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Going with the Flow: An Optical Basis for the Control of Locomotion
Published in Richard J. Jagacinski, John M. Flach, Control Theory for Humans, 2018
Richard J. Jagacinski, John M. Flach
The ambiguity created by global optical flow rate has been hypothetically linked to a very dangerous situation connected with low altitude flight. The U.S. military loses a significant number of aircraft due to a problem labeled controlled flight into terrain (CFIT; Haber, 1987). CFIT refers to situations where an aircraft flies into the ground with no obvious mechanical failure, no dangerous weather or meteorological conditions, and apparently no medical problems. The cause seems to be pilot control error. The hypothetical explanation is as follows. The first assumption is that pilots utilize the global optical flow rate as a primary indicant of airspeed. As already noted, this is a smart strategy, as long as altitude is roughly constant. Airspeed is a critical determinant of lift. If airspeed becomes too low, then the amount of lift will be less than the pull of gravity, and the aircraft will essentially begin to fall out of the sky. The minimum airspeed necessary to keep the aircraft in flight is referred to as the stall speed. A wing stall is a situation where the lift generated by the wings is less than the force of gravity.
Equations of motion
Published in Mohammad H. Sadraey, Aircraft Performance, 2017
Speed and its measurement have a significant position in aircraft performance analysis. Although the Global Positioning System (GPS) is a powerful tool in the measurement of several flight variables including speed, but, due to safety reasons and FAA regulations, all aircraft use a device called Pitot tube to measure the aircraft speed. In addition, the GPS only measures the ground speed; not the airspeed. Airspeed is measured by comparing the difference between the pitot and static pressures (Figure 2.18) and, through mechanical linkages, displaying the resultant on an airspeed indicator. A static port (tube) measures only the static pressure, since the hole is perpendicular to the air flow, so the flow must turn 90° to enter into the tube. In contrast, a pitot tube measures the dynamic pressure, since the hole faces the airflow. When a pitot tube has a static port, it is often referred to as the pitot-static tube.
Airport Planning and Design
Published in Dušan Teodorović, The Routledge Handbook of Transportation, 2015
Headwinds will add to the aircraft’s airspeed, whereas tailwinds will subtract from it. As an example, an aircraft flying at a ground speed of 250 km/h with a headwind of 20 km/h will have an airspeed of 270 km/h, whereas the same aircraft at the same ground speed but with a tailwind of 25 km/h will be flying at an airspeed of 225 km/h. For this reason, take-offs and landings should always be performed with either headwinds or calm winds. The direction the wind is blowing from will then determine the direction of take-off and landing operations on a runway.
Command-filtered sensor-based backstepping controller for small unmanned aerial vehicles with actuator dynamics
Published in International Journal of Systems Science, 2018
Lijia Cao, Yongchao Wang, Shengxiu Zhang, Tan Fei
Here, the state vectors are and . is the output of the controlled plant, denotes the input vector of the vehicle, and and are the external disturbances. The functions , , and can be expressed as follows. where is the true airspeed, represents the mass, S denotes the reference area, denotes the dynamic pressure, is reference wing span and is mean aerodynamic chord, represents the thrust. And denotes the angle of attack, denotes the angle of sideslip, are attitude angles; represent angular rates around body axis; Also, the C* is called aerodynamic coefficient, where * denotes all the subscript. Moreover, the constants are defined as , , , , , , , , , where , , are roll, pitch, and yaw moments of inertia, respectively; is a product moment of inertia.