Thanks bracco_n for the website link, it has some great photos and information about U-47 including some pre-war. The assistance and information that everyone here has provided me has been fantastic and has given me the encouragement to move forward with my project.
After reviewing all of the great information that was provided to me, I have have selected U-45 as the subject of my build and have been hard at work this past month. There are a group of excellent photos of U-45 taken in 1938, including some commissioning ceremony snaps that are very good. I will be using both the Revell and Amati kit to model this very early, actually first, Type VIIB. Once I get my digital camera functioning again, I will start a work in progress and post photos. In the meantime, a brief summary of my progress:
I have been concentrating on the conning tower and it is about 90% complete. After reviewing all of the excellent information that was provided to me, I decided that my early attempt on the conning tower could be improved. The biggest challenges were the flooding holes on the sides, the bronze eagle on the front, the conning tower deck, and the attack periscope housing.
After trying several approaches on the flooding holes, I finally found an excellent, but tedious solution, using some obscure railroad photoetch grating that, when modified, provides an exact match for both the hole size and pattern. The results are very impressive.
The bronze eagle emblem that pre-war boats had fastened to the front of the tower was a real scratch building challenge for me. The eagle is very small in 1/72nd scale and has to be curved to conform to the tower shape. I ended up carefully carving/shaping the eagle from an old spare part having the proper curve. The most difficult part involved constructing a tiny swastika for the circle that is grasped in the talons of the eagle. I am not 100% satisfied with the result, once I post a photo perhaps someone can suggest a way to improve my effort. Alternatively, if anyone knows where I can obtain a properly scaled white metal or photoetch eagle, that would be the ideal solution.
Initially, I tried to modify the Amati photoetch conning tower deck. It needs added square holes where the incorrect air duct is located. I did manage to make the holes and attempted to square them somewhat, but the brass is too thick to obtain decent results. After some careful measurements, I found that the Revell Type VIIC tower deck could be modified to an early VIIB configuration. This involved some tricky styrene surgery and very carefully alignment to rearrange the various deck grating pieces. The results are very nice and far superior to the modified Amati brass part.
Based on photos of early VIIB boats, I believe the shape of the attack periscope housing is very different from later boats. It appears to have a more wider base that tapers toward the rear ending in a vertical trailing edge that runs from the deck up to the top. Viewed from above, it would appear as a water drop. The holes and foot rail are also different from later boats and there is an angular bracket attached to the bottom rear of the housing that I think was used to hold a life belt. There is no rail at the top of the housing where the scope tip is located. I think I got it right - I will post a photo as soon as possible.
There is one feature of the scope housing that I am uncertain about. I don't think these very early VIIB's, at the time of commissioning, had a compass attached to the forward part of the scope housing like the later boats. In the photos of these very early boats, I can't see the compass, but I can't be certain. Does anyone know?
Another odd conning tower feature (that others have pointed out to me - thank you) of these early VIIB boats is a device that is located in the extreme forward tower inside just behind the tower wall and just in front of the sky scope. It is a cylindrical tube similar to the sky periscope housing with a short pipe extension coming upward from the centre. The extension has a 90% fitting, like a pipe elbow joint, pointing to the side that ends with a smaller flexible hose which curves around along the front inside edge of the tower until it meets with a smaller cylinder that is bolted to the inside edge of the tower. I can't tell from the photos what extends from the other side of this smaller cylinder, but I think it might be a small hand held speaking tube. I will post some photos of this device and perhaps someone can identify it and explain its function.
Thanks again to everyone that has helped me, look for my U-45 progress photos in the near future as soon as my camera is operational again. In the meantime, your comments and suggestions are always welcome.
Bill