Hi again,
I'm sending you an attempt at replicating the outer form of the bonnet.
You will see that I pasted an OLE image from your initial post and I scaled the image so that I could replicate the contours (kind f like old digitizing). The contours I created are in red and overlaying the image.
I created one quarter of the bonnet using lofted surfaces and a surface plane and SURFSCULPT (like Lee suggested to you).
I mirrored and union-ed the quarters, then I created a closed form to remove the cutouts from the full Bonnet.
I also created a swept object to place along the top of the bonnet for you to create the ribs as desired (probably after you figure your tapers.
This was a fun little replication and I think it's close to what you want!
Cheers,
Blaine
Judging from your real picture, I would proceed my using Taper Faces to add taper or draft where desired.
Blaine Young
Senior Engineering Technician, US Army
