOLAB facility consists of an automated left part and a right part which is manually operated by the astronauts on orbit. The biological and biomedical samples are accommodated in experiment-specific containers, dedicated to each individual experiment. Sample preparation can be performed in the Bioglovebox, storage of biosamples in a cooler/freezer. On-orbit analyses can be performed by means of a microscope. The incubator as the heart piece of BIOLAB includes a life support system and two rotor platforms. Furthermore the video camera system mounted on the rotor platforms enables a regular control of the biosamples via telescience from/to ground. The BIOLAB facility is controlled and monitored by the Microgravity User Support Center (MUSC) as Facility Responsible Center (FRC) at DLR, Cologne, Germany, on behalf of the European Space Agency. MUSC is interfacing with the astronauts on orbit and the partners of the ISS ground segment, space hardware developers and the COLUMBUS Control Center. Main MUSC tasks for BIOLAB are increment preparation, experiment optimization and flight qualification, on-orbit operations via telescience, as well as post-increment evaluation. BIOLAB ground models - complemented by hyper-g and µg simulation devices - are available for experiments. DLR MUSC is supported by the specific expertise of BIOTESC (Lucerne, Switzerland). This review encompasses a description of the BIOLAB facility and exemplarily some experiments hitherto flown.

Study on Pilot Transfer Function Model Gain of Closed-Loop Pilot-Vehicle System

Based on the analysis of pilot handling behavior characteristics, this paper establishes the pilot transfer function model. According to the characteristics of closed-loop pilot-vehicle system and the relationship between pilot and flight quality, the specific calculation method of pilot model steady state gain was given. Take the aircraft roll angle manipulation for example, and simulate the pilot's manipulation of aircraft of dynamic process. The results show that: the pilot model steady state gain calculation method is simple and feasible, and have a certain reference value for the analysis of closed-loop pilot-vehicle system.

A Flight Control Scheme to Improve Position Tracking Performance of Rotary-wing UASs

This paper outlines an innovative and feasible flight control scheme for a rotary-wing unmanned aerial system (RUAS) with guaranteed safety and reliable flight quality in a gusty environment. The proposed control methodology aims to increase gust-attenuation capability of a RUAS to ensure improved flight performance when strong gusts occur. Based on the design of an effective estimator, an altitude controller is firstly constructed to synchronously compensate for fluctuations of the main rotor thrust which might lead to crashes in a gusty environment. Afterwards, a nonlinear state feedback controller is proposed to stabilize horizontal positions of the RUAS with gust-attenuation property. Performance of the proposed control framework is evaluated using parameters of a Vario XLC helicopter and high-fidelity simulations show that the proposed controllers can effectively reduce side-effect of gusts and demonstrate performance improvement when compared with the proportional-integral-derivative (PID) controllers.