Wing Tunnel Lab Technical Report Engineering Essay

The chief intent of this experiment was to hold a expression at air current tunnel proving and to analyse this experiment with a scaled-down theoretical account of Boeing 747 aircraft. In this trial we examine how the changing angle of onslaught and air current speed affect the pitching minute, lift and retarding force forces moving on the modeled trade. A scaled-down theoretical account B747 was tested with theoretical account flying being 66cm and pattern organic structure of 74cm about. This would non be possible with the existent size of the aircraft with basic dimensions: flying span-64.4m, overall length 70.6m and chase height- 19.4m

So with the aid of theoretical account trade we continue with this experiment at different angle of onslaughts in consideration but maintaining the speed invariable, which is 85mm of H2O. Keeping this velocity in the wing tunnel, we calculate out the lift force, fliping minute and the retarding force force, all the physical measures increases with the addition in the angle of onslaught in each instance, from -5degress to 20 grades. Though the first measure of the experiment is to analyze the theoretical account trade by zeroing the balance, which is virtually impossible with all the three weighbeams, attached to do it read as nothing, hence under the first measure we zero the balance under inactive tunnel conditions, which requires lift, retarding force and fliping minute readings when no aerodynamic forces are imposed upon the airfoil.

Further ratings are made puting up the relationship between the lift and retarding force coefficients with their angle of onslaught. And a more elaborate survey on the forces moving with needed computations and mistake analysis impacting the quality of the consequence.


1. INTRODUCTION……………………………………………4



4. RESULTS……………………………………………………….7


6. Detailed DISCUSSION………………………………….8-11

7. CONCLUSIONS……………………………………………….12


9. APPENDIX………………………………………………………13-14


Cl = lift Coefficient

Cd= Drag Coefficient

Cm = coefficient of fliping minute

Vw = speed of the on the job subdivision.

Pw = inactive force per unit area within the on the job subdivision

Ve = speed at the entry of the contraction zone

Pe = inactive force per unit area at the contraction zone

= Density of air

Aw = country of the on the job subdivision

Ae = country of the entrance subdivision

g = gravitative acceleration

H = lift for force per unit area

Lm = lift force

Mm = fliping minute

Dm = drag force

Lz= lift force ( at inactive data point )

Mz = fliping minute ( at inactive data point )

Dz = drag force ( at inactive data point )

R = universal gas invariable

T = temperature of the ambiance

S = flying span country

A? = norm chord length


Wind tunnel is an aerodynamic trial installation. It is largely used to analyze flow forms around organic structures and step aerodynamic forces on them. The organic structures ( called theoretical accounts ) are normally scaled down butgeometrically similar versions of organic structures of involvement like an aeroplane or an car. The consequences from wind tunnel trials can be ‘scaled ‘ to the existent speed and existent organic structure size utilizing suited scaling Torahs.

This study is chiefly to analyze the aerodynamic belongingss of a air current tunnel theoretical account of Boeing747 besides known as ‘jumbo jet ‘ , its aerodynamic behaviour as the angle of onslaught is changed. The chief motive for this trial is to understand the working of air current tunnel with a scaled-down theoretical account interior and to understand how to utilize it and its affect on the trade theoretical account inside.

By keeping a changeless speed and a peculiar angle of onslaught we can find the lift force, drag force and pitching minute. The significance of this can be understood by the consequences that it provides to us, which helps doing betterments and more technological alterations in the existent aircraft when working in a existent scenario.

Flying tunnel experiment helps demonstrates us the forces moving on the existent aircraft chiefly the lift and drag force in mention with a peculiar angle of onslaught so that we can keenly understand the flight and its projection consequently, this study will do us understand cardinal rules of aeromechanicss involved with which we are able to depict different aircraft propulsion units and contrast their several public presentations.


There is a important importance to cognize why do we utilize wind tunnel?

A air current tunnel is used to larn more about how air flows around an aircraft or portion of an aircraft. This information is used to do aircraft that fly better, faster, or more softly.

A air current tunnel consists of a closed cannular transition with the object under trial mounted in the center. A powerful fan system moves air past the object ; the fan must hold unbending vanes to smooth the air flow. The Low Speed Wind Tunnel ( LSWT ) is fitted with an overhead TEM 3 constituent air current balance ( exemplary 4124 ) , which is capable of mensurating lift, retarding force and pitching minute.

A air current tunnel is a device in which a jet of uninterrupted and similar air watercourses flow through out i.e. across the cross subdivision, it simulates the conditions of an aircraft in flight by doing a watercourse of air, it may be a high velocity watercourse or a low velocity watercourse, in this experiment we are proving the abilities of theoretical account trade at low velocity watercourse of air.

The internal construction of air current tunnel comprises driving unit, a settling chamber, an acceleration canal ( either contraction or nose ) the trial subdivision and the diffusor.

Having a elaborate expression onto the internal parts. Driving unit: this consists of a fan, blower a compressor by and large driven by a electric motor this is the utmost start of the air or a gas with unvarying streamlines or better to state uniform belongingss up till the terminal chamber. Settling chamber: after the air flow is started it is settled in a big chamber called settling chamber, the chief work of this chamber is to unbend the flow and do it more unvarying all through by taking abnormalities from the air flow. Contraction: than comes the contraction chamber in which after modifying the air flow i.e. doing it more similar and straighten, this portion of the air current tunnel helps the air flow to speed up up till the trial subdivision therefore the contraction chamber is really tactfully designed ( bring forthing speed with minimal perturbation ) . After making the testing subdivision, the theoretical account is mounted on wires so that lift and retarding force forces and even the pitching minute ( i.e. through the TEM 3 as mentioned before ) and in the terminal the air blows out of the fumes. This sequence is design for us to execute the trial through which we can more suitably work on the existent bigger theoretical account of the aircraft ( as in here B747 ) .

Wind tunnel testicle a important factor in any type of vehicle design, from aeroplanes including cars. It is of import in the anticipation of forces and minutes in sailing. Structural applied scientists alsouse aeromechanicss, and peculiarly aero-elasticity, to cipher air current tonss in the design of big edifices and Bridgess.

Figure: Cislunar Aerospace ( 2002 )



Conducting the lab the first measure: observing down the value of forces ( lift and retarding force ) and fliping minute moving on the scaled-down theoretical account at inactive data point place, this is necessary because we need to cognize these values when the wing tunnel is balanced with the airfoil, to cognize what existent sum Acts of the Apostless at inactive place.

Second measure: running the wing tunnel at a changeless velocity we fix this velocity at 85 millimeter of H2O ( or about near to it as possible ) and from the TEM 3 fitted upon the proving subdivision we calculate out the lift and retarding force forces and even the pitching minute.

Third measure: we set a peculiar angle of onslaught, the start is from -5 grades to 20 grades and one by one maintaining in consideration each angle of onslaught we measure the value or the forces and fliping minute severally.

From the barometer we measure the force per unit area which is 754mmHg at a temperature of 23degree C or 296K, looking at the tabular array for tallness of the quicksilver at 2.39mmHg so we calculate out the existent atmospheric force per unit area by deducting and multiplying by 100.213 KPa, from here by the expression P =RT we get the denseness as 1.17964 kg/m3

The given force per unit area to us by the expression ( Vw2 ) /2 is 890.55N/m2 and with this we calculate the working speed Vw.

We besides calculate out the mean chord of B747 from the root chord and the tip chord taking out the norm of them, this mean chord is than used for ciphering flying span country but we have given the ratio of the theoretical account trade to the existent trade is 1:97 therefore we get the concluding wing span country as 5.579m2

After this we calculate out the coefficient of lift, retarding force and fliping minute by utilizing the several expression and the values of lift force, drag force and fliping minute from the tabular array values we calculated out during the lab at each angle of onslaught.

During the lab we calculate Pe and Pw i.e. 27.8cm of H2O and 19.4cm of H2O severally, taking the mistake from them by deducting it by 2 and composing every measuring in SI units

Using this two force per unit areas in SI unit we calculate out the existent speed in the on the job subdivision once more by the expression ( Vw2 ) /2, so now we have the value of Vw from whatever was the given informations ( theoretical ) and denseness, and once more we have existent value of Vw, with this we can mensurate the per centum of mistake in the speed. For this we chiefly use Bernoulli ‘s equation and the farther with given equations.

Finally we compare the coefficients with each angle of onslaught, so that we get a better apprehension of what is go oning to the lift, retarding force and pitching minute at different angle of onslaught accordingly a better apprehension of the existent state of affairs of existent Boeing 747.


Experimental readings:

Inactive Datum

Lift Force, Lz ( pound )

Fliping Moment, Mz ( pound. Immigration and Naturalization Services )

Drag Force, Dz, ( pound )




First of all we calculate out existent atmospheric force per unit area from the barometer

Actual force per unit area = ( 754 – 2.39 ) mmHg = 751.61mmHg = 751.61*0.133224 = 100.213KPa

From this atmospheric force per unit area we calculate out the denseness

P = RT, which is equal to 1.17964 kg/m3

Bing given,

( Vw2 ) /2 = 890.55 N/m2 therefore we get theoretical Vw from here as 38.857 m/s

Given following relation as: VwAw = VeAe, and mensurating Ve we get it as 9.83m/s

By making some research we get the,

Root chord = 12.56m

Tip chord = 4.22m

Making the norm of these values i.e. adding and plunging it by 2 we get the AVERAGE CHORD = 8.39m

With these mean chord and flying span by the hunt taken as 64.44m we calculate WING AREA = 64.44*8.39 = 541.2m2

The ratio of the theoretical account dimensions to that of the existent trade is 1:97, so mean chord = 8.39/97

Therefore we get the concluding wing span country S = 541.2/97 = 5.579m2

Now after this all computations we have every value needed to happen out the coefficients

Cl ( at -5 angle of onslaught ) = L/ ( Vw2 ) S/2 = -3.7597*10-3

Further analysis for coefficient of lift can be found in the appendix.

Cadmium ( at -5 angle of onslaught ) = D/ ( Vw2 ) S/2 = 1.879*10-3

Further analysis for coefficient of retarding force can be found in the appendix.

Cm ( at -5 angle of onslaught ) = M/ ( Vw2 ) SA?/2= -1.103*10-3

Further analysis for coefficient of fliping minute can be found in the appendix.


We have Pe and Pw centimeter of H2O each being 27.8 and 19.4 severally

Removing mistake from both by deducting it by 2 we get 25.8 and 17.4 centimeter of H2O

Converting into the SI unit: Pe = 2.52KPa, Pw = 1.7KPa

To cipher out the existent speed from the experiment performed we use

Vw2 ) /2 = 1.068 * ( Pe – Pw )

Vw = 38.53 m/s

Hence per centum of mistake in speed would be:

100 – ( 38.53/38.857*100 ) = 0.8415 %


Taking the angle of onslaught as the mention, from the graph we can analyse that from -5 up till 15 there is a gradual incrementin lift along with the angle of onslaught after achieving a peak value, it somewhat decreases. Increasing AOA increases the speed on the topside of the aerofoil. It does the same thing as increasing the chamber but is less efficient at it. The Newton ‘s 3rd jurisprudence reaction force upward on the wing provides the lift. Increasing the angle of onslaught can increase the lift, but it besides increases drag so that you have to supply more push with the aircraft engines. The lessening in the lift force after certain angle of onslaught might be due to purl or friction effects.An inordinate angle of onslaught, referred to as the critical angle of onslaught ( normally about 20 & A ; deg ; ) will bring forth a stalled condition-laminar air flow above the wing is displaced by disruptive air flow, and differential force per unit area prostrations. ( Tom Benson, 2010 )

Harmonizing to the above graph retarding force is a spot changeless up till angle of onslaught 5 grades than there is a gradual addition retarding force force with that of angle of onslaught.

As the angle additions above 5 grades, the drag rapidly rises because of increased frontal country and increased boundary bed thickness. As an object moves through the air, air molecules stick to the surface. This creates a bed of air near the surface called a boundary bed which, in consequence, changes the form of the object. , but this consequence changes after a stall spread, after stall the relationship is quiet complex and comes into image the retarding force coefficient. ( Tom Benson, 2010 )

Here there is a singular alteration in relation between fliping minute and angle of onslaught foremost of all there is a little addition up to 0 than a dramatic decrease at angle of 10 and than once more increasing from 15 to 20. In aeromechanicss, the fliping minute on an aerofoil is the minute ( or torsion ) produced by the aerodynamic force on the aerofoil if that aerodynamic force is considered to be applied, non at the centre of force per unit area, but at the aerodynamic centre of the aerofoil. The fliping minute on the wing of an aeroplane is portion of the entire minute that must be balanced utilizing the lift on the horizontal stabilizer. There is ever stableness in fliping minute as by default we take fliping minute as positive when moving on the airfoil.

The relation of coefficient of lift with angle of onslaught is about same as that with lift force, it increases as the angle of onslaught does, but after a peculiar angle of onslaught i.e. at 15 it decreases.As the angle of onslaught of a fixed-wing aircraft additions, separation of the air flow from the upper surface of the flying becomes more marked, taking to a decrease in the rate of addition of the lift coefficient.

( Wikipedia, 2012 )

Up to certain angle of onslaught i.e. from -5 to 5 the retarding force coefficient is about changeless, but after 5 there is a drastic increase in the coefficient of drag relation with that of angle of onslaught. In basic footings, the physical beginning of this drag coefficient is both skin clash retarding force and force per unit area drag due to flux separation. The amount of these 2 effects yields the profile retarding force coefficient for the aerofoil of Boeing 747. From this graph, we can state that Cd is sensitive to Re, which is to be expected since both clash and flow separation are syrupy effects.

Coefficient of fliping minute and angle of onslaught even has the same fluctuation as that of fliping minute and AOA dramatic decrease at first and than increasing with angle of onslaught. Fliping minute coefficient is cardinal to the definition of aerodynamic centre of an aerofoil. The aerodynamic centre is defined to be the point on the chord line of the aerofoil at which the pitching minute coefficient does non vary with angle of onslaught, or at least does non vary significantly over the operating scope of angle of onslaught of the aerofoil. ( Wikipedia, 2012 )

Harmonizing to this graph there is a relation between lift to drag ratio and angle of onslaught, the ratio has the straight relative consequence with that of angle of onslaught up boulder clay 5 grades, this suggest us that the best state of affairs for Boeing 747 winging status would be at 5 grades.


This experiment helps us to understand the aerodynamic belongingss like lift force, drag force and fliping minute fluctuations through angle of attack.It helps us to understand that neither uninterrupted addition in lift force is good for trade to wing nor the retarding force force, we can see from the graphs that at certain angle take it as 5degrees the lift force has a sufficient value and drag force is stable so this a good symbol for flight.

There is an mistake between the theoretical value of speed and existent value of it, which shows that there is a difference between existent winging state of affairss. Looking on to the graphs for farther analysis, here inquiry may originate as to what may go on after a peculiar angle of onslaught, lift and coefficient of lift are some what straight relative to angle of onslaught, retarding force and coefficient of retarding force are a spot stable or better to state changeless boulder clay 5 grades but after this it experiences an increase which is drastic and even may go the ground for haltering the lift force or the action of lift on the theoretical account, so we should maintain in head a point where though the retarding force acts on the trade we have a maximal value for lift, and here is the instance at 5 grades which can be seen from the graph of lift/drag ratio and angle of onslaught.

The trial helps us to understand the stall consequence, which is normally the ground for alterations like addition or lessening in the lift, and retarding force forces. The consequences what we got are the existent values of air current tunnel experiment differing somewhat from the theoretical value given, the Bernoulli ‘s principal used helps to pull strings its practical usage in this trial and even other given expressions ( likecoefficients of lift, retarding force and fliping minute ) and other equations, we understand the working of barometer by taking the atmospheric force per unit area readings.

Finally, I would reason that this experiment and the several study for it enhances our cognition and give us an mentality about the practical aerodynamic universe.


Cislunar Aerospace ( 2002 ) The K-8 Aeronautics Internet Textbook [ online ] Available At:

& A ; lt ; hypertext transfer protocol: // & A ; gt ; [ 13 Dec 2012 ]

Tom Benson ( 2010 ) Inclination Effects on Drag [ online ] Available At:

& A ; lt ; hypertext transfer protocol: // & A ; gt ; [ 13 Dec 2012 ]

Wikipedia ( 2012 ) Fliping Moment [ online ] Available At:

& A ; lt ; hypertext transfer protocol: // & A ; gt ; [ 13 Dec 2012 ]

July 27, 2017