A journal following the history, design, construction and operation of Bernard Kempinski's O Scale model railroad depicting the U. S. Military Railroad (USMRR) Aquia-Falmouth line in 1863, and other model railroad projects.
©Bernard Kempinski All text and images, except as noted, on this blog are copyrighted by the author and may not be used without permission.

December 13, 2012

Rail Gun - Finished

I finished up the remaining details on the rail gun. I replaced the coupler on the rear. The first one was too big.  Since I laser cut the parts from 1/16th inch acrylic, it was a simple matter to reduce the height of the center part and and reinstall it. The nut detail is actually engraved. The coupler simply is glued to the wood frame.

The brake wheel hangers were the next challenge. I made the parts from 0.020 inch strip brass, a .042 inch brass rod and an etched brass wheel from my spares box. To fashion the parts I used my drill press with an x-y table to drill holes in a straight line. Then I used a new sharp  file to shape the parts. I secured the parts to the model and then added NBW details with CAA. I added a cast white metal gear to the shaft to represent the locking pinion.  To simulate the pawl, I added a small silver of wood.

I had to use brass for the parts  because the next step involved soldering the brake chain to the wheel shaft and the brake linkage on the truck. With everything soldered up, I tested the brake mechanism. It does work, though it would need some adjustments if this were to be an operating model.

Next I added an elevation wheel to the gun (not visible in these photos). I also mounted a small rod on the bottom   front of the gun carriage and added a wood strip with an iron strap on the rear. This allows the gun to deflect a limited amount in the casement while also tilting the gun forward. The tilt allows the gunners to run the gun out for firing, while the up slope helps absorb some of the recoil.

Next I must build the base to display the gun, and an acrylic case to protect it.

Having studied this gun, I am convinced that it was built solely as a weapon to counter other rail mounted iron clad guns. The heavy 32 pound cannon is impractical as a field weapon against mobile infantry and artillery targets. The limited traverse also hinders its use as a general field piece. The heavy armor only on the front meant that they did not expect it to be engaged from the sides.

To my mind the design of this gun supports Dr. Schneider's thesis that this was the "Dry Land Merrimack" that Lee had Brooke build for the Peninsula Campaign in 1862. They built the gun as a response to reports that the Union were also developing an ironclad  railroad gun. The Lee-Brooke gun was used once, probably found impractical as the Union did not have a matching railroad ironclad, and then retired to a siding, where it was discovered a few years later by Union soldiers.


  1. I -still- wonder about how well those brakes handle the gun's recoil

  2. Still a great piece of work, Bernard. The museum can be proud with this model in her collection in 2013 together with the other one.

    It would be a great piece here in the Netherlands on the coming summer show in our Dutch Railway Museum: -http://www.spoorwegmuseum.nl/news__press/tracks_to_the_front.html

    This will show several pieces in 1:1 that are related to the war over the years. I know it will behold very special items in real and in model. My layout will also be part of it as oldest working railroad that had a relation to war and railroad.

    Maybe one more to build? ;) Keep up the fine work, my friend!

    Grtz, Ronald.

  3. Thanks for the full history of the piece. I was unaware of any use of a weapon of this size and was interested in finding the rationale for its construction. Having been an Armor Officer for 20+ years I was having difficultly comprehending the effective use of such a large weapon with such limited Traverse capability. I know the Coastal Artillery folks used their big guns on a curving siding so they could move the weapon to the needed point on the siding to be able to bring the weapon to bear on the ship they were targeting. Thanks for the explanation and the B&O Museum is going to have an excellent artifact for discussion of the battles of the ACW.

  4. I have never seen anything like that before. Well done.