Chapter II CAD modeling21 IntroductionBefore moving onto Essay

Chapter II: CAD modeling

2.1 Introduction

Before moving onto aerodynamic modeling, we should complete the 3D model of the Century. In this chapter we will talk about the existing model that we have, then we will detail the missing parts and the concept of work we’ve chose to each part.

Don't use plagiarized sources. Get Your Custom Essay on
Chapter II CAD modeling21 IntroductionBefore moving onto Essay
From as low as $9/Page
Order Essay

2.2 Existing model

The modeling process of Century airplane has already begun in Avionav, the existing model is shown in the figure 11.

The material used for this type of aircraft is aluminium because it offers very good deformation capabilities and good weldability.

Plus, it has a high resistance to corrosion. In order to develop their product, Avionav had changed some of the constituent of their aircraft which are the canopy and its stand. The shape had been developed and the material as well, we will detail these changes in the next section.

2.3 Reverse engineering

In the scientific literature, the reverse engineering have a lot of definition switch the field of application:

– The process of retrieving the new geometry of a fabricated part by digitizing it and modifying its existing CAD model [4] and applications in mechanics are diverse [5]:

– Inspect and compare the geometry of the real object with the CAD model [6]

– Measure the behaviour of manufacturing tools (control of wear, for example)

– Capture factory or production line geometry to use CAD software for piping design, boiler room, ventilation, air conditioning; Capturing the deformations of an object, in a load case of a beam for example; in order to compare the piece of information with the predictions of the finite element analysis

– To capture the shapes of an existing part whose CAD model does not exist so that a piece of replacement is manufactured by rapid prototyping for example.

Reverse Engineering RE is used for many applications such as business, virtual reality, gaming, to intrust how competitor products are manufactured and how they work… RE is decomposed in 3 general steps:

1- Data acquisition: the physical object is numerically divided into two or three dimensional data using 3D scanning technologies like CMMs, laser scanners, structured light digitizers, or Industrial CT Scanning (computed tomography). , The measured data are represented as a point cloud, lacks topological information and design intent.

2- Data processing: data can be segmented, for example, to extract data from canonical surfaces (plane, cylinder, and sphere) or complex surfaces by converting the point cloud to a triangular-faced mesh.

3- The reconstruction of the cad model: the extracted surfaces can for example be ‘thickened’ and if necessary reworked to rebuild a 3d solid.

In this section, we will present the steps we had used in order to model the bonnet and the winglet of the airplane.

The bonnet of the plane is composed of two parts: a top one (figure 12) and a lower one. That are assembled together and added to the airplane in order to protect the engine.

The modeling of these parts is very difficult using the direct modeling method, that’s why we decided to use the reverse engineering: scan to CAD using CATI V5 tools.

2.4 Scan

We had as scan the smartphone Lenovo Phab 2 Pro (figure 13) that includes tango which is a new technology from Google that enables augmented reality (AR) gaming and utilities. This technology offers a lot of particularities that make this device an innovative one.

2.5 SCAN to CAD

The scan to CAD is the development of a 3D model from a cloud of points witch is the scan of an object. This operation takes place in 5 steps:

1st step: importing the cloud of point using the «digitized sheep editor »

Figure 14: Cloud’s points importing

Figure 15: Cloud of points

2nd step: Cleaning of the cloud of points: deleting of useful points: the points from noise

Figure 16: Deleting of point

Figure 17: Deleting of point

3rd step: Filter

Figure 18: Flirtation

4th step: meshing

Figure 19: Meshing

Figure 20: Mesh

5th step: creation of the plan section

In this step we should choice carefully the position and the direction of the plan sections. In effect, the number of curves influences the surface quality.

Figure 21: Plane Section Tools

Figure 22: Plane Section

6th step: creation of curves

There is 3 types of curves: curves on scan, curves on mesh and 3d curves.

The curves on scan are the intersection of the plane section with the cloud of points. And the curves on mesh are the intersection of the plane section and the mesh. However, the 3d curves are independent of both scan and mesh.

Figure 23: Curves on scan

7th step: surface’s creation

In this step, we create the surface from the mesh.

We can use 4 methods:

1- Surface network: From curves network composed of guide curve and contours. It’s easy to get but it have bad surface quality.

Figure 24: Curves network

Figure 25: Surface network

2- Multi-Suctions: From profile curves and curves of guide. It takes time and requires a huge number of curves. But, it can get an acceptable surface’s quality.

Figure 26: Multi-section surface

3- Power fit and filling: from a contour or intersection of curves. It requires a huge number of intersections and get a bad surface’s quality.

Figure 27: Power fit

4- Automatically Surface: The easiest method. But it requires an acceptable scan and mesh quality. And we get a mediocre quality.

Figure 28: Automatic Surface generator

Figure 29: Automatic surface

So, to get the best surface quality by the easiest way we develop this methodology:

1- Use the automatic surface generator to get the initial surface

2- Determine areas to correct.

3- Use multi-scan with 3D curves

4- Analyse the surface using analyse tools from free style workshop

5- Repeat the 2nd, 3rd and 4th point until getting the best surface quality that respect the more possible details and curves continuity.

Finally, we get this result:

Figure 30: Final Surface

Figure 31: Final result analyses

We use this methodology to for modeling the top cover. And we get this result (next figure).

Figure 32: Top cover

2.6 Conclusion

In this chapter, we used reverse engineering technology: SCAN to CAD, to complete the 3D model of the storm. This model well be used in the next chapter to find the geometry and the aerodynamic coefficients for the Simulink model. But, before that, we should have a theoretical study of the different aerodynamic models to choice our mathematical model.


The Homework Writings
Order NOW For A 10% Discount!
Pages (550 words)
Approximate price: -

Our Advantages

Plagiarism Free Papers

All our papers are original and written from scratch. We will email you a plagiarism report alongside your completed paper once done.

Free Revisions

All papers are submitted ahead of time. We do this to allow you time to point out any area you would need revision on, and help you for free.


A title page preceeds all your paper content. Here, you put all your personal information and this we give out for free.


Without a reference/bibliography page, any academic paper is incomplete and doesnt qualify for grading. We also offer this for free.

Originality & Security

At, we take confidentiality seriously and all your personal information is stored safely and do not share it with third parties for any reasons whatsoever. Our work is original and we send plagiarism reports alongside every paper.

24/7 Customer Support

Our agents are online 24/7. Feel free to contact us through email or talk to our live agents.

Try it now!

Calculate the price of your order

We'll send you the first draft for approval by at
Total price:

How it works?

Follow these simple steps to get your paper done

Place your order

Fill in the order form and provide all details of your assignment.

Proceed with the payment

Choose the payment system that suits you most.

Receive the final file

Once your paper is ready, we will email it to you.

Our Services

We work around the clock to see best customer experience.


Flexible Pricing

Our prices are pocket friendly and you can do partial payments. When that is not enough, we have a free enquiry service.


Admission help & Client-Writer Contact

When you need to elaborate something further to your writer, we provide that button.


Paper Submission

We take deadlines seriously and our papers are submitted ahead of time. We are happy to assist you in case of any adjustments needed.


Customer Feedback

Your feedback, good or bad is of great concern to us and we take it very seriously. We are, therefore, constantly adjusting our policies to ensure best customer/writer experience.