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How Do Rockets Work?
Published in Travis S. Taylor, Introduction to Rocket Science and Engineering, 2017
First and foremost, thrust is a force and is measured in newtons (N). Older rocket scientists might often revert to using pounds of thrust, but we will stick to the International System of Units here. It is a force generated by some propulsive element in order to overcome other forces acting on a body in order to manipulate that body’s position and velocity vector. It is the force that is used to propel a rocket or a spacecraft to the destination trajectory or orbit or the landing site desired. Airplanes use propellers or jet engines to generate thrust. Rockets use rocket engines to generate thrust.
Technological Constraints
Published in Steven D. Jaffe, Airspace Closure and Civil Aviation, 2016
The primary components of FANS include: Communications A data link to the Airline Operation Center (AOC) to uplink new routes, winds, and position reports though a data link.A data link to Air Traffic Control, replacing the traditional voice communication, enabling the digital transmission of clearances, route requests, altitude changes, and other advisoriesNavigation GPS precision navigation systems fully integrated into the airplane's flight management system (FMS).Required Navigation Performance (RNP) capability, enabling the airplane to remain within the acceptable navigational parameters, notifying the flight crew if a deviation occurs.Surveillance Automated Dependent Surveillance (ADS), broadcasting position reports read directly from the FMS sent automatically via data link to ATC, providing, timely and accurate surveillance without radar.
Environmental challenges and the aerospace industry
Published in Wesley Spreen, The Aerospace Business, 2019
A partially turboelectric concept developed by NASA has high-power generators integrated with each of the two wing-mounted turbofan engines. In addition to producing thrust, the engines generate megawatts of electricity that is routed to the tail of the airplane, where an electric motor and aft fan provide thrust and reduce drag by reenergizing the low momentum boundary layer air flow.
Social distancing in airplane seat assignments for passenger groups
Published in Transportmetrica B: Transport Dynamics, 2022
Mostafa Salari, R. John Milne, Camelia Delcea, Liviu-Adrian Cotfas
Social distancing is one of the unprecedented measures that became a new norm in travel and other activities (De Vos 2020). It reduces interactions between individuals to restrict the spread of the coronavirus. The World Health Organization (WHO) stressed the importance of social distancing measures to reduce the rate of infection among people who share the same activities (WHO 2020). The preventive measures associated with social distancing include keeping sufficient distance among people, closing public places, and avoiding crowded gatherings (Nguyen et al. 2020). The above-mentioned preventive measures offer effective non-pharmaceutical attempts to reduce the disease spread (Ferguson et al. 2006). Enforcing social distancing measures for airplane passengers has been recently advised by the European Union Aviation Safety Agency (EASA). As its report instructs, ‘airplane operators should ensure, to the extent possible, physical distancing among passengers’ (EASA 2020). The best practice of social distancing among passengers in an airplane requires both the passengers’ willingness to respect social distancing guidelines as well as a well-structured seat assignment methodology. Salari et al. (2020) and Pavlik et al. (2021) address the social distancing in airplane seat assignment to minimize the transmission risk on airplane (Pavlik et al. 2021; Salari et al. 2020), while Haghani and Bliemer (2020) underlines the need for methods and solutions for crowd management and safety needed in confined spaces such as airplanes.
Plan B for Eliminating Mode Confusion: An Interpreter Display
Published in International Journal of Human–Computer Interaction, 2021
The pilot does not understand how a mode will behave or is not aware of actions the autopilot is taking: Asiana Boeing 777 accident, San Francisco, 2013 – On approach to San Francisco, the pilot inappropriately selected a flight level change mode to descend more rapidly, but the airplane started climbing to the MCP altitude, which is how that mode works; this surprised the pilot. He then grabbed the thrust levers to stop the airplane from climbing. Manually positioning the thrust levers put the autothrottle into a mode (HOLD) that will not manage airspeed for the approach (even though the autothrottle was engaged); the flightcrew was unaware that they needed to manage airspeed. Airspeed decreased until the stick shaker was triggered. The flightcrew failed to recover from the stall.Aeroflot Nord Boeing 737–500 accident, Perm, Russia, 2008 – Late in the flight, the two thrust levers became miscalibrated – i.e., positioned at different angles to produce the same thrust. Unaware of this, the pilot matched the thrust levers (positioned them together), which produced more thrust on one engine than the other, but the autopilot was engaged, and it managed the unmatched thrust with other flight controls. The Captain was not aware that the autopilot was managing this situation. When the Captain later disengaged the autopilot, he could not handle the sudden difference in thrust. Inappropriate control inputs led to a crash.
Design and functions of floating architecture – a review
Published in Marine Georesources & Geotechnology, 2019
Yuan-Ho Lin, Yung Chih Lin, Han-Shih Tan
The principle underlying how turbines operate is simple. Wind energy turns two or three blades like propellers, and that activates a rotating assembly. That rotor is connected to a shaft which rotates a generator, thus creating electricity. There are two basic groups of wind turbines. One has a horizontal-axis, like an airplane propeller, and one has a vertical-axes design, like an egg-beater. Energy that is produced by wind turbines can range from 100 kW to several megawatts, and large wind turbines are grouped together into wind farms. Within the last few years, the number of offshore wind farms has increased so as to take advantage of the huge potential of wind energy off the coasts of the U.S. and other countries (Energy.Gov: Office of Energy Efficiency and Renewable Energy 2015).