Modeling a P-38 Lightning Fighter

Lockheed P-38 Lightning model

In this tutorial you will create the exterior of a WWII classic warplane, the Lockheed P-38 Lightning. You'll use primitive objects and modifiers to create the parts. You'll use viewport background bitmaps as a guide to shape your plane.

Finding the Files

Most of the tutorial topics ask you to begin by loading a starting file. You will find these files in the subdirectories under gmax\tutorials. These scene and map files are not installed as part of the basic gmax install. You get these files when you download and install gmax_tutorials.exe. If you can't find a file, trying searching for it using Windows Explorer or My Computer; you might have inadvertently installed the files to a different location.

Note that this tutorial is an exception, in that it doesn't ask you to load many starting files, due to a peculiarity in the behavior of viewport backgrounds. It does ask you to load some bitmaps which you should find the gmax\tutorials\P38 directory.

Setting Up Units

The first task is to change the modeling units to feet and inches. Since the P-38 is a vintage US plane, the specifications are in US standard measurement types. As a default, gmax is set to generic units, so you'll need to change this.

Set up units of measurement

1        From the Customize menu, choose Units Setup.

The Units Setup dialog appears.

2        Choose US Standard, then click OK.

Now when you create anything, the dimensions will be displayed in feet and inches.

3 In the Create panel, on the Object Type rollout, click Cylinder.

Look at the Parameters rollout; the values are now displayed in feet and inches.

The next step is to set up the viewport backgrounds.

Setting Up Viewport Backgrounds

You can load images or drawings in viewport backgrounds to use as patterns for building your warplane. Each viewport can have its own background, so you can load a corresponding image in the Front, Side, and Top viewports to guide you as you build the model.

In general, when modeling something you've previously visualized or seen, it's best to start with sketches from several different viewpoints, such as top, side, and front. Also, the drawings should all be to the same scale, if possible. In this exercise, you'll use three drawings of an P-38 Lightning taken from WWII plane-spotting cards.

Three views of the P-38 Lightning from plane-spotting card

Set up viewport backgrounds

1        Activate the Top viewport.

2        On the menu bar, choose Views > Viewport Background.

3        In the Viewport Background dialog's Background group, click Files.

4        Navigate to the \gmax\tutorials\p38 directory and choose p38topview.jpg.

5        In the Aspect Ratio group, choose Match Bitmap. Click Apply.

A sketch of the top view of the fighter is visible in the Top viewport.

Top viewport displays the Top view background image.

6        Click OK to close the Viewport background dialog.

7        Turn off the grid display by pressing the G key.

8        Choose Views > Viewport Background to again open the Viewport Background dialog.

9        In the Apply Source And Display To group, click the arrow by the Viewport field, and choose Left.

The Left viewport should become active.

10    Click Files and choose p38leftview.jpg for the Left viewport. Again, choose Match Bitmap. Click OK. Turn off the grid display again.

Top and Left viewports with background images

11    Click the Front viewport, then choose Views > Viewport Background. Click Files again and choose p38frontview.jpg for the Front viewport. Choose Match Bitmap, then click OK. Turn off the grid display.

The three images are displayed in the appropriate viewports

Zoom the background images

You can zoom and pan the background images in the viewport if you want to center or enlarge them. To zoom or pan the background images do the following:

1        Activate the viewport, then choose Views > Viewport Background.

2        Make sure Match Bitmap is on, then turn on Lock Zoom Pan.

Now you can use the zoom or pan buttons in the viewport navigation controls to make the background image larger or shift it horizontally or vertically.

3        Be sure to turn Lock Zoom Pan off when you finish with each image.

Tip: gmax automatically turns on Lock Zoom Pan when you maximize a viewport or save your work and exit the program. Sometimes the background image can shift out of alignment with your geometry when this happens. This is inconvenient, but there is a workaround.

If you open up a saved file and the background has shifted do the following:

Use the viewport navigation Zoom and Pan buttons to make the background images the correct size and position in the viewports.

·    Turn off Lock Zoom Pan, and then use the same navigation tools to align the geometry with the bitmaps.

You can use CTRL+ALT+B to toggle Lock Zoom Pan.

·    After doing this, don't maximize, zoom, or pan the viewport.

Turning display of the Tab panel on or off can also cause viewport backgrounds to shift.

Next you will make a calibration box, to make sure the 3 viewports are in the same scale, and that the plane will be an appropriate size .

Calibrate the viewports

The P-38 has a wingspan of 52 feet, and a length of 37’10". With the wheels extended, it has a height of 9'10". You'll use this information to make a box of that size, then align the viewports to that box.

1        Activate the Top viewport.

2 In the Create panel, on the Object Type rollout, click Box.

The Box button turns orange to show it's active and ready to create.

3        Open the Keyboard Entry rollout, and enter the following values:

·    Length: 37'10"

·    Width: 52'0"

·    Height 9'10"

Tip: You can use the Tab key to move from one field to the next.

4        Once these values are entered, click Create.

A box appears in the viewports.

5        In the command panel, name the object calibration box.

6 In the viewport navigation controls at the bottom-right corner of the interface, click Zoom extents all.

The box is now visible and centered over the three background bitmaps. It doesn’t matter if your box is a different color than the one in the illustration.

Calibration box centered over the background images

Now starting with the Top viewport you will zoom and pan each view to match the box and the bitmap background.

7 In the viewport navigation controls, click Zoom. Zoom the Top viewport until the width of the box matches the width of the wings. Match the wingspan as closely as you can.

8 Click Pan in the viewport controls, and then pan the viewport to center the box over the bitmap vertically. It won't be perfect, the two rudders will extend slightly beyond the calibration box.

Top viewport aligned with calibration box

9        Zoom the Front viewport. Again match the wingspan first using zoom, then pan to adjust the vertical height. You'll have to imagine where the wheels should be, they aren't illustrated in the plane-spotting card.

Front viewport aligned with calibration box

10   Now repeat for the Left viewport.

Left viewport aligned with calibration box

All three viewports are now calibrated so the picture in the viewport represents the approximate dimensions of the P-38.

Hide the calibration box

1        You don't need the calibration box now, so you can hide it. To do so, select the box in any viewport, right-click, and then choose Hide Selection from the quad menu.

You can always unhide the calibration box and repeat the above procedure to recalibrate. To unhide the box, go to the Display panel and choose Unhide By Name, then in the dialog, select the box.