Hi, everyone, and welcome to this new class in dynamics.
Today, we will be discussing several types of wing configurations, as well as some topics on wind
performance, manufacturability and more.
So first of all, the design of a wing of an aircraft requires thorough research in terms of aerodynamic
performance.
As mentioned at the beginning of the course, many jobs in the aerospace engineering domain are actually
related to computational fluid dynamics and the analysis of optimal wing configurations.
In this course, we intend to give a necessary context to understand what are the main variables playing
a role in the design of such things.
So first of all, we saw in last class that wingtips and induced drag particularly plays an important
role to wing performance.
So this is a diagram which illustrates how relevant lift induced drag really is to the overall drag
of the aircraft.
Note that parasitic drug, the drug due to the shape of the aircraft, as well as the drug due to the
skin of the aircraft.
This will depend on the geometry of the aircraft, the materials used and really the smooth surfaces
of the aircraft and increase it will increase with the square of the velocity.
This is why we see this somewhat exponential trend.
On the other hand, induced drug, which we mentioned before, is actually reduced with flight velocity.
And this is due to the fact that the induced drug disturbance diminishes when the aircraft is flying
at high speeds.
This makes sense since at high speeds, the flow cannot be disturbed as easily as in slow speeds.
So I wanted to show this curve because it illustrates an interesting phenomenon, and that is that a
certain flight velocity.
Right?
The total track of the aircraft is a local minimum.
So this, of course, is relevant when designing an aircraft, and this class will do different for
each type of aircraft, OK, in terms of aerodynamic performance.
The elliptical wing is the best.
It was at least theoretically that to obtain a maximum lift and minimum drug for an aircraft, the wing
should be elliptical.
Why?
Well, two main reasons.
First, the lift is maximized and has this parabolic distribution.
Note that in this image that the lift distribution is parabolic, right?
And that at the edges, it quickly reduces to zero.
Second, the induced drag at the edge of the wing is minimum.
This means that the overall drag of the aircraft will also be smaller.
Not that the wing tip of an elliptical wing is very small.
All right.
So if you're interested in the math for this deduction, you can actually Google these Stanford Chapter
12 Wings of Finance spun.
And you should be able to find this article, OK?
It's an interesting outlook, full of math, really full of math, OK, demonstrating mathematically
why lift and drag optimal under these conditions?
So as you can see, this is the Super Marine Spitfire, which is the typical example of an elliptical
wing and did not have a wingtip, as you can see.
Since the induced drug is already optimized due to the elliptical shape, right?
So moving on from the ideal elliptical wing shown before a key variable of a wing, it's is is actually
its aspect ratio, right?
The aspect ratio is simply defined as the ratio between the span of the wing.
Divided by the court, the average court of the wing.
Low aspect ratio aircraft have relatively long courts with respect to the span.
Whereas high aspect ratio.
They will have elongated wings, right?
And they will be a relatively slim.
So this parameter is a key design factor to take into account if we are interested in designing an aircraft
that is aerodynamically efficient with allow induced drag.
We will be looking for a high aspect ratio aircraft.
However, if and if these aircraft are dynamically more efficient, right, they come with a few drawbacks.
First, the lift loads are distributed throughout the wing, meaning that in this case.
OK.
In the high aspect ratio case.
The structural demand of the wing will be more severe with the wings having to tolerate, you know,
higher bending moments.
So.
The wing must be slim, right, for it to be for it to have a high aspect ratio, meaning that such
structural difficulties have to be overcome with advanced materials with grade mechanical properties.
OK.
So it's really difficult to actually make high aspect ratio aircraft even if they perform better.
They are in terms of structural demands.
They are more severe.
OK.
So in addition, these aircraft have less maneuverability.
Due to the long distance to the Algerians.
All right.
Located at the wing end.
And finally, also, they are less practical since they do not allow for an easy storage of the landing
gear and the fuel tanks.
On the other hand, low aspect ratio aircraft, they will have more induced drag, meaning that they
will be less efficient aerodynamically.
However, they are structurally more robust and the lift loads are located closer to the fuselage,
right?
Making this a great option from the structural point of view, they also present higher maneuverability
and will fit other systems and components easier.
So these are two examples of high and low aspect ratio aircraft.
The first case is a glider has a very stable flight with limited maneuverability, whereas the fighter
jets hover here, you know they are designed to be unstable and highly maneuverable.
In addition, the glider does not have an engine, meaning that aerodynamically it has to be as efficient
as possible so as not to fall or be slowed down too quickly.
So minimizing drag in this case is priority number one.
However, on the other hand.
Minimizing drag is not the objective of a fast aircraft, but rather reacting quickly and being highly
maneuverable.
So note, finally, that commercial aircraft are a combination of both worlds.
They combine reasonably big wings, long wings to fit components and be reasonably maneuverable and
also to have high aerodynamic performance.
OK, so it's always a trade off between all of these variables.
These are some of the wing configurations that typically can be found on aircraft.
The constant cold wings, which are these ones over here are the ones that will produce the highest
induced drag.
This is due to the large cord at the end at the edge of the wing.
So clearly, the constant court aircraft will require big wingtips to avoid large vortices appearing
over the edge of the wing.
It can have a huge impact on this type of thing.
OK.
He induced a drug.
Kirsten Cordes, I nevertheless easily manufactured because it's just the same airfoil, the same cross-section
for all of the lengths of the wing, meaning that the profile is standard and can be mass produced.
So this type of wing is cheap and easy to manufacture.
Another very interesting wing conflagration is, of course, the elliptical one, which has the best
optimal lift to drag ratio, as we discussed previously, maximum amount of lift, a minimum amount
of induced drag.
Optimal in terms of aerodynamic performance.
However, the main problem of elliptical in configuration is that it is not easily constructed.
As mentioned.
To manufacture such wings, we need a very detailed construction of the different structural elements
with different sizes, volumes and potentially even materials.
So is not a good solution in terms of manufacturability.
Typekit wings in general terms are the most common and provide the most balanced type of wood type of
wings considered.
All the trade offs.
Generally speaking, they are the best because they provide good performance.
Of course not as optimal as the elliptical, but still a reasonably good performance.
And then at the same time, they're pretty easy to manufacture, since even if the length and sizes
of the components vary, they can be calculated easily and manufactured also in mass production.
So in general terms, most of the airplanes tend to go to the tapered, particularly with wingtips at
the end is to correct for the potential induced drag.
They also allow us to put systems in the inside, such as the fuel tanks, landing gear and so on.
So I really can see that there's a lot of potential conflagrations in addition for aircraft design.
It always comes down to the same OK trade offs between variables mentioned, particularly manufacturability,
cost aerodynamic performance and structural robustness.
A good balance between such variables should allow for the design of wings and all of these potential
options.
So however, note that if we take into account current trends in aircraft design, almost all of the
commercial aircraft today are Typekit tapered, whereas military and other civil aircraft may change
due to specific requirements.
Also, it's interesting to note that in supersonic flight or hypersonic flight, we may encounter this
type of delta wings, which have these different configuration, this configurations over here, just
they are just optimized for hypersonic fluid dynamics, which really work differently to supersonic
fluid dynamics.
And in this case, the propagation of shock waves and the requirements for optimal aerodynamic performance
in supersonic flight result in such geometries, typically to be found on high speed aircraft flying
off course at speeds higher than the speed of sound.
So these are some examples of wing configurations that you may encounter.
Usually, as we saw, we have tapered wings, this type of wing, which you can see that the cord at
the root of the wing is quite large compared to the wing tip.
You can also see that there's a wing tip used in these cases.
Not much.
It's quite small, actually, but in most cases this is not.
So you just need some little element to provide the difference in pressure to avoid the induced drag
that we saw before.
Note that the wing roots is actually providing the structural strength.
To withstand different loads off the wing, right, with respect to the fuselage, the lift generated
by the wing is structurally connected to the fuselage, which will move up as a consequence.
So this surface over here has to withstand a lot of stress, as mentioned.
So this is why tapered wings are overall a good solution to all variables mentioned.
In this case, this is the Boeing 747.
You can see a very similar configuration.
And in fact, you may notice that in some of the photos and actually generally board the Boeing 747
has a very rigid, solid body.
Also, the connection between the roots of the wing and the fuselage is very strong, and this is a
little aircraft hangar where you can see quite similarly.
That is also a taped wing.
And it's just a bit more uniform, and you can understand that the stresses here are lower, right,
because the amount of lift which will be produced by this wing is lower than in this case.
Just to discuss a bit further, also showing different configurations on other type of aircraft.
This is, of course, the Super Marine Spitfire, which is one of the Britain's most legendary aircraft
I mentioned and described before.
This is the P-51 Mustang from the United States with a tapered wing platform.
This is an old biplane aircraft with two constant cord wings and actually no wingtip.
You can imagine that the induced drag for such aircraft was noticeable.
A design feature that could put this aircraft in competitive disadvantage with respect to others.
Note also that the airfoil seems to be plain, right?
With no cable or advanced air full geometries.
You can see that, of course, the desire to have, you know, the design of these type of aircraft
at this point in history was not as advanced as it is today.
And this is just the Concorde, which was, of course, the Delta Wing, because, as you may remember,
the Concorde was designed to fly at supersonic flights.
So this is a summary of the most common wing configurations that you will see in the aircraft from the
past and today.
Other geometries are possible, of course, and may emerge in the coming years.
However, it seems like tapered wings will continue to be the most used in commercial aircraft and delta
wings for those military aircraft.
We will have to see what the future has to say about wing designs.
So now we can move to the next topic on aerodynamics.