Chris's Build of Battleship Ohio Engine

[crueby]

Hi all,
This is going to be a long-term build, partly since I need to convert the original plan sheets to CAD then pick a scale to build from, but its worth starting the thread now to help keep it all straight and show progress along the way.
Here is a picture of the battleship Ohio, BB-12, commissioned in 1904. It was one of three ships in the Maine class (these are the next generation AFTER the Maine that blew up in Havana Harbor). It was part of the Great White Fleet that did a world tour.


More pictures on these websites:
https://www.history.navy.mil/our-collections/photography/us-navy-ships/battleships/ohio-bb-12.html
http://www.navsource.org/archives/01/12a.htm

'Steamer' Dave very kindly gave me a copy of the set of plans he has of the engine from this ship. It had two of these 8000 HP (yes, 8 THOUSAND HP) triple expansion, 4 cylinder engines (two LP cylinders). Massive engines, very hard to find any pictures of that style engine. It was a German design that the US Navy used, and built them in the US for the battleships. They include a two-cylinder barring engine at the end that turns a pair of worm gear sets to turn the main engine, a shaft driven set of pumps at the other end, and a single piston reverse 'engine' in the middle that moves the reverse gear linkages back and forth (these days it would be done with a single hydraulic piston).

Right now I'm still studying the plans, 8 large sheets, trying not to drool on them too much. So far it looks like a pretty complete set of measured drawings, nice detail on the cylinders, base, con rods, etc. There are a few areas on the frame and the eccentrics where the details are slight, but there is enough there to build from.

Once the studying/drooling is done, I'll start up the CAD drawing of the parts, starting with the engine beds and moving up from there. I'll post screen shots as that goes on, and eventually will have enough to start building. This will be a nice background project as the Ransome Tree Feller build goes on over in the workshop.  My initial back-of-napkin guess is that the scale of the model will be somewhere in the 1:12 to 1:16 range, have to see how the part sizes work out vs what will fit on my lathe/mill. Whatever the scale, it will be another big model, like the Holly water pumping engine was (that was 1:32 scale). One nice thing from a build point of view is that the crankshaft, while very long, was made in four bolted-together lengths, which will help a lot on my small Sherline lathe.
A few specs on the engine:

• Cylinder bores: 35.5" HP, 53" IP, two 63" LP cylinders
• Stroke 48"
• Steam pressure: 250 PSI
• Speed: 125 RPM, 18 knots

Stay tuned, more details to follow as the CAD work starts and Dave and I continue to add more background as the research continues.

Chris

[cnr6400]

 

Standing by, here in the stokehold as usual, sir!   

[Craig DeShong]

ooooooooooooooooh boy!, this will be exciting. 

 

[tghs]

right up the predred time frame,, look at those pretty steam cutters moored alongside..

[crueby]

Boats and ships back then DID look great, didn't they!

[tghs]

me and a couple of friends think so

[crueby]

Oooh, those are beautiful models!  Scratch built?

[tghs]

all scratch 1/96th, my USS Brooklyn and a friends USS Maine, my USS Raleigh and a friends USS Chester,, I also have a USS Minneapolis and a the BB1 USS Texas started.. and a USS vesuvius (dynamite Cruiser) in 1/48...

[cnr6400]

Marvelous ships tghs! Thanks for posting the photos / info!

[Chipswitheverything]

Do the plans that you are inspecting have any sort of GA drawing that would give an idea of the overall scheme of the complex engine?  Would be interested to see something like that.  In the UK, Commander Barker built a series of large and highly accurate marine engine models that were illustrated in Model Engineer magazines of the 1950's, they might have some relevance.  A quick Google search just now didn't bring up specific references, though searching for "Quads" ... did bring up more material than I had expected to see.
 I have a copy here of the 1908, 9th edition of Sennett and Oram "The Marine Steam Engine" 500 pages, which contains a lot of detail of componentry and auxiliaries for these large engines.  Also, 2 volumes of Sothern's "Verbal notes and sketches for Marine Engineers" , subtitled A Manual of Marine steam Engineering practice" with comprehensive information on all aspects of the subject, not dated, maybe 1920?   And a few other tomes similar, in date and content, they were fond of large and rather fiercesome text books at that period!  If I can dig anything out of these books that might be helpful, happy to have a look.  Dave

[crueby]

Absolutely - I should have included these shots in the first post. Here are two views from the plans, showing the general layout:



The first photo shows the side view of the engine, cutaway down the center for most of it. The HP cylinder is on the right, and the two LP cylinders on the left. I'm assuming that they split the LP cylinder, which typically would have been much larger diameter and 120 degrees off from the HP and IP on the crank, into two cylinders just a little larger than the IP to keep the engine narrower (though longer) to fit in the hull better. It does change the crankshaft, they have the HP and IP 180 degrees apart, and each of the two LP pistons 180 apart/90 from the other two, which is interesting. Properly sized, the four cranks more evenly distribute the forces on the output shaft. Also note the conical-shaped pistons heads, and hard to see in the small photos but the tops of the IP/LP valves have small pistons to balance the weight of the valves, which are quite large.

[ddmckee54]

4 cylinders x 2 cylinder heads per cylinder = an awful lot of tiny holes for you and the elves to drill and tap.

Don

[tghs]

those piston profiles look familiar!!!!

[crueby]

4 cylinders x 2 cylinder heads per cylinder = an awful lot of tiny holes for you and the elves to drill and tap.

Don

Not to mention all the holes in the engine beds, frames, crossheads... Fortunately the bolts on the real one are large diameter, so at model scale most will be around a 2-56 size. Once the CAD model is made I will fiddle with the math on the largest/smallest parts and see how the scale works out. That tapping stand will be paying for itself yet again!

[crueby]

those piston profiles look familiar!!!!

Same on the engine you are building? 


Do you know why they did conical rather than flat piston heads? Same overall height of the engine, but it would reduce the height at the outer edges.