Neutral stability and relaxed stability analysis: advantages and disadvantages. A neutrally stable airplane has the following characteristics: 1) there is only one elevator trim displacement that gives a steady flight speed. If we slightly increase the up trim, the aircraft will progressively pitch up until it stalls. Adding a little amount of down trim, the aircraft will move into an ever-steepening dive. 2) If this particular trimming setting is held, the aircraft is able to be still in trim at any airspeed. In addition the trimmed operating speed depends completely on the history of elevator control inputs, not on the trim setting. Hence, after shifting pitching attitude, a neutrally stable aircraft does not spontaneously revert to its precedent airspeed. [NOTE: The FAA would not certify an aircraft that did not have positive static and dynamic stability!!] Case of MD11: neutrally stable civil aircraft [AS2]. 1. The MD-11 was designed with a smaller horizontal stabilizer than other airliners. That, plus the shifting of its centre of gravity further aft, all to reduce drag and thus fuel burn, causes it to be unusually light on the controls. That design, known as “relaxed stability,” is common to fighter planes but is not normally found in the pitch axis of a civilian airliner. The MD-11 uses computers to provide neutral speed stability. In other words, the CG of the MD-11 appears to be at the neutral point. The MD-11 uses elevator deflection to hold attitude at any speed within the normal flight envelope, then trims the stabilizer. This is known as an "attitude hold" system. The computer (LSAS) is used to compensate for neutral stability. The CG is indeed moved aft in cruise, but the LSAS makes it stable. 2. Some well-kn... ... middle of paper ... ...to a very dangerous flight situations. Such issues make really unrealistic adopting such configuration for any civil aircraft without any specific countermeasure. Indeed, the rectification of these stability and control deficiencies and the provision of adequate flying qualities will require a very high authority augmentation system. Thus, a multiple-redundant command augmentation system must be implemented to make a neutral or slightly negatively permanent flying setting even only conceivable. [AS1]Ref: Roger H. Hoh, David G. Mitchell, Flying Qualities of Relaxed Static Stability Aircraft- Volume 1 and 2, US department of transportation, 1982 [AS3]Ref: Aircraft pitch-axis stability and command augmentation system,US 6325333 B1, [AS2]Ref: http://airlinesafety.com/faq/faq9.htm [asbook]Daniel P.Raymer,Aircraft Design:A conceptual approach,AIAA education series,2006
In today’s world, the use of airplanes in wars or in everyday life has become a part of how we live as human beings. Removing the air forces of the world is like taking a step back in time when wars were only fought on land or sea. WWI began only eleven short years after the Wright brothers achieved powered flight in 19031 and yet aircrafts were being used for surveillance and eventually combat purposes. It is understood that these aircrafts were primitive, but they laid down the foundation for what we know today as fighter jets. The Fokker Eindecker “revolutionized air combat by successfully employing a synchronized forward -firing machine gun mounted on the engine cowling”2. Because this airplane became the first to successfully use a synchronized machine gun, it allowed its pilots to become the first aerial combat tactitions3.
Ever since I was little I was amazed at the ability for a machine to fly. I have always wanted to explore ideas of flight and be able to actually fly. I think I may have found my childhood fantasy in the world of aeronautical engineering. The object of my paper is to give me more insight on my future career as an aeronautical engineer. This paper was also to give me ideas of the physics of flight and be to apply those physics of flight to compete in a high school competition.
The airmobility concept is one of Army Aviation’s most prominent battlefield innovations, almost single handedly shaping the Vietnam War and in many ways, helping to influence how we fight wars today. In its essence, airmobility is a concept that utilizes Army aircraft in order to enhance the ground forces’ ability to perform the five fundamentals of combat: command and control, firepower, intelligence, mobility, and communications (Rottman, 2007). At the zenith of the airmobility concept is the airmobile assault or commonly known today as, the air assault. The airmobile assault was more than just moving troops from point A to point B; it involved intense planning and preparation. When implemented correctly, the airmobile assault provided light infantry greater mobility on the battlefield, along with the ability to seize the initiative and to synchronize attacks.
Debunking the 9/11 Myths: Special Report - The Planes - Popularmechanics.com. (n.d.). Automotive Care, Home Improvement, Tools, DIY Tips - Popularmechanics.com. Retrieved April 26, 2010, from http://www.popularmechanics.com/technology/military/news/debunking-911-myths-planes
First of all you will have to understand the principles of flight. An airplane flies because air moving over and under its surfaces, particularly its wings, travels at different velocities, producing a difference in air pressure, low above the wing and high below it. The low pressure exerts a pulling influence, and the high pressure a pushing influence. The lifting force, usually called lift, depends on the shape, area, and tilt of the wing, and on the speed of the aircraft. The shape of the wing causes the air streaming above and below the wing to travel at different velocities. The greater distance over which the air must travel above the curved upper surface forces that air to move faster to keep pace with the air moving along the flat lower surface. According to Bernoulli’s principle, it is this difference in air velocity that produces the difference in air pressure.
Nearly all pilots have experienced a strange phenomenon during landing. While everything is happening as it should during decent, a 'cushion' of air gets trapped below the wing during the last few meters to the runway. This throws off the rate of decent and can be dangerous if the pilot has already begun to flare up and decelerate for landing. This means the plane would climb again while slowing down, which would easily lead to a stall.
In order to effectively manage the national airspace system in the future we will need to implement Free Flight. Free Flight is a concept designed to enhance safety and efficiency of the airspace by allowing aircraft to choose their own route instead of using victor airways (www.ads-b.com 1). Along with this freedom there is still the problem of aircraft separation which when on an instrument flight plan is air traffic control's (ATC) responsibility. In free flight there may be areas where ATC cannot give the required collision avoidance necessary. In order to safely manage the safety zone around an aircraft, pilots will need to rely on systems installed in the aircraft for better separation.
Flight is one of the most important achievements of mankind. We owe this achievement to the invention of the airfoil and understanding the physics that allow it to lift enormous weights into the sky.
- - -, dir. “Tactical Air Control Party Specialist (TACP).” U.S. Air Force. U.S. Air Force, n.d. Web. 7 Feb. 2012. .
The drag force is always working against the forward motion of a runner, trying to move them in the negative horizon...
The basic concepts of lift for an airplane is seen. The air that is flowing splits to move around a wing. The air that that moves over the wing speeds up creating lower pressure which means that the higher pressure from the air moving slower under the wing pushes up trying to equalize the pressure. The lift generated can be affected by the angle at which the wing is moving into the flowing air. The more surface area of the wing resisting against the flow of air can either generate lift or make the plane dive. This can be easily simulated in everday life. Next time you are riding in a car with someone stick your hand out the window. Have your fingers pointing in the direction of the motion of the vehicle. Now move your hand up and down slightly. You can feel the lift and drag that your hand creates.
... problem are under constant development and analysis, in a hope to avoid these situations. The civilian industry continues to lead in development due to commercialization, with the military not far behind. The only real deficiency in CRM program development seems to be the area of general aviation as described earlier. Until this problem is addressed, there will still be a glaring weakness in the general area of aviation safety. However, with the rate of technology increase and cheaper methods of instruction, we should begin to see this problem addressed in the near future. Until then, aviation will rely on civil commercial aviation the military to continue research and program development for the years to come, hopefully resulting in an increasingly safe method of travel and recreation.
Tice, Brian P. (1991). Unmanned Aerial Vehicles – The Force Multiplier of the 1990s. Airpower Journal.
In order to further decrease the number of airplane accidents stricter measures of evaluating an aircrafts operability prior to take off need to be implemented. Additionally, better training of pilots can also lead to a more preferable outcome should a problem arise as the pilot will be better equipped to handle an emergency.
Bosnor, Kevin. "How Flying Cars Will Work." Howstuffworks. How Stuff Works Inc., 1998. Web. 24 Jan.