First steaming of my Stuart Score

jamespetts · First steaming of my Stuart Score

I steamed my Stuart Score for the first time yesterday:

(Here is the link in case embedding does not work)

The engine fast depleted the boiler pressure, and it took a long time to restore the pressure. There certainly wouldn't be enough sustained steaming capacity to power a computer as things stand at present. My father suggested raising the ceramic gas burner to be closer to the water tubes in the boiler to increase its heating efficiency, and I wondered whether adding another air hole at the bottom of the burner's ring (which will be usable if the burner is raised above the ground) would help. Lagging the pipes will help a little: that has not been done yet, since I wanted to test the pipes to see how they withstood steam pressure - as will be noted, there were three failures that need fixing.

If I am not able to get the boiler to produce enough steam reliably to produce enough power to run a computer, I shall have to think of a good electronic use for a more modest amount of power (perhaps an OLPC or a palmtop sized computer? Perhaps a charger for a mobile telephone?), and postpone plans to build a steam powered desktop computer until I can afford/assemble a larger engine and boiler.

In any event, here are some pictures of the engine in steam:

Nick

Very interesting.

Thanks for posting it!

IndianaRog

James, what a beautiful engine and powerful engine...plus you have it set up with all the trimmings. Loved the boiler as well.

Question, is the Score supposed to have ONE or TWO flywheels? It looks like it could take a second one on the open shaft end.

cheers,
Roger

Les

Reid

Don't get the least bit worried, James.
Surely it will sort out in time, partly by running-in,
and in part by the modifications you will be making.

The shorter the steam pipes,
the higher the burner,
the more air supply,

all these things will make gains.

I noted that the pressure runs down as you say.
My D21 has a 100mm diameter flywheel that I use for driving the dynamo at a high rate.
I wonder and wish you can get a five inch-or-so diameter flywheel for the Score;
thereby run the engine at higher pressure but at lower speeds than would otherwise be needed.

pi time radius squared... the surface speed of a larger flywheel may be an asset,
saving you from having to run at an uncomfortable, steam-eating 2k rpm.

But will that boiler keep up the pressure?
I think it is a matter as you already suspect, of optimizing the heat supply.

Few people put these engines to do any real work at all.
Part of the fun of this project will be to make the plant operate the way you need and want.
I wonder if the Stuart people really rate their boiler/engine combinations with a wet thumb held up in the air!
No matter: you'll make it work. Remember what Edison said...

----

Aside from all that: it looks the business. It's beautifully painted and so well assembled.
This is an heirloom engine and it's no model:
you're using it to power shop equipment after all.
It's all very good.

Now I am wanting to get a 10H some day,
and put a six inch flywheel on it (raising the engine or putting it on a table base)
and chuff it at 800 rpm or so and yet---get perhaps ten watts of juice to....

THOUGHT: you can run the Score's electrical power into nicad or lead batteries,
and take the output of that to run your computer.

That is, if the plant in the end can't sustain 35W output,
it can surely charge batteries to run a computer.
It would be a good plan anyway, to buffer the power output,
filter and regulate and allow for stops to go have a cup of tea
without leaving the engine unattended OR having to go offline.

BTW, congratulate your dad. He does good work too. He got you up and running very well indeed!
All good things come to a new beginning.
Now it's time for the first round of refinements.
You have much to think about, and no worries.

jamespetts

Thank you all for your replies

IndianaRog: Stuart's website shows the Score with only one flywheel, and it is only equipped with one in the kit. It is possible to attach another to the other end of the crankshaft, and sometimes people do, but it is not necessary. (I think that the Score looks better with the default one). Also, on my model at least, the crankshaft is shorter at one end than the other, the longer end being the flywheel end.

Reid: thank you for your detailed post, as ever

I cannot take credit for the painting and assembly: I bought it fully painted and assembled from eBay - the cheapest way to get hold of Stuart engines, in fact, is to buy them over eBay from people who have home-machined them from castings. Your aspiration to get a 10H is a noble one indeed: they are good engines (and more powerful than the otherwise similar S50), although you will have to silver solder the pipes, and procure a suitable boiler (the boilers direct from Stuart are very expensive, although there are still some new-old stock 504/501/500s on eBay that you can get at knock-down prices; beware asbestos in old boilers, however). See here for some examples.

As to battery charging, the main problem with that is inefficiency: one only gets out of a battery about 80% of what one puts in so, if I were to try to run a computer from a car battery, and re-charge the car battery at the same time, it would be charging for far longer than it would run for. Added to that, of course, it is far more impressive to have a system that works directly from the dynamo's supply rather than being propped up by a battery.

If improvements cannot procure enough of an advantage to be able to generate 36W at a constant rate, I shall probably purchase the same dynamo as you did (rated for 18W - better than the PM Research or Stuart models, rated at 10W, although not as good to look at), and try to find some more modest electronics to power - an OLPC, perhaps, or a Palm/Pocket PC. Perhaps a mobile telephone charger? I did plan to have car cigarette lighter sockets as outputs. If the 504 cannot generate the requisite steam, I shall have to defer my plans to build a desktop computer-powering engine until my finances, engineering skills and available space can muster one of the larger Stuart engines, such as no. 4 or a no. 9, and boiler to match.

As to the improvements, I have already begun to make them:

Boiler stripped of kaowool cladding and top fittings ready for re-cladding:

Copper sheet cut and bent ready to cover the replacement kaowool cladding (Reid's idea if I remember correctly):

Copper sheet on the boiler (as yet without kaowool) to test for size:

Test section of pipe insulated (wrapped in string, then covered by PTFE tape):

Mark-One

A fellow on youtube once asked me about the possibility of powering a ham radio with a steam engine.

When you're lugging a load your RPMs will be down too, so it's not going to eat up the steam as horribly fast (though it still will). Just some observations I had with my Jensen 20 in it's original configuration.

I had in my hands one of those little Asus eee PC's last week and I didn't think to look at the power rating of the wall adapter. But with no moving parts (ie drives to suck amps as they spin up), maybe that's the way to go? $300 for the entry level model that we got to demo at the schools.

Bogstandard

I had to run and rerun your vid a few times to see the burner and how it was running.

IMHO two main faults. The first is that the burner is way too low in the casing, it should be a lot nearer to the boiler. A lot of energy is being wasted just by air coming and going around the bottom of the boiler casing.
The other and more critical thing that I noticed, the burner is not being run efficiently. The flames seem too high with no discernable 'cones'. Suggesting that the gas /air mix is way off. The ceramic plate should be glowing red hot on the tips of the ceramic material, and covered all over with tiny blue cones about 1/4" high, with a distinct hissing sound. What you have there is equivalent of most probably a meths burner, with only about 25% efficiency of what it should be running at, just like an old fashioned gas light.

I would check that you have got the right size jet in for the burner, or that it isn't partially blocked. Or if by the wearing of gloves, suggesting it was cold, the gas in the tank was too cold and not supplying enough pressure to get the gas/air mix working correctly.

With a burner that size, you should have no trouble running the engine you have coupled to it, and maintaining full pressure. In fact you should almost be able to run the engine at full wack and still have the safety blowing the excess off. But engines like that are more efficient running at a much lower speed, they have a lot of low end torque.

A little bit of good news for your project. During WWII Stuart Turner produced a small steam engine package in a box for operatives that were dropped into France and the resistance. It ran on twigs and bits of wood and was used to charge the batteries to power the radio, and those radios I am sure were a lot more hungry for power than a laptop.

A bit more info for you.

http://www.jerry-howell.com/10H-Steam.html

http://www.xlistplans.demon.co.uk/MiscEngines.htm

M 68 Steam Generator Set
M 68 Steam Generator Set

http://www.royalsignals.org.uk/photos/steam.htm

John

jamespetts

Mister Occlusion and Bogstandard - thank you very much for your replies and suggestions: they are much appreciated

Mister Occulusion - you are probably right about RPMs: steam engines are more efficient at lower speeds and higher torques. I am thinking of ways to gear up much more than I had hitherto planned, although that means finding a way to fit a very large sprocket wheel onto the spare side crankshaft, which might not be an easy task. For oiling, I am considering either standard oiler cups on the big end bearings and/or dripping oil onto the big end bearings using minature buckets filled with oil with very small holes drilled into the bottom, suspended above the big ends somehow. As to eee PCs, that sounds very interesting, although I think that I should like to see whether Bogstandard's tips work before I consider scaling down just yet, given his encouraging remarks about firing.

Bogstandard - my father said the same thing that you did about the height of the burner, so we are going to cut cross-sections from old tin cans to raise it so that it is as close as possible to the water tubes without touching.

As to the gas/air mix, this is a more difficult problem to solve. Am I right in thinking that the gas/air mix is wrong in that there is too much gas and not enough air? There are presently three large air holes in the ceramic burner next to the jet (which is the recommended size: a no. 16) - one at the top, and one at each side. If the burner is to be raised off the ground, would there be any use in adding a fourth hole at the bottom? My father also said something about "streamlining" the holes to ensure better air flow, by filing down the corners - do you think this advisable?

I was able to get a blue flame with cones, if I turned the gas down much lower. However, when I did that, the engine ran noticeably slower than when I turned the gas up, even though it was producing a yellow flame at a higher setting. My father suggested that the boiler was heated more by the yellow flame, not because more heat was being produced overall, but because the flame height had increased, so that the hottest part of the flame was much nearer the water tubes - is this correct? Would I actually be better off with the gas turned lower with the burner closer to the water tubes, or ought I be able to get a blue flame with the gas turned all or most of the way up?

As to gas pressure, it was indeed a cold day - it was Easter Sunday, which was about 4C in this area. The gas cannister would get even colder than the ambient temperature, of course, because of the rapid decompression of the liquid contents into gas. Taking a tip from Keith Appleton, I ran the exhaust pipe under the gas tank to try to warm it, although it still got cold enough to produce condensation on the tank (probably from the steam leaking from a nearby leaky gasket). No ice formed on the tank.

I did notice that, if I blew hard on the gas burner when turned to the highest setting, the flame would turn blue, but, if I kept blowing hard for long enough to make a difference, I'd be the one turning blue! Would forced aeration of some sort be a solution, do you think, or will that not be necessary if other improvements are made?

If gas pressure is a problem, one solution that I had considered was linking two gas tanks to one burner, silver soldering a T-piece into the gas line to the burner. That would also enable a smooth changeover of gas cylinders when they are empty, provided that I untwist the cylinder from the regulator without detaching the pipe from the regulator. Do you think that this would be a viable or beneficial solution? Would there be any insurmountable safety hazards in doing things that way?

Thank you again very much for your thoughtful and encouraging reply, and I shall look forward to learning more about your impressive marine turbine project

Edit: Incidentally, I already knew about the Stuart Mk. 814 Generator Set from information on the Station Road Steam website (incidentally, they seem to have one for sale at present for £845), although the Sirius engine that powered it is somewhat larger in scale than the Score, being a 1"x1"x2 cylinder model, rather than the 3/4"x3/4"x2 cylinder Score, although I am intrigued by the reference in your post to plans for a "model" of this set using the now sadly discontinued 3/4"x3/4"x2 Stuart Sun.

Bogstandard

James,

The way a ceramic burner of the type you have, works by radiant heat. That was what I was saying about the surface of the ceramic needs to glow red hot. If by turning the gas down, you achieve this, then that is the correct setting. Without actually being there, it is difficult to suggest anything with regards to modification. I would try, if it allows it, moving the jet in and out of the sliding holder (if it has one), that way you can get the gas mixing as it should. On my ceramic burner I use in my boiler, the tapered part of the jet is just showing in the air holes around the mixing area. If it is too far into the holes, not enough air can get in for an efficient mix.
If you can get the radiant effect, then 1/2" below the tubes would be ideal.

In the model boat brigade, what we used to do for steaming in the winter, was to make up a small round pot containing water, the gas tank was popped into that and the steam exhaust pipe was run thru the tank to warm everything up, then back to where it was normally exhausted. It was made removeable so it could be taken out in the summer, as the tanks didn't freeze up then.

Hoped this has helped.

John

jamespetts

Bogstandard,

thank you again for your reply

We did adjust the position of the jet when we first tested the burner: the position that it is in now is the one that can best achieve the blue flames and cones, but only with the gas turned down. I have just looked at the position of my jet, and it is quite similar to what you describe with yours. Do you think that a fourth air hole would help?

Thank you for the interesting advice about a gas tank hot water bottle

Although I am aware of the chilling issue, I suspect that this may not be the problem here, since, when testing the burner/jet initially, the flame would be yellow with the gas turned high, and even on Sunday when I was running it, I could get a blue flame with cones when turning the gas down (but the boiler would not boil as well as with the gas turned up and the larger yellow flames, quite possibly due to the distance from the flame to the boiler).

Thank you again for your most helpful reply

Bogstandard

James,
If it is a commercially made burner, I personally wouldn't do any mods to it at all. If the manufacturer is any good, it will be correct.

It all points to either a partially blocked jet, or not enough gas pressure. The velocity for mixing just doesn't seem to be there.
Get a bit of pipe and when it is running, gently blow into the holes around the jet, if you get an instant response in the correct direction, it proves my point about velocity, and one or other of the fixes above should be tried.

What is the physical size of the burner? The size of jet you mentioned seems rather large for these type of burners. Unless of course you have bought a real biggun. Mine is 2" diameter (round) which equates to approx 6 sq ins, and that uses a No 5 jet.
I have only ever seen blue cones, never yellow on any burner I have either bought or made, so there is definitely something wrong with the mixing.

John

jamespetts

Bogstandard,

thank you again for your reply

You are very helpful. The burner is this one, which states "jet size, 8, 12, 16". The people at Forest Classics recommended the no. 16 in an e-mail. Do you think that one of the smaller jet sizes listed (the no. 12 or

would make for better mixing without forced ventilation? (Note: Forest Classics, from where I bought the burner, do not seem to carry the no. 12 size).

I did try blowing into the burner, albeit without using pipe, and, as noted above, when I blew hard into the jet area of the burner, the flame became blue, with cones.

As to the pressure of gas, one thing is confusing me, which I should be grateful if you could clarify: the burner produces a blue flame, with the desired blue cones, when I turn the gas regulator valve to a lower setting. Presumably, with the regulator valve turned down, the gas pressure in the pipe is lower than with the regulator turned up. When I turn up the gas (open the regulator valve more), the flames become yellow - presumably, in that instance, there is more gas pressure at the jet. Unless I am missing something (and please tell me if I am), that is not consistent with the gas pressure being too low.

The thinking behind drilling a further air hole is that the ceramic burner is evidently designed to run resting on a flat surface, where there would be little point in a hole in the bottom. Given the suggestions to raise it, my burner will no longer sit on a flat surface, but will be suspended above the floor of the firebox in the air. If the problem is that not enough air is getting into the mix of gas and air, a sensible solution would seem to be to find a way of introducing more air. Or is there some flaw in that reasoning that I have not spotted (for example, a problem with the assumption that drilling a further air hole will lead to more air in the air/gas mix getting to the burner)?

In any event, thank you again very much for all your help - it is most appreciated.

Edit: I have ordered a no. 8 gas jet to test to see whether fitting that would improve the air/gas mixing.

jamespetts · Gas jet update

I received the no. 8 jet in the post yesterday, and tried it this afternoon. I did not notice any improvement: it was still quite light when I tried it, so blue cones were not easy to see, but I did notice that I only got that bright blue colour when I blew into the burner hard (but not so hard as to blow it out). I still had large yellow flames at maximum gas at any position of the jet. I am still considering drilling a fourth hole in the burner ring to admit more air. Does anyone have any suggestions as to how further to improve combustion?

Bogstandard

Have you tried, with the burner running, away from the engine.

Push the jet fully fwds so that is at the other side of the holes, then gently pulling it back and see if it starts to improve, it might be getting too much air and slowing the gas down. It will only take a few minutes to try.
Also, before starting, and the burner getting hot, remove the jet assembly completely and look down the hole into the burner, there should be some sort of baffle or round bar in there, standing up from the burner base, the gas hits that and distributes the gas evenly around the inside of the burner chamber. If it is missing, that could cause the same sort of problems. If you can't see it, very gently poke a rod down the hole and see if it is there. It will be in different positions on different burners. DO NOT REMOVE THE CERAMIC PLATE.

If none of that works, I have no further ideas.
I have made big ones, little ones, square, round and oblong ones, but never had the sort of problems you are having.

John

jamespetts

Bogstandard

James,

Well done, and good luck.

John

Cedge

James
Have you seen this?
http://www.guardian.co.uk/uk/2006/jul/11/topstories3.arts

You could simply be caught out by working at too small a boiler scale.

Steve

jamespetts · Progress this week-end

More progress this week-end as pictured below:

Copper shroud for holding in place and protecting the friable kaowool insulating material completed and painted:

Firebox riser to lift the gas burner higher so that the flames are nearer the water tubes and heat the boiler more effectively completed:

Copper inset for firebox to protect the kaowool from damage by the burner cut and painted:

And, finally, some nuts and screws on the engine tightened to remove rattles that were present during the first steaming:

Cedge, I had indeed seen that article, long before I started work on the project

That gentleman is powering a full sized desktop computer from his steam engine, so it is no wonder that he needs a boiler taller than himself: a full sized desktop computer can consume over 300w of electricity: the small, energy-efficient mini-ITX machine that I intend to make should take little more than a tenth of that.

First steaming of my Stuart Score

Gas jet update

Progress this week-end