Aerodynamics Wing assignment1. Introduction

Aircraft fly because they possess an aerofoil (or airfoil) which when it ‘cuts’ the air creates a lower pressure region of air above the wing and a higher pressure region below. Since high pressure air moves towards lower pressure air the high pressure air

‘pushes’ the wing up. The faster the airplane travels the greater the difference in pressure and the more lift is generated. When the lift force is large enough to overcome

the force of gravity the airplane will begin to fly.

As this is such a fundamental part of flight it stands to reason that the aerofoil chosen when designing an aircraft must specifically match the aircrafts purpose.

2. Boeing 747-400

First released in 1989 by Boeing Commercial Airplanes they sold almost 700 of these planes. It utilised a glass

cockpit layout which eliminated the need for a flight engineer lowering costs for companies and greatly contributing to its success as a commercial carrier plane.

It uses a four-engine wide-body design and is among the fastest airliners in service with a high-subsonic cruise

speed of Mach 0.855 (920 km/h). It is able to carry up to 660 passengers in its 2-floor frame. Another

feature of this plane is its horizontal fuel tank in the tail that gives it a range of 13,450 km. The wing structure features 6 ft. (1.8m) extensions on the wingtips and winglets that greatly improve fuel efficiency.

The Boeing 747-400 is primarily purposed for transporting large numbers of passengers over large distances as efficiently as possible.

Dimensions:

Wing Span - 64.4 mWing Area - 560 m²Aspect Ratio - 7.4Aerofoil - BAC 463

FLIGHT CALCULATIONS TAKEN AT CRUISING ALTITUDE OF 35 000 ft.

Reynolds Number:

ReynoldsNumber=Density×Velocity×Characteristic LengthDynamicViscosity

Density = 0.3737581 kg m∙ -3

Velocity = 260 m s∙ -1

Characteristic Length = 9.35 mDynamic Viscosity = 1.414 × 10-5 kg m∙ -1 s∙ -1

Reynolds Number = 6.27 × 10 7

Mach Number (At 35 000 ft.):

MachNumber= Aircraft SpeedSpeedOf Sound

Aircraft Speed = 253 m s∙ -1

Speed of Sound = 295 m s∙ -1 (At 35 000 ft.)

Mach Number = 0.858

Control Surfaces:

The Boeing 747-400 incorporates many innovative features with respect to control surfaces. Fowler flaps that extend from the back of the wing before hinging downwards enable it to overcome the potential for increased drag whilst still being able to increase the area of the wings and generating additional lift. On the other side of the wing Krueger flaps function like slats that lie flat when stowed under the wing but form a curve shape when brought forward. This increases the wing area, and hence lift, at increasing angles of attack without adding much weight.

Deployed during landing, the 747 also has speed brakes made up of 6 panels on each wing which stop lift being generated by the wings and increase the efficiency of the wheel braking by increasing friction due to the increase in weight on the wheels and the ground. The panels greatly reduce the length of runway needed for landing.

On each wing there are two sets of ailerons, an outboard and an inboard one on the trailing edge of the wings which enable rolling of the plane. At low speeds when flaps are used both sets must be used as roll won’t occur without additional drag. Outboard ailerons may be locked during cruise with pilots only using inboard ailerons for course correction as this will be sufficient for roll to occur. If both sets are used at high speed the aircraft may become uncontrollable.

3. Cessna O-2 Skymaster First entered service in 1967 the O-2 Skymaster made by Cessna

features a push-pull style piston engine configuration. This configuration features two engines working simultaneously with

one pulling the aircraft and the back one pushing the aircraft forward. This centre line thrust layout eliminates many problems in other twin

engine layouts especially asymmetric flight handling when only one engine is in use e.g. engine failure. Another feature that combats this problem with twin engine planes are the twin horizontal stabilisers which further help a pilot combat asymmetrical flight handling

conditions. The primary purpose of this plane was to be able to effectively fly with one or two engines operating and especially in

the case of the O-2 which was mostly used for aerial reconnaissance or scout flying where pilots may come under fire which could likely cause an engine failure.

Dimensions:

Wing Span – 11.6 mWing Area - 18.8 m²Aspect Ratio - 7.2Aerofoil – NACA 2412

Reynolds Number:

Density = 0.697244 kg m∙ -3

Velocity = 89.44 m s∙ -1

Characteristic Length = 1.6 mDynamic Viscosity = 1.604 × 10-5 kg m∙ -1 s∙ -1

Reynolds Number = 6.2 × 10 6

Mach Number (At 20 000 ft.):

Aircraft Speed = 89.4 m s∙ -1

Speed of Sound = 315.9 m s∙ -1

Mach Number = 0.28

Control Surfaces:

Slotted flaps on the inboard trailing edge hinge downwards creating a gap allowing higher pressure air from under the wing travel over the upper surface of the flap increasing lift generated. The aircraft has ailerons on the outboard side of the flaps as because of the Skymaster’s relatively low speeds the change in the wings shape must be significant for roll to occur.

4. McDonnell Douglas AV-8B Harrier II

The McDonnell Douglas AV-8B Harrier II made its maiden flight in 1981. It is a V/STOL (Vertical or Short Takeoff

and Landing) aircraft specialising in light attack and multi role missions such as ground attack, close air support and

armed reconnaissance.

Powered by a single turbofan engine it has vectorable nozzles around the turbine as well as valve controlled nozzles in the wingtips, nose and tail for control at low. Many weight reducing technologies have been utilised

in this aircraft such as widespread use of carbon fibre composites.

The harrier is made more versatile by the variety of configurations in which it can be used as a weapons platform. One centreline fuselage hardpoint and 6 on the wings as well as two fuselage mounts for GAU-12 cannons give it the ability to carry 4 200 kg of weaponry consisting of air-to-air missiles, air-to-surface missiles, air-to-ship missiles in addition to both guided and unguided bombs.

Dimensions:

Wing Span – 9.25 mWing Area – 22.6 m²Aspect Ratio – 4.0

Reynolds Number:

Density = 0.1936448 kg m∙ -3

Velocity = 666.67 m s∙ -1

Characteristic Length = 4.7 mDynamic Viscosity = 1.414 × 10-5 kg m∙ -1 s∙ -1

Reynolds Number = 4.3x10^7

Mach Number (At 20 000 ft.):

Aircraft Speed = 89.4 m s∙ -1

Speed of Sound = 315.9 m s∙ -1

Mach Number = 0.28

Control Surfaces:

It has horizontal stabilisers and shoulder mounted wings with a prominent anhedral slope. This one-piece supercritical wing increases the lift-to-drag ration and improves performance. The wing has a high lift configuration that uses flaps and drooped ailerons when manoeuvring for increased control.

5. Antonov An-72 Coaler

The Antonov An-72 is a Soviet era Russian troop transport that was designed

for short takeoff and landing operations. It had a specially strengthened

undercarriage which could allow it to land at unprepared airfields where a normal landing surface wasn’t available. It is highly versatile with an adaptable interior able to be optimised for a range or troop transport or cargo carrying

operations. It is also allows for airdropping of troops/cargo.

Dimensions:

Wing Span – 39.8 mWing Area – 98.6 m²Aspect Ratio – 16.1

Reynolds Number:

Density = 0.412659 kg m∙ -3

Velocity = 166.7 m s∙ -1

Characteristic Length = 3.1 mDynamic Viscosity = 1.449 × 10-5 kg m∙ -1 s∙ -1

Reynolds Number = 1.47 × 10 8

Mach Number (At 30 000 ft.):

Aircraft Speed = 166.7 m s∙ -1

Speed of Sound = 301.7 m s∙ -1 (At 35 000 ft.)

Mach Number = 0.55

Control Surfaces:

The An-72 has fowler flaps to increase the surface area of the wing in order to increase the surface area and lift of the wing without increasing drag at small angles of attack like when taking off. It also features slats on the wing that extend forward from the leading edge to allow air to pass over the top of the wing creating more lift. Like the 747 it has two sets of ailerons and only the inboard ones are used at high speeds to avoid control issues. Also similar to the 747 it has spoiler panels which allow much shorter landings via large increases in drag.

6. English Electric Canberra

Designed and built by English Electric the Canberra the Canberra is partly made out of wood in order to keep the weight down as it is intended to be a light

weight bomber capable of evading interceptors due to its high maximum speed and altitude (it set the world altitude record in 1957 with a max height of 70 310 ft.). It featured a cantilevered wing and conventional controls consisting of

ailerons, four-section flaps and airbrakes on both the top and bottom of the wings.

It had a crew of 3 and could carry a total bomb payload of 4.5 tonnes in bomb bays and a further 900 kg on underwing pylons. It was powered by a pair of 30kN

turbojet engines which were significantly more advanced than contemporary piston-engine aircraft.

Dimensions:

Wing Span – 19.5 mWing Area – 89.2 m²Aspect Ratio – 4.27Aerofoil – NACA 64012

Reynolds Number:

Density = 0.412659 kg m∙ -3

Velocity = 166.7 m s∙ -1

Characteristic Length = 3.1 mDynamic Viscosity = 1.449 × 10-5 kg m∙ -1 s∙ -1

Reynolds Number = 1.47 × 10 8

Mach Number (At 30 000 ft.):

Aircraft Speed = 166.7 m s∙ -1

Speed of Sound = 301.7 m s∙ -1 (At 35 000 ft.)

Mach Number = 0.55

Control Surfaces:

Slotted flaps on the trailing edge of the wings with one outside the engine and one between engine and fuselage on each wing can be extended to both increase the area of the wing and increase drag. Unlike other high speed planes only outboard hinged ailerons are used as the ability to quickly turn is very useful for outrunning fighters. Spoilers are used as speed brakes on the upper surface of the wings allowing for shorter landing distances.

Aircraft Critical Analysis Boeing 747-400Cl Cruise = 0.26Cl Max = 2.50Cd Cruise (80% Thrust) = 0.03V Stall = 84.88m/s

The 747-400 is capable of carrying 660 passengers with a total weight almost 400 000 Kg. For this reason a huge amount of lift is required in order to lift the aircraft into the air. Such lift is enabled through the deployment of both the aircrafts fowler and Krueger flaps. These flap types have been chosen as unlike alternatives they are lighter in weight and don’t result in unwanted drag when set to take-off configuration. As well as a heavy lifter this aircraft promises to deliver its passengers and freight to their destination in a timely manner thanks to its swept back wings at an angle of 37.5˚ delaying the onset of transonic wave drag allowing high speeds to be efficiently reached and maintained.

0-2 SkymasterCl Cruise = 0.46Cl Max = 6.06Cd Cruise (80% Thrust) = 0.05V Stall = 24.59m/s

The high wing design of the 0-2 Skymaster has effectively enabled its use as a military observation aircraft through its ability to offer pilots a clear view of the ground below. This high wing structure also enables the aircraft to achieve greater lift as the top of the aircraft fuselage essentially works to increase the surface area of the wing. The inline positioning of the aircrafts two engines enables fuels to be delivered through a simple straight fuel line especially to the rear engine from tanks found in the wing. Wing and tail configuration as well as having both engines in the centreline of the fuselage solves many problems associated with twin engine aircraft when operating on only one engine.

AV-8B Harrier IICl Cruise = 0.14Cl Max = 19.15Cd Cruise (80% Thrust) = 0.04V stall = 56.77m/s

The AV-8B Harrier II was designed to be a versatile V/STOL fighter with a diverse range of combat package options ensuring it can fly a range of mission types. With a specially designed supercritical aerofoil made out of a carbon fibre composite that worked to delay the onset of wave drag while at transonic speeds the harrier II was a significant development in military jet aircraft engineering. Slotted flaps, additional air-lift devices and a retractable lateral fence that assists in capturing a cushion of air while in hover mode. The wings had their sweep specially configured and were extended for better lateral control and cruising. This also had the effect of improving rolling as the thrusters were set further apart.

An-72 CoalerCl Cruise = 0.56Cl Max = 7.62Cd Cruise (80% Thrust) = 0.18V stall = 45m/s

The An-72 Coaler was purpose build to enable military operations in remote undeveloped regions where long suitable airstrips are unavailable but supplies must still be received. For this reason the Coaler was engineered to make these short field take-offs and landings by placing the aircrafts two Lotarev D-36 turbofan engines on top of the aircrafts high mounted wings. This location of the engines sees the intake section of the engines extend over the leading edge of the wing enabling the engines exhaust gases to blow over the aircrafts wings upper surface. This part of the wing is constructed out of titanium to withstand these extremely hot exhaust gases. The result of this process is that lift is increased due to the air travelling over the top travelling at a far greater speed than if it were moved only at the velocity created by the aerofoil moving through the air.

English Electric CanberraCl Cruise = 0.27Cl Max = 5.37Cd Cruise (80% Thrust) =0.08V Stall = 55.56m/s

The Canberra is a bomber designed with the capability to out fly enemy interceptors. For this to be achieved it had to be able to manoeuvre and handle at both low and high altitudes. In order to achieve this, a combination of long characteristic length, low aspect ratio and light wing loading had to be ensure. The long characteristic length of the aircraft means that a large amount of lift can be achieved at high or low speeds ensure stability when the aerofoil is at almost all angles of roll. The extremely low wing loading as a result of the aircrafts massive wing area results in a decreased stall speed which can again be used as an evasive or attacking manoeuvre.

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