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[DBS88]

While I was looking through photos and video of the Proteus Steam Plant I realised it would be helpful to share this video of the first Proteus Steam plant with the Cheddar ABC with the Dénes replacement sight glass sensor. Its about 3 1/2 minutes but it shows the engine running at a higher speed with the gas valve opening to full and then shutting down to pilot as it maintains the pressure at around about 60psi. It also shows the servo controlled water valve opening and closing to keep the boiler topped up with water. The pump is running continuously either to fill the boiler or to pump water in a loop to and from the glass jar. This is an early video where I am experimenting and you will notice that the original Cheddar ABC sensor is still in place, but not connected. This test confirmed it was the Cheddar sensor not working rather than an issue with the electronics. https://youtu.be/cDypu_L4PGM


You will hear the engines revs increase when the water valve sends water round the by pass and also hear the boiler going on and off and see the lights flashing on the ABC unit. The engine is running at about half speed and you will hear the rpm vary as the pressure goes up and down in response to the gas valve operation and the land put on the engine by the water pump over the boiler pressure which is at 4 bar 60psi to fill the boiler. This shows how the electronic controls can be used to keep the engine and boiler performing at a high level.

[KNO3]

Very informative videos, thanks!

[KBIO]

As per the  book ! 
You are proving that electronic can be a good help when used properly.

[DBS88]

Thank you for your messages and encouragement. Its time to look at the pressure/temperature sensor. This sensor fits in the top of the boiler, usually in the steam dome, sometimes they are placed in the top of the sight glass fitting, but they can be in any of the convenient bushes in the boiler. Whilst the sensor is called a pressure sensor, it actually measures the temperature, for example at 6 bar or 90 psi the water temperature will be approx 160C. So the sensor tells the black box of electronics the temperature and it then black box knows what the pressure is.


Now I am not an electrician or versed in the dark arts of electronics, but I do own a multimeter. What has come to light during testing is that the original Cheddar Sensor has a resistance value of 120. The Stuart sensor for the gas controls mentioned earlier also has a resistance value of 120. Their wires are black and white. The Cheddar replacement sensors available to purchase online have a different resistance value of 540, its wires are orange.


The difference in resistance affects the the way the Control unit read the pressure when used with the old Cheddar and with the Stuart sensor. The maximum pressures were lower, in the region of 30psi. When used with the replacement Cheddar sensor the normal range of pressure adjustment was achieved. I believe the Dénes ABC will now work with either of these sensors and that Dénes now supplies his own sensors to ensure the sensor works with the ABC, one of which can be seen installed in the steam dome of the Proteus boiler.

[Dainesh]

Dear Gents,


As Dave mentioned above the Pressure sensor is measuring temperature originally.
The steam inside the boiler is called super heat steam, which means that the steam temperature is above the boiling point (normally 100 degC), but because the size of the boiler hasn't change the boiling point will be higher and higher as the temperature is raising.

If you interested in a bit deeper please read pages like:
https://en.wikipedia.org/wiki/Gas_laws
I would highlight the Combined gas law.


Satureted steam pressure by temperature (this is how I set the pressure according to the temperature):
https://www.tlv.com/global/TI/calculator/steam-table-pressure.html


Here is my short video about the sensor:
https://www.youtube.com/watch?v=PPN9Z0fumv8&ab_channel=DesignDenes


The problem of the different pressure/temperature sensor is the difference in their curve. In the case of Denes Design pressure sensor I use an NTC (Negative Temperature Coefficient).

As you can see it is not linear, it is exponential, to decoding the measure value I had to use the extended Steinhart-Hart equation, which I wrote into the firmware.
The problem is that each NTC sensor families has their own parameters, if these parameters are close to each other the counted values will be really close to each other and the tempreture/pressure sensors are compatible with each other, in any other case not.
Please check that you are using the right pressure sensor, for the right unit.

[Dainesh]

So sorry I missed the curve

[DBS88]

Having spoken about the pressure/temperature sensor we may as well have a look the gas valves that they are controlling via the electronics.

• The first gas valve is a simple servo controlled valve that the servo moves from a pilot setting to full on, then when the desired pressure is reached the servo returns the valve back to the pilot setting. Simple but a bit fiddly to set up the pilot setting.
• Another valve is the Cheddar/Stuart gas valve, this one came with the Proteus Steam Plant. It has the addition of a screw adjustment for the pilot light, the servo then opens the valve up from pilot to full and back again when the desired pressure is reached. The advantage of this valve is the ease of setting the pilot light, and then later adjusting it up or down a bit, so in winter when the gas is not working so well you might increase the pilot setting a bit to be confident that it is strong enough to remain lit as the gas pressure drops. It is still available to purchase from Stuarts.
• Regner also make a very neat servo controlled valve which I have not yet tried but it will be going into the Bustler Tug soon so we can find out together how it performs.

Next there are options for controlling the valves, we have spoken about the Cheddar ABC and have started talking about the Dénes ABC, both of which will control the above gas valves, moving them from pilot to full on when the pressure in the boiler drops and shutting them down to the pilot when the desired pressure is reached.


There is also an option from Stuart that will control the above gas valves, moving them from pilot to full on when the pressure in the boiler drops and shutting them down to the pilot when the desired pressure is reached.


Then there is an option from Dénes that really is a bit of a game changer. Its has some clever and useful additions. The first is the use of a dial that moves the servo that allows a very quick and simple set up of the pilot light and then later adjustment if needed.  The next is that rather than turning the gas on to full and or pilot, it cleverly monitors the boilers pressure, and, as the desired pressure is approached, it starts to turn the flame down in increments until the desired pressure is reached. It then monitors and maintains the boiler pressure by opening the valve just a small amount, again in increments, it continuously does this. The result is that when running the engine rpm will remain rock steady, also and more important, because its using gas in small amounts rather than full on, it will help reduce the gas cooling that occurs when gas is drawn quickly from the tank. This unit behaves in the same way as mechanical attenuator, but without the issues attenuators suffer from with the membranes, springs and variations in gas pressure.

[DBS88]

Here are a couple of videos that I took during late December of the Dénes Gas Control Unit. It was during an earlier test that the issue with the pressure sensors came to light. The sensor being used in the boiler, for the videos is the one with 540 resistance that is available on line


The first shows the setting of the pilot light, then the start up and finally the burner on full gas.
  https://youtu.be/ACWF3svmx_8

The second shows the GCU controlling the gas supply to the fast running proteus engine that is pumping water into the boiler as required and round the bypass when its not. What you will notice as the unit constantly monitors the boiler pressure, the gas servo moves in small incremental movements as it keeps the boiler pressure really steady at 60psi, you can tell its doing this because the engine rpm hardly waivers. If you compare this to the Cheddar ABC control of the boiler pressure in an earlier video, which was good, you will notice the control achieved with this unit is even better.
https://youtu.be/_R2GHkaP1vM           
In the video you notice that there are two pressure sensors in the boiler steam dome, the one on the top is the replacement, you will see its orange wires in the GCU. The other sensor was the original Cheddar which only allowed the GCU to reach 30psi.
When the blue gas indicator light is flashing its maintaining the boiler pressure.

[KNO3]

I'm curious about the Regner servo gas valve. Does it do the same as the Cheddar unit?

[DBS88]

KNO3 re the Regner gas valve, I initially purchased it because I wanted the ability, via radio control, to cut the gas supply off totally from the lakeside, this unit will do that. The ability to have a kill switch function for the gas is something I am keen on, I have seen experienced steamers have their boilers running dry and black smoke rising from a steam model is something no one wants to see. I have seen steam boats get caught in the weed and overhanging branches and I have seen steam boats when the flame has gone out but gas is still on. No one wants or expects these things to happen but they do.


The ability to kill the gas from the Bankside is something that I have experimented with and have installed in two of my boats. Here is a photo of the set up that is installed in HMS Daring my Torpedo Boat Destroyer. If you follow the gas line from the gas tank it goes to a 90 degree on/off rc controlled gas valve, this is purely an on/off via channel 5 on the rc transmitters two position switch, it provides the kill function. The gas then goes to a mechanical attenuator to control the gas turning the supply down to a pilot flame when the desired boiler pressure is reached, the gas then goes to the burner.


My plans are to experiment further with some different the gas installations in this Bustler Tug, one will use the simple gas valve, another will use the Regner, but they will all be controlled by the electronic boiler controls. For the Regner valve, there are a number of suggested ways of using the valve, here are the instructions, with a note of caution they have been translated using a translator as suggested by a fellow Mayhemer, thank you, so may not be entirely accurate.


REGNER Operating options: - Without RC operation - With RC operation and emergency flame - With RC operation and emergency stop The normal gas tap must continue to be used, since the RC tap should only be used for regulation, the final gas shut-off always with the gas tap 50811 ! Without RC: Servo is at zero. The flame is adjusted with the handwheel, as usual. With RC/emergency flame: Servo is at zero, handwheel is set to emergency flame. Then control via the servo. With RC/emergency stop: servo is opened to fire. handwheel to zero. The flame goes out when the servo is closed. (Addition: The trim is set a little higher so that the flame does not accidentally crackle during operation. The flame catches on zero setting plus trim)

[DBS88]

Over the festive season I spent some time experimenting with the first Proteus steam plant and installed the Dénes Automatic Boiler Controller to see how it worked. The sight glass sensor with the Dénes ABC has four wires rather than the three wires with the Cheddar Replacement sensor and it needs either the pressure sensor available on line with a resistance of 540, or the Dénes pressure sensor. Rather than me trying to explain what the ABC does here is a link to a video where Dénes explains how it works. https://youtu.be/C69xPz-z6Lk


That will leave me free to share with you how I have found it to be both on the workbench and on the water in the Bustler Tug

[KNO3]

Thanks for the explanation!

[steamyjim]

The next is that rather than turning the gas on to full and or pilot, it cleverly monitors the boilers pressure, and, as the desired pressure is approached, it starts to turn the flame down in increments until the desired pressure is reached. It then monitors and maintains the boiler pressure by opening the valve just a small amount, again in increments, it continuously does this. The result is that when running the engine rpm will remain rock steady, also and more important, because its using gas in small amounts rather than full on, it will help reduce the gas cooling that occurs when gas is drawn quickly from the tank. This unit behaves in the same way as mechanical attenuator, but without the issues attenuators suffer from with the membranes, springs and variations in gas pressure.

Interesting that you say a mechanical attenuator works in that manner. I am using a Bix attenuator in my steam powered gramophone (Puffin engine and Proteus horizontal boiler) as the main speed control system. The Bix gas valve alternates between a pilot and full flow, and although it works reasonably well there is room for improvement (I'm expecting more of it than it is designed for I appreciate).


Do I understand correctly that a Cheddar mechanical gas attenuator has a variable gas flow setting Vs operating as per the Bix version? I feel one of these may improve my speed control if so. I want to avoid having electronics in the gramophone.

[DBS88]

Steamyjim, I have looked at your videos, its a very interesting project in which you have achieved a lovely item. I think you will be able to control and achieve a constant engine speed far better with something like a flyable regulator. Installing one will add to the mechanical beauty of what you have already created, it works by directly regulating the amount of steam to the engine and hence its rpm.


The attenuator is not directly controlling the amount of steam, its reacting to the boilers pressure, it has a tolerance, so the boiler pressure will always vary by a few psi, and therefore so will the amount of steam produced, hence the rpm fluctuating. Your engine has a maximum operating pressure of about 3bar.


The attenuators are not on off devices, and they all work in the same way. As the steam pressure rises, the steam pushes on a diaphram, the pressure the steam has to overcome is controlled by a spring on the other side of the diaphram, so 3 bar, because its pushing against a spring and moving a diaphram, the movement is gradual. As a result it gradually reduces the flow of gas down to the pilot light setting at in our case 3 bar. As the boiler pressure drops the spring allows the diaphram to move and more gas flows to increase the boilers pressure again.


The springs get tired or set in position, the diaphrams split and perish. Here is one of mine that I have had issues with.

[steamyjim]

DBS88 - thankyou for the reply. I appreciate I'm attempting to control the speed in a slightly backwards manner (in so much as it isn't based in feedback from the engine) but it is simple and works 'well enough' shall we say. In always looking for improvements and have the original gramophone friction governor that I'm planning to add back in to the mechanism at some point, however from my experiments so far it's not actually helped the control at all, I need to have another tinker. The issue with small steam engine governors is they require a lot of finesse in their manufacturing to get anything like sensible performance. The chaps building large scale miniature traction engines have issues enough with governors at 1/3 full size let alone in the size I'd need to put in here. I do think it an avenue worth investigating however.


It appears that the Bix (Forest Classics) attenuator is a 'binary' system as such in that it cycles between a full flow and a pre-set pilot state (much like the old Cheddar EGV) - I'm basing this on the notes on the Bix instructions and the sound from the burner (there is a step change in the burner 'roar' not a gradual increase/decrease). From what you are saying it appears that this is not the norm for attenuators and I reckon that it is worth experimenting with fitting an old Cheddar unit before I get too involved in further, more in depth modifications.


A link to the Bix unit:


https://www.forest-classics.co.uk/ceramic-burners/gas-essentials-and-jets/automatic-boiler-pressure-regulator-bix-029


I'm not aiming for total perfection with the speed - when I was developing it I was aiming that it would play one record reasonably well. As it has ended up you can leave it running for several hours with only occasional tweaks to the water feed bypass or engine speed so I consider that a success. There is always room for improvement however!


I don't want to distract from your thread so happy if you'd rather PM me in response to this.

[DBS88]

Having decided to put the Proteus Steam Plant into the Bustler Class Tug, I needed to prepare the hull, full details of the work to the exterior of the hull are here on Mayhem https://www.modelboatmayhem.co.uk/forum/index.php/topic,67980.0.html
Here a couple of photos, I had strip the hull below the water line back to virtually bare metal and used an angle grinder to cut out rusty sections of the steel plating. The hull below the water line was repaired and sealed using thin fibre glass matting and epoxy resin. The outcome is added strength, it no longer leaks and best of all the craftsmanship that went into creating this hull with so many individually cut and shaped steel plates that have been soldered together to form the hull, is still visible for all to see. The third photo is of the epoxy resin finish on the hull below the waterline. The aim was for a sympathetic restoration, I wanted to keep as much of the original paint as possible so only cleaned the paintwork above the water line.

The next step was to prepare the inside of the hull which looked a mess and was full of rubbish, cobwebs another undesirables. First I reduced the height of the wooden blocks that were glued to the inside of the hull, I then added further wooden blocks to create level bearers to support a removable floor that could be put into the hull for the steam plant. The idea was to be able to remove the whole steam plant easily for maintenance.
The wooden bearers also created a space low down in the hull for ballast weights. I used some 0.45Kg lead ingots bought online.

With the floor ready, the interior of the hull was cleaned with methylated spirits and prepared for painting with a self priming all purpose cream paint that I had available. It didn't go on as well as I had hoped and it required three coats it cover the red, the result is not perfect, but it is lighter and brighter.

[Dainesh]

This was an extremly huge job....

[DBS88]

With the Proteus engine, two servos are needed to control it, one for the throttle and the second to allow the selection of forward and reverse. Before I could install the steam plant I needed to sort out how I was going to install the servos. The Proteus engine uses the Maudsley mechanism for reversing, photo of the mechanism is below.


There are a variety of other reversing mechanisms on the different steam engines, there is the Stephenson linkage used on Reeves and Stuart engines and the Hackworth used on the Graham Industries TVR1 engines, and there are others too. The point here is that for radio control two channels are required, which needs to be thought through.
   

[derekwarner]

Dave


.......with Stephenson or Maudsley, one consideration is an ACTion electronics P96 controller on the Fwd/Rev servo....... with this, you can set the servo speed together with independent positioning of each endpoint....this then leaves just two [2] servo R/C controls [steering & engine speed] for stick control


https://manualzz.com/doc/25659279/p96-webpage.cdr---action-electronics



This engine direction reversal [servo + P96]  could be controlled by one [1] toggle switch.......so the engine is always in one direction or the other


I appreciate you mention thorough thought, and I suppose the are many ways to consider a failsafe ...' cannot command reverse if engine is not stationary' scenario.....however with your proposed installation being a Tug Boat......... I am not sure any high speed  reversing would be required


Derek

[DBS88]

Derek, thank you I will have a closer look at the Action P96. You are right that it would be useful to combine the throttle and gear selection onto one of the transmitter joysticks, also, your last sentence re fail safe and not engaging reverse if the engine is not stationary was at the centre of long discussions over the winter. I am keen on combining the channels since with the stick in the central position, you move the stick forward, forward is selected and the throttle is opened. Move the stick back the throttle closes, move the stick back further move though the centre position towards reverse, reverse is selected and the throttle opens.


Two discussions from over the winter about combining the channels in this way and automating the process are worth airing here.
First -  The theory of changing from forward to reverse is - close throttle, pause, engine stationary, select reverse, open throttle. Now in practice with a model steam boat in the middle of the lake, is this what really happens? or is the change made - close throttle make change from forward to reverse at low rpm and then open the throttle?


Second - with the direction selected (it does not matter if its forwards or reverse) so lets say its forwards, moving the stick forwards increases the rpm, pulling it back towards the centre reduces the rpm, once the stick is in the centre, no steam so no rpm. So with the transmitter stick in the central position, the discussion was around should the gear mechanism also be moved to neutral/central position or stay with the direction selected, in our case forwards?


Here is a photo of a Saito T2DR, it has the Stephensons linkage and you will see the operating lever for selecting forwards or reverse, it worth noting that it has only a small angle of movement to effect the change, certainly a lot less than 90 degrees.

[KNO3]

Combining throttle and reverse on a single radio stick if perfectly possible and there are two ways to achieve it. You either use one of the more advanced radios which are programmable (the have lots of other options and you can set servo travel, combine them etc), or, if your radio is not programmable, use a separate device in the boat, which combines the two channels, like Derek recommended.

However, I would rather use two channels manually for controlling throttle and reversing. It feels more like driving a real boat and gives you the important advantage of being able to use the whole stick travel distance (end to end position) to sensitively control throttle (not just half the travel, center to end).

[DBS88]

Here are some videos which show the operation of the various reversing mechanisms,

• The Saito T2DR with the Stephenson Reversing Linkage, https://youtube.com/shorts/tLaM3-Wr_A8?feature=share
• The Graham Industries TVR1ABB with he Hackworth reversing mechanism https://youtu.be/w5-hT0efT4k
• The Proteus with the Maudsley Reversing mechanism https://youtube.com/shorts/S6uXrJmN7rM?feature=share

These engines are two cylinder double acting engines so are deemed as self starting. I have limited experience with their reversing mechanisms and my personal experience, again limited, both on the bench and on the lake is that care is needed when changing from forwards to reverse and back again - the changes were not always successful. The outcome was on occasion a stopped engine - far from ideal. This was most times cured by moving the direction selection back and forth between forwards and reverse, never the less, a worrying few moments with a stationary boat on the water.


The problem of the stopped engine appeared to happen more frequently when
A) the throttle was closed, the engine let stop, the direction change made, then the throttle opened again.
B) the gear linkage was moved over to the middle/neutral position each time the throttle was closed.

This could be down to the engines I was using, the TVR1A is new (not run in), so was the Saito T2DR, the Reeves Marcher is run in but maybe its not set up as well as it could be?

The problem did not happen when
A) the change in direction was made at low rpm
B) With the direction selected (forwards or reverse), lets say forwards, the throttle is closed and the direction change is not moved, so when in forwards it stays in forwards. So most times with forwards selected and you you close the throttle, the next operation will be to open the throttle to continue going forwards. The change to reverse happening when the transmitter stick moves through the central position to reverse, then the linkage moves, no pausing in neutral.

The problem occurred most frequently with the Stephenson Linkage, the Hackworth and Maudsley were more reliable, again this may be issues with my engines, what are your experiences?

[rhavrane]

Bonjour Dave,

I am the lucky owner of a lot of different machines, including yours and lives the same experience with the slide valves one, from 2 to 20+ cm3.

I like stopping , reversing and accelerating gently again and I would not say I miss every time but quite more than from time to time.

As my reverse is on a 0 - 1 acting servo, if I miss the reverse, I keep the steam open and double reverse again, it is OK then at 99 %.

Please take in account that my working pressure is always around 2 bar / 30 PSI, even much less during my tests, that means a wet steam which condensates quickly (but I like its lubricating ability).

Example : https://www.youtube.com/watch?v=C4OlL3aZ2a4

Other point to be taken account, None of my machines are able to operate exactly the same in both directions !

[derekwarner]

It can be difficiult to compare apples with apples

Just looking at 5" Gauge scale steam locomotive engines, we have the weight of the engine [100-150 kg] on the track, so when the steam regulator is opened [gradually], the valving [Stephenson, Hackworth etc] will admit steam at boiler pressure to the cylinders to provide work.....so the difference here essentially is the load upon the engine/system which allows a relatively smooth acceleration [if not spinning the wheels]

The simple steam valves employed on model boat steam engines in most cases is little better than a 'stop type plug valve with on/off' performance, but with little progressive volume of steam to the engine to apply the required effort/inertia to rotate the paddle shaft & propeller

Having a little knowledge of full sized steam and fluid systems valving as used in the Steel Industry, in 2005, I purchased a radio control model steam regulator from ACS Engineering Scotland [Sandy Campbell] - a properly designed balanced, spring loaded, self regulating, disk valve construction component ....it is literally a 3/4" cube of bronze+bronze with stainless trim -  [at the time of purchase probably twice the cost of el'cheapo alternate valving which had no credential of design and regulating capacity]

The valve performs exactly as described when supplied with 2 Bar lubricated steam ....[worth every penny an more  ]

I will describe the engine detail later........

The Saito T2DR [12x12] test you show is absolutely typical of this Brand in Videos on the Net, where the engine will tick over relatively smoothly between directions and at low speed, which also suggests a lower pressure applied to the engine. This also suggests it is OK to swap engine drive directions in the model at speed. I am not suggesting for one moment that the Saito product has poor manufacturing tolerances to enable smooth operation [from unused, or not requiring a run-in period

The Graham Industries TVR1ABB in your video clearly required a higher air pressure & hence higher speed to achieve a direction reversal

The only engine I have is also a Saito, but the Y2DR horizontal twin [1960 design vintage and 12x20], also near mirrors  the unloaded reversing functionality at low speed you show. This engine also has some 1.8kg of mass to rotate [engine flywheels +1/4" diameter brass paddle shaft + 160 diameter brass paddle wheels]

The Y2DR & drive with the paddles in water with 2 Bar boiler pressure available, will slowly commence engine rotation of the wheels slowly without any real jerkiness - an ACTion electronics P96 controller is installed to both engine reversal of direction lever and the ASC steam regulator.....both shown in the second image

[I apologise no videos to support this]

My conclusion to this issue of non start from Zero speed, or jerkiness is the inherent distribution of the steam within the engine, irrespective of differing design valving, and often compounded by the choice of ineffective design external steam regulating valving and an unloaded function at commencement of work


Comparison testing of steam engines on air is if by necessity is a good yardstick, however the same engines may display differing actions, timing or speeds when tested on steam

To compound a conflicting to my thoughts, I am happy to say it's OK to throw an electric motor drive from full ahead to full astern in one movement [without considering a cessation of rotation in the middle], however have certain fear and reservation in ordering the same command for my steam engine


[The only reference for this are comments & advice offered by an elderly Steam Engineer, was that repeated at speed reversals [marine steam engine] resulted in expansion-deformation of an eccentric link outer band, to the degree that correct valve timing is lost - the steam still expanding, with so much potential and kinetic energy that must be absorbed, so by design was preferable for a bronze band to deform [go egg shape] than a crankshaft journal shear ]
 
Derek
 

[KNO3]

Hello, the problem you have observed, with the engines not restarting after steam shut off and reversing gear moved to reverse, can also be due to the valves lifting slightly from the port faces during this population. The fact that moving the reversing gear with steam on a few times cures the problem, supports the idea that by movement the valves get reseated by the steam pressure.

I have observed this problem too in some steam engines.