Mark Voskuijl

Flight Mechanics Modeling of the PrandtlPlane for Conceptual and Preliminary Design

The conceptual and preliminary design of a 300-passenger box-wing aircraft configuration, designated the PrandtlPlane, is investigated. Currently there are still a number of technical issues which must be investigated thoroughly to demonstrate the feasibility of this configuration. This research study is focused on two aspects of the PrandtlPlane design, (1) the propulsion system and (2) the flight control system. A nonlinear aircraft model is created with an in-house developed flight mechanics toolbox, which is designed for its application in the conceptual and preliminary design phase. The resulting propulsion system design has two conventional turbofan engines at the tail of the aircraft. For a large version of the PrandtlPlane, it might be beneficial to consider large open-rotor systems underneath the rear wing. The volume of the wing system, which is smaller than that of conventional aircraft, poses constraints on the fuel system design. Flight control of the PrandtlPlane is quite different from the control of conventional aircraft. If control surfaces are placed on the front and rear wings, then a pure moment can be created by differential deflection of these controls. Furthermore, a combined deflection of the front and rear wing control surfaces allows the use of direct lift control. The aircraft exhibits good inherent handling qualities in the longitudinal axis. The Dutch roll mode is slightly unstable. Improvements are expected if the vertical tails of the aircraft are redesigned. Finally, a model-based inversion flight control law is presented which provides a rate command response type in all axes. An additional outer control loop is designed which provides direct lift control. The control law is tested on the nonlinear aircraft model and demonstrates the potential of the PrandtlPlane control characteristics.

Automated generation of multiphysics simulation models to support multidisciplinary design optimization

To ensure a consistent design representation for serving multidisciplinary analysis, this research study proposes an intelligent modeling system to automatically generate multiphysics simulation models to support multidisciplinary design optimization processes by using a knowledge based engineering approach. A key element of this system is a multiphysics information model (MIM), which integrates the design and simulation knowledge from multiple engineering domains. The intelligent modeling system defines classes with attributes to represent various aspects of physical entities. Moreover, it uses functions to capture the non-physical information, such as control architecture, simulation test maneuvers and simulation procedures. The challenge of system coupling and the interactions among the disciplines are taken into account during the process of knowledge acquisition. Depending on the domain requirements, the intelligent modeling system extracts the required knowledge from the MIM and uses this first to instantiate submodels and second to construct the multiphysics simulation model by combining all submodels. The objective of this research is to reduce the time and effort for modeling complex systems and to provide a consistent and concurrent design environment to support multidisciplinary design optimization. The development of an unstable and unmanned aerial vehicle, a multirotor UAV, is selected as test case. The intelligent modeling system is demonstrated by modeling thirty-thousand multirotor UAV designs with different topologies and by ensuring the automatic development of a consistent control system dedicated for each individual design. Moreover, the resulting multiphysics simulation model of the multirotor UAV is validated by comparing with the flight data of an actual quadrotor UAV. The results show that the multiphysics simulation model matches test data well and indicate that high fidelity models can be generated with the automatic model generation process.

Conceptual Design of a Magnetic-Assisted Take-Off System for Mid-Range Transport Aircraft

Due to ever stricter regulations on noise production it has become more difficult for airports to expand. By adding a ground-based propulsion system airplanes can accelerate to higher lift-off speeds and climb faster. Such a system is presented in this paper and the associated take-off performance characteristics are analyzed. Since 80% percent of all take-offs from Schiphol airport are performed by airplanes weighing less than 90 metric tons, the take-off system was sized for this airplanes falling in this catergory. The system consists of a cart, which is magnetically propelled by a linear motor. The cart has been designed to produce a propulsion force of 227kN. This force is transferred to the airplane via a launch bar of 4.5m which connects to the keel beam of the airplane, ahead of the most forward position of the center of gravity. Automatic positioning of the launch bar is ensured by two hydraulic actuators and the motion of the cart. To assess the potential impact of the ground-based take-off system six different take-off scenarios were investigated, three of which included an increased lift-off speed of 100m/s. Results show that depending on the take-off scenario a 20% reduction in awakenings is possible for a single departure from Schiphol airport. Furthermore, alternative take-off scenarios show a 60% reduction in fuel burn or a 20% decrease in required take-off field length. These figures illustrate the potential benefit of a magnetic-assisted take-off system.

Take-Off and Landing Using Ground-Based Power-Simulation of Critical Landing Load Cases Using Multibody Dynamics

AbstractA novel take-off and landing system using ground-based power is proposed in the EU-FP7 project GABRIEL. The main feature of this system is the complete removal of the landing gear from civil aircraft. The proposed system has the potential to reduce aircraft weight, emissions, and noise. A feasibility study of the structural design of the connection mechanism between aircraft and ground system has been performed by simulating the landing procedure on a moving ground system. One of the key challenges is the landing on a moving ground system under high crosswind conditions. The main focus in the current research is the calculation of the critical dynamic loads on both aircraft and ground system for a wide range of landing conditions (sink rate, velocity differences between aircraft and ground system, etc.). For comparison, conventional landing procedures with a traditional landing (TL) gear have also been simulated. The aerodynamics of the aircraft is represented by an accurate empirical model. The r...

Nonlinear Attitude Control Laws for the Bell 412 Helicopter

Helicopters generally exhibit a ratelike response type in pitch and roll axes, and when feedback control is used to increase the level of augmentation to provide attitude command and attitude hold, there is generally a reduction in performance. Use of nonlinear elements in the control system can lead to recovery of some of this performance. The paper investigates such use of nonlinearities in the pitch control loop of a helicopter with a full-authority digital fly-by-wire control system. The nonlinear elements are used to specify the rate of response and thus the attitude quickness. Describing function analysis was used to test compliance with the relative stability requirements of MIL-F-9490D. The control laws were successfully flight-tested on a Bell 412 modified for fly-by-wire research and results from those tests are presented. Control laws of the type presented here can potentially be optimized to maximize agility within the available actuator limits. The first control law presented was intended to test the concept; modest pitch-axis performance was therefore specified. The second control law was designed to provide ADS-33E-PRF level-1 handling qualities for noncombat-mission task elements. Both controllers gave a stable closed loop and provided the required response type. Closed-loop bandwidth predictions based on analysis of linear models were close to the bandwidths achieved in flight. Likewise, the attitude quickness achieved in flight was very close to that specified via the nonlinear element.

Preliminary Evaluation of the Environmental Impact Related to Aircraft Take-off and Landings Supported with Ground Based (MAGLEV) Power

The goal of this paper is to model and simulate various take-off scenarios related to advanced take-off and landing (TOL) operations supported by a magnetic levitation system as ground-based power. It gives the technical feasibility and the potential benefits of using ground-based power to assist TOLs, and briefly introduces the preliminary design of the ground-based system, based on a cart-sledge system and a maglev track. The paper introduces the developed simulation tool that enables the assessment of the (i) noise impact in the vicinity of the airport, (ii) aircraft field performance (TOL distances) and (iii) energy consumption. For different scenarios, the potential gains and emission levels are quantified, and compared to conventional operations. Results show the significant potential in the proposed maglev assisted TOL system, which can either drastically reduce the fuel consumption during a take-off or significantly cut the noise impact in the vicinity of the airport by performing a high speed take-off at reduced thrust setting. Finally, the most appropriate take-off scenarios are defined to cut various emission factors in the airport vicinity.

Enabling control software generation by using mechatronics modeling primitives

Mechatronic systems are characterized by the synergetic integration of mechanic, electronic, software and control design aspects. The development of control software requires data and information from all design domains in order to create the required integrated functionality. This paper proposes a method that combines function modeling and multi-domain modeling primitives to generate control software automatically. An architecture model, based on the Function-Behavior-State modeling paradigm, provides the decomposition and flow of both functionality and implementation, which serves as input to a knowledge-based engineering application. The control software is subsequently extracted from a virtual product model composed of instantiated modeling primitives. A case study of a mobile robot shows how for a specific application the modeling are defined and how a high-level function model for an environment mapping mission is translated into directly implementable software code. This approach could be extended to real-life mechatronic products, and will improve consistency and reduce development time and cost.

Mechatronic Design and Optimization Using Knowledge-Based Engineering Applied to an Inherently Unstable and Unmanned Aerial Vehicle

A novel design method for mechatronic systems, based on knowledge-based engineering techniques, is proposed in this research study. The method is particularly suited for mechatronic vehicles which are inherently unstable and require control systems for stabilization. The method is implemented in a dedicated software tool in which physical entities of the product are defined as classes with attributes. Nonphysical elements of the system and procedures for the design and analysis of the system are defined as functions with variables. The method has two key features. First, multiphysics simulation models and associated analysis functions are generated automatically within a multidisciplinary analysis and optimization framework. These models are not restricted to geometrical aspects for mechanical design, but also include the system architecture, dynamics, aerodynamics, electronic control systems and associated software codes. Second, for each representation of a design, a dedicated control system is developed completely automatically, based on the multiphysics simulation model, using model inversion control. These two features make it possible to analyze the dynamics and performance of inherently unstable mechatronic vehicles already in the early design phases when the vehicle is still subject to large configuration design changes. The method is demonstrated for the design of a multirotor unmanned aerial vehicle. Thirty thousand possible design solutions are evaluated by the system without manual interference. For each design, a dedicated control system is created and five flight test maneuvers are simulated in order to assess the aircraft performance and flying qualities. A global optimization process is applied for two conflicting requirements and the process is convergent at two optimum solutions.

Knowledge Based Engineering to Support Automotive Conceptual Design and Automatic Control Software Development

The global motor vehicle production is rising steadily year by year. These vehicles have an increasing amount of electronic components and associated control software. As a result, the control software development becomes a key aspect and time consuming part of the design.

Formation Flight - Fine-tuning of Theoretical Performance Prediction

of wind tunnel walls and Reynolds number scaling. A formation of two and three aircraft is considered with a separation distance of 10 to 100 spans. It is demonstrated that in some earlier simulations, discussed in open literature, an incorrect lift coecient is used which leads to erroneous prediction of the induced drag reductions. The application of positive sweep, taper and winglets are all found to have benecial eects on formation ight induced drag reduction, while aircraft trim causes a slight decrease of induced drag reduction. Furthermore, the wing aspect ratio was not found to have a signicant inuence. According to the calculation model, a typical medium aircraft exhibits a total drag reduction around 13% when ying behind an identical aircraft. Good agreement between scaled and full scale simulation induced drag reduction is found in terms of both trend and induced drag reduction at the so-called sweet spot. The addition of wind tunnel walls causes a large increase in maximum induced drag benets, which signies the need for accurate windtunnel wall corrections in case of future windtunnel tests.