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[malcolmbeak]

Kno3 you wanted to know about this plant. The red oil trap has already been explained.
First I should explain that this boat was designed to compete in a 24 hour scale sail many years ago.

The large tube at the top is in fact a brass tube and a glass one clamped end to end. The glass tube has a smaller id than the brass one. A double ended piston runs inside them. You can just see the piston rod and the small end inside the glass tube. On the left of the piston you can see that the tube is filled with oil.  If equal pressure is applied to both ends, the piston moves towards the glass end. The brass end is connected to the boiler, and the glass end to the regulator, both through needle valves. At either end is a shut off valve – the hex brass bit seen at the end of the brass tube. You can also see a small vertical pipe; there is a similar one at the other end. With the needle valves shut and the shut off valves open, the lubricator is isolated from the boiler pressure and oil pumped in through the vertical pipe at the oil end, pushing the piston back and emptying condensate from the steam end. It was all made this way so that the oil could be replenished with the boiler at full pressure. In fact the lubricator allows several hours running before it has to be refilled.. I have gor a sketch/drawing somewhere, but can't lay my hands on it. If you really want to see it, I'll try and find it.

The light alloy block to the left of the trap is a combined gas regulator and attenuator – as the boiler pressure comes up, the gas flow is reduced. I see that you are also on the Paddleducks forum. If you go to the downloads/members submissions. Page 3 you will find an article about it.

The engine is not the same one I used in the 24 hour event – that one had no reverse. This one has a rather unusual valve gear. I first came across it in one of Basil Harley's articles. It was fitted to an engine made by a Mr. Lieber of New York. I've since been told that it bears a close resemblance to a Mumford gear. The pictures hopefully show how it works. With a gear on both the crankshaft and the eccentric shaft, a frame above them carries two more gears that can be swung from side to side which alters the relationship of the crank and eccentric shafts giving forward and reverse. This needed rather too much power for a normal servo to operate reliably, so a steam cylinder and double acting piston is used together with an easily operated valve thus allowing forward and reverse to be easily selected. Works well Full ahead to full astern instantly! A feed pump is driven directly off the crankshaft. Not shown in the engine shots although the drive pin is in position..

Just to the right of the oil trap can be seen the pump valve chest. Feed is from the top, across the trap and into a full flow by-pass valve. The brass lever lying almost horizontal should be vertical, and operates this valve. The lever is worked by a servo that is connected to the automatic water level control system. See Paddleducks download section as above.

Malcolm

[kno3]

Thanks for the explanation, you have a very cool steam plant.

The valve gear seems very similar to what Cheddar used on their Gemini and Proteus engines. Quite ingenious. I wonder why nobody makes them nowadays.
Do you have a plan for the engine?

[MONAHAN STEAM MODELS]

Neat steam plant!

Thanks for sharing.

[malcolmbeak]

Yes - the valve gear is very like what Chedder used - I seem to remember John Woodruff having a long colse look at my engine!
The engine was originally designed in 1983 and had Hackworth reversing gear, but this was not a success and it was modified to how you see it now. Although I made drawings for it in it's first form, the mods were merely sketches, some of which I don't seem to have any more. I'll post them here if you really want them, but it will be some days before I can sort out and draw the missing parts.

I've found the drawing for the large lubricator - see below
Malcolm

[PT Sideshow]

very ,very neat power plant yes please post the drawings when you find them.

[bogstandard]

That is a wonderfully compact engine Malcolm. Whenever I get to try to design something like that, mine come out twice as large, maybe it is because I think of trying to get my pork sausage fingers in to tighten everything up. I have trouble with fiddly things.

Were the castings your own, or could it be easiy made from solid?

John

[malcolmbeak]

Thanks for the kind words guys.
John - there are only two castings, we used to have a wonderful chap at work who made splendid models for our wind tunnels, engineering in wood I guess. Prior to that he had been a patten make. Luckily I was good friends with him and he made the pattens for this engine (amongst others}. I still have a pair of castings and the pattens. The main problem seems to be finding a decent foundry close to me (St.Albans) who are prepared to take on small jobs. Should you wish to borrow the pattens and/or have the castings you would be very welcome.
Obviously, castings aren't essential, just rather a waste of material.
The photos show the two items for the 5/8" twin and the four items for a similar 1/2" twin.
Drawings/sketches to follow in a few days - watch this space.
Malcolm

[bogstandard]

Malcolm,

Your offer is very kind, but I must decline, the amount of work that I have planned will mean I hope they have lathes and millers inside the pearly gates.

I have been unloading all my projects I will never get around to, let someone else have the enjoyment from them.
 
I asked because I always like to see how other people get around problems, and blatantly pinch their ideas.

Just to diversify slightly on getting castings made.
Twenty or so years ago, there were small casting shops and foundries everywhere within easy striking distance, unfortunatley now, all sadly gone. The ones that do survive are very reluctant to do one off jobs at a reasonable price, they have to make a living out of it, whereas before there was always an apprentice or slack time at the end of a job to get one offs made, nowadays everything is geared towards keeping the foundry a viable proposition. Hence the high cost of anything with castings in the build.
We used to have a massive foundry in Crewe, that cast the rolls for steel rolling mills, they were cast by digging deep holes into the 'basement' and cast standing up on end. Sadly that has now closed, along with the source of getting my castings done by a friend who used to work there.

I am looking forwards to your plans and sketches.

John

[malcolmbeak]

John
I sort of guessed that might be your reply - never mind - if you ever do change your mind just ask.
Have to rush now as I'm being picked up shortly to go to the Midlands Model Boat Show.
Malcolm

[kiwimodeller]

Malcolm, did you ever go back to the flash boiler you originally planned to use with this? Having read the original article I was always keen to try a flash boiler, not for speed but just instead of a heavy great boiler in a cruising boat. If we can sort out the freight I will order a 50" Pickett boat from Models by Design and I have a Rayman single engine and a nice big variable pitch prop to play with. I am not up to playing with fancy electronics as per some of the recent discussion on flash steam but for a long time I had toyed with the idea of using an electric water pump (car washer pump or similar) with a speed controller to vary the water delivery. It seems that no-one has yet solved the problems of drawing gas out of cannisters rapidly although my idea of two cannisters in tandem helped and I am sure your regulator would even that out more. Any comments or suggestions most welcome even if it is just to tell me I am dreaming! Thanks, Ian.

[malcolmbeak]

Ian V
To answer your first question, no I didn't progress with the flash boiler for the picket boat. The coil was wound in a figure 8 configuration, and I made a twin poker type burner for it.  For insulation, I carved something out of firebrick and surrounded the whole lot with a sheet steel casing. It all ended up surprisingly heavy. At this time, I was told about work done by someone on fitting a probe in his loco boiler in order to light up a couple of LEDs indicating high and low water levels so he could see what was happening when running at night. Now I'm not into electronics, but I did realise that if you could light a LED, you could do all sorts of things. Discussing this with Roy Verden (whom I believe you have been in contact with)  He designed a system for operating a servo that would open and close a by-pass valve using a single sensor in the boiler. So the flash boiler was abandoned and replaced with a return flue one.  Surprisingly, this weighed about the same as the flash setup.
Moving on, as you are only interested in running at relatively low pressure, the following may be of interest. Before building the picket boat, I had a model of the Victorian steam yacht "Greta". This was 44" long with a 5" beam and weighing around 15lbs. Over it's life it had about four different boilers and six different engines. One of the most successful combinations was with a flash boiler and V twin oscillator. But in addition to the flash coil, a steam drum was mounted above the coil. Unfortunately I've no photos. As far as I can remember, the coil was about 10ft of thin wall 1/8" stainless tube wound round a ¾" former giving a coil some five or six inches long. This was curved upwards at the outlet end, and fed into a copper drum one inch diameter and around four inches long. This drum was purely a steam reservoir and retained pressure well enough for the engine to be stopped for up to 30 seconds or so. It was fitted with a safety valve set at 30psi. The engine was a ½" bore and stroke V twin oscillator with feed pump driven at 1/3 engine speed. The large gear had a range of tapped holes in it so that the pump stroke could be altered. Firing was with a gas blowlamp. Propane rather than one of the butane mixes.
This all worked quite well. With any change in throttle setting, the amount of water pumped in obviously varied, the only downside was that the burner was always at the same setting.  The coils got very hot with the engine stopped, but this did not seem to be a problem.
Hope this is of interest
Regards Malcolm

[kiwimodeller]

Malcolm, it is all of interest, ever since I found out what flash steam was I had wanted to try it, not in a race boat but just in a launch that was using water from the lake if possible. I have read and partly understood most of the postings about it over the last couple of years, collected the Westbury book and the Model Boats article (Ooyah). Phil is trying to get me a copy of the Rayman and ? book when they do a reprint so every little bit of info helps to fill in the gaps and the idea of a steam reservoir makes sense. I have taken fron Ian G's postings that it is possible to leave the flame constant, dispense with a throttle and just control engine output by controlling the water flow to the boiler. If I am correct then my plan when I get around to playing is to use an electrically driven water water pump (in an 80" hull I have plenty of room for a SLA battery etc) controlled by a speed controller. He is doing it all with fancy electronics which would be great if I understood how but I am hopeful that it will work with manual control. It may be that I have to go away from gas to parrafin or petrol but again I have room for more than one large gas cannisters which seems to help with the gas pressure variation due to cooling problem. It might be that I can find a simple way to turn the flame up at the same time as I increase the water supply. If it does not work I will have lost nothing except some time that I will enjoy putting in to the experiment. Cheers, Ian.