Where to start, how to proceed

Win 7, Sketchup 17.2.2555 (it should not really matter)

I want to model the front roof section of a trailer, but I really don’t have a clue on how to get started.

Imagine there is an arc on the YZ plane. The arc starts at (0,0,0) and goes to (0,100,0). The peak is at (0,50,10). Thickness is add to the arc and it is pulled in the positive X direction for 10 so that the endpoints of the arc are now (10,0,0) and (10,100,0)

The arc is now rotated through the axis of those two endpoints. As the arc is rotated 90°, the peak of the arc goes to zero. There will be some projection ahead of the axis of rotation.

This is the best I can describe what I want. How would you start after placing the arc on the on the YZ plane ?

Are you talking about something like the top front of a horse trailer?

Assuming the curve of the roof and the curve at the front are the same, you could create a path and a profile and use Follow Me. I expect the curve really shouldn’t be an arc but that’s a place to start.

That is a good start ! But the curve at the top will likely be a true arc and as that shape continues to rotate another 90° I want it to come out flat. I want a vertical wall so I can mount LP tanks on the tongue.

I’d probably use an extension like Curviloft from Sketchucation to stitch together the top and front curves. Maybe something like this.

Once you have the basic shape you can extend it backward and down with Push/Pull.