Make a box type fuselage for hi-wing plane

Make a box type fuselage for hi-wing plane.

Create a long box from primitive > cube.

Cut at several place to make fuselage frames.

Select the surface to slide downward.

Select each point, and arrange it step by step.

Cut some more place, if you need to make the shape smoother.
And arrange the shape.

Next, we have to arrange the width of the fuselage.
And make each fuselage frame to the suitable width.

Finished! I recommend you to delete the upper face that will be under main-wing.

You can down load this fuselage. here