Model sternwheel engines.

[Bill Hudson]

I  have been researching engines for my (some day to build) model of the City of Eugene stern wheeler (see my photos in photos section). I have the specification (12"x 60") of the engines in an early newspaper account of the launching.  I found a reprint of  the 1902  version of The Marine Iron works Of Chicago U.S.A. stern wheeler catalogue which also contains engines of the same specifications.  

 Although I am not a steam engine design engineer I tried to draw up and engine in 1/2" =1' scale.  I come up with 1/2' x 2 1/4" engines in scale.  Taking in consideration the hull size plus the engines I come up with a boiler size of 106.08 Square inches of heating surface minimum.    
My concern is the long stroke and the long length of steam travel from the boiler may cause the steam to cool and condense in the cylinders, even with superheated steam.  The boat will be equipped with condensers but  don't want the steam to condense  too soon.  

E.Westbury's stern wheeler engines are 5/8" x 1 3/4"  which are fairly close to my engine size.  I thought about using his engine plans but have a couple of concerns. First is that his stroke is quite short for stern wheeler operation.  I am concerned that it would be a problem to operate at slow speeds.   Second, his engines are not of the traditional stern wheeler design.  In all of my research I have not come across such engines with the steam chest mounted on the sides rather than on top  of the cylinder.  I am sure some one will prove me wrong but in my research (of U.S.A Western river boat engines I have only come across top mounted steam chests. The valve rod action is transfered to the side by rocker arm type gear.  I like the idea as it makes for a more visual engine.  I  think I will use Westbury's  basic engine  design but hybrid it with my engines using the longer stroke smaller bore .  Comments welcome.

Bill

[Eddy Matthews]

Perhaps Sandy from ACS Engineering would be the best to answer your questions Bill - I know he's pretty busy at the moment, so he hasn't been on the forum too much, but hopefully he'll see your message and reply?

I can see all sorts of problems with long steam lines from the boiler to the engine - About the only really succesful steam powered sternwheeler I've seen personally, used a dummy boiler at the front of the boat and the "real" boiler was mounted close to the engine under the superstructure. That isn't an ideal solution, but it may be something worth considering?

[Bill Hudson]

Bear with me this is on topic.   I needed an electric melting pot for my white metal casting equipment.  I built the pot to be heated by a 6" electric range surface element. It was not too efficient. It melted ok but was slow in recovery and I kept burning my hands on the side of the pot. At that time I was working as a draftsman for a blimp company. One division was  designing  large lighted signs to  go on the blimp envelope. The problem was heat transfer to the envelope and helium bags from the signs. To solve the problem they used a space industry ceramic wool insulation.  Looked like 3/4" thick cotton batting or waste but very efficient in blocking heat.  I can hold a sheet on my hand and not feel  the heat from a torch through it.  I took some home to wrap my pot. it brought the 600+ degree pot sides down to where I could hold my hand on it with out pulling it away. It also made the pot so efficient that I could control it via a  computerized Omron control unit.  I have some of this wool left over and plan on lagging my boiler with it. It cuts nicely with household shears so I am thinking of cutting 1/8" thin strips of the stuff and wrapping the steam lines with it much as was done on the regular boats.  I am thinking  of then wrapping  it all with the plaster gauze used to make casts or in model rail road scenery. Should look authentic.

Bill

[Eddy Matthews]

I think it may be a good idea to do some testing prior to fitting the whole lot into a boat Bill - Rig up the intended boiler and engine and run steamlines that are the same length as you'll need to use in the model, at least that will give you a good idea if it's going to work before you spend a lot of time and effort fitting everything to the model....

I wish I could be more help on this as the subject fascinates me, but sadly it's beyond my experience... Hopefully someone (Sandy?) will jump in and give some constructive advice?

[Bill Hudson]

Eddy,

I plan on doing just that.  In fact I plan on building the boiler, engines  and paddle wheel as one unit so  it can be removed from the boat for testing, maintenance  and exhibit.  My friend is building a drifter (sail/ steam). He is using the same boiler, I plan to build,  to run a 4 cylinder wobbler. The drifter is the same length as my paddler.  I figure I will have six to eight more inches of steam line to my engines than he has. Although his is not yet mounted in the boat it has run quite well on the bench.  His first boat, similar in size and using  the same boiler to run a two cylinder engine is one fine steaming vessel.   Just thinking out loud until some one kicks in with suggestions.     I have not heard of many (any) stern wheeler model boats with long stroke engines. Maybe it is a problem. I  have heard of using regular steam engines with gearing  to run the paddle wheel.  I am not fond of the idea of a false boiler plus the real one. I am concerned about my limited space for fuel, water, batteries and RC controls.

Bill

[derekwarner_decoy]

Hi PD's - &  I am too am eagerly waiting for Sandy to sit down & talk with us again :gather -   - I understand in principal we should keep our steam tube runs as short as possible, however we see many examples of French model marine steam plant & they all seem to use hard drawn brass tube over copper as it stays straight & polishes well - this is on operational vessels without loss of functionality but clearly with the resultant thermal loss

You made a  :post on the benefits of good quality insulation & this is clearly reinforced in the say 10 page document set that accompanied my boiler package full kit from ACS [boiler, burner, steam regulator, lubricator.......]

Being from the far off land of OZ & of humble convict Irish stock, I have been known on PD's to maketh a comment that was not QUITE correct, [but at least I can admit it ] - so from this I think the 7" longer HP tube runs will be of little consequence provided  adaquate insulation is provided & this may include insulation + wooden banding to the engine cylinder OD's  which was I think in keeping with the originals

So this only leaves the VEXING question of long cylinder stroke & low RPM    but after another cup of   my thought is..... if the bore to stroke ratio of a twin cylinder slide valve model engine is relative to the full size engine, then the model engine will work from rest & achieve & maintain LOW RPM...... a requirement may have something to do with rotational mass  :?:  :?: - Derek

[Bill Hudson]

Some where in my file cabinet or a book is a formula for figuring out areas of the steam passages for an engine and steam chest.  It would seem to me  that large passages would be necessary as the steam will be quite wet by time it is exhausted.  

Bill

[derekwarner_decoy]

Hi PD's  - just thinking  :idea: again Bill - can you get access to an SKF digital thermo pen or a digital laser pyrometer? - if so take your colleagues Drifter boiler, add 2" of silicone tube to the relief valve chimney vent tube, then add a 12" length of 5/32 brass tube.... more silicone....another 12" of 5/32 brass tube....fire up the boiler & initially leave the lengths of tube uncovered & check the tube temperatures from the chimney.. to first joint... then second joint etc

Depending on the temperature loss, try & wrap the brass tube lengths in tightly wound cotton string or & retake the temperatures

I did some similar tests on Decoys steam package some months back as I was concerned with potential overheat in the hull, however when I posted them over to ACS Engineering....Sandy came back with all OK - I will post a copy & a snap of the temperature recording method -

All of the calculations in this world can sometimes never convince me, however a simple practical test makes me   ......Derek

Oh BTW, if you are concerned about SOGGY steam at the cylinders, a steam dryer line in the final pass from the boiler will help............

[rayman]

Hello Bill Hudson and others, I have had first hand experience on a a live steam stern wheeler. She ran in New Zealand, was 230 ft. long, the steam run was about 170 ft. from boiler to engines in 3" lagged pipe suspended up under the deck-head. The engines were about 18"x60" stroke, wheel about 16' dia. x 18 or 20 ft. wide. ( bit of a guess here but I do have photo's.Exhaust drains were about 5ft. long and went straight overboard to get rid of condensate then swapped over to funnel discharge when running hot. Valve gear was Stevensons link with "D" valves, not like the rocking beam with pitman arms as used in the western rivers towboats. The boiler was a drum about 12ft dia. with center flue, double  fire doors and operating pressure 100. p.s.i. I think there were 18 floats on the wheel. regards  rayman

[rayman]

Hello Bill Hudson and others, I have had first hand experience on a a live steam stern wheeler. She ran in New Zealand, was 230 ft. long, the steam run was about 170 ft. from boiler to engines in 3" lagged pipe suspended up under the deck-head. The engines were about 18"x60" stroke, wheel about 16' dia. x 18 or 20 ft. wide. ( bit of a guess here but I do have photo's.Exhaust drains were about 5ft. long and went straight overboard to get rid of condensate then swapped over to funnel discharge when running hot. Valve gear was Stevensons link with "D" valves, not like the rocking beam with pitman arms as used in the western rivers towboats. The boiler was a drum about 12ft dia. with center flue, double  fire doors and operating pressure 100. p.s.i. I think there were 18 floats on the wheel. regards  rayman

[rayman]

Hello Bill Hudson and others, I have had first hand experience on a a live steam stern wheeler. She ran in New Zealand, was 230 ft. long, the steam run was about 170 ft. from boiler to engines in 3" lagged pipe suspended up under the deck-head. The engines were about 18"x60" stroke, wheel about 16' dia. x 18 or 20 ft. wide. ( bit of a guess here but I do have photo's.Exhaust drains were about 5ft. long and went straight overboard to get rid of condensate then swapped over to funnel discharge when running hot. Valve gear was Stevensons link with "D" valves, not like the rocking beam with pitman arms as used in the western rivers towboats. The boiler was a drum about 12ft dia. with center flue, double  fire doors and operating pressure 100. p.s.i. I think there were 18 floats on the wheel. regards  rayman

[Bill Hudson]

Hello rayman, thank you.

Hello rayman, thank you.

Hello rayman, thank you.

             :clap2

Bill

[sandy_ACS]

Hi PD's      :music

At last I have managed to sit down and do some post work.
I know our illustrious DW has informed you of my threatened post so here goes.

Things have been rather hectic here at ACS over the last few months with more than a few problems to contend with...1st I had the lathe bearings issue (now totaly resolved) which put me well behind schedule, this was followed, :x  :cry:  :cry:  :twisted:  :  at the end of May, by a total loss of the ACS computer system due to a nasty virus that somehow got past the firewall (probably attached to an e-mail) and virus scanner and totaly wrecked my hard drive.
(Reading the posts, it would appear that Eddy was also plagued by these things, fortunately not so severely).
The result has been a lot of extra  :computer work replacing the hard drive and operating system (yes that got scrambled also) followed by a lengthy excercise in recovering lost (licensed) software, including my web site authoring package, Paypal and other bank account access etc.
I now have an external 200Mb hard drive which is a clone of the main drive, this gets updated every week (incrementally).

Thankfully,      I have now recovered most of the important stuff relating to ACS business, however, I still have a fair bit of work to do recovering some of my other stuff.

Ok, enough of the sob story.....back to PD's stuff....  

1st off...engineman...how are things going with that lovely engine you made? you mentioned some issues with boiler pressure vessel paperwork  so if you need to discuss these then perhaps a direct e-mail would be appropriate.

2nd...I attach a lengthy (PDF) document aimed at Bill Hudson PD_1, which may help answer some of his issues regarding steam ports, condensation etc, however, since this is a very extensive subject I have left some of it for a second installment :twisted:  :twisted:  :wink:  :wink:

Interestingly..his questions are quite topical for me at this time, since I have obtained via a friend, an almost complete Dumas kit of the Creole Queen. Just the drive motors and a few minor parts missing.
Now I know the Creole Queen was not steam powered, however,
I am intending, over the next 18 months, to build this up with a few changes to be more like the Belle of Louisville, which was steam powered, complete with LONG STROKE  steam engines having Pitmans and Lever operated valve gear, complete with full California cutoff.....      :music ...should be fun.

Consequently, any drawings/plans of the Belle of Louiseville, or any of her sister ships would be very helpfull. I am particularly interested in the engines/boiler locations.

ok..enough already :nose  

Finally..for this post anyway..I also attach some photos of a recently finished SCOTT water tube boiler, which now resides in NZ.

This has a barrel length of 8" x 2 1/2" dia and is fitted with 17 water tubes and a superheater. It is rated for 75psi but has the safety set for 60psi as requested by the customer.
The white coloured stuff on the inside of the end plates is 2mm thick Kaowool insulation, the main outer wrapper is lagged inside with 8mm Kaowool.
The burner is 6" long x 2" wide and it will raise steam from cold (ambient) to 60 psi in just about 3 minutes max.


Ok PD's I will stop blowing my trumpet now//    :news  :yeah and get this posted.

More to follow soon....HONEST..I am getting an artical on steam generation sorted and also one on ceramic burners.

Regards to all    :respect2  

Sandy

[Eddy Matthews]

A fascinating PDF document Sandy, that I'm sure will be very useful to lots of our fellow PD'ers. My god this steam stuff is complicated! :-)

I hope you'll post your progress on the Belle of Louiseville once you get started - I've never seen a proper working steam powered sternwheeler, only one with a cobbled together inline twin oscillator.

Finally, if you could knock up a boiler, burner, condensor and triple expansion diagonal steamplant for me to evaluate (free of charge of course), I'll happily submit a totally unbiased report on your craftsmanship here on Paddleducks and in Model Boats and Marine Modelling magazines..... Can't say fairer than that now can I?  

[ky paddlewheeler]

good to hear some one modelling the B.of L. you dont see that to often its going to be tuff to change the C.Q. over. I plan on riding her soon so I might be able to get some pictures of it for you.