Author Topic: SS Xantho John Penn trunk engine  (Read 16268 times)

Offline Gippy

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Re: SS Xantho John Penn trunk engine
« Reply #15 on: January 16, 2014, 11:21:24 PM »
Big fan of John Penn.
Will be watching with interest.
thanks for thread.
Gippy

Offline Pedro

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Re: SS Xantho John Penn trunk engine
« Reply #16 on: January 17, 2014, 02:34:29 AM »
Wow folks I'm deeply impressed by the level of response. Thanks for all the posts. You found much better pics than I could find. I've been offline 'cos the hated Windows finally died but I've got a Linux now and wish I'd done it ages ago.
My interest in this engine was in fact sparked by Ericsson's monitor engines, and when I saw an engraving of Penn's was stricken by the elegance of it. (Also that it's within my capability to do a reasonable if not fantastic replica.) One major difference with the engravings of other Penn engines (of which I have one from *The Engineer* Dec24 1897) is the more substantial framing, which is perhaps due to the higher pressure or just scaling, it being small after all.
Drawings definitely did exist, so I'm having another try at the museum. It was 20 years ago, so maybe they're just not on the boil any more and need a little prompting.
There was also a Model Engineer article on the original and the model (3 June 1994). I'm currently waiting for it to arrive.
  Not surprisingly, sealing the trunks is reported as being an issue, and while it's no big deal on a model, I feel that modern ptfe rod seals should crack it for a working engine.
When I started looking I naively assumed that models of this type would be common, but so far it seems not.
Once again, many thanks and it looks like I' m not the only one feeling inspired!    Ps special thanks to PatJ
« Last Edit: January 17, 2014, 09:53:18 AM by Pedro »

Offline Pedro

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Re: SS Xantho John Penn trunk engine
« Reply #17 on: January 17, 2014, 09:22:36 AM »
I have a very good book on the history of the US steam navy up through WW1.   I know there are quite a few cuts of trunk guided engines like that, I can scan them.....if you're patient..... :ShakeHead:


Dave
    Thanks for the offer but I suspect the US engines are of Ericsson's monitor type, though they themselves seem not to have been modelled much, other than Rich Carlstedt's fabulous example.
« Last Edit: January 17, 2014, 09:26:12 AM by Pedro »

PatJ

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Re: SS Xantho John Penn trunk engine
« Reply #18 on: January 17, 2014, 12:29:08 PM »
Pedro

Thanks for pointing out this interesting bit of history.
Facinating engine and story that goes along with it.

I did a lot of research on the Monitor trunk engine a few years ago, and even started making a bar stock engine.
Then I got into 3D modeling and castings, and discarded what I had started.

I think Rich saw a model of the Monitor engine in a museum in the US, and then built his own model.
I got to see Rich's model and what a fabulous engine it is.
The detailing on that engine is extraordinary.
Rich is suppose to be working on a 3D model of that engine, and I have not persued the Monitor or Monadnock since any 3D model that Rich makes would be far more detailed, and he has talked of publishing plans some day.

If nothing else, I would like to rough out the geometry for this engine to get it to a functional stage.
I can do that fairly quickly with Solidworks.  The fine detailing would still have to be added, but at least the major parts of the engine could be assembled and run in simulation to know that it will work well.

Maybe if I get some time in the next few weeks I will look at it again.

Thanks again for bringing this engine to light.

Pat J

Offline steamer

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Re: SS Xantho John Penn trunk engine
« Reply #19 on: January 17, 2014, 01:13:56 PM »
I have a very good book on the history of the US steam navy up through WW1.   I know there are quite a few cuts of trunk guided engines like that, I can scan them.....if you're patient..... :ShakeHead:


Dave
    Thanks for the offer but I suspect the US engines are of Ericsson's monitor type, though they themselves seem not to have been modelled much, other than Rich Carlstedt's fabulous example.

I don't know about that.    The US was in its infancy steam wise....we copied or bought a lot of equipement .....right up into the early 1900's
I'll dig up this book over a brew this weekend..and see....but I have a race truck to prep first... :ShakeHead:

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline Pedro

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Re: SS Xantho John Penn trunk engine
« Reply #20 on: January 17, 2014, 03:25:53 PM »
PatJ, I'm delighted in the interest in the topic. My first enquiry was with the ME forum, and the lack of interest was resounding, other than a suggestion to try this site. I remain surprised that trunk engine models are so rare when there are loads of models of other types, particularly since it appears the design lends itself to machining from barstock by manual machines.
Assuming the reported 21"*11"*12" dimensions are true, 1/8 scale looks like a good choice, giving 2 5/8" bore and 1 3/8" trunk, so commercial seals should be available. Speaking of which, are they a bad idea? My pump background suggests that they should be fine. There is one type that is basically a standard O ring with a filled TFE working face bonded either to the ID or OD. (eg O.L.seals.dk) which look promising. Stainless for the piston is an obvious choice with such seals, and possibly even the cylinder. Any comments would be gratefully appreciated.
I'm still trying the museum. If nothing else, a few essential dimensions would make life easier. The photos show pistons with a noticeably greater axial dimension than the engravings do, which obviously reflects on the cylinder length. 

Steamer, on reflection I'm sure you're right, and may well turn up some gold. Thanks, and enjoy your truck!
« Last Edit: January 17, 2014, 03:30:10 PM by Pedro »

PatJ

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Re: SS Xantho John Penn trunk engine
« Reply #21 on: January 17, 2014, 04:40:03 PM »
When I first saw Rich's Monitor, I was really scratching my head about what was happening inside the engine.

I ignored the engine for about a year, and then curiousity got the best of me, and I had to figure out what was in there.

I started studying trunk engines, and found sections of a few.
I will try and find those and post them here.

Trunk engines vary in that you may have a single trunk or dual trunks on a single piston.

The Monitor engine seems to be somewhat unique in that it combines two single cylinders into a common cylinder with a cylinder head installed inside the engine at mid bore.  This creates a very compact two cylinder engine, with the drawback being that some rather cumberson levers are required to get the power from the ends of the cylinders back to the crankshaft.

But generally, I found almost nothing about how the Monitor worked.
I finally found a section of the engine on some obscure website, and then was able to work out the geometry for a working engine, and make the simulation for the Monadnock engine.

I was surprised that the Xantho engine had two trunks on each piston, since you could operate the engine with one trunk only, which is generally how most steam engines operate (with a piston connected to a rod, and the rod is on one side of the piston only).
I have seen some German engines and others that had the piston rod extended through the top cylinder head and into a guide, but generally that was not used on the majority of engines I have seen.

When it comes to design, I am new school; ie: I use solidworks for engine design, and find it to be an invaluable tool if used correctly.
When it comes to materials and construction, I am very old school, and I never use any material or fastener that would not have been used on the original engine.
So that means no cap head screws, no loctite, no modern materials like teflon or o-rings, and generally studs with nuts, or bolts, but the nuts and bolts have to have the same profile as the old ones, which is generally a taller head or nut.

And I use gray cast iron, and cast the engines myself, generally from hand made wood patterns, but I have used 3D prints for patterns in some cases.
I prefer a wood pattern most of the time unless the shape has a lot of compound curves in it, and wood is much cheaper than a good 3D print.
You have to be good at woodworking to make good wood patterns.

And for bearings, I like to pour babbitt.
I don't use modern bearings.

I make piston rings from cast iron.
Packing material is a rope like material and it does sometimes have some sort of teflon in it, but that is not necessary, but probably works a little better, and is undetectable.

My interest is in small workshop engines generally in the 1/2 hp range, designed to work under load continously and indefinitely.
Models don't interest me as much because they require a lot more skill to make, and are very tedious to detail with their small and intricate parts.

I greatly admire those who make models, but I don't have enough patience or skill to do a good job with them.
My determination for engine size is made by taking the smallest screw on the engine, and dropping it on the floor, letting it roll under the workbench.
If I can find it again easily, then the engine is the right size for me.

Below are some engravings I have.
I am not sure if all of them are trunk engines or not, but I will post what I have.

PatJ

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Re: SS Xantho John Penn trunk engine
« Reply #22 on: January 17, 2014, 04:44:04 PM »
A few more engravings.

PatJ

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Re: SS Xantho John Penn trunk engine
« Reply #23 on: January 17, 2014, 04:44:38 PM »
And a sketch I drew.

Offline smfr

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Re: SS Xantho John Penn trunk engine
« Reply #24 on: January 17, 2014, 05:06:53 PM »
My determination for engine size is made by taking the smallest screw on the engine, and dropping it on the floor, letting it roll under the workbench.
If I can find it again easily, then the engine is the right size for me.

 :ROFL: I like that, Pat!

Some very intersting engines here, and thanks for doing the research and posting the pictures. I'm following along!

Simon

Offline Pedro

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Re: SS Xantho John Penn trunk engine
« Reply #25 on: January 17, 2014, 08:06:55 PM »
I second smfr. interestingly, a few engines in those engravings are of the back-acting crosshead type, of which Maudslay supplied the other half of the Crimean gunboat order.
Re single trunk engines, they have two obvious design weaknesses. Firstly they are not guided well on full extension, which must cause them to rock a little, putting strain on the packing and sliding surfaces. I believe I saw somewhere a reference to this regarding Ericsson engines, but I'm not sure.
The other issue is uneven power pulses, which can induce unwanted torsional vibrations. I don't know if that is any more than  theoretical. Ericsson's design reduces this greatly.
Pat, I'm with you on fasteners and external appearance, and understand the argument for traditional materials. I'm undecided, on the subject, but leaning towards more modern internals depending on the likely use, which admittedly will be little.

PatJ

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Re: SS Xantho John Penn trunk engine
« Reply #26 on: January 17, 2014, 10:08:16 PM »
With a single trunk, and with a trunk that large, there would be a difference in pressure on the piston comparing the trunk side to the non-trunk side.

This may have been compensated for to some extent with the valve gear, but there would still be uneven power strokes on the in and out stroke most likely.

Probably not a big problem at low rpm.

Offline tvoght

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Re: SS Xantho John Penn trunk engine
« Reply #27 on: January 18, 2014, 01:01:27 AM »
Regarding back-acting engines, the engine of the former gunboat USS Ranger is claimed to be the last in existence and is apparently on exhibit at the American Merchant Marine Museum in Kings Point, New York.

This page contains a link to a downloadable brochure with illustrations:

https://www.asme.org/about-asme/who-we-are/engineering-history/landmarks/112-tv-emery-rice-steam-engine

--Tim

Offline peatoluser

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Re: SS Xantho John Penn trunk engine
« Reply #28 on: January 18, 2014, 01:24:22 AM »
If you look at about the 4 min. mark on this youtube clip, there's a good selection of horizontal engines


you can recognize some of the ones in PatJ's engravings

...and come early march I hope to be in London, so I think I know where I'll be going for a visit!

peter

Offline Pedro

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Re: SS Xantho John Penn trunk engine
« Reply #29 on: January 18, 2014, 06:38:29 PM »
That's a fine exhibition. Time I took another look at it too. When I last went some 20 years ago they had totally reorganised and lost the plot by trying to be "relevant". The entire manufacturing technology section had disappeared, the Industrial Revolution erased from history with the vacated space turned into a kid's play area.  I mentioned it to a long serving curator who shook his head sadly and mumbled something about new management.

 I've had a friendly reply from the WA museum saying the relevant person is away, but back in a few days. I'm still waiting for the Model Engineer with the Xantho article to arrive. Does copyright law allow me to post photos from it or will I get the forum in trouble?