The cockpit canopy in this particular model is a bubble canopy, one of the canopy options for the P-47. The pilot sits in a glass bubble. The forward windshield is flanked by two side windshields, and the three windshields are backed by a metal strut like a rollbar.

  open \modeling\p47\p47_04.max,
            
  select the P-47.
               On the ribbon 
 Polygon
               Modeling panel, click Modify Mode.
            
 Edit panel, turn off  
  (NURMS).
            Adjust the shape of the front windshield:
Now you can see the canopy again.

  Orbit,  
  pan, and  
  zoom the Perspective viewport
               to get a closer view of the canopy.
  Select the canopy and if
               you need to, press F4 to
               display Edged Faces.
  (Vertex) sub-object level.  
  Select the vertex at the
               top center of the front windshield.
 Edit panel, activate  
  (Constrain To Edge). Then  
  move the vertex upward to
               give the front windshield more of a peak.
  (Select Object) to deactivate Move.
            
 Edit panel, activate  
  (Constrain To None).
            Add edges to reinforce the metal parts:
 Edit panel, turn on  
  (SwiftLoop).
            
  (Edge) sub-object level.
            
  Click and Ctrl+click to select the two edges
               at the top front of the “rollbar” strut.
 Edit panel, activate  
  (Constrain To Edge). Then  
  move the edges forward a
               bit to give the strut a more even width.
  moving them back slightly
               so the width of the frame is more even.
  (Select Object) to deactivate Move.
            
 Edit panel, activate  
  (Constrain To None).
            
  (Polygon) sub-object level.
            
  (Zoom Extents All Selected).
  Click away from the canopy
               to deselect all polygons. Then click and Ctrl+click
               the polygons that correspond to the glass parts of the canopy. You
               will need to use the Top viewport to select polygons that aren’t
               visible in the Perspective view.
Top view

Perspective view

 Polygons panel, Shift+click  
  (Extrude).
               
            

  (OK) to accept the extrusion.
            
 Modify Selection panel, click  
  (Grow).
               This selects the side faces that were created when you extruded the metal parts. These faces should be metal, too.
