Advanced Aerodynamics and Flight Performance Quiz

When climbing at a constant mach number, the density of the air decreases with altitude, causing the CAS to decrease as well, since CAS is affected by air density. This is due to the relationship between CAS and true airspeed being inversely proportional.

True Airspeed (TAS) is the speed of an aircraft relative to the surrounding air mass. As temperature decreases, air density also decreases, leading to a decrease in TAS when climbing at a constant Mach number.

Leading edge slats and leading edge flaps have distinct functions and effects on the aerodynamics of an aircraft. Understanding their differences is crucial for proper aircraft design and operation.

As the aircraft climbs above FL300, the true airspeed (EAS) will increase due to the lower air density at higher altitudes. The indicated airspeed (IAS) will also increase as it is calculated based on the impact pressure of the air on the pitot tube. Therefore, both IAS and EAS stall speeds will increase as the aircraft climbs above FL300.

As an aircraft transitions through the speed of sound (1.00 Mach), the coefficient of drag initially increases due to shock waves forming, then decreases as the airflow becomes more supersonic and the shock waves detach from the aircraft.

In the isothermal layer above the tropopause, temperature remains constant. This means True Airspeed (TAS), which is directly related to temperature, will also remain constant during a climb with a constant Mach number.

In a constant Mach number climb, indicated airspeed (IAS) will decrease due to decreasing pressure and the density of the air molecules when climbing into the isothermal layer above the tropopause.

Mcrit is the speed at which supersonic airflow first occurs, marking the transition from subsonic to supersonic flow in aerodynamics.

The speed of sound is directly proportional to the square root of the absolute temperature. Therefore, temperature has the most significant impact on the speed of sound.

When an aircraft exceeds its critical Mach number (Mcrit) without Mach Trimmer, the first noticeable effect is the nose of the aircraft pitching down. This is due to the aerodynamic forces acting on the control surfaces as the aircraft approaches transonic speeds.

Delaying the formation of wing shockwaves helps in reducing drag, which in turn keeps the drag penalty to a minimum and improves overall performance.

Supercritical wing sections are designed to delay the onset of wave drag by reducing the top wing surface acceleration, allowing for higher speeds without significant drag penalties.

Aileron control reversal occurs when the wing twists about its lateral axis due to high aerodynamic loads at high speed. This causes the ailerons to respond opposite to the pilot's input. Pilot error, equipment failure, and improper calibration can lead to other issues but do not directly cause aileron control reversal.

Exceeding Mcrit causes the center of pressure to move rearward, resulting in a nose down pitch as the aerodynamic forces are no longer in equilibrium.

At transonic speeds, the coefficient of lift will first increase due to the compressibility effects, then decrease as the aircraft approaches the speed of sound where shock waves are formed.

A Mach trimmer is designed to maintain pitch stability by ensuring that as the aircraft's speed increases, it will tend to pitch up, helping to maintain control and stability during flight.

At transonic speeds, airflow can become turbulent and cause separation ahead of the ailerons, decreasing their effectiveness in controlling roll. Spoilers are used in conjunction with ailerons to counteract this issue and maintain adequate control of the aircraft.

A yaw dampener specifically helps in stabilizing the aircraft by minimizing the need for rudder control inputs, especially at high altitudes and high Mach numbers to prevent yaw oscillations.

Wing sweep results in an increase in the stalling angle of attack because the swept wing CL is less than the straight wing CL for any given body angle.

Wing sweep is crucial for high speed flight as it helps in delaying the drag effects of shockwaves, which is essential for minimizing drag and attaining efficient performance at high speeds.

During a stall on a swept wing aircraft, the wing tip stall causes a drop in lift on the outer portion of the wing, leading to a nose pitch up moment. Additionally, the effective CP (center of pressure) moving forwards also contributes to the nose pitching up.

Most swept wing aircraft are fitted with a stickpusher for safety reasons related to stall protection and recovery potential.

The maximum rate of climb for a jet aircraft is determined by the excess power it has available compared to its weight. This excess power allows the aircraft to climb at a faster rate.

Vs, or the minimum steady flight speed, is a critical parameter for transport category aircraft as it represents the lowest speed at which the aircraft can maintain level flight. It is essential for safe operations and is one of the key factors considered during aircraft certification.

Flying at an altitude where the use of engine design RPM would result in a speed of Vimd helps in maximizing the airborne time as it optimizes the engine efficiency and fuel consumption for prolonged flight duration.

To achieve maximum angle of climb, you want to climb at the speed for maximum climb performance (Vimd) using maximum thrust. Climbing at any other speed or utilizing minimum thrust will not result in the best climb angle.

In large jet aircraft, the rate of climb is fairly constant within a certain speed band because the power available and power required curves are nearly parallel. This means that the aircraft can maintain a consistent rate of climb without significant changes in power output.

Va, or manoeuvring speed, is the speed at which an aircraft can safely perform abrupt maneuvers without risk of structural damage due to excessive aerodynamic loads. It is an important parameter for pilots to understand in order to operate the aircraft safely.

The ideal minimal movement of the CP of a transport aircraft wing with speed variations is essential to avoid the need for large trim changes, which would be necessary if there were significant CP movement.

When holding at a specific altitude like 3000 feet, the ideal holding speed is primarily determined by Indicated Airspeed (IAS) considerations, as it accounts for the aircraft's performance and handling characteristics in relation to air density and pressure.