Recently people have been joining me on my Sunday Walks in Downtown Albany. Typically, I walk in Albany when I'm scheduled as a tour guide on the USS Slater. A slide show and a map are detailed at this blog entry. I plan on walking on Memorial Day, Monday, May 27. You can contact me at: dedocent@gmail.com.

More on the USS SLATER (www.ussslater.org).
Showing posts with label 40mm. Show all posts
Showing posts with label 40mm. Show all posts

Monday, July 20, 2009

07/19/2009 - Quiz the Docent


The USS Slater has been real busy this year. Someone in the PR department is doing great job. I need to start an informal poll to see why business has been so good.

Today the weather was fine, a little on the warm side. It was a bright sunny day. This makes it a little tough below decks and in smaller compartments like CIC. It gives you a good incentive to keep the group moving forward.

On Sunday I gave three tours. I
t was non-stop except for a brief interlude, while we showed the seven minute video introduction. At least the groups were good size. I was able to get everyone into all the compartments.

During one tour I was asked a lengthy series of very detailed stories. It seemed like the visitors were playing a new game - "Quiz the DE Docent". I enjoyed the mental exercise.





40mm Manuals

One very tough question, what was the load rating of the recoil springs for the 40 mm guns? I checked all my resources and I don't think I'm going to find a definitive answer. However, I can make an educated guess! Surprisingly, there is Internet access to two excellent sources of info on the 40mm: the Service Manual (40 MM Antiaircraft Gun, OP 820, 1943); and the catalog of Naval Weapons (Gun Mount And Turret Catalog, Ordnance Pamphlet 1112, 1945).

Before writing this post I read these manuals. I can now tell you that the spring in question is a Recoil Spring, part # 298666-1. I can tell you how to assemble/disassemble the spring (described on page 82 of OP820. ) And, I can tell you that to assemble/disassemble the recoil spring, you need a Spring Compressor Tool (298860).

The primary means of slowing down the recoil of the 40 mm gun is not the recoil spring, but the recoil cylinder (Described on Page 86 of OP820). The primary purpose of the recoil spring is to provide counter-recoil. Counter Recoil is the process of returning the gun to it's firing position. If we turn to the catalog of Naval Weapons (Pamphlet 1112) - Section on 40mm twin mounts, we can see that the weight of the oscillating assemblies is 2,300 pounds (for two guns). Since the spring is used to return a 1,150 pound oscillating assembly to a neutral position I would say that this has to be it's minimal load rating. And, I doubt that the tension would be a great deal higher since this would slam the assembly into the stop when the gun returned to it's firing position. So the load rating of the spring is probably in the range of 1,500 to 2,000 pounds.

Sorry I couldn't come up with a definitive answer. That's about as close as I can come!




How many Cooks were on Duty?

A little while ago I wrote a post about the shipboard organization of a Destroyer Escort. Here's a link to the 1944 DE Organization Table (USS Stewart). The table refers to a DE that was slightly smaller than the Slater. It notes that there were 3 cooks assigned (1st class, 2nd class and 3rd class). They were supplemented by 8 mess cooks. During the tour I believe that I guessed that there would be 2 cooks supplemented by 5 or 6 mess cooks (while the ship was at sea). Based on the shipboard organization link, I think that this guess was basically correct.


How many loaves of bread were baked each day?


This is a recurring question. I believe that there is a local professor/teacher that assigns a tour of the USS Slater as an assignment (btw - thanks for the business!)

I searched and had trouble finding any published account on the Internet. I'm going to ask around and when I come up with an answer I'll publish an account. I asked around on Sunday and on Tuesday and no one had a good answer. One guide noted that when he was asked the question, he answer "they baked enough to feed the crew!"

Regarding the baking of bread, I remember it being baked in the morning. However, a few accounts mention it being baked my night after dinner. Since I was a Gunnersmate my only involvement with bread was eating it. Perhaps my recollection is wrong. I'll check this out as well.

Tuesday, May 5, 2009

5/2/2009 - Busy Day

It was a busy day. I managed to give three tours in approximately four hours. The Michigan DE sailors were also aboard, to start they annual reunion/work week. The weather was nice. It was slightly overcast and relatively cool.

On the 1st tour I had a well informed WWII enthusiast who bombarded me with questions. I hope I passed the test? I really did enjoy it. It keeps you on your toes. One of the questions, was how many decks the Slater Had? I had to form a mental image - and came up with seven decks (detailed in the uploaded image below). On the USS Slater web site you can click on the deck image and see details (USS Slater Deck Index).

In between tours I had a discussion about the drives for the 40mm gun mounts with a Fire Control Tech from the Michigan Reunion Group. I was under the impression that the drives were amplidyne (all electric). It turns out that the Slater has electro-hydraulic mounts. Onboard there's excellent documentation about the mounts so it was quite easy to check out the details. Regarding the 40mm there's also a great deal of information available on the web:

Tuesday, September 25, 2007

Tour 9/22/2007, 40mm Bofors

Another beautiful fall day, not too hot and not too cold, and perfectly clear. Tour-wise it was pretty slow day. We had plenty of guides and only a few visitors. I only gave one tour to a small group. From a visitor's perspective a small group is great. You get to go at your own pace and get details on any topic you want. After six years I can answer a lot of questions, but I still have a lot to learn.





During the tour, while sitting on a 40mm gun mount (trainer position), a young visitor pointed to an instrument dial and asked what it was for? I was stumped (while on active duty I worked on 5" mounts and had limited exposure to 40mm mounts). I asked a few other Slater volunteers, and they appeared to be stumped as well. Finally, Eric Rivet (Education Coordinator) told me it was used to measure the deviation that occasionally occurred between the Mark 51 Fire Control Director and the 40mm Gun mount.

Each 40mm could be aimed automatically by a Mark 51 Fire Control Director. The pointer (the sailor who sat on the left side of the mount and moved the gun up and down) and the trainer (the sailor who sat on the right side of the mount and moved the gun right and left) would raise a control lever to the remote position and the 40mm mount would track automatically based on input from the fire control director. It appears that sometimes the 40 mm mount would lag from the intended aiming position that was transmitted to the mount by the Mark 51 Fire Control System. In extreme cases the mount could drop the signal altogether. The gauge in question would measure the lag and would be monitored by the pointer and trainer for obvious safety reasons.


Links:

Wikipedia 40mm Bofors
USS Slater 40mm Page
DE 220, Destroyer Escort Fire Control
Navy Weapons - Mark 51 FCS
Navy Weapons 40mm Bofors
Swedish web site regarding Bofors
Photo Site - source of 40mm Gage Picture

On the next week, 9/27 I managed to do a little more research. The proper name for the instrument is a 40mm lag meter. This text is from the WWII-era 40mm technical manual (page 161):

"The lag meter is primarily a milliammeter which operates in automatic control to indicate if the gun is in or out of synchronism with the director (i.e., the error). The pointer and trainer both have lag meter units (as shown on figure 130). Only early mods have the rectifier circuit.

If the pointer's meter reads to the left of zero, it indicates that the gun is elevated higher than the gun order. Conversely, if the meter reads to the right of zero it indicated gun elevation is less than gun order. When the gun position corresponds exactly with gun order, the pointer of the lag meter is stationary at the zero mark. The meter pointer may be adjusted for zero position by inserting a screw driver through an access hole in the case and turning the zero adjuster screw. ......."


This weekend I also had an opportunity to talk with John - Mechanic For Hire, the other USS Slater Blogger. It seems like his next project may be a cut away depth charge detailing the firing and safety mechanisms. This would be a great prop and it would add a new dimension to the tours. I'm looking forward to this addition.