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Engine performance
Published in Mohammad H. Sadraey, Aircraft Performance, 2017
An aircraft piston engine is similar to an automobile engine with a few slight differences. In the aircraft design process, weight is a primary consideration. Thus, the aircraft-weight-to-engine-power ratio is generally lower for an aircraft engine as compared to an automobile engine of a comparable size. Today’s piston engines’ output power ranges from <1 hp to more than 2000 hp.
Margins in design – review of related concepts and methods
Published in Journal of Engineering Design, 2023
Arindam Brahma, Scott Ferguson, Claudia Eckert, Ola Isaksson
Beginning in the mid-late nineteenth century, the term ‘Factor of safety’ started being used. For instance, Rankine (1872) suggests a multiplication factor in the context of bridges and tunnels. Wilson (1874) provides guidance on selecting a proper ‘coefficient’ or ‘factor of safety’ in boiler design against uncertainties such as defects, wear and tear. The concept of a factor of safety was driven by serious boiler explosions in the late 1800s and the early 1900s, resulting in formal discussions on measures to prevent boiler accidents (Peters and Pham 2018). As the aircraft industry became established, such factors became a part of the aircraft design process. Wilbur Wright comments in a letter that he is constructing his machine to sustain about five times his weight and considers the ramifications of a crash landing (See an excerpt from the letter in Figure 2). Shanley (1962), when tasked with rationalising U.S. civil-airworthiness requirements in 1932, introduced a 1.5 ‘ultimate factor of safety’ (Muller and Schmid 1977) and a ‘load factor’ of about 6 for a typical aeroplane. Shanley’s notes reveal that these numbers are not ‘sacred’ but were generated by considering the properties of prior aircraft that had ‘good service records’ (Shanley 1962).
Life-cycle analysis of electric vertical take-off and landing vehicles
Published in Transportation Planning and Technology, 2023
Khashayar Khavarian, Kara M. Kockelman
Antcliff, Moore, and Goodrich (2016) claim that for aircraft design studies, VTOL concepts must meet these criteria to be feasible. For feasibility purposes, noise must be reduced by more than 20 dB. Additionally, safety must be comparable to automobile safety, and have a price competitive with the average ride-hailing trip (costing about $2 per mile in the U.S.). Demand studies should consider the current user trends of various transportation modes and demonstrate the VTOLs’ market value costs, fleet size, service area, and vehicle utilization rates from hour to hour and day to day. It also is important to anticipate mode choices and connectivity of modes for these inter-modal trips: aside from walk-time and distance-cost penalties, VTOL route choice and vertiport and (smaller) vertistop capacity constraints must be considered. Apart from all the demand and mode choices, costs of operation, noise, and other challenges, an aerospace study is necessary to show routes and trajectories without conflicts in each region, which may differ from existing studies’ evaluations.
Recent Features and Industrial Applications of the Hybrid SPH-FE Method
Published in International Journal of Computational Fluid Dynamics, 2021
Paul Groenenboom, Bruce Cartwright, Damian McGuckin
Aircraft ditching is an emergency situation that needs to be studied during aircraft design and certification phases. The physical phenomena involved in ditching are highly complex and the use of simulation tools is becoming current practice in both research and design (Groenenboom and Siemann 2015). The capability of simulating the aircraft structure by means of a non-linear Finite Element (FE) model coupled with water modelled with SPH has received some attention in recent years. The high velocity creates a local, but very pronounced pressure peak which generates waves. Another effect which is aggravated by the high horizontal velocity is the break-up of the free surface and generation of spray. Effects due to aerated water and cavitation may also need to be considered. There exists also a tendency of the water flow to remain attached to the aircraft skin after initial contact; this suction effect is known to strongly affect the aircraft kinematics. To simulate the entire event, the computational domain must be quite long which makes the numerical simulation computationally demanding.