Aerodynamics and Glide Performance Quiz

Theory of Flight

• Four forces act on an aircraft: Thrust, Lift, Weight, and Drag.
• Thrust propels the aircraft forward, opposing Drag.
• Lift opposes Weight, keeping the aircraft aloft.
• Weight is the force of gravity pulling the aircraft downwards.
• Drag is a resisting force, opposing Thrust.

Introduction

• Students will be able to describe the relationship between lift, weight, thrust and drag.
• Students will be able to explain glide ratio.
• Students will be able to detail steady state flight and performance.
• Students will be able to describe the theory of the turn.
• Students will be able to explain load factor and its influence on stalling, flight envelope and structural limitations.
• Students will be able to describe methods of lift augmentation.

Four Forces of Flight

• Lift is the upward force created by airflow over and under the wings.
• Weight is the force of gravity pulling the aircraft downwards.
• Thrust is the forward force, propelling the aircraft through the air.
• Drag is the backward force that resists the aircraft's movement through the air.

Vectors

• Arrows representing forces acting on an aircraft are called vectors.
• The length of the arrow represents the magnitude of the force.
• The direction of the arrow represents the orientation of the force.
• Multiple forces acting on an object simultaneously combine to create a resultant.

Lift

• Lift is the key aerodynamic force that opposes weight.
• An aircraft is in equilibrium in straight and level flight when weight and lift are equal.
• The wing's design creates a pressure difference, with higher pressure below the wing and lower pressure above the wing, which creates lift.

Weight

• Weight is directly related to the aircraft's mass and the force of gravity.
• Lift is required to counteract the weight. It acts perpendicular to the relative airflow.

Centre of Gravity

• Centre of Gravity (CG) is the point where all weights of the aircraft are concentrated.
• CG position affects stability: forward CG increases tendency to rotate nose-down, rear CG increases tendency to rotate nose-up.
• Aircraft stability greatly depends on CG position.

Adverse Forward Center of Gravity

• Shifting the CG forward increases the tendency to dive.
• Difficulty in raising the nose during landings is likely.
• Oscillation tendency and spin characteristics increase.

Adverse Rear Center of Gravity

• Moving the CG aft results in decreased flying speed and range.
• Increased risk of stalling and spin are present.
• Stability decreases significantly.

Aircraft Glide Ratio

• Glide ratio is calculated as the distance traveled horizontally in still air for every foot of altitude lost.
• To maximize glide ratio, the minimum gliding speed must be found on the glide angle.
• An aircraft's glide ratio depends on its drag and lift.

Aircraft Glide

• The aircraft glide angle is a key factor in calculating gliding flight.
• The tangent of the glide angle equals the altitude lost over the distance flown.

Glider Fly

• Glider flight uses the four essential forces to maintain glide.
• The lift and drag must oppose weight and airspeed must be appropriate for the gliding range.

Gliding Flight

• In power-off glide, thrust equals zero, and lift is equal to weight.

Equations of Motion for Power-Off Glide

• Drag equals weight multiplied by sine of the flight path angle.
• Lift equals weight multiplied by cosine of the flight path angle.
• Glide angle and lift are inversely proportional; higher glide angles correspond to less lift.

Load Factor

• Load factor (n) is the ratio of lift to weight.
• The load factor is important in turns.

Level Turn (Coordinated Turn)

• The vertical component of lift is equal to weight.
• The horizontal component of lift is equal to centripetal force.
• These forces prevent the aircraft from losing altitude/ gaining altitude during flight.

Sideslip

• Sideslip is a condition where the aircraft's sides move past relative airflow sideways.
• An aircraft sideslip happens when the sideslip is not correctly compensated for leading to uncontrolled movements.

Skidding

• Skidding occurs when the lateral component of lift is not sufficient to counter the effect of centrifugal force.
• This leads to uncontrolled movements.

Sideway Landing

• Sideway landings involve precise maneuvering and technique.

Cross Wind Landing

• Cross-wind landings involve compensating for winds which are at an angle to the intended trajectory or path.

Balanced Turn

• In a balanced turn, the pilot experiences no sliding forces.
• The effective weight is proportionate to the lift in balanced turns

Turning Flight and The V-n Diagram

• Radial acceleration and curved flight path are associated with coordinated turns, pull-up and pull-down maneuvers.
• The change in altitude varies, depending on the type of turning maneuver being performed.

Level Turn (Coordinated Turn)

• Horizontal plane, front views and top views, and associated symbols (F, R, w) are important considerations for flight.
• The lift, weight and resultant forces must be in equilibrium for level turning maneuvers

Load Factor / Angle of Bank

• With a greater angle of bank, a greater load factor is experienced, which is important for ensuring adequate lift during a sustained maneuver.
• An increase in stalling speed is associated with increased angles of bank.

Wing Loading

• Wing loading is all up aircraft weight divided by the wing area.
• Lower wing loading corresponds to lower speeds.
• Higher wing loading corresponds to higher minimum speeds (and stalling speeds).

Wing Loading Stalling Speed

• Higher wing loading is associated with higher stalling speeds and lower wing loading is associated with lower stalling speeds.
• Higher weight leads to higher factors across the entire range for a particular aircraft with a constant wing loading

"g" Limit

• Aircraft structural designs have "g" limits to avoid structural damage resulting from high load factors.
• Gross weight is a further structural design constraint.
• No aircraft can exceed structural limits.

How to survive high G force?

• High G-force can cause significant physical stress.

"g" Limit from V-n diagram

• V-n diagram is a graphical representation used for maneuvering aircraft during high G maneuvers.
• Diagram shows different flight conditions, including maneuver point, stall limits, structural limits, high speed limits.

V-n diagram (Low speed), V-n diagram (High-speed).

• The V-n diagram is used for low and high speed limits.

Maneuver point

• Maneuver point corresponds to the highest possible load factor and lift coefficient within a particular range of flight conditions.

Corner velocity (V*)

• Corner velocity is the speed at which a particular aircraft can experience the largest rate of turning during a particular maneuver.

Corner velocity (V*) / V Diagram

• At a specific corner velocity, the load factor, CL and velocity match the aircraft limits.
• The corner velocity on a V-diagram can be calculated using particular equations associated with lift and weight and load factor ratios.

Test your knowledge on the principles of aerodynamics, particularly focusing on glide performance and the factors affecting an aircraft's center of gravity. This quiz covers essential concepts such as drag minimization, glide ratios, and lift-to-drag ratios, which are critical for effective flight operation.