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[davep]

Hi all,
I've developed an interest in model steam engines since retiring from a career in mechanical engineering a few years ago and have built a very simple single acting twin cylinder engine with Corliss valvegear mainly from offcuts found around my workshop. It seems to run ok on compressed air but now needs a boiler and control system to drive it properly.
I found this forum whilst researching what type of construct, this has led me (rightly or wrongly) toward a flash or semi flash type and found the posts from SteamboatPhil really intering and informative.
I would be interested to hear from anyone who has information about starting a project such as this.
 
 

[flashtwo]

Hi Dave,

There are several types of flash (monotube) steam applied to model boating:
a)      The tethered hydroplanes as described on the website http://www.onthewire.co.uk/
b)      The straight runners as per Steamboatphil and others.
c)      The monotube boiler with automatic controls.

Both the hydroplanes and straight runners use conventional manually adjusted controls, such as fuel and feed flow, and are only suitable for running for seconds or a few minutes respectively. That is not a criticism, but only a description for what can be a very exciting application. Both have been used successfully for the best part of a hundred years.

The biggest danger of the above systems is the application of very extreme steam conditions to an engine – ordinary engines are unlikely to survive very long.

To get a performance for more leisurely craft and operating times in excess of an hour or more, automatic control of the feed and fuel flows is required. With the advent of computer technology this has become possible as I have describe in the long running thread on this website regarding “flash steam plant control”.

In the February and March 2012 editions of the “Engineering in Miniature” magazine, I have described a method of automatically controlling flash, or monotube boilers. I have written the article from first principles with the aim of saving people a couple of years in developing their own system.

In a nutshell – the monotube boiler is the cheapest (£50) and simplest to make (an hour to wind the coil), but on the downside need automatic controls for conventional model boat applications.

I have been running my monotube boiler on an experimental boat for four years now and have recently started the construction of  a 75 inch Edwardian steam launch to transfer the monotube steam plant into.

I admire the fact that you have built an engine with the Corliss valve gear, not the most simplest to construct I’m sure.

Ian

[davep]

Hi Ian,
Thanks for the prompt reply I'll read through it all thoroughly in due course, I've not really thought about the type of boat yet but would probably prefer it to run fairly sedately and for some time.
It sounds like I need to learn a bit about programming some form of micro computer, but that all adds to the interest.
 
Dave.