IntroductionSeveral factors affect

Introduction
Several factors affect aircraft performance including the atmosphere, aerodynamics, and aircraft icing. Pilots need an understanding of these factors for a sound basis for prediction of aircraft response to control inputs, especially with regard to instrument approaches, while holding, and when operating at reduced airspeed in instrument meteorological conditions (IMC). Although these factors are important to the pilot flying visual flight rules (VFR), they must be even more thoroughly understood by the pilot operating under instrument flight rules (IFR). Instrument pilots rely strictly on instrument indications to precisely control the aircraft; therefore, they must have a solid understanding of basic aerodynamic principles in order to make accurate judgments regarding aircraft control inputs.
Aerodynamic Factors Chapter 2

The Wing
To understand aerodynamic forces, a pilot needs to understand basic terminology associated with airfoils. Figure 2-1 illustrates a typical airfoil. The chord line is the straight line intersecting the leading and trailing edges of the airfoil, and the term chord refers to the chord line longitudinal length (length as viewed from the side). The mean camber is a line located halfway between the upper and lower surfaces. Viewing the wing edgewise, the mean camber connects with the chord line at each end. The mean camber is important because it assists in determining aerodynamic qualities of an airfoil. The measurement of the maximum camber; inclusive of both the displacement of the mean camber line and its linear measurement from the end of the chord line, provide properties useful in evaluating airfoils.



Review of Basic Aerodynamics
The instrument pilot must understand the relationship and differences between several factors that affect the performance of an aircraft in flight. Also, it is crucial to understand how the aircraft reacts to various control and power changes, because the environment in which instrument pilots fly has inherent hazards not found in visual flying. The basis for this understanding is found in the four forces acting on an aircraft and Newton’s Three Laws of Motion. Relative Wind is the direction of the airflow with respect to an airfoil. Angle of Attack is the acute angle measured between the relative wind, or flight path and the chord of the airfoil.
Flight path is the course or track along which the aircraft is flying or is intended to be flown.

The Four Forces
The four basic forces [Figure 2-3] acting upon an aircraft in flight are lift, weight, thrust, and drag.

Lift
Lift is a component of the total aerodynamic force on an airfoil and acts perpendicular to the relative wind. Relative wind is the direction of the airflow with respect to an airfoil. This force acts straight up from the average (called mean) center of pressure (CP), which is called the center of lift. It should be noted that it is a point along the chord line of an airfoil through which all aerodynamic forces are considered to act. The magnitude of lift varies proportionately with
speed, air density, shape and size of the airfoil, and angle of attack. During straight-and-level flight, lift and weight are equal.

Weight
Weight is the force exerted by an aircraft from the pull of gravity. It acts on an aircraft through its center of gravity (CG) and is straight down. This should not be confused with the center of lift, which can be significantly different from the CG. As an aircraft is descending, weight is greater than lift.

Thrust
Thrust is a force that drives an aircraft through the air and can be measured in thrust and/or horsepower. It is a component that is parallel to the center of thrust and overcomes drag providing the aircraft with its forward speed component.


Drag
Drag is the net aerodynamic force parallel to the relative wind and is generally a sum of two components: induced drag and parasite drag.
Induced drag
Induced drag is caused from the creation of lift and increases with angle of attack. Therefore, if the wing is not producing lift, induced drag is zero. Conversely, induced drag decreases with airspeed.
Parasite drag
Parasite drag is all drag not caused from the production of lift. Parasite drag is created by displacement of air by the aircraft, turbulence generated by the airfoil, and the hindrance of airflow as it passes over the surface of the aircraft or components. All of these forces create drag not from the production of lift but the movement of an object through an air mass. Parasite drag increases with speed and includes skin friction drag, interference drag, and form drag.
• Skin Friction Drag
Covering the entire “wetted” surface of the aircraft is a thin layer of air called a boundary layer. The air molecules on the surface have zero velocity in relation to the surface; however, the layer just above moves over the stagnant molecules below because it is pulled along by a third layer close to the free stream of air. The velocities of the layers increase as the distance from the surface increases until free stream velocity is reached, but all are affected by the free stream. The distance (total) between the skin surface and where free stream velocity is reached is called the boundary layer. At subsonic levels the cumulative layers are about the thickness of a playing card, yet their motion sliding over one another creates a drag force. This force retards motion due to the viscosity of the air and is called skin friction drag. Because skin friction drag is related to a large surface area its affect on smaller aircraft is small versus large transport aircraft
where skin friction drag may be considerable.
• Interference Drag
Interference drag is generated by the collision of airstreams creating eddy currents, turbulence, or restrictions to smooth flow. For instance, the airflow around a fuselage and around the wing meet at some point, usually near the wing’s root. These airflows interfere with each other causing a greater

Figure 2-4. Newton’s First Law of Motion: the Law of Inertia. drag than the individual values. This is often the case when external items are placed on an aircraft. That is, the drag of each item individually, added to that of the aircraft, are less than that of the two items when allowed to interfere with one another.
• Form Drag
Form drag is the drag created because of the shape of a component or the aircraft. If one were to place a circular disk in an air stream, the pressure on both the top and bottom would be equal. However, the airflow starts to break down as the air flows around the back of the disk. This creates turbulence and hence a lower pressure results. Because the total pressure is affected by this reduced pressure, it creates a drag. Newer aircraft are generally made with consideration to this by fairing parts along the fuselage (teardrop) so that turbulence and form drag is reduced.
Total lift must overcome the total weight of the aircraft, which is comprised of the actual weight and the tail-down force used to control the aircraft’s pitch attitude. Thrust must overcome total drag in order to provide forward speed with which to produce lift. Understanding how the aircraft’s relationship between these elements and the environment provide proper interpretation of the aircraft’s instruments.

Newton’s First Law, the Law of Inertia
Newton’s First Law of Motion is the Law of Inertia. It states that a body at rest will remain at rest, and a body in motion will remain in motion, at the same speed and in the same direction until affected by an outside force. The force with which a body offers resistance to change is called the force of inertia. Two outside forces are always present on an aircraft in flight: gravity and drag. The pilot uses pitch and thrust controls to counter or change these forces to maintain the desired flight path. If a pilot reduces power while in straightand- level flight, the aircraft will slow due to drag. However, as the aircraft slows there is a reduction of lift, which causes
the aircraft to begin a descent due to gravity.

Newton’s Second Law, the Law of Momentum
Newton’s Second Law of Motion is the Law of Momentum, which states that a body will accelerate in the same direction as the force acting upon that body, and the acceleration will be directly proportional to the net force and inversely proportional to the mass of the body. Acceleration refers either to an increase or decrease in velocity, although deceleration is commonly used to indicate a decrease. This law governs the aircraft’s ability to change flight path and speed, which are controlled by attitude (both pitch and bank)and thrust inputs. Speeding up, slowing down, entering climbs or descents, and turning are examples of accelerations that the pilot controls in everyday flight.

Newton’s Third Law, the Law of Reaction
Newton’s Third Law of Motion is the Law of Reaction, which states that for every action there is an equal and opposite reaction. As shown in Figure 2-6, the action of the jet engine’s thrust or the pull of the propeller lead to the reaction of the aircraft’s forward motion. This law is also
responsible for a portion of the lift that is produced by a wing, from the downward deflection of the airflow around it. This downward force of the relative wind results in an equal but
opposite (upward) lifting force created by the airflow over the wing.


Atmosphere
The atmosphere is the envelope of air which surrounds the Earth. A given volume of dry air contains about 78 percent nitrogen, 21 percent oxygen, and about 1 percent other gases such as argon, carbon dioxide, and others to a lesser degree. Although seemingly light, air does have weight and a one square inch column of the atmosphere at sea level weighs approximately 14.7 pounds. About one-half of the air by weight is within the first 18,000 feet. The remainder of the air is spread over a vertical distance in excess of 1,000 miles. Air density i

Hasil (Bahasa Indonesia) 1:

PengenalanBeberapa faktor mempengaruhi performa pesawat termasuk suasana, aerodinamika, dan pesawat icing. Pilot memerlukan pemahaman tentang faktor-faktor ini untuk dasar prediksi pesawat menanggapi kontrol input, terutama yang berkaitan dengan instrumen pendekatan, sedangkan menahan, dan ketika beroperasi pada mengurangi kecepatan dalam instrumen Meteorologi kondisi (IMC). Meskipun faktor penting untuk pilot terbang aturan penerbangan visual (VFR), mereka harus lebih benar-benar dipahami oleh pilot operasi di bawah instrumen penerbangan aturan (IFR). Instrumen pilot benar-benar mengandalkan instrumen indikasi untuk mengendalikan tepat pesawat; oleh karena itu, mereka harus memiliki pemahaman yang kuat tentang prinsip-prinsip dasar aerodinamis untuk membuat penilaian yang akurat mengenai pesawat kontrol input.Faktor-faktor aerodinamis Bab 2SayapUntuk memahami kekuatan aerodinamis, pilot perlu memahami terminologi dasar yang terkait dengan airfoils. Gambar 2-1 menggambarkan airfoil khas. Garis chord adalah garis lurus yang berpotongan terkemuka dan tepi belakang airfoil, dan akord istilah mengacu chord garis longitudinal panjang (panjang seperti yang dilihat dari samping). Camber berarti adalah garis terletak di tengah antara permukaan atas dan bawah. Melihat sayap edgewise, camber berarti menghubungkan dengan jalur chord di setiap akhir. Camber berarti penting karena membantu dalam menentukan kualitas aerodinamis airfoil. Pengukuran camber maksimum; termasuk kedua perpindahan berarti camber baris dan pengukuran yang linear dari akhir baris chord, memberikan sifat yang berguna dalam mengevaluasi airfoils.Review dari dasar aerodinamikaInstrumen pilot harus mengerti hubungan dan perbedaan diantara beberapa faktor yang mempengaruhi kinerja pesawat terbang. Juga, sangat penting untuk memahami bagaimana pesawat bereaksi terhadap berbagai perubahan kontrol dan kekuasaan, karena lingkungan yang instrumen Pilot terbang melekat bahaya tidak ditemukan dalam penerbangan visual. Dasar bagi pemahaman ini ditemukan dalam gaya yang empat bekerja pada sebuah pesawat dan Newton tiga hukum gerak. Angin adalah arah aliran udara terhadap airfoil. Sudut Serang adalah sudut akut diukur antara angin relatif, atau jalur penerbangan dan akord airfoil.Jalur penerbangan adalah lapangan atau track sepanjang yang pesawat terbang atau dimaksudkan untuk diterbangkan.Empat kuasaEmpat dasar kekuatan [gambar 2-3] bertindak atas sebuah pesawat terbang yang angkat, berat badan, dorong dan tarik.MengangkatAngkat adalah komponen dari Angkatan aerodinamis total pada airfoil dan bertindak tegak lurus angin. Angin adalah arah aliran udara terhadap airfoil. Ini memaksa tindakan langsung dari rata-rata (disebut berarti) Pusat tekanan (CP), yang disebut pusat angkat. Perlu dicatat bahwa ini adalah titik sepanjang garis chord airfoil melalui mana semua kekuatan aerodinamis dianggap bertindak. Besarnya angkat bervariasi secara proporsional dengankecepatan, udara kepadatan, bentuk dan ukuran airfoil, dan sudut Serang. Selama penerbangan lurus-dan-tingkat, angkat dan berat yang sama.Berat badanBerat adalah gaya yang diberikan oleh pesawat dari tarikan gravitasi. Ini bekerja pada sebuah pesawat melalui pusat gravitasi (CG) dan lurus ke bawah. Ini tidak menjadi bingung dengan pusat lift, yang dapat secara signifikan berbeda dari CG. Seperti pesawat terbang turun, berat badan lebih besar daripada lift.DorongDorong adalah kekuatan yang menggerakkan pesawat terbang melalui udara dan dapat diukur dalam dorong dan/atau tenaga kuda. Ini adalah komponen yang sejajar dengan pusat dorong dan mengatasi hambatan menyediakan pesawat dengan komponen maju kecepatan.TarikTarik kekuatan aerodinamis bersih sejajar relatif angin dan umumnya jumlah dua komponen: diinduksi tarik drag dan parasit. Diinduksi dragTarik diinduksi disebabkan dari penciptaan angkat dan meningkat dengan sudut Serang. Oleh karena itu, jika sayap tidak memproduksi angkat, tarik diinduksi adalah nol. Sebaliknya, tarik diinduksi menurun dengan kecepatan.Tarik parasit Tarik parasit adalah semua hambatan tidak disebabkan dari produksi angkat. Tarik parasit dibuat oleh perpindahan udara oleh pesawat, turbulensi yang dihasilkan oleh airfoil, dan rintangan aliran udara seperti itu melewati permukaan pesawat atau komponen. Semua kekuatan ini membuat tarik bukan dari produksi angkat tapi pergerakan objek melalui massa udara. Parasit drag meningkat dengan kecepatan dan termasuk drag gesekan kulit, gangguan tarik, dan drag bentuk.• Kulit gesekan DragMeliputi seluruh permukaan "dibasahi" pesawat adalah lapisan tipis udara disebut lapisan batas. Molekul udara di permukaan memiliki nol kecepatan dalam kaitannya dengan permukaan; Namun, lapisan di atas bergerak atas molekul stagnan di bawah karena itu ditarik sepanjang oleh lapisan ketiga dekat dengan aliran udara yang gratis. Velocities dari lapisan meningkatkan sebagai jarak dari kenaikan permukaan sampai kecepatan gratis gratis streaming dicapai, tetapi semua dipengaruhi oleh aliran gratis. Jarak (total) antara permukaan kulit dan mana gratis gratis streaming kecepatan dicapai disebut lapisan batas. Subsonik tingkat kumulatif lapisan adalah tentang ketebalan bermain kartu, namun gerakan mereka meluncur lebih dari satu sama lain menciptakan kekuatan tarik. Gaya ini menghambat gerakan karena viskositas udara dan disebut drag gesekan kulit. Karena gesekan kulit tarik terkait dengan area permukaan besar pengaruhnya pada pesawat kecil kecil dibandingkan pesawat pengangkut besarmana gesekan kulit menyeret mungkin cukup besar.• Gangguan DragTarik gangguan yang dihasilkan oleh tumbukan menciptakan arus eddy, turbulensi, atau pembatasan untuk kelancaran arus airstreams. Misalnya, aliran udara di sekitar lambung dan di sekitar sayap bertemu di beberapa titik, biasanya dekat sayap yang akar. Airflows ini mengganggu satu sama lain menyebabkan yang lebih besarFigure 2-4. Newton’s First Law of Motion: the Law of Inertia. drag than the individual values. This is often the case when external items are placed on an aircraft. That is, the drag of each item individually, added to that of the aircraft, are less than that of the two items when allowed to interfere with one another.• Form DragForm drag is the drag created because of the shape of a component or the aircraft. If one were to place a circular disk in an air stream, the pressure on both the top and bottom would be equal. However, the airflow starts to break down as the air flows around the back of the disk. This creates turbulence and hence a lower pressure results. Because the total pressure is affected by this reduced pressure, it creates a drag. Newer aircraft are generally made with consideration to this by fairing parts along the fuselage (teardrop) so that turbulence and form drag is reduced.Total lift must overcome the total weight of the aircraft, which is comprised of the actual weight and the tail-down force used to control the aircraft’s pitch attitude. Thrust must overcome total drag in order to provide forward speed with which to produce lift. Understanding how the aircraft’s relationship between these elements and the environment provide proper interpretation of the aircraft’s instruments.Newton’s First Law, the Law of InertiaNewton’s First Law of Motion is the Law of Inertia. It states that a body at rest will remain at rest, and a body in motion will remain in motion, at the same speed and in the same direction until affected by an outside force. The force with which a body offers resistance to change is called the force of inertia. Two outside forces are always present on an aircraft in flight: gravity and drag. The pilot uses pitch and thrust controls to counter or change these forces to maintain the desired flight path. If a pilot reduces power while in straightand- level flight, the aircraft will slow due to drag. However, as the aircraft slows there is a reduction of lift, which causesthe aircraft to begin a descent due to gravity.Newton’s Second Law, the Law of MomentumNewton’s Second Law of Motion is the Law of Momentum, which states that a body will accelerate in the same direction as the force acting upon that body, and the acceleration will be directly proportional to the net force and inversely proportional to the mass of the body. Acceleration refers either to an increase or decrease in velocity, although deceleration is commonly used to indicate a decrease. This law governs the aircraft’s ability to change flight path and speed, which are controlled by attitude (both pitch and bank)and thrust inputs. Speeding up, slowing down, entering climbs or descents, and turning are examples of accelerations that the pilot controls in everyday flight.Newton’s Third Law, the Law of ReactionNewton’s Third Law of Motion is the Law of Reaction, which states that for every action there is an equal and opposite reaction. As shown in Figure 2-6, the action of the jet engine’s thrust or the pull of the propeller lead to the reaction of the aircraft’s forward motion. This law is alsoresponsible for a portion of the lift that is produced by a wing, from the downward deflection of the airflow around it. This downward force of the relative wind results in an equal butopposite (upward) lifting force created by the airflow over the wing.AtmosphereThe atmosphere is the envelope of air which surrounds the Earth. A given volume of dry air contains about 78 percent nitrogen, 21 percent oxygen, and about 1 percent other gases such as argon, carbon dioxide, and others to a lesser degree. Although seemingly light, air does have weight and a one square inch column of the atmosphere at sea level weighs approximately 14.7 pounds. About one-half of the air by weight is within the first 18,000 feet. The remainder of the air is spread over a vertical distance in excess of 1,000 miles. Air density i