Let's begin

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As was seen in previous post, the script to automatically develop elements in Sketchup works.
But since the programming is not the main part of ​​this blog, I decided to start with something more practical.
So we go with the Su-17M. Why this plane? Hmmm ...
It seems to me that a simple fuselage and overall shape decided ...
The place, which surely will bring the problems will be wings.
I think intensively over the folding mechanism of the wings. Maybe I will able to synchronize both sides.

The first stage of design is documentation. Aligning views (up-down-front-page) and appropriate scaling of them is made in any graphics software.

To make modelling easier I removed the background in each of the view and saved it as PNG, which allowed to maintain transparency. Then I inserted everything into SketchUp.

The next step was to trace the shape of the fuselage in views from the top and side. I chose this way of modeling, since the individual sections of the fuselage, available in this set of plans do not fit well to top and side view of plane. So I decided to approach the fuselage modelling from another direction. Because the fuselage sections are approximately round - elliptical, I will draw hull first and then create it's cross-sections.
The outline of the fuselage is dwith BZ CURVES - Sketchup extension that allows you to draw spines and other curves.

I pulled both shapes and made intersection. Then I drew vertical planes in places where I planned bulkheads and after another intersection and removing not necesary geometry I received a series of rectangles.

In the individual rectangles I drew elipses. To do  this, I used to be another extension for SketchUp: TOOLS ON SURFACES.

Fuselage was constructed on defined sections using yet another Sketchup extension: CURVILOFT.
You can also try a different script: SKIN.
Here you can see the effect already made with the wings.










Construction of wings in the next post.

Video !!! How it works so far.

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Welcome again.
It has been a while, but I am back online.
So today a small preview of how it works so far.No voice over - My voice just sounds strange :D
First video is pure Sketchup.
We have 2 definition curves created with Bezier curves.
Note that precision of both curves is set to the same value (50 parts).
There is also another closed curve that will be used as a definition of camouflage.
First we create our surface with another ruby script - skin.
You can see what settings I used.
Then we pull our camouflage definition, and create intersection with our surface.
When cleared from all not necessary parts we can see camo lines on our surface.
Next part is to export points to a files, one for top curve, one for bottom curve and one for all camo points.



Second video is first part of excel calculations.
First we import points for definition curves. On a preview you can see that points are numbered and this will be used for sorting. Calculations are made in a way that curves should go anticlockwise. So our starting point is at bottom, and first point should be where nor point 51 is.Next point would be where now 50's are. Also You can see at the top that on curve 2 ( blue ), there is something wrong ( look at the points 2,1 and 3)
So we go back to curves input , and set points nr 51 on both curves as 1 and points 50 as 2 , after resorting points on first curve You can seethe effect ( best on 3d preview).
Resorting second curve gets us our developer surface.
We can import camouflage line points.
(Error message occurs because there is no points data available.)
We run a macro to develop points onto surface , and after some time we get all points developed.
Time it takes is dependent on number of points to develop and number of points on definition curves.
When all calculations are done we can export all points to CSV file to get it to Sketchup again.


Third part next time.

An advantage of using Sketchup

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Why Sketchup ?
The biggest advantage :  it's free .
You can also extend it's capabilities using multiple Ruby scripts .
From a point of view of a model designer, RHINO has 2 very interesting functions . One is developing of surfaces , and as a bonus Rhino can also develop a lines and curves that are on those surfaces . Second function is a possibility to project curves onto a surface .

How does it look in Sketchup  ?
 

Surface and an element to project

Here we have an surface with an element we want to project .




 

Pushed / pulled surface

We push / pull this element , and then make an intersection between those two .







Result of intersection

We erase pulled element and on our surface we get projected shape .








In sketchup all the curves are represented as a set of lines or a polyline . At first it can look as an disadvantage , but is it so ?
On a picture abowe all the points  (ends of lines) ar bolded . How can we use it ? We can calculate a distance between every point an 2 points of a triangle , and use our algorythm to find this point on a developed surface.

Points inside triangle











To be continued . . .