Sternwheeler steam engine

[derekwarner_decoy]

Hi PD's....& a welcome Pentti.....the engine in the video "King of the River" essentially is a single twin cylinder oscillator engine...but with each cylinder & steam distribution column or plate section mounted remotely from each other  ....most oscillators have the two cylinders mounted on either side of the common distribution column

This example engine has great potential for 'Rod Buckling'...in that the rod is not supported between the cylinder headcap gland & the wheel - most acceptable designs  have a composite guiding element [bronze on steel] to maintain the longitudinal reciprocal motion ...so eliminates such off axis loading on the cylinder gland bush

From this the stern wheel shaft is also of one piece construction but mechanically linked back to each cylinder ...in many cases both cylinder assemblies were mounted on a common base plate thus ensuring accuracy in the placement of major component's

With respect to the timing of the cranks......you may need to research this further....however I did notice that the Delta Queen appears to have the cranks approx 30 degrees out of phase....this is so the engine does not suffer from a dead spot where it could not self start

When you think about the geometry ...if the cranks were 180 degrees out of phase...or anywhere between 90 & 180 degrees the potential exists for a non starting engine ....I am sure some of our PD stern wheeler members will offer comment

I am not aware of any true model steam twin cylinder stern wheel engine kits, nor completed engines etc.... ...Derek

[pentti]

thanks for the info Derek

one more question... Is there a single twin cylinder ocillator engine out there that I could modify to use on a sternwheel?  I don't think I am capable of scratch building an engine or boiler.

Pentti

[derekwarner_decoy]

Hi PD's ...& yes Pentti...the following is one of many informative threads by our PD members world wide...I looked at 2 CC oscillators from different manufacturers and commented as below

http://www.paddleducks.co.uk/smf/index.php?topic=3516.0 .....I think this will be self explanatory

I have a French manufactured horizontal 3 CC steam engine [totally different] ....but my vote with the 2 CC oscillator went elsewhere


If you search PD's & other WEB pages..... ...you will certainly find examples where a twin cylinder close coupled oscillator has been used for both stern & sidewheel models...& you have indicated you can solder    a few bits of brass togther ..so all of the wheel cranks & drive shaft components can be manufactured with a drill press & simple hand or electric tools

Gearing down an oscillator will be a challange but can certainly be achieved...again plenty of examples here...search on PT Reliant ...and spend some reading in our PD's  electronic pages ...you won't regret it.....Derek

[pentti]

Thanks Derek.

Pentti

[mjt60a]

....I am not aware of any true model steam twin cylinder stern wheel engine kits, nor completed engines.....

It looks like someone has tried making one! seems to be running on compressed air here - and looks like there is a 'dead spot' where only centrifugal force (and no load) keeps it turning.....
http://uk.youtube.com/watch?v=p0OmPBQMUXU&feature=related

[Dave_Sohlstrom]

Because of the long stroke and steam cut off mid stroke you get that effect when running on air because of no expansion. If it were running on steam it would be smooth.

I will be casting and building the steam engine for a model of the steam stern wheel tug Portland. engine is going to have bore of .813" and stroke of 3.375". Model will be close to 7 feet long. Will be a long project just getting started.

I was able to get on board the Portland on Monday while she is in dry dock and got lots more pictures and a set of engine plans 

The video posted is the only one I have seen of a steam engine for a stern wheeler.

If you do a search for Portland here you will find pictures of the Portland  that Bill Hudson and I have posted here.

Dave

[kno3]

I don't know the King of the River you were talking about (is it here in another topic?) but there's something about oscillating cylinders that makes them more difficult to modify, should one want to drive a sternwheel directly (not through belts or intermediary links):
The oscillating cylinder needs to move on a set angle to be able to open and close the intake/exhaust ports. That means that if you ant to increase the length of the piston rod, to connect it directly to the sternwheel, you also need to increase the crank arm, to preserve the same angle of movement for the cylinder. This is only doable to a limited extent.

With a slide fixed cylinder engine you don't have this problem, as you can increase the length of the con rod without needing to modify the crankshaft.

[mjt60a]

Because of the long stroke and steam cut off mid stroke you get that effect when running on air because of no expansion. If it were running on steam it would be smooth.

Ah yes, hadn't thought of that, makes sense....
....that's the only live steam sternwheeler engine model I've ever seen too!

[pentti]

What was the usual engine setup on full size sternwheelers?

[derekwarner_decoy]

Hi PD's..... ....yes this was the design method of placing each cylinder axis in line with the pushrod cranks....however photographic evidence in our PD files is clearly limited

My call on this is even if the cylinders were say 25 foot apart....they were part of one singular engine

In OZ...we had some snaps of a model which displayed such construction...'Surrey Park Model Boat Club' ...Peter Webster is our member...but I cannot find the WEB site example........................Derek

Oh BTW...the Coffee is just for Gerald & John......

[Eddy Matthews]

Kno3, the "King of the River" video that was referred to earlier can be found here: http://www.paddleducks.co.uk/index.php?ind=downloads&op=entry_view&iden=757

The engine was made by one of my fellow clubmates, Chris Barnbrook, and it's running on compressed air in this clip..

Regards
Eddy

[kno3]

Thanks.