Aerodynamic Design of a Light Aircraft   By Bandar Marfoa Alshammari Student # 423101804

Objectives What is The Design Problem Aerodynamic Forces ? Aerodynamic Characteristics ? Lift Force ? Lift Coefficient ? Lift Generation ? Variables that affect Lift ? Drag Force ? Drag Coefficient ? Variables that affect Drag ? Thrust Force ? Weight estimates ? Flaps device ? Airfoils ? Light aircraft with two turbofan engines and 5-digit NASA 25012 airfoil with flap changing deflect angle and without flap in Three cases founding that: The Stall angle, Aerodynamic Forces, Boundary Layer, Pressure Distributed, Gamma and Accelerations on Lift and Excess Thrust Directions.

What is the Forces Acting on Airplanes? Weight: Is a force caused by the gravitational attraction of the Earth that is always directed toward the center of the Earth. Lift : Is generated by the motion of the solid objects (airplane) through the fluid (air). Drag: is created by the flow of air over the surface of the aircraft. Thrust: Is the force that puts the aircraft into motion relative to the ground and brings the force of lift into existence.

What is the Weight Equation?

What is the Aerodynamic characteristics? Airfoil It is the cross section of a wing. The airfoil shape and variations in angle of attack are primarily responsible for the lift and profile drag of the wing. NACA airfoils: are wing cross section designs invented by the NACA organization. Geometry Variables of Airfoils: There are four main variables in the geometry : 1. Shape of the mean camber line. 2.Thickness. 3.Location of maximum thickness. 4.Leading edge radius.

Aerodynamic Center: The aerodynamic center is a point along the airfoil or wing about which the moment coefficient does not vary with an angle of attack change. Center of Pressure: A point along the airfoil about which the moment due to the lift is zero, i.e., it is the point of action of the lift. The center of pressure will change its position when the angle of attack changes. Angle of Attack: The angle of attack is defined as the angle between the plane of the wing (airfoil chord) and the direction of motion (free stream velocity). The angle of attack can be varied to increase or decrease the lift acting on the wing. An increase in lift often results in an increase in drag.

Stall: As the angle of attack is increased, lift is also increased up to a certain angle. Beyond this angle airflow can no longer follow the contour of the airfoil's upper surface, as shown in the sequences in figure After the burble point the airfoil goes full stall.

What is Lift?

Factors That Affect Lift

Size Effects on Lift

Shape Effects on Lift

Velocity Effects on Aerodynamic Forces

Inclination Effects on Lift

Reynolds number and Mach number Effect on Lift Aerodynamic forces depend in a complex way on the viscosity of the gas. The important similarity parameter for viscosity is the Reynolds number. The Reynolds number expresses the ratio of inertial (resistant to change or motion) forces to viscous (heavy and gluey) forces. Where: Re: Reynolds number. : Density. : Viscosity coefficient. : Gradient of the velocity. : Second gradient of the velocity. The Mach number appears as a scaling parameter in many of the equations for compressible flows, shock waves, and expansions. incorrect to measure a drag coefficient at some low speed and apply that Aerodynamic coefficient at twice the speed of sound (M=2) . Where: M: Mach number. V: velocity of the object. a: Speed of sound.

What is The Lift Equation? Lift is the force that directly opposes the weight of an airplane and holds the airplane in the air. It is generated by every part of the airplane, but most of the lift on a normal airliner is generated by the wings. It is a mechanical aerodynamic force produced by the motion of the airplane through the air. It is a vector quantity, having both a magnitude and a direction associated with it. It is acts through the center of pressure of the object and is directed perpendicular to the flow direction. Lift Coefficient It is a number that aerodynamicists use to model all of the complex dependencies of shape, inclination, and some flow conditions on lift. Where: CL: The lift coefficient. L: The lift. : Density. V: Velocity. A: Wing area.

What is Drag?

Factors That Affect Drag

Shape Effects on Drag ρ

Induced Drag Effect

What is Drag Coefficient? ρ

What is The Drag Equation? ρ

What is Thrust?

General Thrust Equation

Classification of Light Aero-Plane Engines There are five possible power plants for light aero-planes: Turbofan Engines are quieter and operate efficiently at lower air speeds than turbojets, because of the mixing of a large mass of external ‘cold’ flow by-passing the hot flow through the core of the engine: By-pass ratio total mass of air = (engine + fan)/mass passing through engine core alone.

Comparison Between Turbofan and Turbojet Engines Technical detail Garrett TFE 731-3 Rolls Royce Viper Thrust at SL lbf 37000 37050 Weight lbf 736 790 Specific weight lb/ lbf 0.199 0.21 Width in 34.2 - Height in 39.7 Diameter in 24.55 Length in 49.73 64.6 Specific fuel consumption 0.818 0.94 By-Pass ratio 2.8 Gear ratio 0.555

Basic Motions

Motion at Balanced Forces

Motion at Unbalanced Forces

Weight to Thrust Ratio

What is The Excess Thrust?

Aircraft Rotations

Pitch simulation

Roll simulation

Yaw simulation

What is Banking Turn ?

Thrust and Weight Assumptions Weight of the aircraft (W): Mass of Three adults= 3(200 pounds) =600 pounds Total baggage mass =200 pounds Two engines mass=2(736) =1472 pounds Plane with full Fuel tank mass=1500 pounds Thrust Force produced by the engines: Assume the engine type is turbofan Garret TFE 731-3

The Modified NACA 5-Digit Airfoil NACA 25012 As contrived as it sounds, the first digit is the design Lift Coefficient multiplied by twenty-thirds (20/3). For the most part, it's almost always 2. NACA 25012 The second and third digits combine to designate the horizontal location of maximum camber times two. NACA 25012 As with all of the NACA airfoils, the last two digits combine together to designate how thick the airfoil is as a percentage of chordlength.

NASA 25012 without Flaps Aerodynamic coefficients Angle of attack

NASA 25012 without Flaps at zero lift angle of attack 1.57° Low Pressure Region Stagnation Point 1  High Pressure Region  Stagnation Point 2 Low Pressure Region Lift is zero

NASA 25012 without Flaps at stall lift angle of attack 12° Low Pressure Region Stagnation Point  High Pressure Region Maximum Lift Position

NASA 25012 with Flap Deflects 12 ° Aerodynamic coefficients Angle of attack

NASA 25012 with Flap Deflects 12° at α=12° Low Pressure Region Stagnation Point  High Pressure Region Maximum Lift Position

NASA 25012 with Flap Deflects 22° Aerodynamic coefficients Angle of attack

NASA 25012 with Flap Deflects 22° at α=12° Low Pressure Region Stagnation Point  High Pressure Region Maximum Lift Position

Results Airfoil Type Maximum Lift Force Drag Force Excess Thrust Lift Acceleration Thrust NASA 25012 Without modification with flap deflect 12° deflect 22°

Discussion At Constant Speed (200 mph) and density (0.07648 lbm/ft^3) : The value of Lift force increasing with increasing deflection angle of the flap which proves that the Lift force is a function of the angle of attack and increasing the value of Lift acceleration then the aircraft take more time and distance to arrive the right altitude position. The value of Drag force increasing with increasing deflection angle of the flap which proves that the Drag force is a function of the angle of attack and that’s because increasing frontal area which make change in the value of drag. The value of Excess Thrust decreasing with increasing drag force which decreasing the value of thrust acceleration then the aircraft take more time and distance to arrive the flight velocity.

Recommendations Include the effect of Velocity on Aerodynamic coefficients Use more advanced software to analyze Aerodynamic coefficients. Simulate the aircraft with real dimensions on ANSYS 11. Include the effect of friction on analysis. Study the aircraft at landing position. Use Drag reducing methods. Calculate pitch moment from pitch coefficient. Interested on Lift/Drag ratio and other factors.

Questions Thank You