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PostPosted: Thu Aug 27, 2020 11:37 am 
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Attachment:
recoil -- max piston travel.jpg
recoil -- max piston travel.jpg [ 95.22 KiB | Viewed 133 times ]

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.
Attachment:
recoil slides aft & brake cylinder.jpg
recoil slides aft & brake cylinder.jpg [ 236.16 KiB | Viewed 133 times ]

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.


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PostPosted: Thu Aug 27, 2020 12:42 pm 
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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.

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Chairman Arbeitskreis historischer Schiffbau e.V. (German Association for Shipbuilding History)

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Last edited by wefalck on Sat Aug 29, 2020 3:32 am, edited 1 time in total.

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PostPosted: Fri Aug 28, 2020 8:47 pm 
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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


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PostPosted: Wed Nov 18, 2020 9:02 pm 
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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


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PostPosted: Fri Nov 20, 2020 12:37 pm 
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WWI tank version SIDE.jpg
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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


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