Aircraft Flight Test Research Articles

Taranis and beyond: inspiring aerodynamic capability

AbstractIn his 1916 book,Aircraft in Warfare, the Dawn of the Fourth Arm, F.W. Lanchester wrote:“The supremacy of British aircraft can only be maintained by the adoption of a thoroughly progressive constructional policy, guided constantly by the most recent scientific discovery and research, and by utilising to the full information and experience gained in the Services.”The recent successful flight trials of the Taranis low-observable unmanned demonstrator aircraft provide the latest evidence of the UK’s continued capacity for the entire design, development, manufacture, and flight testing of world-leading combat aircraft, particularly with regard to Aerodynamics. Taranis is both the culmination of many years’ research and development in the UK and a starting-point for the next generation of UK combat air systems.In this lecture, Taranis is reviewed, in such detail as current sensitivities will allow, in the wider context of UK combat aircraft aerodynamic capability, exemplified by the leading roles taken by the UK in the Tornado and Typhoon programmes and the important contribution made to the development of the F-35 Lightning II Joint Strike Fighter.The immediate technical challenges associated with the aerodynamic design and qualification of a low-observable air vehicle are considerable. In this instance they have been compounded by the balanced view taken within the project of trade-offs against many parameters. However, the UK aerodynamics community faces equally stringent challenges in terms of the identification and delivery of the most appropriate future systems; increasingly complex and demanding operational and functional requirements; and, perhaps most of all, maintaining an affordable and cost-effective capability in the face of strict budgetary pressures and austere economic conditions.Nevertheless, those challenges are accompanied by a wide range of opportunities, namely for national and international partnership; radically innovative engineering solutions and approaches; new thinking; and the engagement of the best minds and ideas in the UK academic community.Taranis represented a big integration task, requiring a particular set of skills to pull together the total package, resting on a bedrock of mastery of the technical issues. It has been an inspirational experience for those of us who have worked on it. It has demonstrated that the UK is capable of achieving the most demanding current and anticipated military aerodynamic requirements and has signposted the way to an exciting and nationally important future.

Interacting Multiple Mode Tracking Algorithm Based on Modified Coordinate Turn Model

The continuing success of near space hypersonic aircraft flight test has become a real threat to China's space attack-defense system, In view of the problem that the single model cannot track such target effectively, an interacting multiple model (IMM) tracking algorithm based on modified cornering model (MCT) was proposed. First the characteristics of near space hypersonic target were analyzed, and then the target real-time angular velocity according to the target motion equation was estimated, finally the near space hypersonic target tracking through the IMM was carried out. The Monte Carlo simulation results show that the IMM tracking algorithm can effectively track near space hypersonic target, and the tracking accuracy and stability are superior to single model, it has certain practical significance.

SISTEM PENGENDALIAN JARAK TERBANG PADA PESAWAT QUADCOPTER UNTUK MENGHINDARI LOSS OF CONTROL

This research is to uncover the events spiral out of control ( out of control ) that often occurs at the plane quadcopter causing loss or damage. The importance of taking this topic because the results of the research will be of great benefit in the development of microelectronic technology , especially for the design of UAV aircraft in Indonesia. Sequence starting from designing the study continued until the plane quadcopter flight test. Reliability and accuracy control flying distance flight test conducted and supported by the increase in equipment and repair kirnerja control algorithm. Success of the flight test aircraft reliability and security, determined on setting position effective control distance . Most aircraft can not transmit information if the aircraft in unsafe conditions distance position . Benefits and the subsequent development of this quadcopter eg sensor system to detect and send the data somewhere air conditions can be developed. For aerial photography at an affordable cost while the control plane algorithms can be applied to steer the rocket to the right targets. Thus the results of the design and control algorithms on the plane quadcopter distance is very useful for science and the general public.

SISTEM PENGENDALIAN JARAK TERBANG PADA PESAWAT QUADCOPTER UNTUK MENGHINDARI LOSS OF CONTROL

This research is to uncover the events spiral out of control ( out of control ) that often occurs at the plane quadcopter causing loss or damage. The importance of taking this topic because the results of the research will be of great benefit in the development of microelectronic technology , especially for the design of UAV aircraft in Indonesia. Sequence starting from designing the study continued until the plane quadcopter flight test. Reliability and accuracy control flying distance flight test conducted and supported by the increase in equipment and repair kirnerja control algorithm. Success of the flight test aircraft reliability and security, determined on setting position effective control distance . Most aircraft can not transmit information if the aircraft in unsafe conditions distance position . Benefits and the subsequent development of this quadcopter eg sensor system to detect and send the data somewhere air conditions can be developed. For aerial photography at an affordable cost while the control plane algorithms can be applied to steer the rocket to the right targets. Thus the results of the design and control algorithms on the plane quadcopter distance is very useful for science and the general public.

Numerical simulations of the lightning attachment points on airplane based on the fractal theory

Determination of the aircraft lightning attachment points which can provide the basis for the design of aircraft lightning protection, is a prerequisite for the division of lightning strike zones and the lightning test of aircraft components. In this paper, a novel numerical simulation method based on fractal theory is presented to simulate lightning attachment points on airplane. Firstly, the discharge gap distance, lightning starting coordinates, aircraft attitudes, discharge times and other parameters are determined according to the relevant provisions about aircraft lightning attachment point test in standard SAE-ARP5416. Then, according to the fractal theory, the dielectric breakdown model is used to simulate the fractal growth of the lightning leaders, which accords with physical mechanisms and geometric characteristics of nature lightning. Finally, considering the case where the aircraft itself triggers the bi-directional leader, we obtain the distribution of aircraft lightning attachment points. Because the probability distribution of lightning attachment points on aircraft F-4 obtained through the simulating is almost in line with those obtained through actual aircraft flight test and laboratory test, the proposed method is verified. The proposed method provides a potential way of simulating the lightning attachment points on aircraft. And this method can be used as the foundation of the aircraft lightning protection design and future related research work.

Numerical Simulation for Lightning Zoning on an Aircraft

In this paper, a numerical simulation method based on fractal theory is presented to simulate lightning attachment points on airplane. The dielectric breakdown model is used to simulate the fractal growth of the lightning leaders, which meets physical mechanisms and geometric characteristics of nature lightning. The process of the airplane struck by lightning is simulated according to the relevant provisions about aircraft lightning attachment points test in standard SAE-ARP5416. The distribution of aircraft lightning attachment points are obtained through substantial repeated simulation. Because the probability distribution of lightning attachment obtained through the simulating is almost in line with those obtained through actual aircraft flight test, the validity of the proposed method is verified.

An evolutionary optimizing approach to neural network architecture for improving identification and modeling of aircraft nonlinear dynamics

In this paper, modified genetic algorithm has been used as a simultaneous optimizer of recurrent neural network to improve identification and modeling of aircraft nonlinear dynamics. Weighted connections, network architecture, and learning rules are features that play important roles in the quality of neural networks training and their generalizability in order to model nonlinear systems. Therefore, the main focus of this paper is to apply appropriate evolutionary methods in order to simultaneously optimize the parameters of neural networks for the improvement identification and modeling of aircraft nonlinear dynamics. To validate this study, the results have been compared with the recorded data from a fourth generation highly maneuverable fighter aircraft flight test. Furthermore, having been compared to normal genetic algorithm, the results of the present study have showed significant improvement of the neural networks generalization which leads to better identification and modeling of aircraft nonlinear dynamics.

Cessna Citation X Aircraft Global Model Identification from Flight Tests

During an aircraft development, mathematical models are elaborated from its characteristics, physical laws and modeler prior knowledge of the system. Once the aircraft built, those models (mainly linear models) are tuned with flight test recorded data. Regulation authorities define the precision needed for such models. The purpose of this paper is to build an aircraft global model complying with regulation authorities’ accuracy requirements with minimal prior knowledge of the system. A professional D level simulator has been used as a flight test aircraft. More than 1,000 experimental flight tests were made with numerous configurations in speed (140 to 240 kt), altitude (10,000 to 46,300 ft), mass (24,000 to 33,000 lb) and the center of gravity position (17 to 34 % of the mean aerodynamic chord). Aircraft’s global model is built by identifying linear models at flight points within aircraft flight envelop and the center of gravity limits. Those models are then interpolated to provide a linear model within all the aircraft flight envelop and the center of gravity limits. Linear model identification and interpolation provide accurate results for aircraft’s short period mode. To our knowledge, it’s the first time a study on this subject is conducted from flight test realization to model identification.

An Experimental and Theoretical Investigation of Wave Propagation in Teflon and Nylon Tubing With Methods to Prevent Aliasing in Pressure Scanners

Accurate static and dynamic pressure measurements provide the feedback needed to advance gas turbine efficiency and reliability as well as improve aircraft design and flight control. During turbine testing and aircraft flight testing, flush mounting pressure transducers at the desired pressure measurement location is not always feasible and recess mounting with connective tubing is often used as an alternative. Resonances in the connective tubing can result in aliasing within pressure scanners even within a narrow bandwidth and especially when higher frequency content dc to ∼125 Hz is desired. We present experimental results that investigate tube resonances and attenuation in 1.35 mm inner diameter (I.D.) (used on 0.063 in. tubulations) and 2.69 mm I.D. (used on 0.125 in. tubulations) Teflon and Nylon tubing at various lengths. We utilize a novel dynamic pressure generator, capable of creating large changes in air pressure (<1 psi to 10 psi, <6.8 kPa to 68.9 kPa), to determine the frequency response of such tubing from ∼1 Hz to 2800 Hz. We further compare these experimental results to established analytical models for propagation of pressure disturbances in narrow tubes. While significant theoretical and experimental work relating to the frequency response of connective tubing or transmission lines has been published, there is limited literature presenting experimental frequency response data with air as the media in elastic tubing. In addition, little progress has been made in addressing the issue of tubing-related aliasing within pressure scanners, as the low sampling rate in scanners often makes postprocessing antialiasing filters ineffective.

Gray bootstrap method for estimating frequency-varying random vibration signals with small samples

During environment testing, the estimation of random vibration signals (RVS) is an important technique for the airborne platform safety and reliability. However, the available methods including extreme value envelope method (EVEM), statistical tolerances method (STM) and improved statistical tolerance method (ISTM) require large samples and typical probability distribution. Moreover, the frequency-varying characteristic of RVS is usually not taken into account. Gray bootstrap method (GBM) is proposed to solve the problem of estimating frequency-varying RVS with small samples. Firstly, the estimated indexes are obtained including the estimated interval, the estimated uncertainty, the estimated value, the estimated error and estimated reliability. In addition, GBM is applied to estimating the single flight testing of certain aircraft. At last, in order to evaluate the estimated performance, GBM is compared with bootstrap method (BM) and gray method (GM) in testing analysis. The result shows that GBM has superiority for estimating dynamic signals with small samples and estimated reliability is proved to be 100% at the given confidence level.

Improvement of the Military academy education system for aeronautics students using the flying laboratory

This article describes a proposal to improve the educational process for the students of the Military Academy to support the maintenance of the Serbian Army aircraft based on the introduction of the subject called Aircraft Flight Tests. The article particularly emphasizes the importance of establishing aircraft laboratories with the basic characteristics of the test-measuring equipment necessary to be integrated into the aircraft in order to realise practical tests of an aircraft in flight. The formation of aircraft laboratories would form a very strong didactic tool which would provide an optimal synthesis of theory and practice. This concept of improving the educational process would substantially raise the awareness of the necessity of cooperation and involvement of all research capacities of the scientific institutions in the Ministry of Defense of the Republic of Serbia.

A Response Surface Methodology for Modeling Time Series Response Data

This article introduces extensions to classical response surface methods specifically for modeling and exploiting time series response data such as found in aircraft flight test. Classical response surface methods focus on the analysis of discrete response data. In some complex, nonlinear systems, analysts are concerned with the behavior of time series response data. To date, there does not appear to be any formal methods for examining and exploiting these data within a response surface framework. Thus, a mathematical framework is defined and then demonstrated through a sample analysis of empirical flight test data. Copyright © 2012 John Wiley & Sons, Ltd.

Measuring and Recording Systems Used in Flight Tests of Aircraft

Flight tests and measurements are usually performed for newly built or modernised aircraft utilised by the Polish Armed Forces. In the course of flight tests the airborne equipment is also investigated. The main goal of the performed tests is to verify tactical performance and to identify technical parameters of aircraft and/or equipment under examination. The airborne experimental data is also applied to the aircraft flight dynamics modelling, subsequently used for the design and construction of a flight simulator. The equipment is usually arranged of the following components: ̶ sensors/measuring devices capable of converting physical parameters into optical, mechanical, or electrical signals (indicators, transmitters, sensors, transducers); ̶ conditioning systems - intermediary devices used to amplify and/or adjust any signal gained to some required value or form; ̶ recording and storing devices (data recorders, cameras, etc.); ̶ devices applied to the decoding and processing of the acquired data (decoders, computers). Some selected problems of aircraft flight tests will be discussed in the paper. A brief description of the applied experimental apparatus will be provided first. Next, the attention will be focused on the experimentally gathered data utilised in the identification of aircraft flight dynamics characteristics and on the data applied to the evaluation of selected design parameters.

Study on the Electromagnetic Environment of the Inner and Outer Fuselage and the Hazard of the Environment to Electro-Explosive Systems

To meet the air emergency evacuation needs of aircraft flight test team members, we developed the air emergency opening system of aircraft service port. During the flight tests, the probability of false triggering of the electro-explosive system used in the emergency opening system is called for not more than 0.001 in the confidence of not less than 90% under the interference of external electromagnetic radiation, and when the aircraft experience an emergency, the electro-explosive system can work reliably according to the preestablished instructions to detonate the detonation power unit of the emergency opening system, and the service port will be pushed into the cabin fast and accurately, so that the aircrew could bail out of the aircraft by the barrier-free access. Therefore, this paper examines the electromagnetic radiation environment of the inner and outer fuselage of the aircraft, and then analyzes the hazard of the electromagnetic environment to the electro-explosive system of the emergency opening system as a base for the safety design of the anti-electromagnetic radiation of the emergency opening system.

Active Control of Smart Fin Model for Aircraft Buffeting Load Alleviation Applications

Following the program to test a hybrid actuation system for high-agility aircraft buffeting load alleviation on the full-scale F/A-18 vertical fin structure, an investigation has been performed to understand the aerodynamic effects of high-speed vortical flows on the dynamic characteristics of vertical fin structures. Extensive wind-tunnel tests have been conducted on a scaled model fin integrated with piezoelectric actuators and accelerometers to measure the aft-tip vibration responses under various freestream and vortical airflow conditions. Test results demonstrated that the airflow induced considerable damping to the fin structure, which generally increased with airflow speed as well as the vertical fin angle of attack relative to the airflow direction. Moreover, it was observed that at the angle of attack of 10 deg, the high-speed airflow introduced large deflection to the smart fin structure and caused significant frequency shift to the vibration modes due to nonlinear geometrical coupling of bending and torsional modes. These aerodynamic effects may adversely affect the performance and robustness of the closed-loop control laws developed based on vertical fin dynamic model identified without considering the varying aerodynamic effects. To explore this problem, the structured singular values synthesis technique was adopted to develop robust control law using smart fin model identified without aerodynamic excitations, and the aerodynamic effects on the fin structure were assumed as smart fin parametric and dynamic uncertainties. The effectiveness and robust performance of the control law was demonstrated through extensive closed-loop wind-tunnel tests using various airflow conditions. This provided a verified control law design strategy for future flight tests of the full-scale aircraft buffeting load alleviation system.

Predicting the response of low-aspect ratio, flexible aircraft

AbstractAccurate prediction of the response of low-aspect ratio, flexible aircraft requires correspondingly accurate modeling of the aircraft itself and of the aerodynamic forces, both respectable problems. Assuming that the wing can be modeled as a nonuniform plate, the discretisation process of choice is the finite element method (FEM), which demands a very large number of degrees of freedom for good accuracy. Moreover, accurate modeling of the aerodynamic forces acting on the aircraft suggests the use of computational fluid dynamics (CFD), which requires the use of an extremely large number of variables. On the other hand, feedback control design for the aircraft demands an aircraft model of relatively small order, so that the dimension of the FEM and CFD models must be reduced drastically. Based on physical considerations, reasonably accurate model reductions can be achieved, but a problem remains because the FEM and CFD grids are likely to differ from one another. It is shown in this paper how to achieve desirable model reductions for both the FEM and CFD and how to integrate the aerodynamic forces into the aircraft state equations. A numerical example demonstrates how the theory can be applied to the flight of a flexible aircraft. The analytical/computational approach developed here should permit parametric studies ultimately resulting in a reduction in the time required for aircraft design and flight testing.

Robust Nonlinear Model Predictive Control With Partial State Information

A nonlinear controller methodology is developed based on nonlinear model predictive control and set-membership estimation, resulting in a controller which is robust to model uncertainties and bounded noise sources. The model predictive control makes direct use of the estimated bounds of the states and model parameters through integration as constraints in the optimization problem. This results in lower computation times and the ability to satisfy constraints with partial state information. Stability of the integrated estimation and control algorithm is guaranteed through the use of a contractive terminal cost. Real time implementation is developed through a unique sequential quadratic programming solver, which develops an initial feasible solution very quickly, and continues to optimize as time allows. The estimation and control algorithm is demonstrated in software simulation, hardware simulation, and in uninhabited aircraft flight tests. A formation flight example consisting of two aircraft is presented, showing how the controller can maintain a formation within given constraints and avoid collisions while in the presence of noise. Real time flight control results for an autonomous airplane demonstrate the capability of the algorithms to control a nonlinear aircraft in real time around a suddenly appearing threat, thus avoiding collisions.

Flight simulation and testing of the FanWing experimental aircraft

PurposeThis paper aims to create an accurate computer‐based flight simulation of the FanWing experimental aircraft. The model would then be used to record and document the aircraft's performance and handling qualities.Design/methodology/approachThe project consisted of three phases. The first was to simplify and convert existing aerodynamic data into a form that was compatible with the simulation software. The second phase involved the development of the model, and the third, flight testing.FindingsThe aircraft performance and handling qualities of the aircraft were recorded in all flight phases.Research limitations/implicationsThe FanWing's aerodynamics are unusual and software limitations prevented its characteristics from being implemented directly. This meant that certain flight tests could not be carried out accurately.Practical implicationsThe model will likely be used as a preliminary training tool for the FanWing's first pilots. It is also a useful publicity tool for the aircraft, and provides an insight into how this unusual aircraft flies, from a pilot's perspective.Originality/valuePrior to this research, only aerodynamic data had documented the aircraft's performance. The simulation model allowed for conventional flight data to be recorded, and compared with similar aircraft.

Flight flutter testing and aeroelastic stability of aircraft

Purpose – To provide a general review of the flight flutter test techniques utilized in aeroelastic stability flight testing of aircraft, and to highlight the key items involved in flight flutter testing of aircraft, by emphasizing all the main information processed during the flutter stability verification based on flight test data.Design/methodology/approach – Flight flutter test requirements are first reviewed by referencing the relevant civil and military specifications. Excitation systems utilized in flight flutter testing are overviewed by stating the relative advantages and disadvantages of each technique. Flight test procedures followed in a typical flutter flight testing is described for different air speed regimes. Modal estimation methods, both in frequency and time domain, used in flutter prediction are surveyed. Most common flight flutter prediction methods are reviewed. Finally, key considerations for successful flight flutter testing are noted by referencing the related literature.Findings ...

Flight Tests of the KO-1 Aircraft at Night

The KO-1 aircraft which has the functionality of tactical observation, was successfully developed in August of 2004 in South Korea. It is important for the KO-1 aircraft to achieve successful missions at nighttime as well as during daytime. The aircraft, equipped with interior and exterior lighting systems and lighting control panel modified from those of the KT-1 basic trainer, provides improved safety, operational effectiveness, and situational awareness during operation at night when used with night-vision goggles (NVGs). KO-1 is the first domestic aircraft that utilizes the night-vision imaging system (NVIS) technology in Korea. KO-1 NVIS was developed with the goal of defining the components of NVIS and establishing test and evaluation procedures for both the subsystems and main system. In this paper, we present the establishment of a KO-1 NVIS lighting system, NVIS component development, and representative ground and flight test results.