An Aerial Deployed Unmanned Autonomous Glider for Cross-Channel Flight

This paper describes the technical and operational challenges of the first cross-Channel flight performed by an unmanned autonomous glider. The glider chosen for the attempt was a quarter scale Slingsby Type 45 Swallow. It was found to have a lift-to-drag ratio of 8, as verified by wind tunnel force balance tests. Essential retrospective aerodynamic refinements to the design, including modifications of the wing root and tip sections and wing aspect ratio, were modelled analytically and found to increase the aircraft’s lift-to-drag ratio to 19. The launch mechanism devised for the modified glider featured a bespoke crate suspended under an airborne helicopter at an altitude of 10,000 ft, from which the aircraft was released from an internal recess. The glider was pre-programmed to fly autonomously via waypoint navigation and completed the 22 mile mission in less than one hour at an average ground speed of 27 knots, a sink rate of 3 ft/s and with 3,500 ft altitude to spare. The successful flight, which was filmed from onboard cameras and a chase helicopter, represents a unique first in autonomous aviation and is unofficially the longest straight distance flight for an unmanned engineless glider

Development and Validation of on-board systems control laws

Purpose - The purpose of this paper is to describe the tool and procedure developed in order to design the control laws of several UAV (Unmanned Aerial Vehicle) sub-systems. The authors designed and developed the logics governing: landing gear, nose wheel steering, wheel braking, and fuel system. Design/methodology/approach - This procedure is based on a general purpose, object-oriented, simulation tool. The development method used is based on three-steps. The main structure of the control laws is defined through flow charts; then the logics are ported to ANSI-C programming language; finally the code is implemented inside the status model. The status model is a Matlab-Simulink model, which uses an embedded Matlab-function to model the FCC (Flight Control Computer). The core block is linked with the components, but cannot access their internal model. Interfaces between FCCs and system components in the model reflect real system ones. Findings - The user verifies systems' reactions in real time, through the status model. Using block-oriented approach, development of the control laws and integration of several systems is faster. Practical implications - The tool aims to test and validate the control laws dynamically, helping specialists to find out odd logics or undesired responses, during the pre-design. Originality/value - The development team can test and verify the control laws in various failure scenarios. This tool allows more reliable and effective logics to be produced, which can be directly used on the system

Threat Management Methodology for Unmanned Aerial Systems operating in the U-space

This paper presents a threat management methodology for Unmanned Aircraft Systems (UAS) operating in the civil airspace. The work is framed within an Unmanned Traffic Management (UTM) system based on the U-space initiative. We propose a new method that focuses on providing the required automated decision-making during real-time threat management and conflict resolution, which is one of the main gaps in the current U-space ecosystem. Our method is capable of handling all commonplace UTM threats, as well as selecting optimal mitigation actions, trading off efficiency and safety. Our implementation is open-source and fully integrated in a UTM software architecture, implementing U-space services related to emergency management and tactical deconfliction. We demonstrate our methodology through a set of realistic use cases with actual UAS operating in civil airspace. For that, we performed field experiments in an aerodrome with segregated airspace, and we showcased that the methodology is capable of autonomously managing heterogeneous threats in real time.Unión Europea - Horizonte 2020 77629

Longitudinal dynamic modeling and control of powered parachute aircraft

Powered parachutes (PPC) represent a very unique class of aircraft which have thus far seen limited use beyond recreational flight. Their slow flight and large payload characteristics make them a practical platform for applications such as aerial spraying and surveillance. The portability of the units when not airborne, fast transition to flight readiness, inherent stability, and simplicity of control enhance their appeal for use as Unmanned Aerial Vehicles (UAV). The aircraft fly using only three control inputs consisting of two steering lines and a throttle for control of climb and descent. One of the more interesting characteristics that distinguish PPC from conventional aircraft is the pendulum stability which is a consequence of suspending the majority of the aircraft weight so far from the wing surface and which introduces an appreciable amount of lag into the system. Another interesting phenomenon is their speed stability which causes the aircraft to fly at a relatively constant speed whether it is climbing, descending, or flying straight-and-level. The current study seeks to examine the effects of throttle on the longitudinal dynamics of PPC, using a small-scale aircraft. A dynamic model has been derived using analytical methods and computer-simulated in MATLAB and Simulink, developed by The Mathworks. The validity of the model was then verified using data recorded from the small-scale PPC. Effects of parameters such as aircraft weight and thrust were examined and related to flight characteristics such as airspeed and climb rate. Finally, a control system was developed to deal with the aforementioned lag and demonstrate accurate altitude-hold capability for a powered parachute

Landing site reachability in a forced landing of unmanned aircraft in wind

Autonomous contingency management systems, such as a forced landing system which reacts appropriately to an engine failure is important for the safe operation of Unmanned Aircraft Systems (UAS). This paper details a method to ascertain the reachability of any possible emergency landing site for a forced landing in steady uniform wind conditions. With knowledge of the aircraft’s state, such as speed heading location and orientation of a landing site, a method to calculate a minimum height loss path is developed based on aircraft glide performance. Wind direction and speed are taken into account using a trochoidal approach by defining the minimum height loss turn path. To facilitate real-time implementation, simplified gliding equations are developed without accuracy loss. The reachability of each site can be calculated, as well as how much safety margin an aircraft would have. This method is generic and could also provide decision support for human pilots in forced landing situations. Two types of aircraft Airbus A320-400 and the Cessna 172 have been investigated to demonstrate the usefulness of the method, using Monte Carlo simulations in a synthetic X-Plane R simulation environment, in order to demonstrate the performance and effectiveness of the proposed approaches

System and Method for Air Launch from a Towed Aircraft

The invention is a system and method of air launching a powered launch vehicle into space or high altitude. More specifically, the invention is a tow aircraft which tows an unpowered glider, with the powered launch vehicle attached thereto, to launch altitude. The powered launch vehicle is released from the unpowered glider and powered on for launch

Advanced flight management system for an unmanned reusable space vehicle

The innovative architecture of an advanced Flight Management System (FMS) for Unmanned Reusable Space Vehicle (URSV) applications is presented with the associated re-entry trajectory computation algorithm. The SL-12 unmanned space vehicle, developed by Cranfield University as a part of the 2012-2013 Aerospace Vehicle Design (AVD) Group Design Project (GDP) is used as the reference platform. The overall avionics architecture of the future space transportation vehicle is described. A detailed architecture is developed for the FMS and the core functions of such an FMS are described. A dedicated computation algorithm is presented for re-entry trajectory planning, which involves determination of the path of re-entry vehicle by means of angle of attack and bank angle modulation. Simulation case studies are performed in a realistic re-entry operational scenario resulting in the generation of efficient and feasible trajectories, without violating any of the defined constraints

Involuntary Signal-Based Grounding of Civilian Unmanned Aerial Systems (UAS) in Civilian Airspace

This thesis investigates the involuntary signal-based grounding of civilian unmanned aerial systems (UAS) in unauthorized air spaces. The technique proposed here will forcibly land unauthorized UAS in a given area in such a way that the UAS will not be harmed, and the pilot cannot stop the landing. The technique will not involuntarily ground authorized drones which will be determined prior to the landing. Unauthorized airspaces include military bases, university campuses, areas affected by a natural disaster, and stadiums for public events. This thesis proposes an early prototype of a hardware-based signal based involuntary grounding technique to handle the problem by immediately grounding unauthorized drones. Research in the development of UAS is in the direction of airspace integration. For the potential of airspace integration three communication protocols were evaluated: LoRa WAN, Bluetooth 5, and Frequency Shift Keying (FSK) for their long range capabilities. Of the three technologies, LoRa WAN transmitted the farthest, however the FSK module transmitted a comparable distance at a lower power. The power measurements were taken using existing modules, however, due to LoRa using a higher frequency than the FSK module this outcome was expected

Basic Considerations and Conceptual Design of a VSTOL Vehicle for Urban Transportation

On-demand air transport is an air-taxi service concept that should ideally use small, autonomous, Vertical Short Takeoff and Landing (VSTOL), “green”, battery-powered electric aircraft (eVSTOL). In addition, these aircraft should be competitive with modern helicopters, which are exceptionally reliable machines capable of the same task. For certification and economic purposes, mobile tilting parts should be avoided. The concept introduced in this paper simplifies the aircraft and makes it economical to build, certify and maintain. Four contrarotating propellers with eight electric motors are installed. During cruise, only two of the eight rotors available are not feathered and active. In the first step, a commercial, certified, jet-fueled APU and an available back-up battery are used. A second solution uses a CNG APU and the same back-up battery. Finally, the third solution has a high-density dual battery that is currently not available. A conceptual design is shown in this paper

Modelling the Risks Remotely Piloted Aircraft Pose to People on the Ground

Worldwide there is much e ort being directed towards the development of a framework of air- worthiness regulations for remotely piloted aircraft systems (RPAS). It is now broadly accepted that regulations should have a strong foundation in, and traceability to, the management of the safety risks. Existing risk models for RPAS operations do not provide a simple means for incorporating the wide range of technical and operational controls into the risk analysis and evaluation processes. This paper describes a new approach for modelling and evaluating the risks associated with RPAS operations near populous areas based on the barrier bow tie (BBT) model. A BBT model is used to structure the underlying risk management problem. The model focuses risk analysis, evaluation, and decision making activities on the devices, people, and processes that can be employed to reduce risk. The BBT model and a comprehensive set of example risk controls are presented. The general model can be applied to any RPAS operation. The foundations for quantitative and qualitative assessments using a BBT model are also presented. The modelling and evaluation framework is illustrated through its application to a case-study rotary wing RPAS for two operational scenarios. The model can be used as a basis for determining airworthiness certification requirements for RPAS