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Herschel and Planck satellites have recently undergone the thermal vacuum and thermal balance (TVTB) test which was performed in the ESA-ESTEC Large Space Simulator for Herschel and in Centre Spatial de Liège (CSL) for Planck. One of the specific targets of the Herschel test was the verification of the thermal stability of two HIFI units (required to be better than 3.10−4 °C/s) and of the Star Tracker mounting plate (required to be better than 2.5.10−3 °C/s), with particular attention on the performance of the relevant feedback control loops. Control system design and model predictions are presented and compared against the test results. Further discussion on the requirement verification is provided.

Humidity control within confined spaces is of great importance for current NASA environmental control systems and future exploration applications. The engineered multifunction surfaces (MFS) developed by ORBITEC is a technology that produces hydrophilic and antimicrobial surface properties on a variety of substrate materials. These properties combined with capillary geometry create the basis for a passive condensing heat exchanger (CHX) for applications in reduced gravity environments, eliminating the need for mechanical separators and particulate-based coatings. The technology may also be used to produce hydrophilic and biocidal surface properties on a range of materials for a variety of applications where bacteria and biofilms proliferate, and surface wetting is beneficial.

The commercial turbofan trend of increasing bypass ratio and decreasing fan pressure ratio has seen its latest market entry in Pratt & Whitney's PurePower™ product line, which will power regional aircraft for the Bombardier and Mitsubishi corporations, starting in 2013. The high-bypass-ratio, low-fan-pressure-ratio trend, which is aimed at diminishing noise while increasing propulsive efficiency, combines with contemporary business factors including the escalating cost of testing and limited availability of simulated altitude test sites to pose formidable challenges for engine certification and performance validation. Most fundamentally, high bypass ratio and low fan pressure ratio drive increased gross-to-net thrust ratio and decreased fan temperature rise, magnifying by a factor of two or more the sensitivity of in-flight thrust and low spool efficiency to errors of measurement and assumption, i.e., physical modeling.

An aircraft environmental control system (ECS) is commonly designed for a cabin that has been divided into several thermal control zones; each zone has an air flow network that pulls cabin air over an isolated thermocouple. This single point measurement is used by the ECS to control the air temperature and hence the thermal environment for each zone. The thermal environment of a confined space subjected to asymmetric thermal loads can be more fully characterized, and subsequently better controlled, by determining its “equivalent temperature.” This paper describes methodology for measuring and controlling cabin equivalent temperature. The merits of controlling a cabin thermal zone based on its equivalent temperature are demonstrated by comparing thermal comfort, as predicted by a “virtual thermal manikin,” for both air-temperature and equivalent-temperature control strategies.

In several industrial fields, the integration of functions is a key technology to enhance the efficiency of components in terms of performance to mass/volume/cost ratio. Concerning the space industry, in the last few years the trend in spacecraft design has been towards smaller, light-weight and higher performance satellites with sophisticated payloads and instrumentation. Increasing power density figures are the common feature of such systems, constituting a challenging task for the Thermal Control System. The traditional mechanical and thermal design concepts are evidencing their limits with reference to such an emerging scenario.

As aircraft programs currently ramp up, productivity of assembly processes needs to be improved while keeping quality, reliability and manufacturing cost requirements. Efficiency of the drilling process still remains an issue particularly in the case of CFRP/metal stacks: hot and long metallic chips are difficult to remove and often damage the surface of CFRP holes. Low frequency axial vibration drilling has been proposed to solve this issue. This innovative drilling process allows breaking up the metallic chips in such a way that jamming is avoided. This paper presents a case of CFRP/Ti6Al4V drilling on a CNC machine where productivity must be increased. A comparison is made between the current regular process and the MITIS drilling process. First the analysis and comparison method is presented. The current process is analyzed and its limits are highlighted. Then the vibration process is implemented and its performances are studied.

Critical control systems are often built as a combination of a control core with safety mechanisms allowing to recover from failures. For example a PID controller used with triplicated inputs. Typically those systems would be designed at the model level in a synchronous language like Lustre or Simulink, and their code automatically generated from those models. In previous SAE symposium, we addressed the formal analysis of such systems - focusing on the safety parts - using a combination of formal techniques, ie. k-induction and abstract interpretation. The approach developed here extends the analysis of the system to the control core. We present a new analysis framework combining the analysis of open-loop stable controller with those safety constructs. We introduce the basic analysis approaches: abstract interpretation synthesizing quadratic invariants and backward analysis based on quantifier elimination.

This paper is devoted to a method of creating of the automated ballonet system for pressure control inside an airship envelope. Along with the study of the effects of the positional control system parameters, the authors develop novel control scheme. It is based on a new hybrid controller, which combines positional approach to forming the output control signal with a contour of continuous correction of input signal, which defines the pressure drop on the surface of the envelope as a function of the flight altitude. This approach allows reducing the effect of self-oscillations of airship envelope internal pressure on the flight altitude. In order to prove the new approach the mathematical model is being obtained. The results of the derivation and simulations of the control system operation are presented in this paper.

A multi-axis serially redundant, single channel, multi-path FBW (FBW) control system comprising: serially redundant flight control computers in a single channel where only one “primary” flight control computer is active and controlling at any given time; a matrix of parallel flight control surface controllers including stabilizer motor control units (SMCU) and actuator electronics control modules (AECM) define multiple control paths within the single channel, each implemented with dissimilar hardware and which each control the movement of a distributed set of flight control surfaces on the aircraft in response to flight control surface commands from the primary flight control computer, and a set of (pilot and co-pilot) controls and aircraft surface/reference/navigation sensors and systems which provide input to a primary flight control computer and are used to generate the flight control surface commands in accordance with the control law algorithms implemented in the flight control computers.

This paper presents a set of numerical computations with different turbulence model on an air jet flowing tangentially over the curved surface. It has been realized that jet deflection angle and the corresponding thrust are important parameter to determine with great care. Through the grid independence analysis, it has been found that without resolution of the viscous sub-layer, it is not possible to determine the computationally independent angle of jet deflection and boundary layer thickness. The boundary layer analysis has been performed at different radius of curvature and at jet Reynolds number ranging from approximately about 2400-10,000. The boundary layer thickness has been determined at the verge of separation and found a relation with the radius of curvature and jet Reynolds number. The skin-friction coefficient has been also studied at the verge of separation in relation to the surface radius and jet Reynolds number.

Locked wheel protection is an important part of antiskid control for aircraft brake control system. Locked wheel protection compares the wheel speed of two or more wheels, if one of the wheels is too slow, locked wheel protection releases the brake pressure on the slow wheel. This work aims to study the control logic for locked wheel protection. Locked wheel protection control logic consists of 3 key factors: paired wheels, active threshold and inhibit velocity. Focus on comparison different options of these 3 factors, all aspects of control logic for locked wheel protection had been expounded in this study. Simulation and calculation analysis is applied for different locked wheel strategies to evaluate the effect. One conclusion is that the greatest wheel speed of the wheel under control shall be set as a reference speed for locked wheel protection. This study provide the basis to design a proper locked wheel protection function of aircraft brake control system.

This study investigates the self-adjusted cutting parameter technique to improve the drilling of multi-stacked material. The technique consists in changing the cutting strategy automatically, according to the material being machined. The success of this technique relies on an accurate signal analysis, whatever the process setting. Motor current or thrust force are mostly used as incoming signals. Today, analyses are based on the thresholding method. This consists in assigning lower and upper limits for each type of material. The material is then identified when the signal level is stabilized in between one of the thresholds. Good results are observed as long as signal steps are significantly distinct. This is the case when drilling TA6V-CFRP stacks. However, thrust force level remains roughly unchanged for AA7175-CFRP stacks, leading to overlapping thresholds. These boundary limits may also change with tool geometry, wear condition, cutting parameters, etc.

Global aviation is growing exponentially and there is a great emphasis on trajectory optimization to reduce the overall environmental impact caused by aircraft. Many optimization techniques exist and are being studied for this purpose. The CLEAN SKY Joint Technology Initiative for aeronautics and Air transport, a European research activity run under the Seventh Framework program, is a collaborative initiative involving industry, research organizations and academia to introduce novel technologies to improve the environmental impact of aviation. As part of the overall research activities, “green” aircraft trajectories are addressed in the Systems for Green Operations (SGO) Integrated Technology Demonstrator. This paper studies the impact of large commercial aircraft trajectories optimized for different objectives applied to the on board systems.

Radical new electrically propelled aircraft are being considered to meet strict future performance goals. One concept design proposed is a Turboelectric Distributed Propulsion (TeDP) aircraft that utilises a number of electrically driven propulsors. Such concepts place a new and significant reliance on an aircraft's electrical system for safe and efficient flight. Accordingly, in addition to providing certainty that supply reliability targets are being met, a contingency analysis, evaluating the probability of component failure within the electrical network and the impact of that failure upon the available thrust must also be undertaken for architecture designs. Solutions that meet specified thrust requirements at a minimum associated weight are desired as these will likely achieve the greatest performance against the proposed emissions targets.

Environmental Control Systems (ECS) ducts on airplanes are primarily fabricated from aluminum or thermoset composites, depending on temperature and pressure requirements. It is imperative to fabricate lightweight, cost effective, durable, and repairable systems with minimal tooling. It is also important that the duct systems are easy to assemble even with alignment issues resulting from structural variations, tolerance accumulation, variation from thermal expansion of different materials, and inherent duct stiffness. These requirements create an opportunity and need for a technology that can address all of these issues, while increasing performance at the same time. This report provides a background on current ECS ducting systems.

The strategic planning and tactical execution of Air Traffic Control (ATC) provided by Air Navigation Service Providers (ANSP) are often not aligned and lead to inefficiencies in the Air Traffic Management (ATM) system. This paper proposes an analytical framework for the air traffic control system based on a system-of-systems paradigm, with a hierarchy of nested and cascaded feedback control loops—one or more for each type of control service. The framework is then used to assess the stability and response to random variables, such as poor weather and equipment failures. The performance of each control loop is then described qualitatively and validates the framework for investigating the benefit of new policies and technologies.

Many real world engineering systems are sensitive to temperature, and temperature control is vital to the success and operation of a broad spectrum of engineering applications. This paper investigates the use of numerically generated frequency response data to simulate the control system behavior of a simple but realistic finite element based nonlinear thermal model. Using an IDEAS TMG finite element model, a thermal control system Bode plot was computed. The Bode plot was then used to determine the transfer function of the thermal system and design an appropriate control compensator to implement thermal control. The performance of the compensated thermal system was then predicted first by MATLAB, and second by TMG. The response predicted by MATLAB using transfer functions was corroborated by its close agreement with a TMG finite element transient response simulation.

The Swift mission Burst Alert Telescope (BAT) Detector Array thermal control system includes two propylene loop heat pipes (LHPs), eight ammonia constant conductance heat pipes (CCHPs), a radiator that has AZ-Tek's AZW-LA-II low alpha white paint, and precision heater controllers that have adjustable set points in flight. The Power Converter Box (PCB) and Image Processor Electronics (IPE) boxes (a primary and a redundant) of the BAT have Z93P white paint radiators. Swift was successfully launched into orbit on November 20, 2004. The spacecraft (S/C) was placed into a safehold mode on August 10, 2007 after an anomaly on inertial reference unit (IRU) #3. It was returned to inertial pointing on August 16 and instrument power up followed. This paper presents a thermal assessment of the BAT instrument thermal control system (TCS) shut down and recovery as a result of the S/C safehold mode. The recovery required starting up the LHPs manually.

For diesel emission control technologies, reduction efficiencies of Particulate Matter (PM) control systems have been traditionally reported based on mass-based criteria. However, particle number-based criteria are now receiving increased attention. In this paper, results of real-time particle size distribution and number based evaluation of the effectiveness of multiple PM control technologies are reported on an HDD engine. An Engine Exhaust Particle Sizer (EEPS) was used for comparative analysis. The technologies that were evaluated included diesel oxidation catalysts (DOC), a DOC with an uncatalyzed wall-flow filter as a continuously regenerating diesel particulate filter (CR-DPF) system, a DOC with a catalytically coated wall-flow filter as a catalyzed CR-DPF (CCR-DPF), and a DOC with a partial filter as a continuously regenerating partial filter (CR-PF).

The paper presents an innovative approach for the functional specification of complex and highly integrated aircraft control systems, such as the Environmental Control System (ECS), by applying model based specification methods. Complexity and effectiveness of modern ECS have significantly increased during the last few years along with development of new technologies and innovations in control engineering as well as digital data distribution and processing. Efficient management of cabin air flows on the one hand makes the ECS more energy-saving and on the other hand more complex with regard to its functionality and interaction with other interfaced aircraft systems. Numerous data interfaces to other systems and a high degree of automation are typical for a modern ECS. The aircraft manufacturer specifies the entire ECS functions and its interactions within the aircraft.