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[rfurzer]

Ooh! How super.

Is that a piston- operated (disc or poppet) inlet, uniflow exh arrangement? That would explain the higher pressure- benson and rayners book describe the compression ratio effect ( the residual exhaust gets compressed before the inlet opens. Short cut-off too.

[Synthpunk]

Its single acting, (semi?)uniflow (just one large exhaust port per cylinder) and valveless. No pistons, slides, poppets or disc valves, apart from the three main pistons which also act as their own valves. All just done with pipework. Almost unbeleivably simple. Ill buy you a drink if you can tell me how its done... ;c)


It has two built in pumps, one runs at shaft speed and one is geared down. Im planning on plumbing it into the feedwater system as well, to see what happens. Maybe ill get lucky and itll only need the electric pump for starting....

[Synthpunk]

The full list of moving parts :
1 crankshaft
3 pistons
3 crank rods
3 screws that act as compression release valves during the exhaust cycle. They are in the top of the pistons and are pressed up by little pips in the crank rods.
And thats it. No more moving parts, just pipes.








The crankshaft is only supported at the ends, its an inch thick. In fact, every major dimension of pretty much every component  is either an inch, a quarter inch or an eigth. Its like an excercise in reductive engineering, its so simple its beautiful!

[Synthpunk]

Today i tried running the engine and boiler with two small gas canisters, half the size of the ones in the video. They cooled down far too fast, it generally wasnt a success.


However ive now mounted the two burners in the casing permanently, with a nice combustion space above them and around the coils. They burn best with the exhaust forcing a draft through the chimney. the flames are contained within the casing, unless the first burner doesnt light properly, in which case there are flames more or less everywhere but inside. I checked it after dark, it was quite exciting!. The flames generally burn blue unless theres no draft in which case they go more yellow.


I also experimented with using a pwm speed controller on the pump motor to see if i could use that to slow the motor right down and get rid of my external gearing down. It didn't work. Kept stalling when the load increased along with the pressure. When funds permit Im going to try it with a 100:1 ratio motor and gearbox combo and retire this one to backup duties. Till then its back to externally gearing it down..


Tomorrow im going to give the boiler a run with a true high speed (18,000 rpm) flash steam hydro engine, a twin cylinder single acting piston valve unit built in the seventies and quite compact. It may work, it may not. It was a pig to run on compressed air when i have tried it in the past but that probably had more to do with a rubbish compressor.


The three cylinder engine thats in the rig at the moment excels at lower speed stuff. Which is what the coil design of the boiler is for, after all. But it will be interesting to see how the boiler fairs with the racing engine. Until i put the water pump back to its geared down state, id guess not well at all!

[TurboTyne]

 Hi Rich
I’m very impressed by your steam plant!!
I have a couple of questions:
Can you please say something about the brake that you have coupled to the BB10 in your first video? E.g. Is it a converted centrifugal water pump?  If it’s a purpose built brake, how does it work?
Also, I am curious about the useful-looking aluminium strips to which to fix your equipment? Looks like they have slots and loads of tapped holes.  Does this stuff have a name and do you know where to get it? 
Cheers
Mike
 

[Synthpunk]

Hi mike! Cheers! That green thing is indeed a stuart turner centrifugal pump. The bb10 is part of an original pumping set, its quite rare. I had been planning on trying the centrifugal pump as a pump for the plant, but i havent got round to it yet!
My 'torque Brake' was simply a wooden clothespeg held by a clamp with the 'pointy ends' in between the flywheel and engine mounting, with another half a peg clamped in the jaws and tensioned by a selection of elastic bands to a hook some inches away. I adjusted it to give the same amount of pressure as my usual test, ie pressing my thumb quite hard into the flywheel until the engine almost stalls and then backing it off a bit.


My flatmate is a crazy slovakian ex army helicopter mechanic. We often socialise in my workshop, drinking shots and talking about machinery. He tested the big triple for me; it was his 41st birthday so hed been celebrating since breakfast, and was quite 'refreshed' by the time he wandered out to see the triple running for the first time. "Lets test the torque!!" He shouts, then grabs the spinning 96 tooth gear that it has instead of a flywheel... Hes a well built, strong guy. Apparently (and i quote)
" yes thats a good one. Nearly tore my hand off.... Drink?" :)


The aluminium mounting bars is extruded in a very complex cross section, you can slide strips of the tapped stuff into it for infinite adjustment. Its what large, super expensive recording consoles are made from. This stuff came from the old mixing desk from BBC radio norwich in the uk...
I cant remember what its called, but if you have access to an RS catalogue its in the enclosures section, but be warned- its extremely expensive! Its also used for making modular rack subassemblies, makers like BICC- Vero and Schaeffer do them, its a system commonly known as EuroRack. You can often find old modular sub rack assemblies in skips outside businesses that are having telecoms/server room upgrades if you are the kind of person who enjoys dumpster diving. Its where i get all my best stuff...



Cheers!


Rich

[TurboTyne]

Hi Rich
Thanks for the explanations and I see what you mean about the rail systems being pricey. I have just been looking and discovered that there's a whole world of these varioius profiles for racking systems out there. This made me think about using something like Al curtain track or lamp-mounting rails as a cheap alternative.

I certainly do look in skips but I doubt I'll be lucky enogh to find anything like the Z-rail and strips of threaded holes, but you never know.   

Regards

Mike

[Synthpunk]

My latest findings with this coil:


I bought two small (100g) gas cylinders, and they are too small to run the big engine. It ticks over, just, but its a smaller amount of heat than just one burner connected to a larger tank. Im going to buy bigger tanks next time. Better surface area to volume ratio, and the propane and isobutane dont burn off so soon, just leaving boring butane.


I found the spec on the burners im using. The two burners, with isobutane/propane mix fuel, and large tanks, have a maximum combined output of 5000 watts. So my boiler runs at maximum as a 5kilowatt heater. Bloomin' eck! Thats nearly 7 horsepower of heat!


Id like to try making a more compact version of the coil, possibly in a folded configuration, with 12 feet of tube arranged in figure 8s going side to side and another 12 foot layer above it going front to back. Im a bit more experienced at how to bend coils now, i reckon i can do a much neater, more compact job than i did with this, my first coil.
Seeing as the current test article will run the big triple slowly or the stuart 10 very fast on one burner and a large tank, even with half the coil effectively out of the flames, i reckon its worth a try to see if i can get the whole length heated by one 2.5kW burner. It would also be able to arrange things so the water flows in at the top, and steam out the bottom(counterflow) which isnt really possible on the current single layer design.


If i can make a boiler with 24 feet of kunifer 3/16 pipe that fits into, say, a 4.5 inch diameter steel pot with burner at the bottom and exhaust at the top that would be cool.
Cause then i can make another one. With 1/4 stainless pipe, and its own 2.5 kw burner. And then connect them in series, so id have separate fine control over the main boiler(kunifer) and superheater (steel) sections, which seems like it would be super useful. I have some ss tubing that would be perfect.
And 40 odd feet of pipe would be an interesting experiment, although id need to man up the pumps, which brings us to--->


Ive also upped the pump motor to a mfa como 100:1 unit, its really good and powerful. No more stalling pumps! Im building a duplex pump arrangement with opposed rams on a common driving crank to try and get a more even flow, and also to double the flow rate possible with this motor/gearbox combination.


I am beginning to wear out components with the constant testing, taking apart, modifying, reassembly and re testing, i dont think this particular coil is going to ever get on the water. It will serve as a testbed, at any rate.


Ive also experimented with extra water pumps driven off the engines output shaft. Sucked lots of power out of the engine, and made it slow and surgey. Too much feedback in the system as well as extra load. Terrible idea. I may fit a magnet and tach to the flywheel, and use the resulting control signal (after some processing) to control a smaller 'acceleration pump' powered by another electric motor. Could also wire in a spinning balls speed governor with the lever arm connected to a control potentiometer controlling the same pump to try and control the surging. I have a suitable governor, reckon its worth a try!


Also i reattached the forced lubrication system to be big three cylinder engine. Theres a dashpot, a pump driven from the output shaft (geared down) and some check valves and a bypass valve involved. There is now over six feet of copper 5/32 pipe connecting everything together in the whole system..


Overall, its now resembling a 2 foot by 6 inch by 8 inch miniature oil refinery.
Or possibly a rocket motor.


Wahey!


Cheers


Rich