Hotchkiss 6 pounder QF in Rhino3D

[mcg]

With the brake cylinder mounted, it is now possible to make some basic measurments of the maximum possible travel associated with a recoil. The travel is limited absolutely by the distance that can be moved by the piston inside the shock absorber.

This turned out to be 80 mm, as shown. Not sure this is a realistic value and would welcome comment. It implies that in a single cycle, the piston (actually the cylinder) traverses about 6 inches altogether through the glycerine fluid -- 3 inches aft and then 3 inches forward.

Shown from below at the full extent of a recoil. The slides, their mounting ring, the gun tube and the brake cylinder all shift aft as an integral unit with the recoil. Note the slides protruding aft from the guides. Inside the brake cylinder can be seen a fixed disk and retainer that provide the base for the internal springs. The cylinder freely slides past this disk as the gun recoils.

[wefalck]

If the 80 mm is what you measured, then this is likely to be true. I have never seen any such gun been fired, but have been surprised to see in drawing over how short distance the recoil was stopped. I think we are often mislead by cinema films, where guns either don�t show any recoil or jump madly. I think on youtube you can see some late 19th/early 20th century guns being fired.

A major concern would be the heat dissipation from the recoil brake. The glycerine would heat up fast after a few shots, the kinetic energie being converted into heat. In some guns this seems to have limited the rate of fire, rather than the level of training of the gun crew.

[mcg]

Many thanks wefalck. I will assume the displacement of the barrel is a reasonable approximation and proceed to the next step � probably the pintel.

Keen observation about the exaggerated recoils depicted in movies. Michael

[starseeker]

Is the following relevant? It's an Army application, but perhaps there are similarities?

Handbook for the Q.F. Hotchkiss 2.244-inch, 6-pdr., 6-cwt. Mark II gun with tank mounting.
https://cdm16040.contentdm.oclc.org/dig ... ll9/id/943

[mcg]

Thank you Cliff. This shows a WWI version of a Hotchkiss 47 mm. The recoil mechanisms we have been discussing are more highly evolved, or maybe adapted to work inside of a tank. The designer has separated the springs and the shock absorber. The shock, now identified as a "counter recoil" is mounted above the gun tube. The springs, two of them, go below. In this system the cylinders are fixed in position and the piston moves with the gun tube.

In the early 57 mm I am modeling, the whole system, spring plus shock, is designed within a single long cylinder. The handbook makes it easier to understand the variety of recoil systems that turn up in photos taken across the years. And it is great to see some 3-view machine drawings, rather than perspectives! Michael

[taylormade]

Very interesting post with an amazing amount of detail I wish I had seen this before I modeled my Hotchkiss for my virtual model of the French cruiser Cosmao (1889). It's not that detailed as it's part of a much larger model and the file size is already quite large. Here is what I came up with.

[mcg]

Excellent! A search for the cruiser Cosmao turned up a photo linked here:

http://www.cosmaodumanoir.fr/images/Cro ... entier.jpg

Would love to see more images of your model of this ship. The tumblehome hull and especially the bow are exotic. Michael

Ah. Found your build thread:

viewtopic.php?f=13&t=315018

Beautiful work.

[NavyShooter]

A fascinating project!

Someone mentioned earlier in the thread about RCN Saluting guns.

Here are some photos of current service RCN Saluting guns - these appear to be WW2 6 Pd AT guns mounted on modified original 3Pd QF mounts from VS&M in some cases dated 1901.