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[derekwarner]

Hi all...a question for Bunkerbarge from 19.12.04........as per the .jpg attachment I see you used a gauge for the gas tank pressure.....but in later snaps the gauge is replaced with a regulator

So was the gauge functional....to read say 10 Bar???

I also acknowledge this same question was asked some few weeks ago ....... ...Derek

[ian kennedy]

Derek,

The two engines are fed steam from the same boiler, the steam line is split to feed the two ACS regulators independently, then to each engine which has separate reversing control.

Using the rudder and the regulators when making a turn to port the inboard engine has its steam pressure reduced or stopped, whilst the outboard engine is given full ahead pressure, to increase the tightness of the turn the inboard engine is thrown into reverse and steam is then fed back into the engine through the regulator, giving reverse thrust.

This i admit is a slightly complicated control system but i need 6 proportional functions to achieve this maneuver, 1 for main steam pressure, 2 for independent regulator control, 2 for engine reversing gear and 1 for rudder control.

The system works well and when used to it's quirkiness is very quick and responsive nearly as good as electric motor control.

Ian

[derekwarner]

Hi all.....well Ian says ...

The system works well and when used to it's quirkiness is very quick and responsive nearly as good as electric motor control.....

My call on this is different...in that any joe blow can control the electrics....but it certainly requires engineering understanding to get the electronics & mechanics to control the steam

Well done Ian.......Derek............................ 

[Proteus]

Derek,

The two engines are fed steam from the same boiler, the steam line is split to feed the two ACS regulators independently, then to each engine which has separate reversing control.

Using the rudder and the regulators when making a turn to port the inboard engine has its steam pressure reduced or stopped, whilst the outboard engine is given full ahead pressure, to increase the tightness of the turn the inboard engine is thrown into reverse and steam is then fed back into the engine through the regulator, giving reverse thrust.

This i admit is a slightly complicated control system but i need 6 proportional functions to achieve this maneuver, 1 for main steam pressure, 2 for independent regulator control, 2 for engine reversing gear and 1 for rudder control.

The system works well and when used to it's quirkiness is very quick and responsive nearly as good as electric motor control.

Proteus,

Ian

If you had twp of the units cheddar sold for it's gemmini and Proteus engines you could have used a standard mixer and run the whole lot of ONE channel.

[ian kennedy]

Proteus

that is very true, but the tvr1a's require a two channel set up per engine anyway so a minimum of four servo's are required to give trouble free reliable service.
Unlike the gemini and proteus engines which had a mixer valve for directional and speed control

I could never afford the expensive cheddar steam engines so went down the Graham industry engine route with mods to the bearings and valve gear and some material changes, just to beef them up for higher pressure and speed use.

I would love to do away with the hackworth reversing linkages and change to piston valves and a single channel control, i will do this in time when the engines require some work on them.

Ian

[kno3]

Hi Ian,

What exactly did you modify on the Graham engines and why?
Instead of removing the valve and valve gear of the Grahams (which would be a pity, that's their interesting feature) better get a couple of oscillators for Regner or another maker. They are simple, reliable and can be run with a single servo.

[ian kennedy]

Hi kno3,

I have enjoyed your thread on the construction of your engine, you will enjoy it it's great little busy engine to watch running.

The first thing i changed was to do away with the soft brass crankshaft bearing blocks and replace them with sealed stainless steel ball races held in duraliminium blocks bolted down onto the base plate.

Recently I replaced all the aluminium link bars for the valve gear with home made brass components also the horrible aluminium eccentric straps for the valve gear, these have worn quite badly even though i made wick type drip feed oilers from the start of the project for lubrication.

My point about the valve gear was to try and explain to Proteus that these engines operate differently to say the cheddar type, hence the required use of x number of functions, I love the look of these engines working as a pair with the exposed linkages etc and would only consider altering the slide valve to a piston valve to improve long running reliability issues.

One thing i would watch out for is the chemically welded(glued) joints on the slide valve spindles and reversing gear female slides comming apart, this happened to me and i drilled and pinned these joints prior to construction of both engines.

Ian

[Bernhard]

hi..Ian..........eny close up photos of what you did to your engines,,,,,i will like to see that,,,good ide with the ball bearings...

Bernhard

[ian kennedy]

Hi Bernhard,

I am in the process of moving house at the moment so Inflexible is boxed awaiting her new home.....

I will post some photo's when i get her out again at the end of jan 2009 ok?

Regards

Ian

[kno3]

Ian, some close-up pictures of your engines would be great!
Good luck with your moving.

[ian kennedy]

Thanks for the the wishes

Xmas and moving bad timing but it must be done !!

Seasons greetings and the best for the coming year to all fellow steam nuts !!

Regards

Ian

[Proteus]

Proteus

that is very true, but the tvr1a's require a two channel set up per engine anyway so a minimum of four servo's are required to give trouble free reliable service.
Unlike the gemini and proteus engines which had a mixer valve for directional and speed control


Ian

Yes and so did the cheddar unit , It combined two servoes and They can happily used with a Graham industry engine , and I have in the past.I think Stuart are making them again but they are not on there site, and I have had two of ebay in the past because people don't know what they are, none of the bigger engines had a" mixer valve"

[ian kennedy]

Sorry Proteus,

I mis understood you there i think !!

I was not aware of such a unit and thought you meant something mechanical rather than electronic

Regards

Ian

[Bunkerbarge]

Hi all...a question for Bunkerbarge from 19.12.04........as per the .jpg attachment I see you used a gauge for the gas tank pressure.....but in later snaps the gauge is replaced with a regulator

So was the gauge functional....to read say 10 Bar???

I also acknowledge this same question was asked some few weeks ago ....... ...Derek

Sorry for the delay in replying Derek.

The pressure gauge I find is a very effective indication of what is going on in the gas tank.  Obviously as long as there is liquid in the tank the pressure should always remain at the saturation vapour pressure for the gas and when the liquid is gone the pressure will quickly drop off.  The svp of a 70-30 butane/propane mix at 21 deg C is about 45 psi or about 3 bar.

The real benefit however is seeing how much the pressure is dropping off with prolonged use due to the effects of the cooling as the gas evaporates.  You will actually see the gas pressure start to drop off almost as soon as you start to use it, which is why I raise steam pressure on the bank from an external tank. There are then two regulating valves in the discharge line, the first to control the pressure as the heat shunt from the seprator tank warms the tank and the second to regulate the flow depending on boiler pressure. 

I haven't actually steamed it yet with both these valves and the heat shunt in operation so the results of that remain to be seen.  The pressure gauge though is still there and I will probably leave it there anyway to give me an idea of what is happening.

There is also the danger of the heat shunt causing too much condensation as it cools the exhaust too much so I still have a bit of experimenting to do before i'm happy with it all.  I might actually cut the heat shunt into transverse sections and put on as many as is required for the ambient conditions. 

I'm trying to finish the model though before I get completely distracted by power plant experiments again!!

[derekwarner]

Hi all.......thanks Bunkerbarge..........things are a little different on each side of the equator 

Many European model vessels display steam discharge as heating coils around the gas tanks to maintain gas temperature

Some time ago in Paddleducks.......we did some P1V1/T1 = P2V2/T2 gas calcs & had great racious debate    ..........

Sandy Cambell suggested  that in OZ.......filling a 70/30 tank @ 21 degrees C then exposing the tank in an open vessel to a 40 degrees C ambient direct sunlight radiation would require a pressure gauge of 10 Bar on the discharge side of the tank....prior to the regulator

regards Derek

[Bunkerbarge]

As usual though nothing is quite so straightforward!

Exposed to 40 deg maybe but what temperature is the gas?  You have to take into acount the cooling effect of it evaporating as well as the fact that it will take time to heat up the liquid inside the tank.

Taking the extreem case where you put the boat in the water and let the sun heat up the entitre contents of the tank to 40 deg you will still only achieve a pressure of about 85 psi, which is still less than 6 bar.

I'll let you take that to the Paddleduck debate though!!

[derekwarner]

Hi all....mmmmmmmm Bunkerbarge........your nominations are totally in line with that offerd by Sandy Campell...the premise offered was that if the delta P was to 6.6 Bar....then using the DIN standard recommendation for maxinium WP for pressure gauges to be 0.6 of FSD =~~~~~~ then the recommended 10 Bar scale gauge is line ball with the requirement........................Derek

[Bunkerbarge]

Certainly an interesting thought Derick and I can't fault the logic however I would question the situation.

What you are doing is designing something to accomodate the worst case scenario, which from a safety aspect, cannot be argued, however you are shooting yourself in the foot as regards the use of the gauge.  You want the gauge to spend most of it's life at about 50% of full scale deflection, giving you the best accuracy and the most usefull range of operation.  If you design the gauge to accomodate such an extreme then it is going to spend most of it's life at the very low end of its range giving you very little deflection for a change in pressure and greatly reducing its value and accuracy.

How far do you want to take it though.  Do you go back through historical records and find the maximum recorded temperature for a given location?  If you want to operate your model in another place do you check the maximum recorded temperatures there as well and change the pressure gauge? 

I want a gauge that operates most of it's time at 50% deflection and, for my own climate, a 100 psi FSD gauge is fine.  If however I was that worried about operating in extremes situations then perhaps a cock in the gauge line could be used to protect the gauge.

The perfect solution would, of course, be a logarithmic scale gauge, but I don't think we are ever likely to see one of those in a modelling scenario and if we did it would probably cost more than the rest of the plant!!

[MCR]

Little more progress made,

[knoby]

i have recently started to convert my electric powered tug from electric to steam. I originally wanted to have it steam powered, but the budget wouldn't stretch to it.
I have been collecting parts for some & I am able to start now. First job was to remove the old propulsion system & fit mounting plates for the steam plant.
 Glenn

[kno3]

Nice, looks like a pretty big boat. Why don't you make a separate thread for the steam engine installation?

[derekwarner]

Knoby....as suggested by kno3....this would be a great new thread 

The only comment I could make is......don't repeat my errors

I had three individual mounting plates for my steam components ...which = thirteen tubes of 1/8" or 5/32"....& yes very short lengths with short bend radii

After 16 months I gave up as steam engine tubes must only horizontal or straight up or down 

I invested in one new mounting plate & must demolish some deck sections to install the plate ......jpg attached......Dererk

[logoman]

that is superb Derek, I love that little diagonal engine, I'd love one of those. I love that Niggel lubricator too - in fact every part of that plant is a little gem. A darker baseplate would set them off properly.

[kno3]

Derek, I have seen every now and then pix of your paddlesteamer project in various topics, but is there a dedicated topic for it? I couldn't find it...

[knoby]

thats a g8 looking boat Derick. hope mine looks half as good. T hanks for the advice on the pipes, I'm only having 2 plates & i think i can keep the steam pipes fairly simple.
however its the water pump feed & return that seems to be getting complicated. i want to use a cheddar ABC system & its not easy fitting it in. I admire your courage to rip off the old deck & re make it, I'm not sure i will be that brave
Cheers Glenn