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Modeling the life-cycle cost effects of distributed electric mobility in army aviation
Get PDFA procedure for economic analysis of electric and hybrid-electric aircraft is detailed. Specific examples of cost prediction using the method are given for aircraft concepts suitable for applications in the distributed mobility paradigm of transportation as it could be applied to both military and civilian roles. The insights gained through the adaptation of existing aircraft cost models and the development of new cost models for the unique features of electric aircraft are discussed with a view to future modeling applications that will evaluate the specific benefits of distributed electric mobility aviation
Hardware-in-the-loop evaluation of a quick-start system for helicopter gas turbine OEI operations tested in simulated flights
Get PDFThis paper first outlines a hardware-in-the-loop environment for helicopter flight simulations with a real turboshaft engine. The setup uses an Allison 250-C20B engine equipped with a pneumatic impingement system, named as Quick-Start System (QSS). The hardware-in-the-loop engine and the QSS are connected to the Rotorcraft Simulation Environment (ROSIE), a fixed-based pilot-in-the-loop rotorcraft simulator. In parallel, a visual and audio augmentation system based on a standard helicopter head-down instrumentation and a future-proof multimodal cueing concept is used for pilot workload and handling qualities investigations. Next, the paper covers the design and proceeding of a hardware-pilot-in-the-loop simulator flight test campaign along ADS-33 PRF flight test standards conducted together with five helicopter test and fleet pilots from German Armed Forces. Finally, the paper reports the results of piloted simulation tests of different mission task elements (MTE), embedded to a wide spectrum of helicopter Intended Single Engine Operation (ISEO) and One Engine Inoperative (OEI) operations, where different levels of the QSS and the augmentation concepts had been evaluated by the participating pilots. Results indicate a pilot workload level of Bedford rating level 1 and an enhanced situational awareness with the assistance of visual and audio augmentations. Moreover, the QSS enabled all pilots to recover the helicopter with acceptable loss of altitude at acceptable handling qualities and pilot workload
Computationally efficient ship airwake simulations for rotorcraft shipboard operations using a GPU-accelerated Lattice-Boltzmann Solver
Get PDFIt is desired to achieve computationally efficient mid-fidelity ship airwake predictions to be used in ship– rotorcraft interaction studies. The Lattice-Boltzmann Method (LBM) is a viable candidate to obtain flow field solutions rapidly, owing to its highly parallelizable nature. To demonstrate the LBM’s capabilities and to show the suitability of the method to solve the large computational problem of a ship airwake simulation in a timeefficient manner, a scaled model of the SFS-2 frigate shape was simulated in uniform inflow conditions using a GPU-accelerated Lattice-Boltzmann solver. A convergence study was conducted, and it was found that the LBM results converged already at relatively coarse resolutions, but only for the mean flow quantities. The obtained results were compared to published experimental data. The LBM results showed good correlation with velocity probe measurements on the starboard side of the landing deck, but they did not predict flow asymmetry seen in the measurements. Results were also compared with particle image velocimetry data, and the flow topology as well as the mean velocity magnitudes obtained by the LBM showed excellent agreement. Satisfactory agreement was found for the turbulence intensities that were mostly underpredicted, although the gradients were correct. The LBM model was able to obtain these results in three hours and 25 minutes on eight local GPUs. Considering its computational efficiency and good accuracy for quick turn-around solutions, the current LBM model was concluded to be a good mid-fidelity alternative to high-fidelity CFD methods that require orders of magnitude more time and computational resources for ship airwake simulations
Flight investigation of blended command model in low speed maneuvering
Get PDFThis piloted flight investigation with an UH-60 utility helicopter assessed the handling qualities of a blended command response-type alongside attitude command and rate command response-types in longitudinal and lateral axes with three low speed Mission Task Elements (MTEs) of Aeronautical Design Standard ADS-33E-PRF. The Blended Command Model produces an Attitude Response-Type when the cyclic is near center, produces a Rate Response-Type when the cyclic is distant from center, and produces a blended response at intermediate displacements. The investigation assessed three variations of blended command vis-à-vis proportional attitude and rate commands with the Hover, Depart Abort, and Lateral Reposition MTEs. Among the five options, the evaluation pilots ranked blended command best in a Good Visual Environment by an average of 0.5 better than the second ranked attitude command using the Cooper Harper scale. The pilots assessed blended command second best under a Degraded Visual Environment by an average 0.3 worse than the top-ranked attitude command
Exploring for aerodynamic and structural design constraints in the multi-objective rotor blade airfoil optimization framework
Get PDFA rotor blade design optimization framework has been developed by integrating the Dakota, C81Gen, ParFoil, and RCAS software packages in Galaxy. Parameterizing the airfoils using ParFoil was performed prior to the rotor blade optimization. Using Dakota’s Multi Objective Genetic Algorithm (MOGA), global design optimization was successfully carried out for the UH-60A rotor blade. It shows a 12.2% reduction at ? = 0.4, a 9.4% reduction at ? = 0.35 and a 3.0% reduction in hover. The expansion of flight envelope is also explored by examining the aerodynamic responses of the optimized rotor under high load conditions. It is found that the optimized rotor designed under the normal cruise condition fails to meet performance expectations when it is exposed to high load conditions where rotor encounters the retreating blade stall. Realistic rotor blade design therefore needs to include a high load condition so that a rotor can perform well at high thrust and high speed
Next generation civil tilt-rotor technology demonstrator (NGCTR-TD) tail design
No full textWithin the Clean Sky 2 Fast Rotorcraft platform, a Next Generation Civil Tilt-Rotor technology demonstrator (NGCTR-TD) is under development (Ref. [1]) within Leonardo Helicopters. Such platform allows to deep investigate the key technologies in development of a future European civil tilt-rotorcraft, starting from the experience of in-flight aircraft, and concept ERICA studies. One of the key technologies analyzed is the empennage solution, as per preliminary phase of a new aircraft configuration: the proper sizing and design of the tail is essential for ensuring performance and handling qualities. In order to perform this activity, an appropriate aerodynamic toolchain process is adopted for supporting the tail design; further, requirements are appropriately set and tilt-rotor peculiarities addressed. Aerodynamics analysis on tiltrotor empennage have been deeply validated through computational and experimental activities within Leonardo Helicopter Division programs. Based on validated aerodynamic tools, Vee-tail configuration is properly designed and verified to improve tilt-rotor performances. Additionally, aerodynamic devices are analyzed for Vee-tail configuration, to possibly improve or modify handling qualities during the advanced development phase: such devices, so called “finlet”, are considered to be a winning factor for the benefit introduced with limited impact on tail design, specifically for Vee-tail configuration
Directivity and psychoacoustics focused multi-objective detectability optimisation for low noise rotorcraft trajectories
No full textThis paper considers an advanced optimisation procedure for helicopter detectability as part of a typical approach trajectory. The objectives of the optimisation problem are formulated on the basis of two parameters: noise detectability threshold, and noticeability. Two key studies are undertaken, one purely looking at the optimisation of noise detectability – whether the noise is audible or not, and the other optimising between objective audibility and psychoacoustic noise perception. The detectability of the rotorcraft is then analysed for both cases and measured using a variety of microphone array configurations to investigate helicopter detection range and noise directivity control. These microphone points are the focus points of the optimisation procedure; the optimisation procedure utilises the strong changeability of helicopter noise directivity with trim condition to alter the flight path of the aircraft according to the placement of the microphones. Results within this paper have shown positive evidence that it is possible to optimise helicopter trim condition in flight to reduce helicopter detection and control noise directivity. Results also showed that for initial analyses, SEL and EPNL can be accurate and powerful tools for optimisation procedures to gauge annoyance in the absence of more sophisticated SQ metrics. The weightings given to the objectives within the objective function, and the calculation procedure for the costs associated with each objective were shown to strongly affect the optimal on-ground noise footprints. The relationships between the quantitative metrics used to encapsulate detectability were also found to strongly affect the results – and further study of the relationship between optimised values needs to be investigated in future work
Failure analysis method for the presizing of multi-rotors eVTOL
No full textThe new kind of aircraft electric Vertical Take-Off and Landing (eVTOL) concepts are well suited for the Advanced Air Mobility including Urban Air Mobility. The new paradigm of design for these Advanced Aircraft no longer relies on autorotation capability, but on redundancy. Redundancy is one required condition, but it may not be enough to ensure a safe controlled flight in case of failure of one or more thrust generator systems, i.e. {energy system – controller - motor – propeller}. This paper focuses on the crucial issue of setting a methodology to assess if an eVTOL configuration is able to cope with one or more thrust generator failure(s). This is a crucial step for their predesign because the thrust generators must be sized to withstand the most demanding conditions, which are imposed by the worst critical failure cases. Therefore, the analysis of the different failure cases is needed before the sizing of the rotors and more generally of the thrust generator system. A numerical method is presented as well as results giving a comprehensive overview for the axi-symmetrical circular multi-rotors configurations with or without coaxial rotors and more generally for eVTOL with all rotors thrusting always in the same unique direction
Roadmap towards first SAS engagement
Get PDFT-625 helicopter is a light utility multi role helicopter that is designed by Turkish Aerospace Helicopter Group. It is equipped with a four-axis dual-redundant automatic flight control system (AFCS) and this paper presents the stages of the automatic flight control system design of T-625 helicopter. General architecture of AFCS will be provided and the details of SCAS and autopilot systems will be discussed. Safety aspects of dual AFCS will be described together with an overview of safety-critical system development. Stages of AFCS control law design and their implementation to the Flight Control Computers will be briefed. Details of conducted system tests at the hardware in the loop engineering simulator, as well as during ground and flight tests will be discussed. In overall, this paper summarizes the studies performed towards first autopilot engagement of T-625 helicopter and introduces results from both ground and flight tests