Fuselage Drawing In Detail


The release of the new B17 model was followed by questions about how I created the fuselage of the new model. Here I’m going to list a step by step overview of the process I use. I’m just starting a P 38 Lightning, so I’ll use it as an example.

Note that the basics of creating fuselages (and wings, and texturing) is covered pretty well in the written tutorial “First Model”, but I’m now using a little different technique which I find more accurate and will explain here.

Part of the joy of 3D Modeling is the details of the building process, and the freedom to do it the way you like. There are many ways to draw in DAM and you may have a favorite that differs from this. That’s good! I’m certainly not saying the method I’m talking about here is the best way. Whatever way is most natural to you is best for you.

So, in excruciating detail :) the following is how I draw fuselages in DAM.

Work Folder and Trace Image

First I go to windows explorer (or you can use “my computer” ). I open “My Documents”. I double click on my “Dam Work” folder (if you don’t have one yet, you can make one). I create a new folder in the “Dam Work” folder and name it “P38_Lightning”. Now everything I do for the P38 I will save to this folder. That way I always know where to look.

Next I need a trace image to work from. This is what I do…

  1. I go to Google, set it to image mode, and enter “P 38 Lightning 3 view”
  2. I usually click on the “large” category (shown on the left)
  3. I look at the previews Google shows and select one that I think I can work from
  4. When the website comes up, I click on “full size” (it’s on the right)
  5. When the image finishes showing up, I right click on it and select “save picture”.
  6. I navigate to the “P38_Lightning” folder I created and save it there in bmp or jpg format (not gif).
  7. I start DAM
  8. I create a new sketch in the XZ plane at the origin. The XZ plane is where I will draw the side view of the model.
  9. I click on the trace panel “Setup” button.
  10. I click the “Load Texture” button.
  11. I go the the “P38_Lightning” folder and double click the trace image I just got from the web.
  12. I scroll to the end of the currently loaded textures and click on the trace texture I just loaded.
  13. I click on the “Reset Ratio” button to make the width and height of the image the same as the loaded image.
  14. I click on the “Aspect Ratio Lock” button so this ratio stays the same when I change the horizontal size.
  15. I change the “Horiz Size” to something that seems reasonable. It is in inches. I usually enter something around 90 inches. (I don’t worry about the wingspan of the model at this point. I can always resize the entire model later. I’ll just draw everything to the scale of the image in the trace picture I’m using.)
  16. I click on the “Modify” button.
  17. I hold down the mouse wheel while moving the image so the side view of the fuselage is roughly centered on the origin (center of the drawing).
  18. I click the OK button to close the setup window.

Now I do the initial save of the drawing. I save it to the same “P38_Lightning” folder, and I name it something like “P38_Lightning_A. (Remember, I’ll put everything for the P38 in this folder so I know where it is later) As the drawing develops, when I feel the changes are significant I will save it to a new file, which I call “P38_Lightning_B”, then “P38_Lightning_C” and so on. that way I can always go back to a key point in the drawing and start from there if I don’t like the changes I have made. This helps me have confidence to make changes without worrying about having to start clear back at the beginning!

Guide Outlines

The first thing I trace is the fuselage. I use the line tool. The curve tool is more convenient to use and is fine, I just prefer the line tool because it looks better (less cluttered) without the control points hanging out there in space, and for this I don’t need the accuracy of the curves. I start at the front of the fuselage and make a single polygon that traces the outline of the fuselage side view.

Now I make a new sketch in the XZ plane. I click on the trace panel “Setup” button for this new sketch. I scroll to the end of the currently loaded textures and click on the same trace texture I used in the side view sketch. I go through the same procedure to scale the trace picture, using the same dimension I used before. This time when I move the picture I place the top view of the fuselage so that the front and back line up with the side view polygon I drew in the other sketch. NOTE that you will probably need to rotate the trace picture so the nose of the fuselage in the picture points in the same direction as the nose in the previous sketch. I usually use the “Rotate” button in the “Trace Bitmap Control” window for this. Now I trace the top view of the fuselage, again in a single polygon using the line tool.

I use these two outlines of the fuselage to help guide me when I’m making the former polygons. This picture shows the two finished guide polygons with the view rotated so you can see both, along with the trace picture. The top view sketch (XZ plane) is active, with the top view polygon shown in red. The side view polygon is shown in white.

Former Sketches

It’s time to make the former sketches. This is a set of parallel sketch planes perpendicular to the long axis of the fuselage. Sounds hard, but it is actually quite easy.

Right click on the first sketch (our side view) and choose “Edit Drawing”. (If the drawing moves out of the picture, use the dropdown arrow on the rotate gadget and choose “Flat View and Center”).

Now I look at the fuselage and decide where I think I’ll need formers to build the fuselage. This one looks relative simple, but to make it look good I decide it will take 11 former polygons. I select the “Line” tool. I move the active point to a location directly below the very front of the fuselage. I click to deposit the first point. I hold the control key down and move the active point up, then right click and choose “Restart”. This creates the second point and begins a new polygon. Now I move the active point to the bottom of where I want the next former and click, then hold the control key down and move the active point up, then right click and choose “Restart”. I repeat this for all of the 11 former locations.

Now I right click anywhere in the view and choose “Create Former Sketches”. When the “Former Sketch Planes” window opens, I click on the “Select Former Polys” button. I select each of the lines I drew, in order from the front of the fuselage to the back of the fuselage. I then click on the “Create” button. All 11 of the new sketches will be created. They are lettered from A through K. I can tell which sketch object in the list matches the former location by “counting” them from the front of the fuselage. The picture shows the straight lines at the former locations I decided to use. Notice that the new former sketch objects now appear in the object list on the left.

Former Polygons

It’s time to make the former polygons. I have been using the “D” method, and will show that here. You can also read about it in the separate article in this blog if you like, but I’ll go into more detail here.
It is important to note that I only draw one former polygon, and always use the line tool. This makes the final fuselage easy to control and results in the best appearance.

I usually start with the tallest part of the fuselage. In this case it is the “G” former sketch. Right click on the “Former Sketch G” object and select “Sketch – Edit Sketch”. If the sketch moves to an empty location, use the drop down arrow on the sketch “Rotate” gadget and choose “Flat View and Center”.

In this sketch I want to see the front view of the trace picture lined up with the fuselage outline polygons I’ve already drawn. I click the trace “Setup” button and by the same methods talked about in the first two sketches, I size and position the trace picture where I want it. For the P38 I noticed that the front view is a little larger than the side and top views. With a few trials, I found that a value of 84.5 matched the best.
When I’m satisfied with the location and scale of the front view, I need to put the trace picture in exactly the same position in all 11 former sketches. To do this, I select the drop down arrow on the “Location” button in the trace panel, and select “Store”. Now I right click “Former Sketch A” and select “Edit Sketch”. I select the drop down arrow on the “Location” button and select “Restore”, then click on the “Active” button in the trace panel. The trace image will appear in the correct location and size. I do this for all remaining former sketch objects.

Now go back to the tallest part by right clicking on the “Former Sketch G” object and choosing “Edit Sketch”. I am going to draw the “main” former poly in this sketch. It will be the one that is the tallest, so I sketch the largest part of the fuselage. NOTE that if I draw the entire shape, it is extremely difficult to make the right side exactly the same as the left side. The solution is to only draw one half of the shape (I call this the “D” method). I try to draw this shape in as few points as possible and still get a reasonably good fit to the shape. The reason is that I’m going to copy this poly and resize it and modify it to make all the other former shapes. It is easier to move a few points than a bunch. I used 8 points for this main former shape.

One other important thing to do is to make sure the points at the end of the straight side of the “D” are exactly on the centerline of the sketch. This is easiest to do by turning on the “Grid Snap” and moving these two points to the nearest grid intersection. If the grid resolution is too coarse, you can make it finer by choosing the “Grid Options” from the drop down arrow on the “Sketch Grid” button and changing the “Ticks per Division”. You may need to refresh the view to see the change (easiest to do by rolling the mouse wheel a click).

The picture shows the “D” shape in red as it was drawn in location. The view has been rotated so you can see how it fits into the grand scheme of things.

As I mentioned, I only draw one polygon, then copy it and paste it into the next drawing, and modify its position and shape. This keeps the number of points the same, which I find makes for a better result in the final fuselage.

I select the finished “D” shape and copy it. I then work my way to the front of the fuselage, so I right click the “Former Sketch F” object and choose “Edit Sketch”. I paste the poly. I think about the shape of the fuselage at this former location, and I adjust the size and shape of the poly as I think is needed for this location. Some people are better than others at visualizing how the shape will change. I use the guide polygons to help me. By clicking on the sketch “Rotate” button and rotating the view, I can see how much I need to move the top, bottom and side points to conform to the guide outlines. I alternately click the sketch “Rotate” button, rotate the view to see how much I need to move them, turn off the “Rotate”, move the points, turn on the “Rotate” and examine how close I am, and continue this process until I’m happy. When the top, bottom and side points are in position, I flat view in the drawing and move the rest of the points to get the general shape of the former at this position.

I now copy this polygon (the one in “F”), and edit the next one (sketch “E”), pasting it in position and modifying it to what I think best fits the fuselage shape, using whatever hints I can see in the front view of the trace picture. I continue this for the rest of the former locations going forward until I have finished the very front of the fuselage (sketch “A”). Note that although the former polygon in sketch “A” is very small, I still use the shape with all of its points. I just make it much smaller.

When the front of the fuselage is complete I return to sketch G, copy the polygon from that location, then edit sketch “H”, paste it and modify it. When I’m satisfied, I copy it and paste it in sketch “I”. I continue this for the rest of the former locations going rearward until I have finished the rear of the fuselage.
The picture shows all of the completed “D” shaped former polygons in position. The last former sketch “K” is being edited so you can see the trace picture in that sketch plane.

Skinning the Fuselage

It’s time to put the skin on this half of the fuselage. I click on the Home category and click the “Rotate” gadget there. This get’s me out of the sketch editing mode. I then hide the first two sketches so I can’t accidentally select the outline guide polygons.

Now I see a view with nothing displayed except the 11 former “D” shapes. I click on the Tools tab. I click on the down arrow on the “Extrude” button and choose “Sketch to Sketch”. I click on the “Select Former Polys” button. Now I select all 11 former polygons, in order from front to back. Remember, they have to be selected in order. Now I click on the “Quit Selection” button so I can’t accidentally add another poly.

Now I click on the “Build” button. The program will create the skin on the former polygons. This is the outside shell of the fuselage. I move the mouse cursor into the view and rotate the view so I can inspect what was created. Now I click on the “Points” button and again click on the “Build” button. If you have any former polygons that have a different number of points, you will get a notice that you can’t use point mode. This is one of the reasons I copy and paste the former polygons in all former sketches. That guarantees me each polygon will have the same number of points.

I compare the appearance of the fuselage skin when made with the “Wrap” mode and the “Points” mode. I may choose the other one and click “Build” as many times as I like to do the comparison. The difference between the two modes is usually pretty subtle, but can make a lot of difference depending on the shape and differences in sizes of the former polygons.

For the P38 I like the Wrap mode and click “OK”.

Creating the Other Half

At this point we only have half of the fuselage shape. The shape also has a skin on the flat part. We don’t want this part of the skin, so let’s get rid of it.

First I save the drawing. I may choose to give it a new file and increment the letter as I mentioned earlier.
Now I select all of the Former Sketch objects and hide them. I rotate the view so I’m looking at the flat part of the fuselage half. I click on the “Select Poly” button in the “Mode” panel. I select each of the triangles that make the flat side of the fuselage. In this picture I have about half of them selected, with the next one I’m going to select highlighted.

When they are all selected I click the “Rotate” button to turn off the select poly mode, and rotate the view around to make sure I only selected the polys on the flat side.

I right click anywhere in the view and choose “Object – Make Object”. I accept the “My New Object” name in the requester and click OK. I don’t need this flat part, so I right click on the “My New Object” and delete it.
Rotate the view around. You may be surprised that the skin of the fuselage is not visible from the back side. This is because we have the object’s properties set to “Cull”. Don’t worry. This is what we want.

Making the Other Half

Select the fuselage object. Click on the “Tools” tab. Click on the “Mirror” button. Click on the “XZ Plane” button and click “OK”.

A new object is created that is the mirror image of the first. Now you see why I needed to make sure the top and bottom points of the “D” former polygons were exactly on the centerline of the sketches. These two halves must match up exactly along the length of the body.

Now I select both halves of the fuselage, and right click on one of them. In the context menu I choose “Object – Combine Selected Objects”. A new combined object appears in the list. This is our fuselage. I right click it and choose “Rename Object” and name it “Fuselage”.

The new fuselage is finished, ready to shade and texture. Note that this method guarantees perfect bilateral symmetry, which is otherwise quite difficult to achieve. The picture shows the finished fuselage in position with the top view sketch active so we can see the trace picture.

As a final touchup, I sometimes will use the “Select Point” tool to select various groups of points and use the “Translate” tool to modify their position slightly. But that’s a topic for another article :)

Good Digital Modeling!

Greg
Sunday Flyer Software, LLC

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