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 25, 2012

B&O Ironclad Cars

I started building 1/48th scale models of the B&O Ironclad and Rifle cars.  These models are destined for the B&O Museum collection.  I am working with Dan Toomey of the B&O Museum to try to make these models as accurate as possible, but given the limited and conflicting information we have about the cars, much is educated guess work.  For example, there are several descriptions of an engagement where one of these cars was destroyed. Each account has different descriptions of the car and its construction. Most of them are summarized at this web site . It's is hard to know which one is right.

The cars are described in Alan Koenig's dissertation, "Ironclads on Rails: Armor Returns to the Battlefield, 1861-65. This was our main source as it cites several statements from the builders, as well as  observers that saw the car in service or after it was destroyed.

The ironclads are also mentioned in Robert Hodges, Jr.'s book, "American Civil War Railroad Tactics." The latter includes an artist's concept painting of what the cars may have looked like as no known images of the cars have survived.  While we agree with the overall look of the cars in the painting, there are certain details we will change.

The drawing shows our interpretation of the cars. The approach we used is to assume they started with standard boxcars and added the armor as an applique. These cars were built quickly, so it seems likely they started with existing parts if not whole cars.

According to Koenig, one source says the armor was mounted on a 45 degree angle. That is possible on the front of the car, but not possible on the sides as it would make the car too wide. So we made the side taper more vertical.

Koenig lists one source that states the rail was "T" iron, while another just says "railroad iron." We elected to go with "T" iron, in the form of code 55 rail, which works out to 2.6 inches in full scale. At this point most major railroads were installing 60 to 70 pound per yard rail on their mainlines, which scales down to about code 90 (0.093 inches inches tall). So the rail on this car represents lighter rail that was either destined for yard use or was retired. I had a bunch of code 55 on hand, so I used it.

Is code 55 reasonable? Yes, because heavier weight rail would have overloaded the 10 ton capacity of the car,  which was typical of a box car of the civil war era on two trucks.  The table illustrates that at 30 pounds per yard of rail the car would weigh about 10.2 tons loaded with crew, gun and ammunition. Even rail at 40 pounds per yard would have overloaded the car by 30 percent.
Heavier 60 or 70 code rail would have seriously overloaded the car. (Note that the number of rails per side for larger weight rail would be less than shown here as the the heavier rail is also wider. But the weight increases with the cube of the size, so the weight gain will out-pace the width related savings.)
"T" Rail added by the crew to protect the casement corner on USS Cairo

Some sources say the rail was spiked on, but Dan believes that it was bolted. I used the railroad T armor on the restored USS Cairo as a guide for how such rail would have been bolted on. In the case of the USS Cairo, the rail was bolted with the flat side facing out. I reversed it on the car as it was too hard for me to get the code 55 rail to look correct in that configuration. It would not lie flat as I assembled it.

Most sources state that the cars were equipped with one gun each, mostly small mountain howitzers, but one had a 6 pound brass smoothbore.  The first versions of these cars had cannon mounted in the vehicle suspended from the roof with a series of ropes. But later versions used standard field carriages as we show here.

There is a gun port on the front of the car. The artist concept in Hodge's book shows gun ports and cannon pointing out the side, but the car is too narrow for the standard field cannon to fire to the side. So there is no point to have gun ports on the sides, though there may have been observation ports. We elected to include 3 loop holes on each side instead of additional gun ports.

These cars were operated in sets. An armored train would have ironclads on front and back, with rifle cars between the ironclad and the locomotive. So a gun pointing out from each end of the train might be effective in covering the area around the train, especially if the gun could cover a 60 degree arc from its embrasure.

The gun port was reported to be 6 inches square, but again that is unlikely as such a small size would not allow the gun to defect or elevate very much. The gun port must be a bit bigger. One source, Deffinbaugh, claims he found the gunport of the destroyed car and that it was a solid piece of iron.

The last puzzle was the rear of the car. Again according to Koenig, one source says the rear was also sloped with an embrasure for a gun. But most other sources say that only one gun was mounted in each car. If you put a 6 pounder smooth bore on a standard field carriage on a rail car that can travel along standard gauge tracks, there is no way the car can be wide enough to turn the gun around inside the car.  So one gun cannot serve both gun ports.  It seemed impractical to me for the car not to have a decent size access door, so I added one to the rear.

One of the problems I have noted with some artists' concepts and drawings of artillery mounted on flat cars is that they make the gun carriage too small in relation to the car. The drawing above shows both the gun and car in the same scale.  As you can see, a 6 pounder on a standard field carriage just barely fits in the car. There is some room to deflect the cannon right or left to aim, but firing off the side is not possible.

We welcome your comments or ideas. The famous ship historian and modeler Howard Chapelle once said words to the effect that you should never build a model until you have all the information you need, as others that view the model will not know where you guessed. (for more of Howard's argument see this link.)In this case, we recognize that the information is sketchy about these cars and do not claim that this is a 100 percent accurate representation of the car, but the best we can make.  We hope you enjoy it.


  1. Could the cannon have been mounted in a manner closer to that used on ships? Either a carronade mounting or a trunnion carriage?

  2. According to the sources listed in Koenig's paper the guns were originally mounted via a system of ropes suspended from the ceiling. But that proved inadequate as the recoil caused the tube to swing and hit the roof after each shot. Then the ropes would have to be rearranged for the next shot. So they redesigned it to accept guns on standard field carriages.

    But that begs the question, how did the gun carriages get inside the car? There must have been a door somewhere. My best guess is that there was a door on the rear end. So I think I will add one to the model.

    They used 6 pounders and mountain howitzers, which are small field pieces.

  3. The research I ran across when building my "Yankee Gunboat" ironclad mentioned that the guns were 6 pounders mounted in Naval carriages. You're doing a Bang-Up job with this Bernie. 1/48 allows for much more detail and an easier build in my opinion. The minuscule becomes the tiny.

  4. Scooter- I believe the "Yankee Gunboat" you refer to was the rail gun built for Burnside's Army in North Carolina. the NY Times article you posted to the Yahoo group mentions the naval carriage. The B&O cars have specific information as I cited above about the use of either ropes or field carriages. So we can be relatively certain that a naval carriage was not used.

    It is unlikely that a small 6 pounder would be mounted in a standard heavy duty naval carriage. The chief advantage of the 6 pdr gun was that it was relatively light (about 800-900 pounds) so it was easier to move. At the time of the ACW 6 pound guns were not used by the US Navy. There were some 6 pound "insurance guns" (guns carried by merchant ships for insurance purposes), but I am not sure they propagated to the Navy. And those are also early 19th century. There were many 6 pdr guns used in the Revolution and War of 1812, but usually they were not used in the ACW. What what I can tell the predominant 6 pdr guns in service were the US Army guns of the 1841 design and some variants of that.

    With regard to naval carriages, one must be careful with the type you use as the Union Navy had a special boat howitzer carriage for using smaller field guns on their ships. However, most were 12 pounds or 24 pound howitzers. The carriage resembled a standard field carriage except it was made with light weight wrought iron. It took a specially designed cannon that did not have trunnions, but had under loops. It was designed so that it could be rapidly disassembled for stowage on the ship. There is a copy of one of these at the USS Cairo exhibit at the Vicksburg Museum in Mississippi. There are also several pictures of these iron carriage boat howitzers guns mounted on the decks of ironclad monitors in the LoC and other sources. The purpose of these smaller guns on ironclad monitors was to provide anti-personnel artillery fire against guerillas and other light targets. The big 10 to 15 inch guns were not suitable against mobile infantry and cavalry targets.

    So what would a 6 pdr look like on a naval carriage? At this point I have to say, I don't know. Hope that muddied the waters for you!

    With regard to the model, I am not happy with the way this it is coming out, so I am redoing it. I have not yet found a good way to simulate the iron armor to scale. My second and third attempts yesterday were not successful. But I have some more ideas to try. When I scratch build, I frequently scrap my first and second attempts before I am happy.

    1. Thanx Bernie for this info. I hadn't run across the data for 6 pounders not being a current ACW piece. Where did you locate the data on the B&O cars? I have a couple of drawings of 'supposed' B&O built rail guns though I have been unable to find any specs except mention of them using a long baggage car plated with iron and having a 12 pound gun that shot iron disks stamped from boiler plate.

      Yes, the Yankee Gunboat was built for Burnsides Crew at the shops in/around New Bern, NC. As I read my sources, more than one was created and each successive car was different in some manner. The last one I found info on was in use in 1864 and used 12 pounders.

      As always, I drool over your creations and relish the inspiration I get from your works.

  5. Just read in "The Quiartermaster" by O'Harrow, Jr., that JW. Garrett, B & O President in 1863, assigned 300 men to work 6 days straight to build 10 fortified railclad cars in "the manner of the river ironclad boats.
    (see ya in Savannah in October!)
    Lou Caputo

  6. B & O President, J. W. Garrett, in 1863 assigned 300 workmen to build 10 ironclad railcars. (read in O'Harrow, Jr., "The Quartermaster".