Holt 150 Ton Field Monitor

[rockpaperscissor]

I had so much fun designing and building my recent SCW Barbastro tank Barbastro tank SCW that I decided to start another project in a big way...a really big way.

The Holt 150 Ton Field Monitor (yes, 150 tons), was a 1916 endeavor by Benjamin Holt of Caterpillar fame, that never got off the drawing board. It was literally the size of a house: 54.6 feet long (16.6m), 24.5 feet (7.5m) wide, and 21.6 feet (6.6m) tall. At that time there were competing trains of thought on how a vehicle might best handle difficult terrain. Continuous track won out, but the "big wheel" theory was a contender for a while.

Holt's design if built would have been used against Mexican rebels, our enemy du jour, in the southwest USA and northern Mexico. Its paired 6" naval guns would have intimidated the toughest band of banditos. 10 machine guns were carried in side sponsons, 2 rotating turrets, and one each at the front and rear. The vehicle was to be manned by a crew of 20. The massive hull was supported by four giant 20' wheels and was powered by 2 huge kerosene burning steam engines. An interesting article at the Landships forum provides more detailed information. http://www.landships.info/landships/...s_Designs.html

To my knowledge there is no model of this beast available in any medium, although some intrepid plastic modeler modeler has built one from scratch Holt 150 ton Field Monitor – What could have been. America's 1915 land battleship. - Gallery - All Scale Modeller I've already begun the line drawing of my 1/72 scale version, and hope to have images of the alpha build of the hull later today. Wish me luck, I'm goin' in.

[rmks2000]

Looking forward to see this in Virginia this October.

Bob

[CharlieC]

Just a thought but wheels that size (20 foot diameter) would be extremely heavy if they were a simple drum. I would think that Holt would have designed a dished design to give maximum resistance to buckling at lowest weight. Something like traction engine wheels might give the best trade off between strength and weight. Also would provide a decent challenge for most modellers.
The wheel diameter on the Foster-Daimler tractor (attached) was about 8 feet.

Charlie

[Don Boose]

I am glad to see you working on an early American AFV, DOn, and am glad to have the additonal thoughts from Charlie.

The interwar mechanization of the U.S. Army is one of my areas of particular interest (I think when I die, Charlie will ask to have my gravestone inscribed (he never finished the Landships II article).

Don

[rockpaperscissor]

Thank you for your interest and input, fellas. The alpha build of the main hull went off without a hitch, and photos will follow later today. I used the sideview drawings from the excellent Landships article referenced in post #1 as a starting point. Why reinvent the wheel? Speaking of wheels, I designed the Field Monitor wheels in my head when half asleep last night. As Charlie suggested, they will be "spoked" in a manner of speaking to reduce weight The outer surface will be skinned with steel plates to provide protection and increased strength. I'm going to leave the inside open so that the construction of the wheels will be visible. I'm thinking 12 spokes per wheel. I like to add highlights and shadows to my models, so this will provide an additional challenge when texturing the wheel parts.

After I post a couple of photos of the hull's alpha build, I'll begin the texturing process. Since the vehicle was intended to be used in the American southwest it will be khaki colored, not that this giant thing could really be camouflaged in any meaningful way, LOL.

[rockpaperscissor]

Here are a few photos of the hull alpha build. It's made up of 3 main pieces, as well as a couple of smaller triangular pieces that line the sidewalls of the main gun opening. Everything fit together very well. I'm going to make a few small changes, but overall I'm very happy with the results so far. The fun part for me is texturing, but there is still a lot of design work to be done to complete the hull: side sponsons, main gun emplacements, turrets. Still, I should have a further update tomorrow. Stay tuned.

[airdave]

I don't believe weight was a consideration.
I think these vehicles (having 20' wheels) were to traverse trenches without falling into them.
Thats the reason the track drive was first considered in WW1.
The "terrain" was trenches.
Did they not have trenches in North American war?...they must have...?

Regardless, this is a fascinating and good looking model.

[CharlieC]

Originally Posted by airdave

I don't believe weight was a consideration.
I think these vehicles (having 20' wheels) were to traverse trenches without falling into them.
Thats the reason the track drive was first considered in WW1.
The "terrain" was trenches.
Did they not have trenches in North American war?...they must have...?

Regardless, this is a fascinating and good looking model.

Big wheel designs were quite popular in WW1 before people finally realised that wheels big enough to carry an armoured vehicle over a trench would be a target for artillery and the vehicle would very heavy. There were all sorts of strange trench crossing inventions before tracks proved to be the best solution. Crossing trenches was a British and American thing. The French were obsessed with barbed wire entanglements and trialled a number of devices to flatten and/or cut through barbed wire.

In the last 9 months or so of the US Civil War the main action was trench warfare around Petersburg and Richmond. Ulysses Grant, the Union commander, found he could hold the Confederate forces in place but couldn't break through the entrenchments in spite of the best efforts of his troops. In the end the Confederate forces withdrew and the war ended because of lack of supplies, illness and starvation.

Charlie

[airdave]

Oh, I didnt say any of the ideas worked. lol

The 'tanks' of that era didn't move any quicker, did they? lol

[rockpaperscissor]

I've got a lot done over the past couple of days. I drew up a black line version of a side sponson and printed it out only to discover that it was too small. I'm not sure what happened, but I suspect I had set the working page to the wrong magnification. No biggie. In the end, I double checked the working page magnification setting, and redrew the part - perfect fit!

Once I had the side sponsons sorted, I started on the texturing process. I adjusted the color/hue/saturation of my generic concrete floor image until I had a khaki shade that I liked. I saved this page as a new texture file. I selected and copied the texture file page, and using the "paste into" function, began to fill the B&W drawing with color. I flattened the image and then added the black rivets using the brush tool. Assuming a light source from above and slightly forward, I added appropriate highlight lines to each panel, and highlighted the tops of each rivet. Finally, I surrounded each hatch with a fuzzy shadow outline.

The hull is pretty big and requires internal support. I glued picture framing mat board sections to the inside of the model. When dry, I glued on all the various hatches, which are double paper thickness. I make it a habit to add these small parts before folding and gluing up the main assembly. Finally, I built the side sponsons and glued them to the hull. I neglected to take a photo of a disassembled sponson, my apologies. It's made up of 6 parts - the main part forms the roof, floor, and front face. Then there are two strips that are glued to the front face, and lastly, a center hatch and two side machine gun ports.

The last photo shows the prepared hull with the front piece that will go on next and start to close things up.