Fundamentals Academic Source and Calibration Procedure Of Aviation - Research Paper Example

FUNDAMENTALS OF FLIGHT Name Tutor Institution Date FUNDAMENTALS OF FLIGHT Weekly journals Week 1-mechanics Inertia refers to the resistance offered by a physical object to any change in the object’s state of rest or motion. It is the resistance of an object to motion change. rho is a Greek symbol that refers to the probability density of transition to state 1 from state 2 The international Standard Atmosphere or ISA refers top the atmospheric model showing how the temperature, pressure, viscosity, and density of the atmosphere of the earth changes over a broad range of altitudes (Collicott, Houghton, and Carpenter 2012).  Newton: The Newton is the SI unit for force. It can be equated to the quantity of net force needed to accelerate a 1 kilogram mass at that rate of 1 m/s2 The Newton is Mechanism for measuring motorboat speed The boat’s resultant velocity is the vector sum of river velocity and velocity of the boat. Because the boat is heading across the water in a straight motion and the current goes straight from upstream one vector is at a right angle to the other vector. This means that the Pythagorean Theorem could be used in determination of resultant velocity. If the river is moving at a 3 m/s velocity to the north for example, and the boat moves at 4m/s velocity to the east, then the magnitude of the resultant velocity is found by: (4.0 m/s)2 + (3.0 m/s)2 = R2 16 m2/s2 + 9 m2/s2 = R2 25 m2/s2 = R2 SQRT (25 m2/s2) = R 5.0 m/s = R (Tipler 2004).  The resultant has a direction that is the counterclockwise rotation angle made with due east by the resultant vector. Determination of this angle can be done by use of a trigonometric function as below: tan (theta) = (opposite/adjacent) tan (theta) = (3/4) theta = invtan (3/4) theta = 36.9 degrees (Tipler 2004). This design is limited because it only relies on the observation of a person by eye. Such kind of observation may be subject to many errors of judgment because there are no gadgets to ensure accuracy or store the information gathered (Collicott et al 2012). Pitotic/static system a) Blocked pitot tube When the pitot tube is blocked the resultant effect is that the air speed indicator will have to register a rise in the speed of air whenever the aircraft is climbing even when the real speed of air may be constant. This comes about due to pressure within the pitot system being constant even with decrease in static and atmospheric pressure. Whenever the air craft is descending the reverse will happen since the air speed indicator shows a drop in the speed of air. Figure1: When the pitot system is blocked but the static system is clear Source: (Collicott et al 2012). b) Blocked static port A blocked static port has a bad effect on all the pitot static instruments. It causes freezing of the the altimeter at a constant value which is the altitude where the static port was blocked. Vertical speed indicator freezes at zero then it registers no more change even with increase or decrease in vertical airspeed. The indicator of airspeed reverses the error that occurs in a clogged pitot tube and hence it causes the airspeed to read less than the actual reading when the aircraft is climbing. In a descending aircraft there will be an over-reporting of the airspeed (Dingle, Tooley 2011). c) Both static port and pitot tube blocked If the drain hole and the pitot tube are simultaneously blocked the pressure within the pitot tube will be trapped inside. No change will be noted in the air speed indication if the air speed drops or rises. If unblocking is done in the static port and the altitude of the air craft is changed then the ASI registers a change. This change has no relationship with air speed change but it does with static pressure change. Total pressure within the pitot tube changes not because of the blockage although there can be a change in static pressure. Since the indications of air speed depend on dynamic and static pressure together clogging any of these systems has an effect on the ASI reading (Smith 1992). Week 2 Lift 1 Manoeuvrability: Manoeuvrability is the term referring to the ability of the aeroplane to alter its attitude when influenced by the aeroplane controls. Dynamic energy: Dynamic energy is the amount of energy needed by the airplane to overcome the resistance of the air and the force of gravity and rise up from the ground. Lift coefficient: The lift coefficient is a coefficient with no dimension and it relates the lift that a lifting body generates, the dynamic pressure of the flow of fluid on the body and an area of reference that is associated with the same body. Lift coefficient may also refer to the dynamic characteristics of a lift of a foil section with two dimensions in which the reference area becomes the foil chord. Lift coefficient could be said as the ratio of ‘lift pressure to dynamic pressure where lift pressure is the ratio to lift to reference area.” (Roskan et al 1997). Total reaction: This is the resultant of all aerodynamic forces acting on an air foil or wing section via centre pressure. It acts in a direction 90° to the air foil’s chord line and the flat plate as well. Figure 2: Diagram showing total reaction Source: (Collicott et al 2012). Structural loading: Every part on an air craft has many loads acting on it. In the ultimate air craft structure design it is possible for an engineer to examine many conditions of loading of which hundred may be important for some aero plane parts. To add to the obvious loads like wing bending moments because of aerodynamic lift there are many other loads that should be considered. Included here are items like inertia relief, inertia forces and weight that reduce the bending moments of wings, taxi bump loads, landing loads, local high pressure to the floor, pressurization cycle on fuselage and others. Various simulations, wind tunnel tests and Navier stokes computations are often used in the prediction of these loads (Tipler 2004). In air crafts structural loading is normally divided into ultimate loads and limit loads. Limit loads are the flight loads and they are divided into gust loads and maneuvering loads. Crash loads are the ultimate loads. Determination of maneuvering loads is done on the basis of air craft performance limits whether they are imposed by air craft aerodynamic performance or flight manual (Tipler 2004). Gust loads are determined through statistical means and are obtained from the requirements given by the relevant regulatory agency. Crash loads are bound loosely by human ability to withstand extreme accelerations and are obtained from regulations as well. Ground loads and pressure loads are also important. Ground loads can result from maneuvering on taxi or adverse braking. Cyclic loading also affects air craft through damage tolerance and fatigue. The cyclic loads start cracks and grow them. Thermal loading may also be important in extreme conditions of operation. It must be examined when there are materials with disparate coefficients of thermal expansion (Dingle, Tooley 2011). Theory for lift creation The other theory of creation of lift is in the work of the Bernoulli’s principle where the lift of air craft wings is involved. In this case the design is made to create a differential in speed of the air flowing past the object over and below. In the wings of the air craft this is obtained through the flaps when they move. This level of speed differential causes a difference in pressure between bottom and top of that object. This causes a net force to be exerted downwards or upwards as illustrated in the figure below (Roskam, Chuan-Tau 1997). AnothThis is il Figure 3: Lift of an aircraft wing (Dingle, Tooley 2011).   Week 3- Drag Type of drag wave drag Profile drag Skin friction Interference drag Lift induced drag What it causes It causes shock waves on hence reduced speed Causes resistance to flow of objects Causes friction between surface and air Reduces speed of aircraft Increases amount of fuel used Effect of speed The resistance increases with increased velocity hence more wave drag High or increased speed increases the profile drag Skin friction drag is increased with high speed Reduces when the speed of the air craft is increased With high speed lift induced drag is reduced Reducing it Sweeping the wing or supercritical air foil Use of variable aerosol and taper. Allows more space for wider spar at root of wing Microblowing Technique where little air is blown on a surface vertically through tiny holes Increasimg span efficiency factor to near e = 1, increasing wing span b (or aspect ratio AR), and increasing free-stream velocity V¥.  Areas/types of drag and modifications to reduce drag On the drawing on slide 47 various types of drag can be identified as explained below: From drag: This type of drag is formed at the front part of the lorry since it has to cut through the air and separate it so that some of it flows under while the other flows over the lorry. This drag can be reduced by making the front part more pointed than just flat (Lawford et al 1983). Skin friction: The surface of the lorry has some viscous stresses and this do cause skin friction at the boundary line. This drag can be reduced by making the wall surface of the body of the lorry smoother. This will reduce any friction between the air and the surface. Interference drag: This occurs at the junctions on the lorry. The flow of air is interested with at these junctions. It can be experienced between the bonnet and the wind screen and at the top of the front part of the lorry where there is erected an aerial. Reduction of this drag is possible by reducing the number of junctions and sharp corners on the body of the lorry (Roskam, Chuan-Tau 1997). Wave drag: This drag occurs on the entire surface of the lorry whenever the air becomes sonic on any body part. Modifications to reduce this drag may include coating the surface with material that increases its level of smoothness (Dingle, Tooley 2011). Week 3 Lift augmentation Air craft attitude: This is a term used to refer to the orientation of the aircraft relative to earth. CLmax :It refers to the Maximum lift coefficient of an air craft Deployment: The release of a specific part of the plain to start working for example the flaps during air craft landing Energise: To raise the energy level of an aircraft so that is can rise into the air Kruger flaps: Krueger flaps are devices that enhance lift and are fitted on the leading edge of the wing of an air craft. As opposed to slats the major wing upper side and the nose remains the same. The aerodynamic of slats and slops resembles that of Krueger flaps. However Krueger flaps are hinged at leading edges and they hinge to the front side from the lower surface of the wing thereby increasing the maximum coefficient lift and the wing camber (Tipler, 2004).  Figure 4: Krueger flaps on the leading edge Source: Lawford et al 1983. Flaps increase the drag, they shift the relationship between the angle of attack and the lift, reduce lateral control as well as the maneuvering load factor. Plain flaps and fowler flaps: Plain flaps are fixed on simple hinges and they are inexpensive and simple hence they are found on small air craft. On the other hand fowler flaps are very complicated and are arranged efficiently. Extending fowler flaps: Flaps increase lift by increasing surface are. At take off more lift is required and flaps are not fully deployed. Drag is minimal and lift is high. When flaps are extended the lift coefficient and airfoil camber is increased (Roskam et al 1997). Week 4- Climbing Descending Cosine: In trigonometry, the cosine of any angle can be defined as the sine of a complementary angle to that angle. That complementary angle is equal to a right angle with the given angle subtracted from it. For example if that angle is 30 degrees then the complementary angle to it becomes 60 degrees. Generally, for an angle t, cos t = sin (90° – t). When expressed in the terms of radian measurement the identity will become cos t = sin (/2 – t) (Smith 1992). Sine: In trigonometry again, the sine is a function of any angle. In the right triangle the sine will give the ratio of the opposite side to an angle to hypotenuse length (Smith 1992). Week 5- Controls stability Adverse yaw: This is defined as a yaw moment on the air craft resulting from a roll rate and an aileron deflection that can be seen in exiting or entering a turn. The term adverse is attached to it because it operates in an opposite manner to the yaw moment that is required to bring about the needed turn. Trim controls: Trimming controls are important because they allow the aero plane pilot to make a balance of the drag and lift produced on the wings and on the control surfaces in a broad range of air speed and load. Through this the effort needed to maintain or adjust the needed flight attitude is reduced (Lawford and Nippress, 1983).  Frise Ailerons: An aileron shape was first developed by engineer George Frise who lived between 1897 and 1979. The aileron is used in counteracting adverse yaw. The pivoting of the Frise aileron is at 25 to 30% chord line and close to the bottom surface. Whenever the there is an upward deflection of the aileron (to bring down its wing) the aileron edge that is in front dips into the flow of air under the wing. The leading edge moment in the flow of air helps in moving the trailing edge up hence reducing stick force (Lawford et al 1983).The aileron moving downwards also adds more energy to the boundary layer by the flow of air from the side below the wing that scoops air with the aileron edge. This is the air passing on the upper side of the aileron which creates a lifting force on the aileron upper surface hence helping the lifting of the wing. This causes a reduction in the angle of deflection of the aileron. If the edge ahead of the aileron is bluntly rounded or sharp it adds some drag on the wing which makes the aero plane to turn or yaw in the right direction. However it adds some potentially dangerous and unpleasant aerodynamic flutter or vibration (Lawford et al 1983). A stabilator (All moving stabilizer): Also known as all flying tail or all moving tail plane. This is a control surface within the air craft combining the functions of a horizontal stabilizer and elevator. Many air craft with fixed wings control their pitch by use of a hinged horizontal flap or elevator that is normally attached behind a fixed horizontal stabilizer although certain air craft make the whole stabilizer to move (Dingle, Tooley 2011). Increasing directional stability Directional stability can be associated with the realignment of the flight path or angle of zero slip and the longitudinal axis after a certain disturbance has caused the aero plane to yaw out of the alignment to produce a slip (Kjelgaard1988). Yaw here refers to the rotation on the normal or vertical axis. The rudder or vertical tail is the major component in static directional stability. When in the angle of attack because of the sideslip disturbance it creates sides force that when multiplied with the moment arm or air plane center of gravity to aerodynamic vertical tail center it creates a moment of stabilization that brings the air craft back to the yaw condition or zero sideslip. The aspect ratio of the vertical moment is usually low so that it can prevent stalling. In case of a stall there is instability and this may cause a dangerous sideslip divergence. A more stable yawing moment at big sideslip angles may be achieved through adding a tail that is more vertical using a ventral tail area or dorsal fin extension (Hill and Peterson 1992). Why out of trim condition is dangerous: Air planes need to be trimmed for all flight conditions except in those times when the air craft is changing speed or turning. When an air craft is flown out of trim then it becomes very difficult and wearisome to control it. This means it can lose control and cause an accident. Initial trim settings must be close (Megson 2012). Week 6- propellers When the speed is below 300 kts the propeller is struggling against air resistance and the effect of a powerful drag. This goes on until the speed has reached 300 kts and the propeller has overcome the effect of the drag. At this speed the propeller is no longer opposed by air resistance and therefore it cannot have the push or propelling force on the plane. Therefore its propulsive efficiency falls at this point (Dingle et al 2010). References Collicott S., Houghton E.L, Carpenter W.P (2012) Aerodynamics for engineering students, Elsevier Dingle L., Tooley M., Tooley H. (2010) Air craft engineering principles, Taylor & Francis Megson D. (2012) Aircraft structures for engineering students, Elsevier Dingle L., Tooley M (2011) Aircraft engineering maintenance practice, Elsevier Science & Technology Books. Hill P. and Peterson C., (1992) Mechanics and Thermodynamics of Propulsion, 2d ed. Kjelgaard, S. O. (1988), Theoretical Derivation and Calibration Technique of a Hemispherical- Tipped Five-Hole Probe (NASA Technical Memorandum 4047). Lawford. J. A. and Nippress, K. R. (1983). Calibration of Air-Data Systems and Flow Direction Sensors (AGARD AG-300 - Vol.1, AGARD Flight Test Techniques Series; R. W. Borek, ed.). Accessed via Spaceagecontrol.com (PDF). Retrieved on 02 May 2012. Roskam J., Chuan-Tau E. L.  (1997) Air plane aerodynamics and performance; DarCorporation Smith C. H. (1992) The Illustrated Guide to Aerodynamics, McGrawHill Professional Tipler, P. (2004). Physics for Scientists and Engineers: Mechanics, Oscillations and Waves, Thermodynamics (5th ed.). W. H. Freeman Read More

Total reaction: This is the resultant of all aerodynamic forces acting on an air foil or wing section via centre pressure. It acts in a direction 90° to the air foil’s chord line and the flat plate as well. Figure 2: Diagram showing total reaction Source: (Collicott et al 2012). Structural loading: Every part on an air craft has many loads acting on it. In the ultimate air craft structure design it is possible for an engineer to examine many conditions of loading of which hundred may be important for some aero plane parts.

To add to the obvious loads like wing bending moments because of aerodynamic lift there are many other loads that should be considered. Included here are items like inertia relief, inertia forces and weight that reduce the bending moments of wings, taxi bump loads, landing loads, local high pressure to the floor, pressurization cycle on fuselage and others. Various simulations, wind tunnel tests and Navier stokes computations are often used in the prediction of these loads (Tipler 2004). In air crafts structural loading is normally divided into ultimate loads and limit loads.

Limit loads are the flight loads and they are divided into gust loads and maneuvering loads. Crash loads are the ultimate loads. Determination of maneuvering loads is done on the basis of air craft performance limits whether they are imposed by air craft aerodynamic performance or flight manual (Tipler 2004). Gust loads are determined through statistical means and are obtained from the requirements given by the relevant regulatory agency. Crash loads are bound loosely by human ability to withstand extreme accelerations and are obtained from regulations as well.

Ground loads and pressure loads are also important. Ground loads can result from maneuvering on taxi or adverse braking. Cyclic loading also affects air craft through damage tolerance and fatigue. The cyclic loads start cracks and grow them. Thermal loading may also be important in extreme conditions of operation. It must be examined when there are materials with disparate coefficients of thermal expansion (Dingle, Tooley 2011). Theory for lift creation The other theory of creation of lift is in the work of the Bernoulli’s principle where the lift of air craft wings is involved.

In this case the design is made to create a differential in speed of the air flowing past the object over and below. In the wings of the air craft this is obtained through the flaps when they move. This level of speed differential causes a difference in pressure between bottom and top of that object. This causes a net force to be exerted downwards or upwards as illustrated in the figure below (Roskam, Chuan-Tau 1997). AnothThis is il Figure 3: Lift of an aircraft wing (Dingle, Tooley 2011).

  Week 3- Drag Type of drag wave drag Profile drag Skin friction Interference drag Lift induced drag What it causes It causes shock waves on hence reduced speed Causes resistance to flow of objects Causes friction between surface and air Reduces speed of aircraft Increases amount of fuel used Effect of speed The resistance increases with increased velocity hence more wave drag High or increased speed increases the profile drag Skin friction drag is increased with high speed Reduces when the speed of the air craft is increased With high speed lift induced drag is reduced Reducing it Sweeping the wing or supercritical air foil Use of variable aerosol and taper.

Allows more space for wider spar at root of wing Microblowing Technique where little air is blown on a surface vertically through tiny holes Increasimg span efficiency factor to near e = 1, increasing wing span b (or aspect ratio AR), and increasing free-stream velocity V¥.  Areas/types of drag and modifications to reduce drag On the drawing on slide 47 various types of drag can be identified as explained below: From drag: This type of drag is formed at the front part of the lorry since it has to cut through the air and separate it so that some of it flows under while the other flows over the lorry.

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