Cessna Citation Research Articles

Novel Controller Methodology for the Cessna Citation X Under Turbulence During Cruise

The design of a new control approach for the longitudinal motion of the Cessna Citation X during cruise is performed using a combination of sliding mode control (SMC) system, type 1 fuzzy logic system, and adaptive control system. This methodology is presented for 1) controlling the aircraft pitch rate and 2) stabilizing the aircraft speed during turbulence. The nonlinear model of the aircraft was generated using a simulation platform, which was designed based on flight data obtained from the highest Federal Aviation Administration–certified Level-D Research Aircraft Flight Simulator. The type 1 adaptive fuzzy logic system was implemented to approximate unknown functions for constructing the equivalent part of the SMC system that handled the effects of uncertainties and turbulence. The adaptation laws, derived from the Lyapunov theorem, were used to update the approximated functions in the control law at each flight condition and simulation iteration. Using the control systems combination, the pitch rate could follow the given reference signal, while the aircraft speed remained at a reference value with and without turbulence across the whole flight envelope. Results have shown that the proposed controllers satisfied tracking performance while generating smooth elevator deflection, both of which are important for real-aircraft applications.

New Type-2-Fuzzy-Logic-Based Control System for the Cessna Citation X

This paper presents a new control law based on type-2 fuzzy logic system (T2FLS) for the Cessna Citation X aircraft during cruise. This methodology combines three control systems: a T2FLS, a sliding mode control (SMC) system, and an adaptive control system. Differing from conventional controllers, this control system can deal with uncertainties and aircraft dynamics variations using the T2FLS approximator. The approximated functions were updated during the simulation iterations using adaptation laws derived from the Lyapunov theorem. The adaptability characteristic of this controller allows updating the approximated functions while the other design parameters remain unchanged. This fact simplifies the controller design process and eliminates the need to use a group of conventional controllers with different gains to control the aircraft in various flight conditions. In addition, the sliding mode control system helps to guarantee the aircraft’s stability and robustness, along with two other methodologies in the presence and absence of turbulence. The performance of this control methodology was validated with a nonlinear simulation platform developed for the Cessna Citation X business aircraft using accurate flight data derived from a Level D flight simulator at the Research Laboratory in Active Controls, Avionics and AeroServoElasticity (LARCASE).

Enhanced Fuzzy-Based Super-Twisting Sliding-Mode Control System for the Cessna Citation X Lateral Motion

A novel combination of three control systems is presented in this paper: an adaptive control system, a type-two fuzzy logic system, and a super-twisting sliding mode control (STSMC) system. This combination was developed at the Laboratory of Applied Research in Active Controls, Avionics and AeroServoElasticity (LARCASE). This controller incorporates two methods to calculate the gains of the switching term in the STSMC utilizing the particle swarm optimization algorithm: (1) adaptive gains and (2) optimized gains. This methodology was applied to a nonlinear model of the Cessna Citation X business jet aircraft generated by the simulation platform developed at the LARCASE in Simulink/MATLAB (R2022b) for aircraft lateral motion. The platform was validated with flight data obtained from a Level-D research aircraft flight simulator manufactured by the CAE (Montreal, Canada). Level D denotes the highest qualification that the FAA issues for research flight simulators. The performances of controllers were evaluated using the turbulence generated by the Dryden model. The simulation results show that this controller can address both turbulence and existing uncertainties. Finally, the controller was validated for 925 flight conditions over the whole flight envelope for a single configuration using both adaptive and optimized gains in switching terms of the STSMC.

Methodology for Assessing Retrofitted Hydrogen Combustion and Fuel Cell Aircraft Environmental Impacts

Hydrogen (H2) combustion and solid oxide fuel cells (SOFCs) can potentially reduce aviation-produced greenhouse gas emissions compared to kerosene propulsion. This paper outlines a methodology for evaluating performance and emission tradeoffs when retrofitting conventional kerosene-powered aircraft with lower-emission H2 combustion and SOFC hybrid alternatives. The proposed framework presents a constant-range approach for designing liquid hydrogen fuel tanks, considering insulation, sizing, center of gravity, and power constraints. A lifecycle assessment evaluates greenhouse gas emissions and contrail formation effects for carbon footprint mitigation, while a cost analysis examines retrofit implementation consequences. A Cessna Citation 560XLS+ case study shows a 5% mass decrease for H2 combustion and a 0.4% mass decrease for the SOFC hybrid, at the tradeoff of removing three passengers. The lifecycle analysis of green hydrogen in aviation reveals a significant reduction in CO2 emissions for H2 combustion and SOFC systems, except for natural-gas-produced H2 combustion, when compared to Jet-A fuel. However, this environmental benefit is contrasted by an increase in fuel cost per passenger-km for green H2 combustion and a rise for natural-gas-produced H2 SOFC compared to kerosene. The results suggest that retrofitting aircraft with alternative fuels could lower carbon emissions, noting the economic and passenger capacity tradeoffs.

Aeroelastic Analysis of Actuated Adaptive Wingtips Based on Pressure Actuation

Folding wingtips address the challenges posed by high-aspect-ratio wings, such as airport conformity and increased wing root bending moment. Actuated adaptive wingtips extend the functionalities of folding wingtips by using a stiffness-adaptive aeroelastic hinge that is actively adjustable in flight. The objective of this paper is the aeroelastic analysis of a wing equipped with an adaptive-stiffness hinge. While the structural design of the wingtip actuator based on pressure-actuated cellular structures (PACS) was developed in a previous study, in this study the authors verify the concept of actuated adaptive wingtips through aeroelastic analysis. This study shows that the investigated PACS actuator, structurally designed from glass-fiber-reinforced plastic, is capable of bearing the loads acting on the wingtips of a Cessna Citation X. The adaptive-stiffness hinge, positioned between 86.7 and 91.2% of the semispan, reduces the wing root bending moment by up to 7.8% in a 2.5g maneuver load case, while keeping the wing straight in cruise. A further increase in load alleviation potential can be achieved in the future by extending the actuator’s operating envelope and thus increasing its load-bearing capacity. The functional verification of the actuated adaptive wingtip concept by means of aeroelastic analysis forms the basis for the manufacturing and testing of a functional prototype.

Development of an Adaptive Aero-Propulsive Performance Model in Cruise Flight – Application to the Cessna Citation X

To accurately predict the amount of fuel needed by an aircraft for a given flight, a performance model must account for engine and airframe degradation. This paper presents a methodology to identify an aero-propulsive model to predict the fuel flow of an aircraft in cruise, while considering initial modeling uncertainties and performance variation over time due to degradation. Starting from performance data obtained from a Research Aircraft Flight Simulator, an initial aero-propulsive model was identified using different estimation methods. The estimation methods studied in this paper were polynomial interpolation, thin-plate splines, and neural networks. The aero-propulsive model was then structured using two lookup tables: one lookup table reflecting the aerodynamic performance, and another table reflecting the propulsive performance. Subsequently, an adaptative technique was developed to locally and then globally, adapt the lookup tables defining the aero-propulsive model using flight data. The methodology was applied to the Cessna Citation X business jet aircraft, for which a highly qualified level D research aircraft flight simulator was available. The results demonstrated that by using the proposed aero-propulsive performance model, it was possible to predict the aerodynamic performance with an average relative error of 0.99%, and the propulsive performance with an average relative error of 3.38%. These results were obtained using the neural network estimation method.

Identification and Validation of the Cessna Citation X Longitudinal Aerodynamic Coefficients in Stall Conditions using Multi-Layer Perceptrons and Recurrent Neural Networks

The increased number of accidents in general aviation due to loss of aircraft control has necessitated the development of accurate aerodynamic airplane models. These models should indicate the linear variations of aerodynamic coefficients in steady flight and the highly nonlinear variations of the aerodynamic coefficients due to stall and post-stall conditions. This paper presents a detailed methodology to model the lift, drag, and pitching moment aerodynamic coefficients in the stall regime, using Neural Networks (NN). A system identification technique was used to develop aerodynamic coefficients models from flight data. These data were gathered from a level-D Research Aircraft Flight Simulator (RAFS) that was used to execute the stall maneuvers. Multilayer Perceptrons and Recurrent Neural Networks were used to learn from flight data and find correlations between aerodynamic coefficients and flight parameters. This methodology is employed in here to optimize neural network structures and find ideal hyperparameters: training algorithms and activation functions used to learn the data. The developed stall aerodynamic models were successfully validated by comparing the lift, drag, and pitching moment aerodynamic coefficients predicted for given pilot inputs with experimental data obtained from the Cessna Citation X RAFS for the same pilot inputs.

Aircraft Mathematical Model Identification for Flight Trajectories and Performance Analysis in Cruise

In this paper, a mathematical model for estimating the performance and flight trajectories in cruise is identified from data available in flight manuals. The first part of this paper focuses on the design of a fuel flow and emissions model. Starting from the equations of motion of an aircraft in cruise, a simplified model representing the fuel flow in a corrected form was developed. A practical algorithm was next developed to identify the aircraft model parameters and to determine the mathematical structure that reflects its fuel flow. This process was done using performance data available in the aircraft flight crew operating manual. The emissions model was also developed based on data available in the International Civil Aviation Organization’s engine emissions databank. The second part of the paper deals with the development of algorithms for predicting the trajectories and calculating the optimal speeds (i.e., maximum range, long range, and economy) of the aircraft in cruise. Practical techniques for storing and retrieving information without using optimization algorithms have been considered. The methodology was applied on both a Cessna Citation X business jet and Bombardier CRJ-700 regional jet aircraft. The comparison results showed a very good agreement for the fuel consumption and optimal speed.

A Multi-Platform In Situ Kinematic and Microphysical Analysis of a Hybrid Parallel–Trailing Stratiform Mesoscale Convective System

Abstract Parallel stratiform–type mesoscale convective systems (MCS) have been found to comprise less than 20% of the central U.S. MCSs, but parallel stratiform MCSs have been reviewed by few studies and only a handful have been sampled using airborne platforms. This study conducts a detailed review of the 11 May 2011 MCS that was observed during the Midlatitude Continental Convective Clouds Experiment. In situ data from the University of North Dakota Cessna Citation II Weather Research Aircraft and the Oklahoma Mesonet are used in conjunction with radar reflectivity data and a multiple-Doppler wind retrieval to present an in-depth analysis of the kinematic and microphysical processes within this hybrid parallel–trailing stratiform MCS. Results suggest the MCS started with parallel stratiform characteristics and then developed trailing stratiform features over the course of a couple of hours such as leading line convection and the presence of rear inflow, which is a feature not observed in previous studies of parallel stratiform MCSs. Based on surface observations and multi-Doppler wind field retrievals, the cold pool influenced the 11 May 2011 MCS and may have helped it to transition toward the trailing stratiform mode. Within the stratiform region, in situ measurements show hydrometeor aggregation and sublimation occurring above the melting layer via a faster rate of decline in total hydrometer concentration compared to the total water content, the presence of a bimodal droplet size spectra, and increasing dispersion and decreasing slope, with respect to increasing temperature in both the unimodal and bimodal gamma distributions. Significance Statement The purpose of this study is to investigate the wind pattern of a nontypical type of thunderstorm complex. The wind pattern is found to be a combination of features from both a common type of thunderstorm complex and another less common type. The behavior of snowflakes as they fall through this thunderstorm was also investigated. The snowflakes in this storm grew bigger by linking up with other snowflakes as they fell down, and then melted before they reached the ground. It is hoped that results from this study are useful to future work to improve weather prediction.

System-Theoretic Process Analysis for reliability assessment: Aircraft's wheel braking system case study

To conduct reliability studies, Fault-Tree Analysis (FTA) and Failure Mode and Effect Analysis (FMEA) are among the most used methods. However, with the emergence of software and complex modern systems, such analyses are not sufficient anymore. Therefore, System-Theoretic Process Analysis (STPA) was created to solve such problems and conduct safety analyses but was never used for a reliability analysis. This paper presents a reliability study of the Wheel Braking System (WBS) of the Cessna Citation Mustang using STPA, and a comparison study using FMEA. Outputs of both methodologies were compared and showed that STPA produces better results.

An efficient decision support system for selecting very light business jet using CRITIC-TOPSIS method

PurposeThis paper aims to assure the selection of the most suitable very light business aircraft which is preferred by the passengers based on effectiveness and aesthetic comfort. The proposed approach to determine the light business jet aircraft would provide long-range, less travel time, cozy seating arrangements, on-board lavatory facility, other aesthetic ambiance (audio systems, light systems and temperature-noise control) and appliances at reasonable flight cost.Design/methodology/approachThe selection of a light business jet is obtained through multi-criteria decision-making based on the speed limit ranges from 0.57 to 0.70 Mach number and the distance traveled up to 3,000 km with the best aesthetic comfort level. To validate the approach, case studies of five aircrafts such as Honda Jet HA 420, Cessna Citation jet M2, Embraer Phenom 100, Eclipse 550 and Cessna Citation Mustang are performed. To obtain the best suitable business jet, criteria importance through intercriteria correlation (CRITIC) and technique for order performance by similarity to ideal solution (TOPSIS) is used to determine the rankings of listed aircraft.FindingsThe study concludes that the Cessna Citation jet M2 is chosen as the best Very Light Jet (VLJ) on the basis of speed, range, weight, cost, aesthetic and comfort. Based on the sensitivity, mean absolute percentage error (MAPE) and symmetric mean absolute percentage error analysis (sMAPE), the most and least sensitive criteria for a business jet came out to be cost and speed, respectively.Originality/valueA real case study for several parameters of five different jets such as Honda Jet HA 420, Cessna Citation jet M2, Embraer Phenom 100, Eclipse 550 and Cessna Citation Mustang are shown in this paper. Based on the case study numerical values are assigned with speed, range, weight, cost, aesthetic and comfort which are applied with CRITIC and TOPSIS to obtain the most suitable business jet among the five mentioned jets which are rarely found in the literature.

Method for Calculating Aircraft Flight Trajectories in Presence of Winds

This paper presents a practical method to compute the four-dimensional flight trajectories of aircraft in the presence of winds. The proposed method consisted of numerically integrating the aircraft equations of motion over different segments that compose a typical commercial flight profile. For this purpose, the aircraft vertical trajectory was divided into seven typical flight segments: unrestricted climb at constant airspeed, restricted climb at constant airspeed, climb/level-off acceleration, level flight at constant airspeed, unrestricted descent at constant airspeed, restricted descent at constant airspeed, and descent/level-off deceleration. For each segment, detailed algorithms were designed to solve and then integrate the equations of motion using an Euler scheme. The lateral trajectory, on the other hand, was constructed by connecting a series of waypoints with straight and turn segments. The method was applied and validated on the well-known Cessna Citation X business jet, for which a qualified research aircraft flight simulator (RAFS) was available. A total of 130 tests were carried out with the RAFS over a wide range of operational conditions. The comparison results showed that the trajectory data predicted by the algorithms matched the trajectory data obtained from the RAFS with less than 5% relative errors.

Cessna Citation X Takeoff and Departure Trajectories Prediction in Presence of Winds

This paper presents a method developed at the Laboratory of Applied Research in Actives Controls, Avionics, and AeroServoElasticity for calculating takeoff and departure trajectories of a Cessna Citation X business aircraft. The method consisted of integrating the aircraft equations of motion for each segment corresponding to a typical takeoff and departure profile. For this purpose, the aircraft trajectory was divided into five segments, including ground acceleration, rotation, transition, climb at constant speed, and climb acceleration. For each segment, detailed and flexible algorithms were developed in order to solve the equations of motion, as well as to trim the aircraft under different environmental and operating conditions. In addition, techniques for modeling piloting procedures and reduced takeoff thrust operations were also presented. The moment equation was also included in the methodology to estimate the elevator deflection or the horizontal stabilizer position required to hold a given pitch attitude. The validation of the methodology was evaluated with a qualified research aircraft flight simulator (RAFS) of the Cessna Citation X for a total of 38 tests. Results showed that the trajectory data predicted by the different algorithms matched the trajectory data obtained from the RAFS with less than 5% of error.

Variable Stability In-Flight Simulation System Based on Existing Autopilot Hardware

A variable stability in-flight simulator has the capabilities to change the response of an aircraft in-flight, often without changing the physical properties of the aircraft. The ability to adjust the aircraft response characteristics and handling qualities has various purposes, such as pilot training, control system development, and handling quality research. A variable stability control system is designed for a medium-range business jet using incremental nonlinear dynamic inversion. The performance of the in-flight simulator is verified by two experiments, one conducted in a fixed-base flight simulator and one in a Cessna Citation II laboratory aircraft. The fly-by-wire actuation system in the Cessna Citation II is based on its existing autopilot, inheriting the limited performance and safety protections. The simulator experiment shows differences between the experienced handling qualities for a reference model and the designed controller combined with aircraft dynamics. These differences mainly arise due to actuator saturation for specific handling quality settings. The in-flight experiment supports the simulator findings but also reveals how the available control authority around the initial condition is limited due to constraints of the fly-by-wire system.

Design and flight test of a linear parameter varying flight controller

Future aircraft generations require improved performance and efficiency to enable a reduced environmental footprint. To acquire this goal, for example new material and wing concepts are perused at the moment by the aircraft industry. These developments, which include aspects such as over-actuation and lowly damped flexible modes, give rise to more complex, multi-objective control problems. One candidate method, which delivers a solution to these problems for the whole flight envelope, is linear parameter varying (LPV) control. It naturally incorporates the controller scheduling in the synthesis process, guarantees stability and robustness over the entire parameter envelope, and enables intuitive multi-objective, multiple-input multiple-output (MIMO) controller designs. This paper proves the concept of LPV control in practice: The paper presents and discusses the LPV controller design process, simulation results, motion simulator test and finally, the in-flight validation of the control system on a Cessna Citation II aircraft. The developed inner loop controller structures are inspired by classical flight controllers used on state-of-the-art fly-by-wire airliners. The longitudinal aircraft motion is augmented with load-factor command and the lateral motion controller features a roll rate command with attitude hold behavior. The control laws are validated in flight by automated and actual pilot inputs with respect to functionality, flying and handling qualities. Test results are encouraging with the provided key findings and lessons learned aiming to provide a simplification for future LPV flight controller development and testing campaigns.

New Methodology for Aircraft Performance Model Identification for Flight Management System Applications

This paper presents the validation results of a study conducted at the Laboratory of Applied Research in Actives Controls, Avionics, and Aeroservoelasticity to develop a modeling technique for determining a performance model of a particular aircraft using a limited amount of data. This technique was applied to the well-known business jet aircraft, Cessna Citation X. All the reference data used to design the model were generated using an in-house in-flight performance program. These data were subsequently combined with simplified flight mechanics equations in order to estimate various performance and aero-propulsive characteristics of the aircraft. An original identification algorithm was next developed in order to determine a mathematical model describing the fuel flow, as well as the aircraft thrust and drag aerodynamic coefficients. Validation of the study was accomplished by comparing trajectory data predicted by the model with trajectory data measured with a research aircraft flight simulator (RAFS) of the Cessna Citation X. The results show a very good agreement for the flight time, the ground distance traveled, and fuel consumption.

New Adaptive Algorithm Development for Monitoring Aircraft Performance and Improving Flight Management System Predictions

To compute the most efficient route that the aircraft has to fly, the flight management system (FMS) needs a mathematical representation of the aircraft performance. However, after several years of operation, various factors can degrade the overall performance of the aircraft. Such degradation can affect the reliability of the aircraft model, and the crew would lose confidence in the fuel planning estimated by the FMS. This paper presents the results of a study in which a new adaptive algorithm is proposed for continuously updating the FMS performance model using cruise flight data. The proposed algorithm combines aircraft performance monitoring techniques with adaptive lookup tables to model the aerodynamic characteristics of the aircraft. The methodology was applied to the well-known Cessna Citation X business aircraft, for which a research aircraft flight simulator was available. The development of this methodology was accomplished by creating an initial performance model, adapting it using flight data in cruise, and finally comparing its prediction with a series of flight data collected with the flight simulator. Results have shown that the proposed methodology was able to reduce fuel flow prediction mean errors by about 5%, whereas the standard deviation was reduced by a factor of 3.4.

Modelling and Simulation of Gas Turbine Blade with Different Geometrical Perforated Holes and Blade Materials: Software Analyses

In the gas turbine, the power is generated at higher temperature and large magnitude, the results of which it generates lots of heat, so the cooling of turbine blade is very much required. Geometrical changes in the gas turbine blade as well as the changes in designs of turbine, which may be in the form of perforations, are required for the optimization and efficient cooling. In the present work, effects of perforations on the turbine blade have been studied for small jet engine gas turbine manufactured by Williams International for CJ1 (Cessna Citation Jet ) Model 525 engine by improving its geometry using the software called CATIA and also analyses at different boundary conditions by the analysis software called as ANSYS 14.0 workbench. Material of the turbine blade has also been optimized to improve performance of the gas turbine. After analyses, maximum temperature at tip i.e. 1050°C and minimum heat flux i.e. 509.99 W/m2 have been found for INCONEL-718 blade material without holes but the minimum temperature at tip i.e. 971°C and maximum heat flux i.e. 575.73 W/m2 have been achieved for NIMONIC-115 with holes which are good for gas turbine blade. In this research work NIMONIC-115 has been recommended as blade material and hole in the blade geometry has been suggested as improvement in the design of blade.

An innovative analytic redundancy approach to air data sensor fault detection

ABSTRACTThis article presents a potential analytic redundancy approach to detect faults in the air data sensor of an aircraft. In modern aircraft, fault detection of air data sensors is performed using a complex voting mechanism, which requires the availability of redundant air data sensor in all situations. However, to continuously monitor operation and performance of these sensors, the analytic redundancy-based air data estimation and fault detection is highly preferred than estimation with air data probe measurements. The proposed algorithm uses the kinematics of aircraft to estimate air data and detect air data sensor fault. In this paper, a simple mathematical model is developed, which does not consider the forces and moments acting on aircraft and uses measurements only from the Inertial Measurement Unit (IMU) and Navigation System Data (NSD). In order to implement this approach, the Iterated Optimal Extended Kalman Filter (IOEKF) is developed to estimate air data, which provides an accurate and stable estimation. With the estimated states, the physical air data sensor measurements are compared and the residual is calculated to track each sensor performance and to detect the occurrence of a fault. The key advantage of this approach is that it does not require complex dynamic equations and is free from system uncertainties. The proposed algorithm is simulated in MATLAB software using flight simulator flight data and validated using the real-time flight data of Cessna Citation II transport aircraft.

Identification and Validation of an Engine Performance Database Model for the Flight Management System

This Paper presents the validation studies results of an engine mathematical performance model identification for flight management system trajectory prediction and optimization applications. The methodology was applied to the Cessna Citation X business aircraft, for which the aircraft flight manual and the flight crew operating manual are available. In addition, another data source based on computerized trajectory was also used to generate several climb and descent flight profiles required in the engine model identification process. To demonstrate and further validate the accuracy of the proposed engine performance model, a level-D research aircraft flight simulator of the Cessna Citation X was used as a reference. According to the Federal Aviation Administration (FAA, AC 120-40B), level D corresponds to the highest qualification level for the flight dynamics and engine modeling. Validation of the methodology was accomplished by comparing the prediction model with a series of flight data collected with the flight simulator for different flight conditions and different flight phases including takeoff, climb, cruise, and idle descent. Comparison results were validated with a tolerance of for each engine performance predicted by the model in terms of fan speed, core speed, thrust, and fuel flow.