I decided for the Medium DM as I had the best detailed pictures of this version.
Having only these pictures, the overall dimensions and a lot of conflicting other information ,this model is the result of a lot of guesswork.
Before printing the model in 3D I like to invite you to give you experts any remarks about the result so far.
I am not sure about the back, the previous version Mk D** had a kind of open tub in the back, I have no pictures of the back of the Mk DM, so I guessed it would be similar.
Nice "Secret" official side view blue print of the Medium Tank Mk DM. No dimensions, but should be able to scale it. Found during an unrelated search at the US National Archives College Park Maryland.
Yes, the second US Medium 1922 prototype had the British cable suspension from the Medium D. In October of 1919, the US Ordnance Department obtained detailed specifications and an overall drawing of the first British “Mark D” (Medium D) and the proposed specifications of the latest British Mark “D*” and “D**” tank designs by P. Johnson. Their flexible cable suspension, high speed (18mph) and light weight of 15 tons were very appealing. The Medium D’s strange crew layout, with the driver on top in the normal commander’s position, was considered the only design drawback to be corrected.
There is a small collection of assembly level and detailed drawings of P. Johnson’s tanks, suspension and tracks in the US Archives Tank, Truck and Trailer Division’s post WWI history collection. They appear to be from around this time period of late 1919 and were probably made by P. Johnson’s official Department of Tank Design and Experimentation. A further collection of general arrangement, cross sections and elevations of Johnson’s later DM and Tropical Tanks, were sent on May 30, 1922, from the same British War Office department.
I have attached below the only two prints from this period that I could find in the US Archives of the British Medium D prints. They are both extremely faded. Yes, they are photo enhanced as best I could. It should be noted that when files are archived/stored they are condensed, often numerous times, the first thing removed are all attached prints and photographs. This is especially true of the AFV files from the 1910's, 20's and 30's.
I did find a rather extensive set of extremely large prints for a proposed US version of the Carro Fiat Tipo 2000. I sent photographs of these to the Italian group reconstructing this tank.
There are sixteen print files of the Artillerie "St-Chamond" Tracteur Cuirasse "St-Chamond" DE 90 H.P. and one of the Artillerie "St-Chamond" Char D'Assaut "St-Chamond" in the US Archives Tank, Truck and Trailer Division’s post WWI history collection. The first were used at the Rock Island Arsenal to produce the one US version; the Mark IV and Mark IVA Caterpillar 240mm Model 1918 Howitzer (Schneider).
I have not been checking site for a while but this is fantastic! Hard to believe it's 1/72 and 3D printed! Great work Hans56.
attached extra on rear view of MarkD** which looks to be all open rear of the mufflers. Also from Rockenbach archives from Virginia archives a general arrangement drawing of Mark D, D* and D**. looks like rear was totally open?
There seem to have been two different engines used in the Medium Ds - the Siddeley Puma (240-300hp) and the Rolls Royce Eagle (370 hp).
The source material said the D** was initially fitted with the Puma engine (possibly the two-into-one exhaust) and later with the Eagle (two separate exhaust pipes).
